Deformation of a 50 × 60 km trilateration network that spans the epicenter of the 1992 Landers earthquake(Ms = 7.5) was measured by seven surveys over the 19 years preceding the earthquake. Three moderate earthquakes (1979 Homestead Valley, Ms = 5.6; 1986 North Palm Springs, Ms = 6.0; and 1992 Joshua Tree, Ms = 6.1) occurred within the network during those 19 years. Here we use geodetic and seismic data to construct a dislocation model for each of the three moderate earthquakes. Coseismic changes due to these three moderate earthquakes as predicted by the dislocation models are then removed from the trilateration data. The residual geodetic changes appear to be uniform in time. We take those changes to represent secular strain accumulation. This strain accumulation clearly shows right‐lateral shear across the San Andreas fault but also suggests a northwest‐southeast extension northeast of the eastern end of the “Big Bend” of the San Andreas fault. The Landers earthquake ruptured along a north‐northwest trend across this region of northwest‐southeast extension.
Selected herbicides, atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) metabolites, and NO−3 were examined in near-surface unconsolidated and bedrock aquifers in the midcontinental USA to study the hydrogeologic, spatial, and seasonal distribution of these contaminants. Groundwater samples were collected from 303 wells during the spring and late summer of 1991. At least one herbicide or atrazine metabolite was detected in 24% of the samples collected for herbicide analysis (reporting limit 0.05 µg/L). No herbicide concentration exceeded the USEPA's maximum contaminant level (MCL) or health advisory level. The most frequently detected compound was the at razine metabolite deethylatrazine [2-amino-4-chloro-6-(isopropylamino)-s-triazine] followed by atrazine, deisopropylatrazine [2-amino-4-chloro-6-(ethylamino)-s-triazine], prometon (2,4-bis(isopropylamino)-6-methyoxy-s-triazine), metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1methylethyl)acetamide], alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide], metribuzin [4-amino-6-(tert-butyl)-3-methylthio-as-triazine-5(4H)-one], simazine [2-chloro-4,6-bis(ethylamino)-s-triazine], and cyanazine [2-[[4-chloro-6-(ethylamino)-1,3,5-triazin-2-yl]amino]-2-methylpropionitrile]. Nitrite plus nitrate, as nitrogen (N), exceeding 3.0 mg/L (excess NO−3), was found in 29% of the samples, and 6% had −3exceeding the MCL of 10 mg/L. Ammonium as N was detected in excess of 0.01 mg/L in 78% of the samples. A nonlinear increase in the frequency of atrazine detection occurred with decreases in reporting limit. The frequency of atrazine residue detection (atrazine + deethylatrazine + deisopropylatrazine) was 25% greater than for atrazine alone. Herbicide detections and excess NO−3 were notably lacking in the eastern part of the study region where it was estimated that herbicide and fertilizer use were among the largest in the region. Prometon, the second most frequently detected herbicide, was associated with non-agricultural land use. Herbicide and excess NO−3 were more frequent in unconsolidated aquifers than in bedrock aquifers. Aquifer depth, as direct measurement of proximity to recharge sources, was inversely related to frequency of herbicide detection and excess NO−3.
","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Environmental Quality","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisher":"American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America","publisherLocation":"Madison, WI","doi":"10.2134/jeq1993.00472425002200040002x","usgsCitation":"Burkart, M.R., and Kolpin, D.W., 1993, Hydrologic and land-use factors associated with herbicides and nitrate in near-surface aquifers: Journal of Environmental Quality, v. 22, no. 4, p. 646-656, https://doi.org/10.2134/jeq1993.00472425002200040002x.","productDescription":"11 p.","startPage":"646","endPage":"656","numberOfPages":"11","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":351,"text":"Iowa Water Science Center","active":true,"usgs":true}],"links":[{"id":318847,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United 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\"}}]}","volume":"22","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"56e7e0b9e4b0f59b85d6aa75","contributors":{"authors":[{"text":"Burkart, Michael R.","contributorId":75512,"corporation":false,"usgs":true,"family":"Burkart","given":"Michael","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":622683,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kolpin, Dana W. 0000-0002-3529-6505 dwkolpin@usgs.gov","orcid":"https://orcid.org/0000-0002-3529-6505","contributorId":1239,"corporation":false,"usgs":true,"family":"Kolpin","given":"Dana","email":"dwkolpin@usgs.gov","middleInitial":"W.","affiliations":[{"id":351,"text":"Iowa Water Science Center","active":true,"usgs":true}],"preferred":true,"id":622684,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70230760,"text":"70230760 - 1993 - Klamath Falls earthquakes, September 20, 1993 — Including the strongest quake ever measured in Oregon","interactions":[],"lastModifiedDate":"2022-04-25T15:28:01.877244","indexId":"70230760","displayToPublicDate":"1993-11-01T10:14:34","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2956,"text":"Oregon Geology","active":true,"publicationSubtype":{"id":10}},"title":"Klamath Falls earthquakes, September 20, 1993 — Including the strongest quake ever measured in Oregon","docAbstract":"Earthquakes struck the Klamath Falls area on Monday night, September 20, 1993, resulting in two deaths and extensive damage. The quakes were felt as far away as Coos Bay to the west, Eugene to the north, Lakeview to the east, and Chico, California, to the south.
A foreshock recorded at 8:16 p.m. had a Richter magnitude of 3.9. The first of two main shocks, measuring 5.9 on the Richter scale, rumbled through Klamath Falls at 8:28 p.m. Following 16 smaller jolts with magnitudes between 2.2 and 3.8, the largest quake struck at 10:45 p.m. This earthquake, measuring 6.0 on the Richter scale, is the largest to hit Oregon since the 1873 Port Orford/Crescent City earthquake (Jacobson, 1986). Oregon has been shaken by stronger quakes, but those quakes originated beneath the Pacific Ocean west of Port Orford.
","language":"English","publisher":"Oregon Department of Geology and Mineral Industries","usgsCitation":"Wiley, T.J., Sherrod, D.R., Keefer, D.K., Qamar, A., Schuster, R.L., Dewey, J.W., Mabey, M.A., Black, G.L., and Wells, R.E., 1993, Klamath Falls earthquakes, September 20, 1993 — Including the strongest quake ever measured in Oregon: Oregon Geology, v. 55, no. 6, p. 127-134.","productDescription":"8 p.","startPage":"127","endPage":"134","costCenters":[{"id":300,"text":"Geologic Hazards Science Center","active":true,"usgs":true},{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true},{"id":617,"text":"Volcano Science Center","active":true,"usgs":true}],"links":[{"id":399587,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":399586,"rank":1,"type":{"id":15,"text":"Index Page"},"url":"https://www.oregongeology.org/pubs/pubsearch.htm"}],"country":"United States","state":"California, Nevada, Oregon, Washington","city":"Klamath Falls","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -124.18945312500001,\n 39.977120098439634\n ],\n [\n -118.21289062499999,\n 39.977120098439634\n ],\n [\n -118.21289062499999,\n 47.040182144806664\n ],\n [\n -124.18945312500001,\n 47.040182144806664\n ],\n [\n -124.18945312500001,\n 39.977120098439634\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"55","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","contributors":{"authors":[{"text":"Wiley, T. J.","contributorId":92226,"corporation":false,"usgs":false,"family":"Wiley","given":"T.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":841299,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Sherrod, David R. 0000-0001-9460-0434 dsherrod@usgs.gov","orcid":"https://orcid.org/0000-0001-9460-0434","contributorId":527,"corporation":false,"usgs":true,"family":"Sherrod","given":"David","email":"dsherrod@usgs.gov","middleInitial":"R.","affiliations":[{"id":617,"text":"Volcano Science Center","active":true,"usgs":true}],"preferred":true,"id":841300,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Keefer, David K.","contributorId":77930,"corporation":false,"usgs":true,"family":"Keefer","given":"David","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":841301,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Qamar, Anthony","contributorId":290580,"corporation":false,"usgs":false,"family":"Qamar","given":"Anthony","affiliations":[],"preferred":false,"id":841302,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Schuster, Robert L.","contributorId":19162,"corporation":false,"usgs":true,"family":"Schuster","given":"Robert","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":841303,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Dewey, James W. 0000-0001-8838-2450 jdewey@usgs.gov","orcid":"https://orcid.org/0000-0001-8838-2450","contributorId":5819,"corporation":false,"usgs":true,"family":"Dewey","given":"James","email":"jdewey@usgs.gov","middleInitial":"W.","affiliations":[{"id":300,"text":"Geologic Hazards Science Center","active":true,"usgs":true}],"preferred":true,"id":841304,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Mabey, Matthew A.","contributorId":290581,"corporation":false,"usgs":false,"family":"Mabey","given":"Matthew","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":841305,"contributorType":{"id":1,"text":"Authors"},"rank":7},{"text":"Black, Gerald L.","contributorId":290582,"corporation":false,"usgs":false,"family":"Black","given":"Gerald","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":841306,"contributorType":{"id":1,"text":"Authors"},"rank":8},{"text":"Wells, Ray E. 0000-0002-7796-0160 rwells@usgs.gov","orcid":"https://orcid.org/0000-0002-7796-0160","contributorId":149772,"corporation":false,"usgs":true,"family":"Wells","given":"Ray","email":"rwells@usgs.gov","middleInitial":"E.","affiliations":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"preferred":true,"id":841307,"contributorType":{"id":1,"text":"Authors"},"rank":9}]}} ,{"id":70210407,"text":"70210407 - 1993 - The Manson Impact Structure: 40Ar/39Ar age and its distal impact ejecta in the Pierre Shale in southeastern South Dakota","interactions":[],"lastModifiedDate":"2025-09-15T17:00:55.837453","indexId":"70210407","displayToPublicDate":"1993-10-29T13:16:55","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3338,"text":"Science","active":true,"publicationSubtype":{"id":10}},"title":"The Manson Impact Structure: 40Ar/39Ar age and its distal impact ejecta in the Pierre Shale in southeastern South Dakota","docAbstract":"The 40Ar/39Ar ages of a sanidine clast from a melt-matrix breccia of the Manson, Iowa, impact structure (MIS) indicate that the MIS formed 73.8 ± 0.3 million years ago (Ma) and is not coincident with the Cretaceous-Tertiary boundary (64.43 ± 0.05 Ma). The MIS sanidine is 9 million years older than 40Ar/39Ar age spectra of MIS shock-metamorphosed microcline and melt-matrix breccia interpreted earlier to be 64 to 65 Ma. Grains of shock-metamorphosed quartz, feldspar, and zircon were found in the Crow Creek Member (upper Campanian) at a biostratigraphic level constrained by radiometric ages in the Pierre Shale of South Dakota that are consistent with the 40Ar/39Ar age of 73.8 ± 0.3 Ma for MIS reported herein.
","language":"English","publisher":"American Association for the Advancement of Science","doi":"10.1126/science.262.5134.729","usgsCitation":"Izett, G., Cobban, W.A., Obradovich, J., and Kunk, M.J., 1993, The Manson Impact Structure: 40Ar/39Ar age and its distal impact ejecta in the Pierre Shale in southeastern South Dakota: Science, v. 262, no. 5134, p. 729-732, https://doi.org/10.1126/science.262.5134.729.","productDescription":"4 p.","startPage":"729","endPage":"732","costCenters":[{"id":243,"text":"Eastern Geology and Paleoclimate Science Center","active":true,"usgs":true}],"links":[{"id":495735,"rank":2,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://zenodo.org/record/1231026","text":"External Repository"},{"id":375252,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"South 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A.","contributorId":118300,"corporation":false,"usgs":true,"family":"Izett","given":"G. A.","affiliations":[],"preferred":false,"id":790223,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Cobban, W. A.","contributorId":21577,"corporation":false,"usgs":true,"family":"Cobban","given":"W.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":790224,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Obradovich, J.","contributorId":53953,"corporation":false,"usgs":true,"family":"Obradovich","given":"J.","email":"","affiliations":[],"preferred":false,"id":790225,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Kunk, Michael J. 0000-0003-4424-7825 mkunk@usgs.gov","orcid":"https://orcid.org/0000-0003-4424-7825","contributorId":200968,"corporation":false,"usgs":true,"family":"Kunk","given":"Michael","email":"mkunk@usgs.gov","middleInitial":"J.","affiliations":[{"id":40020,"text":"Florence Bascom Geoscience Center","active":true,"usgs":true},{"id":243,"text":"Eastern Geology and Paleoclimate Science Center","active":true,"usgs":true}],"preferred":true,"id":790226,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70200704,"text":"70200704 - 1993 - Economics and the national oil and gas assessment: The case of onshore northern Alaska","interactions":[],"lastModifiedDate":"2023-01-23T18:02:25.657144","indexId":"70200704","displayToPublicDate":"1993-10-16T13:49:30","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":701,"text":"American Association of Petroleum Geologists Bulletin","active":true,"publicationSubtype":{"id":10}},"title":"Economics and the national oil and gas assessment: The case of onshore northern Alaska","docAbstract":"The National Oil and Gas Assessment of undiscovered recoverable conventional oil and gas resources assigned nearly 36% of the undiscovered U.S. onshore oil resources and 28% of the commercially developable undiscovered oil resources to onshore northern Alaska. Economic screening models were applied to the geologic play assessment to estimate the commercially developable resources. This paper presents the geologic and economic assessment methodology and results; it also focuses on the robustness of estimates of the commercially developable onshore resources to changes in economic assumptions.
With the economic assumptions used in the national assessment, about 60% or 6.49 billion bbl of oil of the recoverable undiscovered resources of 10.76 billion bbl of oil assessed in fields larger than 1 million bbl of oil are estimated to be commercially developable. Changes in facilities costs induced the most significant cost-related response in the commercially developable resource estimates. Price increases or cost reductions that reduce the minimum commercially developable field size to 250 million bbl from the base case size of 380 million bbl added 1 billion bbl of oil to the commercially developable resources. If, through facilities sharing or satellite-field development, the minimum commercial field size is reduced to just below 100 million bbl, estimated developable oil woul increase to 9.17 billion bbl of oil or more than 85% of the assessed recoverable oil in onshore plays.
","language":"English","publisher":"American Association of Petroleum Geologists","doi":"10.1306/BDFF8C72-1718-11D7-8645000102C1865D","usgsCitation":"Attanasi, E., Bird, K.J., and Mast, R.F., 1993, Economics and the national oil and gas assessment: The case of onshore northern Alaska: American Association of Petroleum Geologists Bulletin, v. 77, no. 3, p. 491-504, https://doi.org/10.1306/BDFF8C72-1718-11D7-8645000102C1865D.","productDescription":"14 p.","startPage":"491","endPage":"504","costCenters":[{"id":241,"text":"Eastern Energy Resources Science Center","active":true,"usgs":true},{"id":255,"text":"Energy Resources Program","active":true,"usgs":true}],"links":[{"id":358906,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Alaska","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -145.48080420268553,\n 72.71391257340173\n ],\n [\n -170.8889081934487,\n 72.71391257340173\n ],\n [\n -170.8889081934487,\n 66.46646934602157\n ],\n [\n -145.48080420268553,\n 66.46646934602157\n ],\n [\n -145.48080420268553,\n 72.71391257340173\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"77","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5c111a1ce4b034bf6a8194de","contributors":{"authors":[{"text":"Attanasi, Emil D. 0000-0001-6845-7160 attanasi@usgs.gov","orcid":"https://orcid.org/0000-0001-6845-7160","contributorId":198728,"corporation":false,"usgs":true,"family":"Attanasi","given":"Emil D.","email":"attanasi@usgs.gov","affiliations":[{"id":241,"text":"Eastern Energy Resources Science Center","active":true,"usgs":true}],"preferred":true,"id":750176,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Bird, Kenneth J. kbird@usgs.gov","contributorId":1015,"corporation":false,"usgs":true,"family":"Bird","given":"Kenneth","email":"kbird@usgs.gov","middleInitial":"J.","affiliations":[{"id":255,"text":"Energy Resources Program","active":true,"usgs":true}],"preferred":true,"id":750177,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mast, R. F.","contributorId":210210,"corporation":false,"usgs":false,"family":"Mast","given":"R.","email":"","middleInitial":"F.","affiliations":[],"preferred":false,"id":750178,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70128749,"text":"70128749 - 1993 - The influence of mountain meteorology on precipitation chemistry at low and high elevations of the Colorado Front Range, USA","interactions":[],"lastModifiedDate":"2014-10-14T12:52:28","indexId":"70128749","displayToPublicDate":"1993-10-01T12:49:12","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":924,"text":"Atmospheric Environment","active":true,"publicationSubtype":{"id":10}},"title":"The influence of mountain meteorology on precipitation chemistry at low and high elevations of the Colorado Front Range, USA","docAbstract":"We explored the seasonal characteristics in wet deposition chemistry for two sites located at different elevations along the east slope of the Colorado Front Range in Rocky Mountain National Park. Seasonally separated precipitation was stratified into highly concentrated (high salt), dilute (low salt), or acid-dominated precipitation groups. These groups and unstratified precipitation data were related to mean easterly or westerly zonal winds to determine direction of local transport. Strong acid anion associations were also determined for the stratified and unstratified precipitation data sets. We found that strong acid anions, acidity, ammonium, and high salt concentrations originate to the east of Rocky Mountain National Park, and are transported via up-valley funneling winds or convective instability from differential heating of the mountains and the plains to the east. These influence the composition of precipitation at Beaver Meadows, the low elevation site, throughout the year, while their effect on precipitation at Loch Vale, the high elevation site, is felt most strongly during the summer. During the winter, Loch Vale precipitation is very dilute, and occurs in conjunction with westerly winds resulting from the southerly location of the jet stream.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Atmospheric Environment","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisher":"Pergamon Press","publisherLocation":"New York, NY","doi":"10.1016/0960-1686(93)90402-K","usgsCitation":"Denning, A.S., 1993, The influence of mountain meteorology on precipitation chemistry at low and high elevations of the Colorado Front Range, USA: Atmospheric Environment, v. 27, no. 15, p. 2337-2349, https://doi.org/10.1016/0960-1686(93)90402-K.","productDescription":"13 p.","startPage":"2337","endPage":"2349","numberOfPages":"13","costCenters":[],"links":[{"id":295294,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":295293,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/0960-1686(93)90402-K"}],"country":"United States","state":"Colorado","otherGeospatial":"Rocky Mountain National Park","volume":"27","issue":"15","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"543e3b32e4b0fd76af69cf38","contributors":{"authors":[{"text":"Denning, A. Scott","contributorId":70710,"corporation":false,"usgs":true,"family":"Denning","given":"A.","email":"","middleInitial":"Scott","affiliations":[],"preferred":false,"id":503198,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70113765,"text":"70113765 - 1993 - Analysis of urban regions using AVHRR thermal infrared data","interactions":[],"lastModifiedDate":"2014-06-20T14:13:00","indexId":"70113765","displayToPublicDate":"1993-08-24T14:05:55","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3018,"text":"Pecora 12 Symposium","active":true,"publicationSubtype":{"id":10}},"title":"Analysis of urban regions using AVHRR thermal infrared data","docAbstract":"Using 1-km AVHRR satellite data, relative temperature difference caused by conductivity and inertia were used to distinguish urban and non urban land covers. AVHRR data that were composited on a biweekly basis and distributed by the EROS Data Center in Sioux Falls, South Dakota, were used for the classification process. These composited images are based on the maximum normalized different vegetation index (NDVI) of each pixel during the 2-week period using channels 1 and 2. The resultant images are nearly cloud-free and reduce the need for extensive reclassification processing.
\nBecause of the physiographic differences between the Eastern and Western United States, the initial study was limited to the eastern half of the United States. In the East, the time of maximum difference between the urban surfaces and the vegetated non urban areas is the peak greenness period in late summer. A composite image of the Eastern United States for the 2-weel time period from August 30-Septmeber 16, 1991, was used for the extraction of the urban areas. Two channels of thermal data (channels 3 and 4) normalized for regional temperature differences and a composited NDVI image were classified using conventional image processing techniques. The results compare favorably with other large-scale urban area delineations.
","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Pecora 12 Symposium","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisher":"American Society for Photogrammetry and Remote Sensing","publisherLocation":"Bethesda, MD","usgsCitation":"Wright, B., 1993, Analysis of urban regions using AVHRR thermal infrared data: Pecora 12 Symposium, p. 568-568.","productDescription":"1 p.","startPage":"568","endPage":"568","numberOfPages":"1","costCenters":[],"links":[{"id":288989,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"53ae7629e4b0abf75cf2beb2","contributors":{"authors":[{"text":"Wright, Bruce","contributorId":89929,"corporation":false,"usgs":true,"family":"Wright","given":"Bruce","affiliations":[],"preferred":false,"id":495191,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70017396,"text":"70017396 - 1993 - Factors affecting the geochemistry of a thick, subbituminous coal bed in the Powder River Basin: Volcanic, detrital, and peat-forming processes","interactions":[],"lastModifiedDate":"2025-03-13T16:35:55.671481","indexId":"70017396","displayToPublicDate":"1993-08-06T00:00:00","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2958,"text":"Organic Geochemistry","active":true,"publicationSubtype":{"id":10}},"title":"Factors affecting the geochemistry of a thick, subbituminous coal bed in the Powder River Basin: Volcanic, detrital, and peat-forming processes","docAbstract":"The inorganic geochemistry and mineralogy of three cores from the Anderson-Dietz 1 coal bed, a 15.2-m-thick subbituminous coal bed in the Tongue River Member (Paleocene) of the Fort Union Formation, were examined (1) to determine if the cores could be correlated by geochemical composition alone over a total distance of 2 km and (2) to identify the major factors that influenced the geochemistry of the coal bed. Chemical data (46 elements on a coal-ash basis) for 81 coal samples and 4 carbonaceous rock samples, with most samples representing a 0.6-m-thick (2-ft) interval of core, were grouped into compositional clusters by means of cluster analysis. Seven major clusters were produced; two of these clusters can be used to correlate the coal bed throughout the study area. Data from scanning electron and optical microscope analyses indicate that several factors influenced the geochemistry of the Anderson-Dietz 1 coal bed. The majority of mineral grains in the coal bed are interpreted to be detrital (water borne); evidence includes the presence of rounded to subrounded quartz grains having two-phase, aqueous fluid inclusions characteristic of hydrothermal or low-to-moderate grade metamorphic quartz. These quartz grains are found throughout the coal bed but are most abundant in samples from the midpart of the bed, which was influenced by detrital input associated with the deposition of the clastic rocks that form the split between the Anderson and Dietz 1 coal beds 900 m to the east of the study area. In addition to the detrital minerals mentioned above, volcanic ash that was fluvially transported to the sites of peat deposition or possibly deposited as air-fall volcanic ash also affected the geochemistry of the coal bed. For example, crandallite(?), a mineral reported to form as an alteration product of volcanic ash, is found in seven samples from the coal bed. The presence of quartz grains containing silicate-melt inclusions in eight samples from the coal bed.provides further support for a volcanic ash component. Other factors that probably affected the geochemistry of the coal bed include (1) detrital input associated with the deposition of the roof rocks of the coal bed, (2) peat-forming processes and plant material, and (3) epigenetic ground-water flow.
","language":"English","publisher":"Elsevier","doi":"10.1016/0146-6380(93)90067-L","usgsCitation":"Crowley, S.S., Ruppert, L., Belkin, H.E., Stanton, R., and Moore, T., 1993, Factors affecting the geochemistry of a thick, subbituminous coal bed in the Powder River Basin: Volcanic, detrital, and peat-forming processes: Organic Geochemistry, v. 20, no. 6, p. 843-853, https://doi.org/10.1016/0146-6380(93)90067-L.","productDescription":"11 p.","startPage":"843","endPage":"853","costCenters":[],"links":[{"id":228973,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Montana, Wyoming","otherGeospatial":"Powder River basin","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -107.18328120738457,\n 45.184712018144495\n ],\n [\n -107.18328120738457,\n 44.80397957213873\n ],\n [\n -106.13642425027534,\n 44.80397957213873\n ],\n [\n -106.13642425027534,\n 45.184712018144495\n ],\n [\n -107.18328120738457,\n 45.184712018144495\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"20","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a0eabe4b0c8380cd53577","contributors":{"authors":[{"text":"Crowley, Sharon S.","contributorId":78325,"corporation":false,"usgs":true,"family":"Crowley","given":"Sharon","email":"","middleInitial":"S.","affiliations":[],"preferred":false,"id":376325,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ruppert, Leslie F. 0000-0002-7453-1061","orcid":"https://orcid.org/0000-0002-7453-1061","contributorId":118763,"corporation":false,"usgs":true,"family":"Ruppert","given":"Leslie F.","affiliations":[],"preferred":false,"id":376326,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Belkin, Harvey E. 0000-0001-7879-6529 hbelkin@usgs.gov","orcid":"https://orcid.org/0000-0001-7879-6529","contributorId":581,"corporation":false,"usgs":true,"family":"Belkin","given":"Harvey","email":"hbelkin@usgs.gov","middleInitial":"E.","affiliations":[{"id":241,"text":"Eastern Energy Resources Science Center","active":true,"usgs":true}],"preferred":true,"id":376324,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Stanton, R.W.","contributorId":19164,"corporation":false,"usgs":true,"family":"Stanton","given":"R.W.","email":"","affiliations":[],"preferred":false,"id":376323,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Moore, T.A.","contributorId":91101,"corporation":false,"usgs":true,"family":"Moore","given":"T.A.","email":"","affiliations":[],"preferred":false,"id":376327,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70017427,"text":"70017427 - 1993 - Rock-eval pyrolysis and vitrinite reflectance trends in the Cleveland Shale Member of the Ohio Shale, eastern Kentucky","interactions":[],"lastModifiedDate":"2025-03-13T16:10:58.715426","indexId":"70017427","displayToPublicDate":"1993-08-06T00:00:00","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2958,"text":"Organic Geochemistry","active":true,"publicationSubtype":{"id":10}},"title":"Rock-eval pyrolysis and vitrinite reflectance trends in the Cleveland Shale Member of the Ohio Shale, eastern Kentucky","docAbstract":"Within eastern Kentucky, organic petrographic and geochemical data indicate a southeastwards increase in maturation of the Cleveland Shale Member of the Ohio Shale (Devonian-Mississippian). Reflectance levels of dispersed organic material in the Cleveland Shale increase from 0.5% in the outcrop belt in central Kentucky, to slightly over 1.0% in Pike County, eastern Kentucky. A decrease in fluorescence intensity of liptinitic components, such as Tasmanites, accompanies this reflectance increase, as does a shift in fluorescence color of the alginite towards the red. In the highest rank areas, fluorescence is almost absent. Groundmass fluorescence is observed also, and follows trends similar to those shown by the alginite.
Kerogen in the Cleveland Shale is primarily Type II, as indicated by petrographic observations and Rock-Eval data. Total organic carbon contents of this shale decrease from over 12% in the outcrop belt, to less than 2% in the eastern-most part of the study area. Source rock potential ranges from good to very good, with the highest potentials occurring in the outcrop belt. Tmax values for this unit increase from under 430°C in the outcrop belt to over 450°C in the southeast, confirming the increase in maturation trends indicated by vitrinite reflectance data.
Both petrographic and geochemical maturation parameters place the Cleveland Shale of eastern Kentucky within the oil window. Comparison with maturation data for Pennsylvanian-age coals upsection suggests that maturation indices are retarded, or suppressed, in the Devonian shales. The level of maturation indicated for the Cleveland may be problematical considering that the Ohio Shale is a major gas-producer in this area.
","language":"English","publisher":"Elsevier","doi":"10.1016/0146-6380(93)90058-J","usgsCitation":"Rimmer, S.M., Cantrell, D., and Gooding, P., 1993, Rock-eval pyrolysis and vitrinite reflectance trends in the Cleveland Shale Member of the Ohio Shale, eastern Kentucky: Organic Geochemistry, v. 20, no. 6, p. 735-745, https://doi.org/10.1016/0146-6380(93)90058-J.","productDescription":"11 p.","startPage":"735","endPage":"745","costCenters":[],"links":[{"id":228750,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Kentucky","otherGeospatial":"eastern Kentucky","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -84.45589569619659,\n 39.05613296663111\n ],\n [\n -84.45589569619659,\n 36.585292266153374\n ],\n [\n -83.17531644388323,\n 36.6085497808004\n ],\n [\n -82.06585531164238,\n 37.415766136634026\n ],\n [\n -82.42075192240021,\n 38.03883851836075\n ],\n [\n -82.89289019863669,\n 38.74868039343522\n ],\n [\n -83.74465790803904,\n 38.81618867311012\n ],\n [\n -84.45589569619659,\n 39.05613296663111\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"20","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505aae07e4b0c8380cd86ff8","contributors":{"authors":[{"text":"Rimmer, Susan M.","contributorId":197806,"corporation":false,"usgs":false,"family":"Rimmer","given":"Susan","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":376423,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Cantrell, D.J.","contributorId":8630,"corporation":false,"usgs":true,"family":"Cantrell","given":"D.J.","email":"","affiliations":[],"preferred":false,"id":376422,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Gooding, P.J.","contributorId":6608,"corporation":false,"usgs":true,"family":"Gooding","given":"P.J.","email":"","affiliations":[],"preferred":false,"id":376421,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70127918,"text":"70127918 - 1993 - Monitoring and research at Walnut Creek National Wildlife Refuge","interactions":[],"lastModifiedDate":"2014-10-02T13:55:52","indexId":"70127918","displayToPublicDate":"1993-08-01T13:41:11","publicationYear":"1993","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":9,"text":"Other Report"},"title":"Monitoring and research at Walnut Creek National Wildlife Refuge","docAbstract":"Walnut Creek National Wildlife Refuge-Prairie Learning Center (Walnut Creek or the Refuge) is one of the newest additions to the National Wildlife Refuge System, which consists of over 480 units throughout the United States operated by the U.S. Department of the Interior, Fish and Wildlife Service (the Service). Located about 20 miles east of Des Moines, Iowa, the Refuge has an approved acquisition boundary containing 8,654 acres (Figure 1). Acquisition is from willing sellers only, and to date the Service has purchased approximately 5,000 acres. The acquisition boundary encompasses about 43% of the watershed of Walnut Creek, which bisects the Refuge and drains into the Des Moines River to the southeast. Approximately 25%-30% of the Walnut Creek watershed is downstream of the Refuge.
\nAs authorized by Congress in 1990, the purposes of the Refuge are to (U.S. Fish and Wildlife Service 1992):
\n• restore native tallgrass pairie, wetland, and woodland habitats for breeding and migratory waterfowl and resident wildlife;
\n• serve as a major environmental education center providing opportunities for study;
\n• provide outdoor recreation benefits to the public; and
\n• provide assistance to local landowners to improve their lands for wildlife habitat.
\nTo implement these purposes authorized by Congress, the Refuge has established the goal of recreating as nearly as possible the natural communities that existed at the time of settlement by Euro-Americans (circa 1840). Current land use is largely agricultural, including 69% cropland, 17% grazed pasture, and 7.5% grassland (dominantly brome) enrolled in the Conservation Reserve Program). About 1,395 acres of relict native communities also exist on the Refuge, including prairie (725 acres), oak savanna and woodland (450 acres), and riparian or wetland areas (220 acres). Some of these relicts are highly restorable; others contain only a few prairie plants in a matrix of brome and will be more difficult to restore. When the process of restoration (management and enhancement of existing remnant communities) and reconstruction (reestablishment of native communities on agricultural sites) is completed, it is anticipated that the Refuge will consist of approximately 5,900 acres of prairie, 2,000 acres of oak savanna or woodland, and 750 acres of wetland and riparian communities. Ecological restoration and reconstruction at this scale in the tallgrass prairie ecosystem is unprecedented in the United States.
","language":"English","publisher":"Fish and Wildlife Service","publisherLocation":"Fort Collins, CO","usgsCitation":"Roelle, J.E., and Hamilton, D.B., 1993, Monitoring and research at Walnut Creek National Wildlife Refuge, 34 p.","productDescription":"34 p.","numberOfPages":"34","costCenters":[],"links":[{"id":294861,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"542e6970e4b092f17df5a957","contributors":{"authors":[{"text":"Roelle, James E. roelleb@usgs.gov","contributorId":2330,"corporation":false,"usgs":true,"family":"Roelle","given":"James","email":"roelleb@usgs.gov","middleInitial":"E.","affiliations":[{"id":291,"text":"Fort Collins Science Center","active":true,"usgs":true}],"preferred":true,"id":502683,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hamilton, David B. hamiltond@usgs.gov","contributorId":193,"corporation":false,"usgs":true,"family":"Hamilton","given":"David","email":"hamiltond@usgs.gov","middleInitial":"B.","affiliations":[],"preferred":true,"id":502682,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70210581,"text":"70210581 - 1993 - Mid‐Cretaceous extensional tectonics of the Yukon‐Tanana Terrane, Trans‐Alaska Crustal Transect (TACT), east‐central Alaska","interactions":[],"lastModifiedDate":"2020-06-10T18:08:54.019251","indexId":"70210581","displayToPublicDate":"1993-06-10T12:56:36","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3524,"text":"Tectonics","active":true,"publicationSubtype":{"id":10}},"title":"Mid‐Cretaceous extensional tectonics of the Yukon‐Tanana Terrane, Trans‐Alaska Crustal Transect (TACT), east‐central Alaska","docAbstract":"Mid‐Cretaceous crustal extension played a fundamental role in the structural evolution of the Yukon‐Tanana terrane (YTT) in the northern Cordilleran interior. In the central portion of the YTT northwest of Delta Junction, Alaska, a mylonitic shear zone juxtaposes greenschist facies rocks in the upper plate against middle to upper amphibolite facies metamorphic rocks in the lower plate, a juxtaposition suggesting elimination of as much as 10 km of crustal section. The mylonites form a partial sheath enveloping a domal footwall structure and kinematic analysis of the mylonite zone yields a uniform transport direction of hanging wall to ESE. These relations suggest analogies to the metamorphic core complexes of the southern Cordillera. However, the YTT structures are entirely ductile, suggesting either a relatively deep erosional level or relatively high geothermal gradients during extension. In the study area remnants of an older preextensional thrusting event are preserved at the highest structural levels at the base of the Seventymile terrane and the leading edge of YTT in the Wickersham terrane. However, most areas display a regional, subhorizontal fabric that is superimposed on older fabrics, and in the study area this latest fabric is subparallel to the mylonitic sheath of the apparent extensional structure. Thus the conventional viewpoint that this latest fabric is related to thrusting needs to be reevaluated and this fabric may be entirely extensional in origin. Further evidence for extension is provided by clear similarities between YTT and characteristic features of other extensional terranes. Thus we suggest that the YTT is a deeply eroded view of highly extended continental crust. The tectonic mechanism for the extensional event and the magnitude of the extension is uncertain because of complications in regional timing relationships and in alternative interpretations of the reconstruction of the crustal section. Three end‐member models based on analogies with Neogene extensional systems are presented as working models to accommodate the alternative interpretations: (1) a Jurassic collision and Cretaceous extension model based on comparisons with the Neogene history of the Mediterranean region; (2) an Early to mid‐Cretaceous syncollisional model analogous to the Carpathian Mountains of eastern Europe; and (3) a syncollisional plateau uplift model with extension driven by gravity spreading.
","language":"English","publisher":"Wiley","doi":"10.1029/92TC00860","usgsCitation":"Pavlis, T.L., Sisson, V., Foster, H.L., Nokleberg, W.J., and Plafker, G., 1993, Mid‐Cretaceous extensional tectonics of the Yukon‐Tanana Terrane, Trans‐Alaska Crustal Transect (TACT), east‐central Alaska: Tectonics, v. 12, no. 1, p. 103-122, https://doi.org/10.1029/92TC00860.","productDescription":"20 p.","startPage":"103","endPage":"122","costCenters":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"links":[{"id":375498,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Alaska","otherGeospatial":"Eastern Central Alaska","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -151.78710937499997,\n 64.33990785750463\n ],\n [\n -141.0205078125,\n 64.33990785750463\n ],\n [\n -141.0205078125,\n 67.25505812564363\n ],\n [\n -151.78710937499997,\n 67.25505812564363\n ],\n [\n -151.78710937499997,\n 64.33990785750463\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"12","issue":"1","noUsgsAuthors":false,"publicationDate":"2010-07-26","publicationStatus":"PW","contributors":{"authors":[{"text":"Pavlis, Terry L.","contributorId":52682,"corporation":false,"usgs":true,"family":"Pavlis","given":"Terry","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":790672,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Sisson, V.B.","contributorId":101104,"corporation":false,"usgs":false,"family":"Sisson","given":"V.B.","email":"","affiliations":[],"preferred":false,"id":790673,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Foster, Helen L.","contributorId":56195,"corporation":false,"usgs":true,"family":"Foster","given":"Helen","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":790674,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Nokleberg, Warren J. 0000-0002-1574-8869 wnokleberg@usgs.gov","orcid":"https://orcid.org/0000-0002-1574-8869","contributorId":2077,"corporation":false,"usgs":true,"family":"Nokleberg","given":"Warren","email":"wnokleberg@usgs.gov","middleInitial":"J.","affiliations":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"preferred":true,"id":790675,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Plafker, George","contributorId":3920,"corporation":false,"usgs":false,"family":"Plafker","given":"George","email":"","affiliations":[],"preferred":false,"id":790676,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":5222834,"text":"5222834 - 1993 - Avian communities in riparian forests of different widths in Maryland and Delaware","interactions":[],"lastModifiedDate":"2026-04-27T17:27:19.927957","indexId":"5222834","displayToPublicDate":"1993-06-01T00:00:00","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3750,"text":"Wetlands","onlineIssn":"1943-6246","printIssn":"0277-5212","active":true,"publicationSubtype":{"id":10}},"title":"Avian communities in riparian forests of different widths in Maryland and Delaware","docAbstract":"In agricultural landscapes, much of the remaining forest is in linear tracts along streams. These riparian forests provide habitat for forest birds, but their use by forest interior birds may depend on forest width. We conducted point-count surveys of birds in riparian forests on the Eastern shore of Maryland and Delaware to assess whether the presence of any species was dependent on corridor width. We surveyed 117 corridors that ranged from 25- to 800-m wide. Several area-sensitive neotropical migrants were encountered more frequently in wider riparian forests, and probabilities of occurrence increased most rapidly between 25 and 100 m. Based on these surveys, we recommend that riparian forests be at least 100-m wide to provide some nesting habitat for area-sensitive species. Wider riparian forests would be preferable and should be preserved.
","language":"English","publisher":"Springer Nature","doi":"10.1007/BF03160874","usgsCitation":"Keller, C., Robbins, C., and Hatfield, J., 1993, Avian communities in riparian forests of different widths in Maryland and Delaware: Wetlands, v. 13, no. 2, p. 137-144, https://doi.org/10.1007/BF03160874.","productDescription":"8 p.","startPage":"137","endPage":"144","costCenters":[{"id":531,"text":"Patuxent Wildlife Research Center","active":true,"usgs":true}],"links":[{"id":199529,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Delaware, Maryland","otherGeospatial":"eastern shore","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -75.83714544806597,\n 39.790800560501\n ],\n [\n -75.83714544806597,\n 37.04504078682838\n ],\n [\n -74.82805814280428,\n 37.04504078682838\n ],\n [\n -74.82805814280428,\n 39.790800560501\n ],\n [\n -75.83714544806597,\n 39.790800560501\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"13","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4a82e4b07f02db64afb5","contributors":{"authors":[{"text":"Keller, C.M.E.","contributorId":28332,"corporation":false,"usgs":true,"family":"Keller","given":"C.M.E.","email":"","affiliations":[],"preferred":false,"id":337262,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Robbins, C.S.","contributorId":53907,"corporation":false,"usgs":true,"family":"Robbins","given":"C.S.","email":"","affiliations":[],"preferred":false,"id":337264,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Hatfield, Jeff S.","contributorId":41372,"corporation":false,"usgs":true,"family":"Hatfield","given":"Jeff S.","affiliations":[],"preferred":false,"id":337263,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70243548,"text":"70243548 - 1993 - Drilling successful from ROV Ventana","interactions":[],"lastModifiedDate":"2023-05-11T14:08:49.473306","indexId":"70243548","displayToPublicDate":"1993-05-04T08:35:06","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":7458,"text":"Eos Science News","active":true,"publicationSubtype":{"id":10}},"title":"Drilling successful from ROV Ventana","docAbstract":"Cores of granite and deformed sediment from the walls of Monterey Canyon were successfully recovered from December 30 to 31, 1992, by Monterey Bay Aquarium Research Institute's (MBARI) Remotely Operated Vehicle (ROV) Ventana using a small-diameter, double-barrel drill with a diamond bit. This HSTR (Holloway-Stakes-Tengdin-Rajcula) drill was developed to drill cores horizontally from sulfide/sulfate walls of active black smokers. The drill was first successfully used by the submersible Alvin in October 1991 to drill into massive sulfide chimneys, on the Juan de Fuca Ridge (Eos, June 30, 1992, p. 273), and it was subsequently used with equal success on the chalcopyrite-rich chimneys from 21°N and 9°N on the East Pacific Rise. The recent December dives, however, marked the first time that drilling has ever been attempted from the smaller ROV and the first time coring into the harder igneous rock substrate has been attempted.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/93EO00275","usgsCitation":"Stakes, D., McFarlane, J.A., Holloway, G.L., and Greene, H., 1993, Drilling successful from ROV Ventana: Eos Science News, v. 74, no. 18, p. 210-211, https://doi.org/10.1029/93EO00275.","productDescription":"2 p.","startPage":"210","endPage":"211","costCenters":[],"links":[{"id":416963,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","otherGeospatial":"Monterey Bay, Monterey Canyon, Pacific Ocean","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -122.68098616166509,\n 36.92499203947433\n ],\n [\n -122.68098616166509,\n 36.681267810797536\n ],\n [\n -121.78252661713634,\n 36.681267810797536\n ],\n [\n -121.78252661713634,\n 36.92499203947433\n ],\n [\n -122.68098616166509,\n 36.92499203947433\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"74","issue":"18","noUsgsAuthors":false,"publicationDate":"2011-06-03","publicationStatus":"PW","contributors":{"authors":[{"text":"Stakes, D.S.","contributorId":103792,"corporation":false,"usgs":true,"family":"Stakes","given":"D.S.","email":"","affiliations":[],"preferred":false,"id":872305,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"McFarlane, James A. R.","contributorId":305317,"corporation":false,"usgs":false,"family":"McFarlane","given":"James","email":"","middleInitial":"A. R.","affiliations":[],"preferred":false,"id":872306,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Holloway, G. Leon","contributorId":305318,"corporation":false,"usgs":false,"family":"Holloway","given":"G.","email":"","middleInitial":"Leon","affiliations":[],"preferred":false,"id":872307,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Greene, H. Gary","contributorId":78669,"corporation":false,"usgs":true,"family":"Greene","given":"H. Gary","affiliations":[],"preferred":false,"id":872308,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70243584,"text":"70243584 - 1993 - Sediment export by ice rafting from a coastal Polynya, Arctic Alaska, U.S.A.","interactions":[],"lastModifiedDate":"2023-05-12T16:42:49.176473","indexId":"70243584","displayToPublicDate":"1993-05-01T11:29:12","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":898,"text":"Arctic and Alpine Research","active":true,"publicationSubtype":{"id":10}},"title":"Sediment export by ice rafting from a coastal Polynya, Arctic Alaska, U.S.A.","docAbstract":"Strong offshore winds in early 1989 produced a shore polynya that reached along the entire north coast of Alaska and eastward beyond the mouth of the Mackenzie River in Canada. From January through April, this open water periodically exposed the shelf to sediment entrainment by suspension freezing. This process requires turbulence and supercooled water, which results in the formation of frazil and anchor ice. The resulting granular, sediment-laden ice was observed to extend over 100 km seaward of the outer continental shelf after having been advected offshore. It was sampled to determine sediment type and to quantify the particle load. The particle size was mainly silt and clay, with local admixtures of as much as 27% sand and coarser clasts. Melted ice samples contained from 31 to nearly 600 mg L-1 of sediment. Combining these data with over 400 km of shipboard and aerial observations, photographs, and computer analysis of a summer Landsat image, we estimated the sediment load per unit area of sea ice. Seaward of the shelf, in regions of dense pack ice, a conservatively estimated sediment load was over 289 t km-2. Using a westward summer drift rate of 3 cm s-1, the sediment transport through a 1-km-long north-south segment is 67,418 t during 3 mo. In terms of regional sediment dynamics (littoral transport estimated at 10,000 t during the same period) and sediment budget (continental denudation estimated at 10 t km-2 during the same period), this number is very significant. Benthic microfossils indicate that bottom sediment incorporated in the ice came from water depths ranging from the inner neritic seaward to 50 m. The large load of shelf-derived sediment observed seaward of the continental shelf indicates that ice entrainment and transport cause shelf erosion. Nothing is known about sediment release over the Arctic Ocean Basin from these pulses of dirty ice that are periodically introduced into the Transpolar Drift.
","language":"English","publisher":"Taylor & Francis","doi":"10.2307/1551544","usgsCitation":"Reimnitz, E., McCormick, M., McDougall-Reid, K., and Brouwers, E.M., 1993, Sediment export by ice rafting from a coastal Polynya, Arctic Alaska, U.S.A.: Arctic and Alpine Research, v. 25, no. 2, p. 83-98, https://doi.org/10.2307/1551544.","productDescription":"16 p.","startPage":"83","endPage":"98","costCenters":[],"links":[{"id":416994,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Alaska","otherGeospatial":"Arctic Ocean","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -166.1893628235785,\n 68.8510799545711\n ],\n [\n -165.7927784937305,\n 68.60302294479024\n ],\n [\n -163.59571757549665,\n 68.45306559682152\n ],\n [\n -162.10797619040798,\n 69.25615394607448\n ],\n [\n -157.08199600571925,\n 70.07554650332517\n ],\n [\n -151.61365855031693,\n 69.51002606358901\n ],\n [\n -148.49371558067688,\n 69.28203829095418\n ],\n [\n -146.08719200955667,\n 69.23274785479458\n ],\n [\n -142.86278578656948,\n 69.5068404646222\n ],\n [\n -140.99468181589384,\n 69.07584879432568\n ],\n [\n -141.0126515770738,\n 69.62138774277821\n ],\n [\n -140.17191729737542,\n 71.55828011520083\n ],\n [\n -142.89846249283258,\n 71.71808353148506\n ],\n [\n -158.7712581652307,\n 73.17888787382822\n ],\n [\n -166.19595621130796,\n 71.98411374590395\n ],\n [\n -168.2196648555574,\n 69.9431467369302\n ],\n [\n -166.1893628235785,\n 68.8510799545711\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"25","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","contributors":{"authors":[{"text":"Reimnitz, Erk","contributorId":17963,"corporation":false,"usgs":true,"family":"Reimnitz","given":"Erk","email":"","affiliations":[],"preferred":false,"id":872450,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"McCormick, Michael","contributorId":18791,"corporation":false,"usgs":true,"family":"McCormick","given":"Michael","email":"","affiliations":[],"preferred":false,"id":872451,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"McDougall-Reid, Kristin 0000-0001-6026-0718 kris@usgs.gov","orcid":"https://orcid.org/0000-0001-6026-0718","contributorId":1942,"corporation":false,"usgs":true,"family":"McDougall-Reid","given":"Kristin","email":"kris@usgs.gov","affiliations":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"preferred":true,"id":872452,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Brouwers, Elisabeth M. brouwers@usgs.gov","contributorId":190,"corporation":false,"usgs":true,"family":"Brouwers","given":"Elisabeth","email":"brouwers@usgs.gov","middleInitial":"M.","affiliations":[{"id":501,"text":"Office of Science Quality and Integrity","active":true,"usgs":true}],"preferred":true,"id":872453,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70018235,"text":"70018235 - 1993 - Near-field investigations of the Landers earthquake sequence, April to July 1992","interactions":[],"lastModifiedDate":"2025-09-15T23:10:18.307754","indexId":"70018235","displayToPublicDate":"1993-04-09T00:00:00","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3338,"text":"Science","active":true,"publicationSubtype":{"id":10}},"title":"Near-field investigations of the Landers earthquake sequence, April to July 1992","docAbstract":"The Landers earthquake, which had a moment magnitude (Mw) of 7.3, was the largest earthquake to strike the contiguous United States in 40 years. This earthquake resulted from the rupture of five major and many minor right-lateral faults near the southern end of the eastern California shear zone, just north of the San Andreas fault. Its Mw 6.1 preshock and Mw 6.2 aftershock had their own aftershocks and foreshocks. Surficial geological observations are consistent with local and far-field seismologic observations of the earthquake. Large surficial offsets (as great as 6 meters) and a relatively short rupture length (85 kilometers) are consistent with seismological calculations of a high stress drop (200 bars), which is in turn consistent with an apparently long recurrence interval for these faults.
","language":"English","publisher":"American Association for the Advancement of Science","doi":"10.1126/science.260.5105.171","issn":"00368075","usgsCitation":"Sieh, K., Jones, L., Hauksson, E., Hudnut, K., Eberhart-Phillips, D., Heaton, T., Hough, S., Hutton, K., Kanamori, H., Lilje, A., Lindvall, S., McGill, S., Mori, J., Rubin, C., Spotila, J., Stock, J., Thio, H., Treiman, J., Wernicke, B., and Zachariasen, J., 1993, Near-field investigations of the Landers earthquake sequence, April to July 1992: Science, v. 260, no. 5105, p. 171-176, https://doi.org/10.1126/science.260.5105.171.","productDescription":"6 p.","startPage":"171","endPage":"176","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[],"links":[{"id":227193,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","city":"Landers","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": 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J.A.","contributorId":41163,"corporation":false,"usgs":true,"family":"Spotila","given":"J.A.","email":"","affiliations":[],"preferred":false,"id":378949,"contributorType":{"id":1,"text":"Authors"},"rank":15},{"text":"Stock, J.","contributorId":88889,"corporation":false,"usgs":true,"family":"Stock","given":"J.","affiliations":[],"preferred":false,"id":378960,"contributorType":{"id":1,"text":"Authors"},"rank":16},{"text":"Thio, H.K.","contributorId":95629,"corporation":false,"usgs":true,"family":"Thio","given":"H.K.","email":"","affiliations":[],"preferred":false,"id":378963,"contributorType":{"id":1,"text":"Authors"},"rank":17},{"text":"Treiman, J.","contributorId":89293,"corporation":false,"usgs":true,"family":"Treiman","given":"J.","email":"","affiliations":[],"preferred":false,"id":378961,"contributorType":{"id":1,"text":"Authors"},"rank":18},{"text":"Wernicke, B.","contributorId":84926,"corporation":false,"usgs":true,"family":"Wernicke","given":"B.","email":"","affiliations":[],"preferred":false,"id":378959,"contributorType":{"id":1,"text":"Authors"},"rank":19},{"text":"Zachariasen, J.","contributorId":80834,"corporation":false,"usgs":true,"family":"Zachariasen","given":"J.","affiliations":[],"preferred":false,"id":378958,"contributorType":{"id":1,"text":"Authors"},"rank":20}]}} ,{"id":70200707,"text":"70200707 - 1993 - Small fields in the National Oil and Gas Assessment","interactions":[],"lastModifiedDate":"2023-01-25T14:12:45.996236","indexId":"70200707","displayToPublicDate":"1993-03-01T15:03:05","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":701,"text":"American Association of Petroleum Geologists Bulletin","active":true,"publicationSubtype":{"id":10}},"title":"Small fields in the National Oil and Gas Assessment","docAbstract":"In the 1989 National Oil and Gas Assessment prepared by the U.S. Geological Survey (USGS) and the Minerals Management Service, undiscovered oil and gas resources in small fields were assessed separately from resources in fields containing more than 1 million bbl of oil equivalent. This paper concerns the USGS Part of the study: onshore and state waters in the conterminous United States. After the resources in small fields were assessed by geologists, statistical techniques were used to allocate these resources to field-size distributions at the province level. The total numbers of small fields remaining to be discovered is estimated at about 77,800. They account for about 10.6 billion bbl of oil equivalent or 20% of the undiscovered resources in the conterminous United st tes. When an economic analysis was applied to the small fields, none of the offshore small fields were estimated to be commercially developable. For the onshore study area, about 52% of the small oil fields and 46% of the small gas fields are commercially developable. Overall, because more hydrocarbons are contained in the larger size classes of the small fields, about 70% of the undiscovered resources in small fields is expected to be commercially developable.
","language":"English","publisher":"American Association of Petroleum Geologists","doi":"10.1306/BDFF8C68-1718-11D7-8645000102C1865D","usgsCitation":"Root, D.H., and Attanasi, E., 1993, Small fields in the National Oil and Gas Assessment: American Association of Petroleum Geologists Bulletin, v. 77, no. 3, p. 485-490, https://doi.org/10.1306/BDFF8C68-1718-11D7-8645000102C1865D.","productDescription":"6 p.","startPage":"485","endPage":"490","costCenters":[{"id":241,"text":"Eastern Energy Resources Science Center","active":true,"usgs":true}],"links":[{"id":358917,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"77","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5c1116b0e4b034bf6a815b17","contributors":{"authors":[{"text":"Root, David H.","contributorId":92232,"corporation":false,"usgs":true,"family":"Root","given":"David","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":750187,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Attanasi, Emil 0000-0001-6845-7160 attanasi@usgs.gov","orcid":"https://orcid.org/0000-0001-6845-7160","contributorId":1809,"corporation":false,"usgs":true,"family":"Attanasi","given":"Emil","email":"attanasi@usgs.gov","affiliations":[{"id":241,"text":"Eastern Energy Resources Science Center","active":true,"usgs":true}],"preferred":true,"id":750188,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70186233,"text":"70186233 - 1993 - Chlorine-36 in the Snake River Plain Aquifer at the Idaho National Engineering Laboratory; origin and implications","interactions":[],"lastModifiedDate":"2017-04-03T10:37:49","indexId":"70186233","displayToPublicDate":"1993-03-01T00:00:00","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3825,"text":"Groundwater","active":true,"publicationSubtype":{"id":10}},"title":"Chlorine-36 in the Snake River Plain Aquifer at the Idaho National Engineering Laboratory; origin and implications","docAbstract":"Between 1952 and 1984, low-level radioactive waste was introduced directly into the Snake River Plain aquifer at the Idaho National Engineering Laboratory (INEL), Idaho Falls, Idaho. These wastes were generated, principally, at the nuclear fuel reprocessing facility on the site. Our measurements of 36C1 in monitoring and production well waters, downgradient from disposal wells and seepage ponds, found easily detectable, nonhazardous concentrations of this radionuclide from the point of injection to the INEL southern site boundary. Comparisons are made between 3H and 36Cl concentrations in aquifer water and the advantages of 36C1 as a tracer of subsurface-water dynamics at the site are discussed.
","language":"English","publisher":"Wiley","doi":"10.1111/j.1745-6584.1993.tb01822.x","usgsCitation":"Beasley, T., Cecil, L., Sharma, P., Kubik, P., Fehn, U., Mann, L., and Gove, H., 1993, Chlorine-36 in the Snake River Plain Aquifer at the Idaho National Engineering Laboratory; origin and implications: Groundwater, v. 31, no. 2, p. 302-310, https://doi.org/10.1111/j.1745-6584.1993.tb01822.x.","productDescription":"9 p. ","startPage":"302","endPage":"310","costCenters":[],"links":[{"id":339001,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Idaho","otherGeospatial":"Eastern Snake River Plain ","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -111.87377929687499,\n 44.49650533109348\n ],\n [\n -113.192138671875,\n 43.69965122967144\n ],\n [\n -113.99414062499999,\n 43.34116005412307\n ],\n [\n -115.59814453125001,\n 43.37311218382002\n ],\n [\n -116.3232421875,\n 43.858296779161826\n ],\n [\n -116.52099609375,\n 43.54854811091286\n ],\n [\n -115.12573242187499,\n 42.601619944327965\n ],\n [\n -114.27978515625,\n 42.293564192170095\n ],\n [\n -113.21411132812499,\n 42.391008609205045\n ],\n [\n -111.8408203125,\n 43.31718491566705\n ],\n [\n -111.42333984375,\n 43.731414013769\n ],\n [\n -111.060791015625,\n 43.58039085560784\n ],\n [\n -111.02783203125,\n 44.378839759088585\n ],\n [\n -111.26953125,\n 44.69989765840318\n ],\n [\n -111.81884765624999,\n 44.5435052132082\n ],\n [\n -111.87377929687499,\n 44.49650533109348\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"31","issue":"2","noUsgsAuthors":false,"publicationDate":"2005-08-04","publicationStatus":"PW","scienceBaseUri":"58e35f91e4b09da67997ed12","contributors":{"authors":[{"text":"Beasley, T.M.","contributorId":74788,"corporation":false,"usgs":true,"family":"Beasley","given":"T.M.","email":"","affiliations":[],"preferred":false,"id":687950,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Cecil, L.D.","contributorId":62616,"corporation":false,"usgs":true,"family":"Cecil","given":"L.D.","email":"","affiliations":[],"preferred":false,"id":687951,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Sharma, P.","contributorId":190255,"corporation":false,"usgs":false,"family":"Sharma","given":"P.","email":"","affiliations":[],"preferred":false,"id":687952,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Kubik, P.W.","contributorId":21691,"corporation":false,"usgs":true,"family":"Kubik","given":"P.W.","email":"","affiliations":[],"preferred":false,"id":687953,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Fehn, Udo","contributorId":190256,"corporation":false,"usgs":false,"family":"Fehn","given":"Udo","email":"","affiliations":[],"preferred":false,"id":687954,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Mann, L. J.","contributorId":39392,"corporation":false,"usgs":true,"family":"Mann","given":"L. J.","affiliations":[],"preferred":false,"id":687955,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Gove, H.E.","contributorId":16576,"corporation":false,"usgs":true,"family":"Gove","given":"H.E.","email":"","affiliations":[],"preferred":false,"id":687956,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":70018336,"text":"70018336 - 1993 - Nature of migrabitumen and their relation to regional thermal maturity, Ouachita Mountains, Oklahoma","interactions":[],"lastModifiedDate":"2023-10-17T15:36:36.685397","indexId":"70018336","displayToPublicDate":"1993-03-01T00:00:00","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1511,"text":"Energy Sources","active":true,"publicationSubtype":{"id":10}},"title":"Nature of migrabitumen and their relation to regional thermal maturity, Ouachita Mountains, Oklahoma","docAbstract":"Two grahamite and three impsonite localities are within an 82-km-long segment of the Ouachita Mountains of southeastern Oklahoma. Grab samples were collected to study the petrographic and geochemical characteristics of the migrabitumen at the grahamite-impsonite transition and the relation of the migrabitumen to the regional thermal maturity pattern.
Maximum and random bitumen reflectance values increased from 0·75 to 1·80% from west to east, consistent with the regional thermal maturation trend. Mean bireflectance values increased from 0·04 to 0·38%. The two grahamite samples are classified at the grahamite-impsonite boundary with conflicting petrographic (bitumen reflectance) and bulk chemical (volatile matter) maturity indicators.
The regional maturation trend, based on vitrinite reflectance and bitumen reflectance values, was confirmed by a detailed geochemical investigation of bitumen extracts. Although biomarker analyses were influenced by extensive biodegradation effects, molecular parameters based on the phenanthrenes, dibenzothiophenes, and tricyclic terpanes were identified as useful maturity indicators.
","language":"English","publisher":"Taylor & Francis","doi":"10.1080/00908319308909026","usgsCitation":"Cardott, B.J., Ruble, T.E., and Suneson, N.H., 1993, Nature of migrabitumen and their relation to regional thermal maturity, Ouachita Mountains, Oklahoma: Energy Sources, v. 15, no. 2, p. 239-267, https://doi.org/10.1080/00908319308909026.","productDescription":"29 p.","startPage":"239","endPage":"267","numberOfPages":"29","costCenters":[],"links":[{"id":227200,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Oklahoma","otherGeospatial":"Ouachita Mountains","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -95.39359789520772,\n 34.97935792446523\n ],\n [\n -95.39359789520772,\n 33.65536790182706\n ],\n [\n -94.46276382083498,\n 33.65536790182706\n ],\n [\n -94.46276382083498,\n 34.97935792446523\n ],\n [\n -95.39359789520772,\n 34.97935792446523\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"15","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a639be4b0c8380cd725c6","contributors":{"authors":[{"text":"Cardott, Brian J.","contributorId":106657,"corporation":false,"usgs":true,"family":"Cardott","given":"Brian","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":379266,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ruble, Tim E.","contributorId":55977,"corporation":false,"usgs":true,"family":"Ruble","given":"Tim","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":379265,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Suneson, Neil H.","contributorId":10482,"corporation":false,"usgs":true,"family":"Suneson","given":"Neil","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":379264,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70128312,"text":"70128312 - 1993 - Fire history of southeastern Glacier National Park: Missouri River Drainage","interactions":[],"lastModifiedDate":"2014-10-07T13:14:42","indexId":"70128312","displayToPublicDate":"1993-02-01T12:49:00","publicationYear":"1993","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":9,"text":"Other Report"},"seriesNumber":"Final Report PX 1430-2-0787","title":"Fire history of southeastern Glacier National Park: Missouri River Drainage","docAbstract":"In 1982, Glacier National Park (GNP) initiated long-term studies to document the fire history of all forested lands in the 410,000 ha. park. To date, studies have been conducted for GNP west of the Continental Divide (Barrett et al. 1991), roughly half of the total park area. These and other fire history studies in the Northern Rockies (Arno 1976, Sneck 1977, Arno 1980, Romme 1982, Romme and Despain 1989, Barrett and Arno 1991, Barrett 1993a, Barrett 1993b) have shown that fire history data can be an integral element of fire management planning, particularly wen natiral fire plans are being developed for parks and wilderness. The value of site specific fire history data is apparent when considering study results for lodgepole pin (Pinus contorta var. latifolia) forests. Lodgepole pine is a major subalpine type in the Northern Rockies and such stands experiences a wide range of presettlement fire patterns. On relatively warm-dry sites at lower elevations, such as in GNP's North Fork drainage (Barrett et al. 1991), short to moderately long interval (25-150 yr) fires occurred in a mixed severity pattern ranging from non-lethal underburns to total stand replacement (Arno 1976, Sneck 1977, Barrett and Arno 1991). Markedly different fire history occurred at high elevation lodgepole pine stands on highly unproductive sites, such as on Yellowstone National Park's (YNP) subalpine plateau. Romme (1982) found that, on some sites, stand replacing fires recurred after very long intervals (300-400 yr), and that non-lethal surface fires were rare. For somewhat more productive sites in the Absaroka Mountains in YNP, Barrett (1993a) estimated a 200 year mean replacement interval, in a pattern similar to that found in steep mountain terrain elsewhere, such as in the Middle Fork Flathead River drainage (Barrett et al. 1991, Sneck 1977).
\nAside from post-1900 written records (ayres 1900; fire atlas data on file, GNP Archives Div. and GNP Resources Mgt. Div.), little fire history information existed for GNP's east-side forests, which are dominated primarily by lodgepole pine. In fall 1992, the park initiated a study to determine the fire history of the Missouri River drainage portion of southeastern GNP. Given the known variation in pre-1900 fire patterns for lodgepole pine, this study was seen as a potentially important contribution to GNP's Fire Management Plan, and to the expanding data base of fire history studies in the region. Resource managers sought this information to assist their development of appropriate fire management strategies for the east-side forests, and the fire history data also would be a useful interactive component of the park's Geographic Information System (GIS). Primary objectives were to: 1) determine pre-1900 fire periodicities, severities, burning patterns, and post-fire succession for major forest types, and 2) document and map the forest age class mosaic, reflecting the history of stand replacing fires at the landscape level of analysis. Secondary objectives were to interpret the possible effects of modern fire suppression on area forests, and to determine fire regime patterns relative to other lodgepole pine ecosystems in the Northern Rockies.
","language":"English","usgsCitation":"Barrett, S.W., 1993, Fire history of southeastern Glacier National Park: Missouri River Drainage, 43 p.","productDescription":"43 p.","numberOfPages":"43","costCenters":[],"links":[{"id":295021,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Montana","otherGeospatial":"Glacier National Park","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"543500a7e4b0a4f4b46a2395","contributors":{"authors":[{"text":"Barrett, Stephen W.","contributorId":32848,"corporation":false,"usgs":true,"family":"Barrett","given":"Stephen","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":502859,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70208097,"text":"70208097 - 1993 - Fluvial response to late Quaternary climatic fluctuations, central Kobuk Valley, northwestern Alaska","interactions":[],"lastModifiedDate":"2020-01-27T14:36:53","indexId":"70208097","displayToPublicDate":"1993-01-27T14:31:43","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2451,"text":"Journal of Sedimentary Research","onlineIssn":"1938-3681","printIssn":"1527-1404","active":true,"publicationSubtype":{"id":10}},"title":"Fluvial response to late Quaternary climatic fluctuations, central Kobuk Valley, northwestern Alaska","docAbstract":"Much of northwestern Alaska remained unglaciated during the Pleistocene and thus offers a favorable setting for examining long-term records of high-latitude geological and biological change. Epiguruk, a large cut bank 3.5 km long and up to 36 m high on the Kobuk River south of the Brooks Range in eastern Beringia, exposes complex sedimentary successions representing cycles of upper Quaternary alluviation and eolian sedimentation, downcutting, and soil formation. A rich record of plants and mammals is also preserved in the section. Deposits of fluvial channels and flood plains, eolian dunes, sand sheets, loess, and ponds, as well as organic soils (Histosols) are represented. Parallel-bedded fine sand and coarse silt couplets that commonly contain root structures, ripple cross-lamination, and silt drapes are flood-plain sediments apparently deposited at the interface of fluvial and eolian environments. Multiple fluvial-to-eolian depositional sequences were caused by influx of eolian sediment to the river from intermittently active dune fields south of the Kobuk River. Alluviation in the Kobuk Valley was coeval with glaciation in the Brooks Range, whereas downcutting occurred during interstadials when dune stabilization limited sediment supply. The depositional model developed at Epiguruk may be useful in interpreting some of the widespread subhorizontally stratified late-glacial deposits of Europe and North America.
","language":"English","publisher":"GeoScienceWorld","doi":"10.1306/D4267C12-2B26-11D7-8648000102C1865D","usgsCitation":"Ashley, G., and Hamilton, T.D., 1993, Fluvial response to late Quaternary climatic fluctuations, central Kobuk Valley, northwestern Alaska: Journal of Sedimentary Research, v. 63, no. 5, p. 814-827, https://doi.org/10.1306/D4267C12-2B26-11D7-8648000102C1865D.","productDescription":"14 p.","startPage":"814","endPage":"827","costCenters":[],"links":[{"id":371595,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United 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\":{\"name\":\"Alaska\",\"nation\":\"USA \"}}]}","volume":"63","issue":"5","noUsgsAuthors":false,"publicationStatus":"PW","contributors":{"authors":[{"text":"Ashley, G.M.","contributorId":99313,"corporation":false,"usgs":true,"family":"Ashley","given":"G.M.","email":"","affiliations":[],"preferred":false,"id":780454,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Hamilton, T. D.","contributorId":36921,"corporation":false,"usgs":true,"family":"Hamilton","given":"T.","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":780455,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70207890,"text":"70207890 - 1993 - Internal structure of the Sierra Nevada batholith based on specific gravity and gravity measurements","interactions":[],"lastModifiedDate":"2020-01-16T16:55:54","indexId":"70207890","displayToPublicDate":"1993-01-16T16:47:49","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1807,"text":"Geophysical Research Letters","active":true,"publicationSubtype":{"id":10}},"title":"Internal structure of the Sierra Nevada batholith based on specific gravity and gravity measurements","docAbstract":"About 6,000 specific‐gravity (SG) measurements of samples collected from nearly 200 granitic plutons comprising the central Sierra Nevada batholith yield a SG contour map across the batholith from 36.25° to 38° north latitude. With notable exceptions, SG decreases from values generally greater than 2.7 in the west to less than 2.6 over a few small areas of high‐silica, high‐potassium granites near the east edge. A good correlation between measured SG and analyzed weight percent SiO2 enables estimation of average silica variations across the batholith. The average SG is 2.69 corresponding to an average of 68 wt. % SiO2 for the 18,000 km² central part of the batholith.
A 1‐km gridded version of the SG measurements has been used to generate a series of synthetic gravity maps, assuming that the SG of rocks at the surface extends unchanged to various depths. The synthetic map computed for a depth of 10 km shows the best correspondence with the isostatic residual gravity map indicating that variations in the observed gravity residuals are largely caused by SG variations of the plutonic rocks exposed at the surface that apparently extend downward to an average depth of about 10 km.
Although the 10‐km synthetic gravity map gives the best overall fit to the observed gravity data, comparison of individual anomalies indicates that the bottoms of the plutons as defined by SG variations at the surface are generally shallower along the west edge of the Sierra Nevada (7±2 km) and deeper in the younger and more felsic eastern part (12±3 km). These depths do not necessarily represent a distinct base of the Sierra Nevada batholith. They may indicate the depth below which density homogenization occurs, either by igneous, or possibly, structural processes.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/93GL01379","usgsCitation":"Oliver, H., Moore, B., and Sikora, R.F., 1993, Internal structure of the Sierra Nevada batholith based on specific gravity and gravity measurements: Geophysical Research Letters, v. 20, no. 20, p. 2179-2182, https://doi.org/10.1029/93GL01379.","productDescription":"4 p.","startPage":"2179","endPage":"2182","costCenters":[{"id":617,"text":"Volcano Science Center","active":true,"usgs":true}],"links":[{"id":371333,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","otherGeospatial":"Sierra Nevada batholith","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -120.08056640625,\n 36.13787471840729\n ],\n [\n -117.94921874999999,\n 36.13787471840729\n ],\n [\n -117.94921874999999,\n 38.272688535980976\n ],\n [\n -120.08056640625,\n 38.272688535980976\n ],\n [\n -120.08056640625,\n 36.13787471840729\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"20","issue":"20","noUsgsAuthors":false,"publicationDate":"2012-12-07","publicationStatus":"PW","contributors":{"authors":[{"text":"Oliver, H.W.","contributorId":16703,"corporation":false,"usgs":true,"family":"Oliver","given":"H.W.","email":"","affiliations":[],"preferred":false,"id":779657,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Moore, Bryan bmoore@usgs.gov","contributorId":2417,"corporation":false,"usgs":true,"family":"Moore","given":"Bryan","email":"bmoore@usgs.gov","affiliations":[],"preferred":true,"id":779658,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Sikora, R. F.","contributorId":21923,"corporation":false,"usgs":true,"family":"Sikora","given":"R.","email":"","middleInitial":"F.","affiliations":[],"preferred":false,"id":779659,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70207741,"text":"70207741 - 1993 - Geochemistry of surface sediments of Minnesota lakes","interactions":[],"lastModifiedDate":"2021-04-07T12:54:19.45039","indexId":"70207741","displayToPublicDate":"1993-01-08T15:50:55","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1727,"text":"GSA Special Papers","active":true,"publicationSubtype":{"id":10}},"title":"Geochemistry of surface sediments of Minnesota lakes","docAbstract":"Analyses of 36 trace, minor, and major elements were used to classify the sediments of 46 Minnesota lakes. Q-mode factor analyses grouped Minnesota lake sediments according to clastic-, carbonate-, organic-, and redox-related elements. Carbonate lakes occur in west-central Minnesota; their sediments have relatively high concentrations of CaCO3, Ba, and Sr. Lakes with sediments containing more than 30% organic matter occur in east-central and northeastern Minnesota; these sediments have high concentrations of organic C, N, and H, and slightly elevated concentrations of Pb. Only three lakes have sediments included in the “redox” group, with relatively high concentrations of Fe, Mn, Mo, La, and Zn. High concentrations of redox-sensitive elements appear to be associated with oxidized iron and manganese minerals, but in Elk Lake, one of the three lakes in this group, a significant amount of iron and manganese is contained in iron phosphate, iron sulfide, and manganese carbonate. Clastic lake sediments are not diluted by large amounts of organic matter, carbonate minerals, or iron-manganese minerals, and are of two types: a western group derived largely from Cretaceous shales in the prairie regions, and a northeastern group derived from Precambrian crystalline rocks in the forested arrowhead region. Western clastic lake sediments have higher concentrations of Al, Na, K, B, Ba, V, Mg, and Sr. Most northeastern clastic lake sediments contain higher concentrations of Cu, Y, Be, and Ni, but several are chemically more similar to those of western prairie lakes.
","language":"English","publisher":"Geological Society of America","doi":"10.1130/SPE276-p115","usgsCitation":"Dean, W.E., Gorham, E., and Swaine, D.J., 1993, Geochemistry of surface sediments of Minnesota lakes: GSA Special Papers, v. 276, p. 115-133, https://doi.org/10.1130/SPE276-p115.","productDescription":"19 p.","startPage":"115","endPage":"133","costCenters":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"links":[{"id":371086,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Minnesota","otherGeospatial":"Lakes of 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\"}}]}","volume":"276","noUsgsAuthors":false,"publicationDate":"1993-01-01","publicationStatus":"PW","contributors":{"authors":[{"text":"Dean, Walter E. dean@usgs.gov","contributorId":1801,"corporation":false,"usgs":true,"family":"Dean","given":"Walter","email":"dean@usgs.gov","middleInitial":"E.","affiliations":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"preferred":true,"id":779147,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gorham, Eville","contributorId":29689,"corporation":false,"usgs":true,"family":"Gorham","given":"Eville","email":"","affiliations":[],"preferred":false,"id":779148,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Swaine, Dalway J.","contributorId":221614,"corporation":false,"usgs":false,"family":"Swaine","given":"Dalway","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":779149,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70207740,"text":"70207740 - 1993 - Holocene climatic and limnologic history of the north-central United States as recorded in the varved sediments of Elk Lake, Minnesota: A synthesis","interactions":[],"lastModifiedDate":"2020-06-18T15:18:26.480542","indexId":"70207740","displayToPublicDate":"1993-01-08T15:36:57","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1727,"text":"GSA Special Papers","active":true,"publicationSubtype":{"id":10}},"title":"Holocene climatic and limnologic history of the north-central United States as recorded in the varved sediments of Elk Lake, Minnesota: A synthesis","docAbstract":"Integration of the results and interpretations of geochemical, paleoecological, and sedimentological analyses of a varved sediment record provides a detailed chronicle of limnological and climatic changes for the past 10 ka at Elk Lake, west-central Minnesota. The early Holocene record at Elk Lake was controlled by circumstances of glacial history (e.g., basin morphometry and surrounding till lithology) in combination with global warming at the end of the Pleistocene. Later, the interplay of climate change and a disintegrating ice sheet determined the character of local environments that were affected by reduction of precipitation and increased windiness during the middle Holocene. Elk Lake became more productive and clastic sediment increased to dominate the record as the forests thinned and prairie vegetation characterized the region. During this prairie period, winters may have been cold because disintegrating northern ice sheets ceased to block winter outbreaks of Arctic air. Correlations of wind-deposited materials throughout much of the eastern two-thirds of the United States suggest that drought conditions and strong winds were widespread between 8 and 4 ka. The mid-Holocene was climatically variable, however, with strong fluctuations in varve thickness at decadal, centennial, and millennial scales testifying to rapid climatic changes. Although the cause of such climatic cycles is not yet clear, correlations between 14C anomalies and varve thickness suggest that variations in solar flux and resulting magnetic storms and zonal winds may have induced strong climatic changes. A particularly strong 600 yr fluctuation to cool and wet climates that may document neoglacial conditions around 5 ka interrupted the prairie period. After 4 ka, the climate at Elk Lake was dominated by a tropical airstream during the summer, and dry arctic and Pacific airstreams during the winter. Large-scale variations ceased, although decadal and multi-decadal variations in varve thickness chronicle changes similar, but not clearly correlative, to historically documented climatic episodes such as the Medieval Warm Period and the Little Ice Age.
","language":"English","publisher":"GSA","doi":"10.1130/SPE276-p309","usgsCitation":"Bradbury, J.P., Dean, W.E., and Anderson, R., 1993, Holocene climatic and limnologic history of the north-central United States as recorded in the varved sediments of Elk Lake, Minnesota: A synthesis: GSA Special Papers, v. 276, p. 309-328, https://doi.org/10.1130/SPE276-p309.","productDescription":"20 p.","startPage":"309","endPage":"328","costCenters":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"links":[{"id":371084,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Minnesota","otherGeospatial":"Elk Lake","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -95.23017883300781,\n 47.17967906219905\n ],\n [\n -95.20442962646483,\n 47.17967906219905\n ],\n [\n -95.20442962646483,\n 47.1981110637904\n ],\n [\n -95.23017883300781,\n 47.1981110637904\n ],\n [\n -95.23017883300781,\n 47.17967906219905\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"276","noUsgsAuthors":false,"publicationDate":"1993-01-01","publicationStatus":"PW","contributors":{"authors":[{"text":"Bradbury, J. Platt","contributorId":91106,"corporation":false,"usgs":true,"family":"Bradbury","given":"J.","email":"","middleInitial":"Platt","affiliations":[],"preferred":false,"id":779141,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Dean, Walter E. dean@usgs.gov","contributorId":1801,"corporation":false,"usgs":true,"family":"Dean","given":"Walter","email":"dean@usgs.gov","middleInitial":"E.","affiliations":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"preferred":true,"id":779142,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Anderson, R.Y.","contributorId":22789,"corporation":false,"usgs":true,"family":"Anderson","given":"R.Y.","email":"","affiliations":[],"preferred":false,"id":779143,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70207737,"text":"70207737 - 1993 - Environment of deposition of CaCO3 in Elk Lake, Minnesota","interactions":[],"lastModifiedDate":"2020-06-18T15:13:04.885935","indexId":"70207737","displayToPublicDate":"1993-01-08T15:06:35","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1727,"text":"GSA Special Papers","active":true,"publicationSubtype":{"id":10}},"displayTitle":"Environment of deposition of CaCO3 in Elk Lake, Minnesota","title":"Environment of deposition of CaCO3 in Elk Lake, Minnesota","docAbstract":"Elk Lake is near the present forest-prairie border in northwestern Minnesota, and is also located on the boundary between hard-water lakes that are typical of once-glaciated parts of the north-central United States and more saline prairie lakes of western Minnesota and the Dakotas. The sediments of the prairie lakes just west of Elk Lake are unusual in that they commonly contain high-Mg calcite and dolomite in addition to low-Mg calcite, which is the dominant carbonate mineral in most marl lakes. During the mid-Holocene dry period, prairie conditions expanded eastward into the forested regions of Minnesota. Variations in types and abundances of carbonate minerals in the Holocene sediments of Elk Lake recorded this climatic change.
Studies of primary productivity, carbonate saturation, water chemistry, and sediment-trap samples show that low-Mg calcite precipitates during the summer, triggered by algal photosynthesis. The epilimnion of Elk Lake is always oversaturated with calcite, and the degree of oversaturation increases progressively during the summer. The pH of the epilimnion increases from <8.0 after spring overturn to almost 9.0 in late summer in response to photosynthetic removal of CO2 during the summer months. The rate of calcium depletion from the epilimnion is proportional to the increase in pH and the rate of photosynthetic carbon fixation.
Today the only carbonate minerals that are accumulating in the sediments of Elk Lake are low-Mg calcite and manganese carbonate (rhodochrosite). Rhodochrosite, and probably manganese oxyhydroxide, precipitates when manganese-rich anoxic bottom waters come in contact with carbonate-rich oxic surface waters. During the arid mid-Holocene prairie period, however, low-Mg calcite, dolomite, aragonite, and rhodochrosite all accumulated in the sediments of Elk Lake. Dolomite formed in Elk Lake during this period in response to a higher Mg:Ca ratio in the water, just as it is forming today in lakes of the prairie regions of western Minnesota. The coincident occurrence of aragonite and biological indicators of high salinity suggests that the salinity of Elk Lake and the Mg:Ca ratio were higher than in any of the present prairie lakes of western Minnesota.
","language":"English","publisher":"GSA","doi":"10.1130/SPE276-p97","usgsCitation":"Dean, W.E., and Megard, R., 1993, Environment of deposition of CaCO3 in Elk Lake, Minnesota: GSA Special Papers, v. 276, p. 97-113, https://doi.org/10.1130/SPE276-p97.","productDescription":"17 p.","startPage":"97","endPage":"113","costCenters":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"links":[{"id":371081,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Minnesota","otherGeospatial":"Elk Lake, Itasca Park","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -95.23017883300781,\n 47.17967906219905\n ],\n [\n -95.20442962646483,\n 47.17967906219905\n ],\n [\n -95.20442962646483,\n 47.1981110637904\n ],\n [\n -95.23017883300781,\n 47.1981110637904\n ],\n [\n -95.23017883300781,\n 47.17967906219905\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"276","noUsgsAuthors":false,"publicationDate":"1993-01-01","publicationStatus":"PW","contributors":{"authors":[{"text":"Dean, Walter E. dean@usgs.gov","contributorId":1801,"corporation":false,"usgs":true,"family":"Dean","given":"Walter","email":"dean@usgs.gov","middleInitial":"E.","affiliations":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"preferred":true,"id":779133,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Megard, R.O.","contributorId":221612,"corporation":false,"usgs":false,"family":"Megard","given":"R.O.","email":"","affiliations":[],"preferred":false,"id":779134,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70207646,"text":"70207646 - 1993 - 40Ar/39Ar thermochronology and Alleghanian development of the southernmost Appalachian Piedmont, Alabama and southwest Georgia","interactions":[],"lastModifiedDate":"2020-06-05T15:13:50.128245","indexId":"70207646","displayToPublicDate":"1993-01-02T11:21:16","publicationYear":"1993","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1723,"text":"GSA Bulletin","active":true,"publicationSubtype":{"id":10}},"displayTitle":"40Ar/39Ar thermochronology and Alleghanian development of the southernmost Appalachian Piedmont, Alabama and southwest Georgia","title":"40Ar/39Ar thermochronology and Alleghanian development of the southernmost Appalachian Piedmont, Alabama and southwest Georgia","docAbstract":"40Ar/39Ar age spectra of hornblende, muscovite, and microcline, and total fusion ages of biotite from metamorphic rocks of the Inner Piedmont, Pine Mountain, and Uchee belts are reported. Mineral cooling ages from the eastern part of the Inner Piedmont are as follows: hornblende, 320 Ma; muscovite, 296 Ma; biotite, 293 Ma; and microcline (diffusional release patterns) Tmax = 267 Ma, Tmin = 234 Ma. A 347 Ma hornblende spectrum from the highest Inner Piedmont structural level sampled is the oldest date determined and implies earlier passage of this level through the 500 °C isotherm. Most release spectra from Pine Mountain belt units are discordant with little or no apparent geologic meaning. Modified saddle-shaped release patterns for hornblende indicate extraneous argon with a maximum age of ∼358 Ma. Muscovite from the Pine Mountain belt cover sequence is 286 Ma (plateau age), and one from the underlying Grenville basement is 277 Ma (correlation age), indicating cooling below the 350 °C isotherm. Plateau ages on Uchee belt rocks are as follows: hornblende, from 297 to 288 Ma; muscovite, 285 Ma; biotite, 276 Ma; and microcline Tmax = 261 Ma, Tmin 230 Ma. Muscovite fish from a Bartletts Ferry fault zone phyllonite have a plateau age of 283 Ma.
The 40Ar/39Ar results combined with other geologic data indicate that (1) a large part of the southern and Inner Piedmonts of Alabama and southwest Georgia experienced a late Paleozoic amphibolite-facies thermal and deformational event contemporaneous with the Alleghanian orogeny observed in the foreland; (2) the tectonic development of this event, characterized by initial crustal thickening followed by right-slip and normal-slip movements, is grossly similar to that described for the amphibolite-facies Alleghanian belt in the eastern Piedmont of South Carolina and Georgia; and (3) extensional movements along the flanks of the Pine Mountain window occurred between ca. 277 Ma and the Late Triassic-Early Jurassic and thus may reflect latest Alleghanian extensional collapse or Mesozoic rifting.
","language":"English","publisher":"GSA","doi":"10.1130/0016-7606(1993)105<0819:AATAAD>2.3.CO;2","usgsCitation":"Steltenpohl, M.G., and Kunk, M.J., 1993, 40Ar/39Ar thermochronology and Alleghanian development of the southernmost Appalachian Piedmont, Alabama and southwest Georgia: GSA Bulletin, v. 105, no. 6, p. 819-833, https://doi.org/10.1130/0016-7606(1993)105<0819:AATAAD>2.3.CO;2.","productDescription":"15 p.","startPage":"819","endPage":"833","costCenters":[{"id":243,"text":"Eastern Geology and Paleoclimate Science Center","active":true,"usgs":true}],"links":[{"id":370931,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Alabama, Georgia","otherGeospatial":"Southernmost Appalachian Piedmont","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -86.572265625,\n 35.02999636902566\n ],\n [\n -86.66015624999999,\n 32.24997445586331\n ],\n [\n -82.265625,\n 32.76880048488168\n ],\n [\n -79.62890625,\n 35.38904996691167\n ],\n [\n -80.771484375,\n 36.38591277287651\n ],\n [\n -86.572265625,\n 35.02999636902566\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"105","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","contributors":{"authors":[{"text":"Steltenpohl, Mark G.","contributorId":178199,"corporation":false,"usgs":false,"family":"Steltenpohl","given":"Mark","email":"","middleInitial":"G.","affiliations":[],"preferred":false,"id":778738,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kunk, Michael J. 0000-0003-4424-7825 mkunk@usgs.gov","orcid":"https://orcid.org/0000-0003-4424-7825","contributorId":200968,"corporation":false,"usgs":true,"family":"Kunk","given":"Michael","email":"mkunk@usgs.gov","middleInitial":"J.","affiliations":[{"id":40020,"text":"Florence Bascom Geoscience Center","active":true,"usgs":true},{"id":243,"text":"Eastern Geology and Paleoclimate Science Center","active":true,"usgs":true}],"preferred":true,"id":778739,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ]}