![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782900564-si1.gif\" "\\"\\"")
![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782900564-si2.gif\" "\\"\\"")
![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782900564-si3.gif\" "\\"\\"")
where T is in oK. At 25°C the logarithms of the equilibrium constants are −8.480 ± 0.020, −8.336 ± 0.020 and −7.913 ± 0.020 for calcite, aragonite and vaterite, respectively.During the past decade, the southern regions of the U.S. have experienced rapid change which is expected to continue into the foreseeable future. Growth in population, industry, and resource development has been attributed to a variety of advantages such as an abundant and inexpensive labor force, a mild climate, and the availability of energy, water, land, and other natural resources. While this growth has many benefits for the region, it also creates the potential for increased air, water, and solid waste pollution, and modification of natural habitats.
\nA workshop was convened to consider the Mobile Bay area as a site-specific case of growth and its environmental consequences in the southern region. The objectives of the modeling workshop were to: (1) identify major factors of economic development as they relate to growth in the area over the immediate and longer term; (2) identify major environmental and resource management issues associated with this expected growth; and (3) identify and characterize the complex interrelationships among economic and environmental factors. This report summarizes the activities and results of a modeling workshop concerning economic growth and concomitant resource management issues in the Mobile Bay area.
\nThe workshop was organized around construction of a simulation model representing the relationships between a series of actions and indicators identified by participants. The workshop model had five major components. An Industry Submodel generated scenarios of growth in several industrial and transportation sectors. A Human Population/Economy Submodel calculated human population and economic variables in response to employment opportunities. A Land Use/Air Quality Submodel tabulated changes in land use, shoreline use, and air quality. A Water Submodel calculated indicators of water quality and quantity for fresh surface water, ground water, and Mobile Bay based on discharge information provided by the Industry and Human Population/Economy Submodels. Finally, a Fish Submodel calculated indicators of habitat quality for finfish and shellfish, utilizing information on water quality and wetlands acreage.
\nThe workshop was successful in identifying many of the critical interrelations between components of the Mobile area system. Not all of those interactions, such as the feedback of air quality as a limitation on development, could be incorporated into the workshop model because of the model's broad spatial scale and because of uncertainties or data gaps. Thus, the value of the modeling workshop was in the areas outlines below, rather than in the predictive power of the initial model developed at the workshop.
\nFirst, participants developed a holistic perspective on the interactions which will determine future economic and environmental trends within the Mobile Bay area. Potential environmental consequences and limitations to grown identified at the workshop included: shoreline and water access; water quality of Mobile Bay; finfish and shellfish habitat quality with respect to dissolved oxygen and coliforms; air quality; and acreage of critical wetland habitat. Second, the model's requirements for specific, quantitative information stimulated supporting analyses, such as economic input-output calculations, which provide additional insight into the Mobile Bay area system. Third, the perspective of the Mobile area as an interacting system was developed in an open, cooperative forum which my provide a foundation for conflict resolution based on common understanding. Finally, the identification of model limitations and uncertainties should be useful in guiding the efficient allocation of future research effort.
","language":"English","publisher":"U.S. Fish and Wildlife Service, Western Energy and Land Use Team","publisherLocation":"Fort Collins, CO","usgsCitation":"Hamilton, D.B., Andrews, A.K., Auble, G.T., Ellison, R.A., Johnson, R.A., Roelle, J.E., and Staley, M.J., 1982, Results of a modeling workshop concerning economic and environmental trends and concomitant resource management issues in the Mobile Bay area, 84 p.","productDescription":"84 p.","numberOfPages":"84","costCenters":[],"links":[{"id":292147,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Alabama","otherGeospatial":"Mobile Bay","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -88.109396,30.26461 ], [ -88.109396,30.673552 ], [ -87.91553,30.673552 ], [ -87.91553,30.26461 ], [ -88.109396,30.26461 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"53edcd4fe4b0f61b386d2453","contributors":{"authors":[{"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":498128,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Andrews, Austin K.","contributorId":85516,"corporation":false,"usgs":true,"family":"Andrews","given":"Austin","email":"","middleInitial":"K.","affiliations":[],"preferred":false,"id":498134,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Auble, Gregor T. 0000-0002-0843-2751 aubleg@usgs.gov","orcid":"https://orcid.org/0000-0002-0843-2751","contributorId":2187,"corporation":false,"usgs":true,"family":"Auble","given":"Gregor","email":"aubleg@usgs.gov","middleInitial":"T.","affiliations":[{"id":291,"text":"Fort Collins Science Center","active":true,"usgs":true}],"preferred":true,"id":498129,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Ellison, Richard A.","contributorId":19087,"corporation":false,"usgs":true,"family":"Ellison","given":"Richard","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":498131,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Johnson, Richard A.","contributorId":81420,"corporation":false,"usgs":true,"family":"Johnson","given":"Richard","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":498133,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"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":498130,"contributorType":{"id":1,"text":"Authors"},"rank":6},{"text":"Staley, Michael J.","contributorId":77859,"corporation":false,"usgs":true,"family":"Staley","given":"Michael","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":498132,"contributorType":{"id":1,"text":"Authors"},"rank":7}]}} ,{"id":905,"text":"905 - 1982 - Water resources data: New Mexico","interactions":[],"lastModifiedDate":"2014-07-09T09:00:51","indexId":"905","displayToPublicDate":"1982-01-01T08:59:12","publicationYear":"1982","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":6,"text":"USGS Unnumbered Series"},"title":"Water resources data: New Mexico","docAbstract":"No abstract available.","largerWorkType":{"id":18,"text":"Report"},"largerWorkTitle":"U.S. Geological Survey water-supply paper","largerWorkSubtype":{"id":6,"text":"USGS Unnumbered Series"},"language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/905","issn":"0364-4065","collaboration":"Prepared in cooperation with the state of New Mexico and with other agencies","usgsCitation":"Water Resources Division, U.S. Geological Survey, 1982, Water resources data: New Mexico, https://doi.org/10.3133/905.","costCenters":[],"links":[{"id":289580,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"}],"country":"United States","state":"New Mexico","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -109.0502,31.3322 ], [ -109.0502,37.0003 ], [ -103.002,37.0003 ], [ -103.002,31.3322 ], [ -109.0502,31.3322 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"53be6490e4b0527d5d4097e9","contributors":{"authors":[{"text":"Water Resources Division, U.S. Geological Survey","contributorId":128075,"corporation":true,"usgs":false,"organization":"Water Resources Division, U.S. Geological Survey","id":527820,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":903,"text":"903 - 1982 - Water resources data: New Hampshire and Vermont","interactions":[],"lastModifiedDate":"2014-07-09T08:47:00","indexId":"903","displayToPublicDate":"1982-01-01T08:44:00","publicationYear":"1982","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":6,"text":"USGS Unnumbered Series"},"title":"Water resources data: New Hampshire and Vermont","docAbstract":"No abstract available.","largerWorkType":{"id":18,"text":"Report"},"largerWorkTitle":"U.s. Geological Survey water-supply paper","largerWorkSubtype":{"id":6,"text":"USGS Unnumbered Series"},"language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/903","collaboration":"Prepared in cooperation with states of New Hampshire and Vermont and with other agencies","usgsCitation":"Water Resources Division, U.S. Geological Survey, 1982, Water resources data: New Hampshire and Vermont, https://doi.org/10.3133/903.","costCenters":[],"links":[{"id":289577,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"}],"country":"United States","state":"New Hampshire;Vermont","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -73.4636,42.7454 ], [ -73.4636,45.3055 ], [ -70.6027,45.3055 ], [ -70.6027,42.7454 ], [ -73.4636,42.7454 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"53be648ee4b0527d5d4097e5","contributors":{"authors":[{"text":"Water Resources Division, U.S. Geological Survey","contributorId":128075,"corporation":true,"usgs":false,"organization":"Water Resources Division, U.S. Geological Survey","id":527818,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70006377,"text":"70006377 - 1982 - Detection of diethylnitrosamine in nitrate-rich water following treatment with Rhodamine flow tracers","interactions":[],"lastModifiedDate":"2026-03-16T16:16:12.072498","indexId":"70006377","displayToPublicDate":"1982-01-01T00:00:00","publicationYear":"1982","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3716,"text":"Water Research","onlineIssn":"1879-2448","printIssn":"0043-1354","active":true,"publicationSubtype":{"id":10}},"title":"Detection of diethylnitrosamine in nitrate-rich water following treatment with Rhodamine flow tracers","docAbstract":"Extremely carcinogenic diethylnitrosamine (DENA) was found to form in up to 75% yield from the reaction of nitrite with the two commonly used water tracing dyes. Rhodamine B and Rhodamine WT, DENA was detected at trace levels (0.13–7.02 μg −1) in river water samples after treatment with the dye and nitrite. Analysis of these chemically treated environmental water samples required extensive separation techniques prior to acquisition of reliable analytical data using highly sensitive instruments for detection. The occurrence of DENA in nitrite-rich water treated with Rhodamines may pose a health hazard to general populations.
","language":"English","publisher":"Elsevier","doi":"10.1016/0043-1354(82)90111-7","usgsCitation":"Abidi, S.L., 1982, Detection of diethylnitrosamine in nitrate-rich water following treatment with Rhodamine flow tracers: Water Research, v. 16, no. 2, p. 199-204, https://doi.org/10.1016/0043-1354(82)90111-7.","productDescription":"6 p.","startPage":"199","endPage":"204","costCenters":[{"id":606,"text":"Upper Midwest Environmental Sciences Center","active":true,"usgs":true}],"links":[{"id":258232,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"16","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059ff73e4b0c8380cd4f1c6","contributors":{"authors":[{"text":"Abidi, S. L.","contributorId":19898,"corporation":false,"usgs":true,"family":"Abidi","given":"S.","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":354414,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70011789,"text":"70011789 - 1982 - The solubilities of calcite, aragonite and vaterite in CO2-H2O solutions between 0 and 90°C, and an evaluation of the aqueous model for the system CaCO3-CO2-H2O","interactions":[],"lastModifiedDate":"2018-03-21T15:17:40","indexId":"70011789","displayToPublicDate":"1982-01-01T00:00:00","publicationYear":"1982","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1759,"text":"Geochimica et Cosmochimica Acta","active":true,"publicationSubtype":{"id":10}},"title":"The solubilities of calcite, aragonite and vaterite in CO2-H2O solutions between 0 and 90°C, and an evaluation of the aqueous model for the system CaCO3-CO2-H2O","docAbstract":"Calculations based on approximately 350 new measurements (CaT-PCO2) of the solubilities of calcite, aragonite and vaterite in CO2-H2O solutions between 0 and 90°C indicate the following values for the log of the equilibrium constants KC, KA, and KV respectively, for the reaction CaCO3(s) = Ca2+ + CO2−3:
\n where T is in oK. At 25°C the logarithms of the equilibrium constants are −8.480 ± 0.020, −8.336 ± 0.020 and −7.913 ± 0.020 for calcite, aragonite and vaterite, respectively.
The equilibrium constants are internally consistent with an aqueous model that includes the CaHCO+3 and CaCO03 ion pairs, revised analytical expressions for CO2-H2O equilibria, and extended Debye-Hückel individual ion activity coefficients. Using this aqueous model, the equilibrium constant of aragonite shows no PCO2-dependence if the CaHCO+3 association constant is ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782900564-si4.gif\" "\\"\\"")
between 0 and 90°C, corresponding to the value logKCahco+3 = 1.11 ± 0.07 at 25°C. The CaCO03association constant was measured potentiometrically to be ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782900564-si5.gif\" "\\"\\"")
between 5 and 80°C, yielding logKCaCO03 = 3.22 ± 0.14 at 25°C.
The CO2-H2O equilibria have been critically evaluated and new empirical expressions for the temperature dependence of KH, K1 and K2 are ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782900564-si6.gif\" "\\"\\"")
, ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782900564-si7.gif\" "\\"\\"")
and logK2 = −107.8871 − 0.03252849T + 5151.79/T + 38.92561 logT − 563713.9/T2 which may be used to at least 250°C. These expressions hold for 1 atm. total pressure between 0 and 100°C and follow the vapor pressure curve of water at higher temperatures.
Extensive measurements of the pH of Ca-HCO3 solutions at 25°C and 0.956 atm PCO2 using different compositions of the reference electrode filling solution show that measured differences in pH are closely approximated by differences in liquid-junction potential as calculated by the Henderson equation. Liquid-junction corrected pH measurements agree with the calculated pH within 0.003-0.011 pH.
\nEarlier arguments suggesting that the CaHCO+3 ion pair should not be included in the CaCO3-CO2-H2O aqueous model were based on less accurate calcite solubility data. The CaHCO+3 ion pair must be included in the aqueous model to account for the observed PCO2-dependence of aragonite solubility between 317 ppm CO2 and 100% CO2.
\nPrevious literature on the solubility of CaCO3 polymorphs have been critically evaluated using the aqueous model and the results are compared.
","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Geochimica et Cosmochimica Acta","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/0016-7037(82)90056-4","issn":"00167037","usgsCitation":"Plummer, N., and Busenberg, E., 1982, The solubilities of calcite, aragonite and vaterite in CO2-H2O solutions between 0 and 90°C, and an evaluation of the aqueous model for the system CaCO3-CO2-H2O: Geochimica et Cosmochimica Acta, v. 46, no. 6, p. 1011-1040, https://doi.org/10.1016/0016-7037(82)90056-4.","startPage":"1011","endPage":"1040","numberOfPages":"30","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[],"links":[{"id":220722,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"46","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bb03ee4b08c986b324d14","contributors":{"authors":[{"text":"Plummer, Niel 0000-0002-4020-1013 nplummer@usgs.gov","orcid":"https://orcid.org/0000-0002-4020-1013","contributorId":190100,"corporation":false,"usgs":true,"family":"Plummer","given":"Niel","email":"nplummer@usgs.gov","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true}],"preferred":true,"id":361964,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Busenberg, Eurybiades ebusenbe@usgs.gov","contributorId":2271,"corporation":false,"usgs":true,"family":"Busenberg","given":"Eurybiades","email":"ebusenbe@usgs.gov","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true}],"preferred":true,"id":361963,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70175019,"text":"70175019 - 1982 - Modeling of tidal and residual circulation in San Francisco Bay, California","interactions":[],"lastModifiedDate":"2016-07-26T16:09:30","indexId":"70175019","displayToPublicDate":"1982-01-01T00:00:00","publicationYear":"1982","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"Modeling of tidal and residual circulation in San Francisco Bay, California","docAbstract":"Several numerical models have been developed and implemented to simulate tidal and residual circulation in San Francisco Bay. Because of a broad distribution in time scales, hydrodynamic models must be formulated to account for the proper time and spatial scales which dominate the transport processes. A complete current survey of the San Francisco Bay system was conducted jointly between NOS/NOAA and USGS (Patchen and Cheng, 1979). Presently, these current meter data are being processed and analyzed, and concurrently further development of tidal and residual circulation models continues. When these data become available, they will be used to calibrate the numerical models and to guide refinement of hydrodynamic models in order to maximize our understanding of the Bay system. Our modeling efforts will be extended to the northern reach of the Bay system.
","largerWorkType":{"id":24,"text":"Conference Paper"},"largerWorkTitle":"Proceedings, Seminar on 2-D Flows","conferenceTitle":"Seminar on 2-D Flows","conferenceDate":"July 1981","conferenceLocation":"Davis, Calif.","language":"English","publisher":"U.S. Army Corps of Engineers","usgsCitation":"Cheng, R.T., 1982, Modeling of tidal and residual circulation in San Francisco Bay, California, in Proceedings, Seminar on 2-D Flows, Davis, Calif., July 1981, p. 172-185.","productDescription":"16 p.","startPage":"172","endPage":"185","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":552,"text":"San Francisco Bay-Delta","active":false,"usgs":true},{"id":5079,"text":"Pacific Regional Director's Office","active":true,"usgs":true}],"links":[{"id":325674,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"579889bce4b0589fa1c6bac6","contributors":{"authors":[{"text":"Cheng, R. T.","contributorId":23138,"corporation":false,"usgs":false,"family":"Cheng","given":"R.","email":"","middleInitial":"T.","affiliations":[],"preferred":false,"id":643618,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":85369,"text":"85369 - 1982 - Population modeling for furbearer management","interactions":[],"lastModifiedDate":"2012-02-02T00:04:01","indexId":"85369","displayToPublicDate":"1982-01-01T00:00:00","publicationYear":"1982","noYear":false,"publicationType":{"id":5,"text":"Book chapter"},"publicationSubtype":{"id":24,"text":"Book Chapter"},"title":"Population modeling for furbearer management","docAbstract":"The management of furbearers has become increasingly complex as greater demands are placed on their populations. Correspondingly, needs for information to use in management have increased. Inadequate information leads the manager to err on the conservative side; unless the size of the 'harvestable surplus' is known, the population cannot be fully exploited. Conversely, information beyond what is needed becomes an unaffordable luxury. Population modeling has proven useful for organizing information on numerous game animals. Modeling serves to determine if information of the right kind and proper amount is being gathered; systematizes data collection, data interpretation, and decision making; and permits more effective management and better utilization of game populations. This report briefly reviews the principles of population modeling, describes what has been learned from previous modeling efforts on furbearers, and outlines the potential role of population modeling in furbearer management.","largerWorkType":{"id":4,"text":"Book"},"largerWorkTitle":"Midwest Furbearer Management. N. Central Sec., Central Mountains and Plains Sec., and KS.","largerWorkSubtype":{"id":4,"text":"Other Government Series"},"language":"English","publisher":"The Wildlife Society","publisherLocation":"Bethesda, MD","usgsCitation":"Johnson, D.H., 1982, Population modeling for furbearer management, chap. of Midwest Furbearer Management. N. Central Sec., Central Mountains and Plains Sec., and KS., p. 25-37.","productDescription":"p. 25-37","costCenters":[{"id":480,"text":"Northern Prairie Wildlife Research Center","active":true,"usgs":true}],"links":[{"id":127973,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4ad6e4b07f02db683e8d","contributors":{"editors":[{"text":"Sanderson, G.C.","contributorId":65573,"corporation":false,"usgs":true,"family":"Sanderson","given":"G.C.","email":"","affiliations":[],"preferred":false,"id":504440,"contributorType":{"id":2,"text":"Editors"},"rank":1}],"authors":[{"text":"Johnson, Douglas H. 0000-0002-7778-6641","orcid":"https://orcid.org/0000-0002-7778-6641","contributorId":70327,"corporation":false,"usgs":true,"family":"Johnson","given":"Douglas","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":295962,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70011872,"text":"70011872 - 1982 - Origin and distribution of tonsteins in late permian coal seams of Southwestern China","interactions":[],"lastModifiedDate":"2024-02-24T01:37:09.918607","indexId":"70011872","displayToPublicDate":"1982-01-01T00:00:00","publicationYear":"1982","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2033,"text":"International Journal of Coal Geology","active":true,"publicationSubtype":{"id":10}},"title":"Origin and distribution of tonsteins in late permian coal seams of Southwestern China","docAbstract":"We have surveyed the areal and stratigraphic distribution of tonsteins in Late Permian coalfields of southwestern China over an area of several hundred thousand square kilometers. We studied the relationship between tonstein distribution and sedimentary environment. Based on mineralogical and petrographic data, we have concluded that these tonsteins originated as air-fall volcanic ashes. Following accumulation in the peat swamps, in situ alteration of the vitric and lithic components took place under acidic conditions, leading to the formation of kaolinite.
Based on petrologic, mineralogic, and chemical analytical data, we have determined that the application of mineralogic and geochemical criteria for tonsteins may be useful in correlating coal beds, predicting coal qualities and reconstructing related sedimentary paleoenvironmental conditions.
Chemical and light-stable isotope data are presented for water samples from the Raft River geothermal area and environs. On the basis of chemical character, as defined by a trilinear plot of per cent milliequivalents, and light-stable isotope data, the waters in the geothermal area can be divided into waters that have and have not mixed with cold water. The non-mixed waters have essentially a constant value of light-stable isotopes but show a large variation in chloride content. The variation of chloride composition is not the usual pattern for deep geothermal waters, where it is normally assumed that the deep water has a single chloride composition. Different mixed waters also have hot-water sources of varying chloride composition. Plots of chloride values on cross-sections show that water circulation patterns are confused, with non-mixed waters having different chloride concentrations located in close proximity. Three models can explain the characteristics of the deep geothermal water: (1) in addition to near-surface mixing of cold and hot water, there is deep mixing of two hot waters with the same enthalpy and isotopic composition but differing chloride concentrations to produce the range of chloride concentrations found in the deep geothermal water; (2) there is a single deep hot water, and the range of chloride concentrations is produced by the water passing through a zone of highly soluble materials (most likely in the sedimentary section above the basement) in which waters have different residence times or slightly different circulation paths; (3) the varying chloride concentrations in space have been caused by varying chloride concentrations in the deep feed water through time. Some of this older water has not been flushed from the system by the natural discharge. Although one model may seem more plausible than the others, the available data do not rule out any of them. Data for water samples from the Raft River and Jim Sage Mountains show that water from these areas is probably the source for the cold mixing water determined from end-members on mixing lines. Data for water samples in the Upper Raft River Valley show that the thermal anomaly found at Almo 1 is probably not related to the Raft River geothermal area. The water is different in type as shown by its placement on a trilinear plot, and the isotopes are different enough to show that it is probably a different water. Isotopic compositions of samples from a wide area around the Raft River geothermal system indicate that the likely source of the recharge water is the southern Albion Mountains and western Raft River Mountains. The recharge area is at one end of the Narrows zone, and the geothermal area is along the Narrows zone; thus it is likely that the Narrows zone defines the circulation path.
","language":"English","publisher":"Elsevier","doi":"10.1016/0375-6505(82)90030-X","issn":"03756505","usgsCitation":"Nathenson, M., Nehring, N., Crosthwaite, E., Harmon, R., Janik, C., and Borthwick, J., 1982, Chemical and light-stable isotope characteristics of waters from the Raft River geothermal area and environs, Cassia County, Idaho; Box Elder County, Utah: Geothermics, v. 11, no. 4, p. 215-237, https://doi.org/10.1016/0375-6505(82)90030-X.","productDescription":"23 p.","startPage":"215","endPage":"237","numberOfPages":"23","costCenters":[],"links":[{"id":221117,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"11","issue":"4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f547e4b0c8380cd4c157","contributors":{"authors":[{"text":"Nathenson, M.","contributorId":46632,"corporation":false,"usgs":true,"family":"Nathenson","given":"M.","email":"","affiliations":[],"preferred":false,"id":361260,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Nehring, N.L.","contributorId":21157,"corporation":false,"usgs":true,"family":"Nehring","given":"N.L.","email":"","affiliations":[],"preferred":false,"id":361259,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Crosthwaite, E. G.","contributorId":83098,"corporation":false,"usgs":true,"family":"Crosthwaite","given":"E. G.","affiliations":[],"preferred":false,"id":361262,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Harmon, R.S.","contributorId":6585,"corporation":false,"usgs":true,"family":"Harmon","given":"R.S.","email":"","affiliations":[],"preferred":false,"id":361257,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Janik, C.","contributorId":82458,"corporation":false,"usgs":true,"family":"Janik","given":"C.","affiliations":[],"preferred":false,"id":361261,"contributorType":{"id":1,"text":"Authors"},"rank":5},{"text":"Borthwick, J.","contributorId":18905,"corporation":false,"usgs":true,"family":"Borthwick","given":"J.","email":"","affiliations":[],"preferred":false,"id":361258,"contributorType":{"id":1,"text":"Authors"},"rank":6}]}} ,{"id":70011874,"text":"70011874 - 1982 - Total individual ion activity coefficients of calcium and carbonate in seawater at 25°C and 35%. salinity, and implications to the agreement between apparent and thermodynamic constants of calcite and aragonite","interactions":[],"lastModifiedDate":"2018-03-21T15:10:24","indexId":"70011874","displayToPublicDate":"1982-01-01T00:00:00","publicationYear":"1982","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1759,"text":"Geochimica et Cosmochimica Acta","active":true,"publicationSubtype":{"id":10}},"title":"Total individual ion activity coefficients of calcium and carbonate in seawater at 25°C and 35%. salinity, and implications to the agreement between apparent and thermodynamic constants of calcite and aragonite","docAbstract":"We have calculated the total individual ion activity coefficients of carbonate and calcium, ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si1.gif\" "\\"\\"")
and ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si2.gif\" "\\"\\"")
, in seawater. Using the ratios of stoichiometric and thermodynamic constants of carbonic acid dissociation and total mean activity coefficient data measured in seawater, we have obtained values which differ significantly from those widely accepted in the literature. In seawater at 25°C and 35%. salinity the (molal) values of ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si3.gif\" "\\"\\"")
and ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si4.gif\" "\\"\\"")
are 0.038 ± 0.002 and 0.173 ± 0.010, respectively. These values of ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si7.gif\" "\\"\\"")
and ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si8.gif\" "\\"\\"")
are independent of liquid junction errors and internally consistent with the value ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si9.gif\" "\\"\\"")
. By defining ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si10.gif\" "\\"\\"")
and ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si11.gif\" "\\"\\"")
on a common scale (![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si12.gif\" "\\"\\"")
), the product ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si13.gif\" "\\"\\"")
![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si14.gif\" "\\"\\"")
is independent of the assigned value of ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si15.gif\" "\\"\\"")
and may be determined directly from thermodynamic measurements in seawater. Using the value ![\"\"](\"http://ars.els-cdn.com/content/image/1-s2.0-0016703782902526-si16.gif\" "\\"\\"")
and new thermodynamic equilibrium constants for calcite and aragonite, we show that the apparent constants of calcite and aragonite are consistent with the thermodynamic equilibrium constants at 25°C and 35%. salinity. The demonstrated consistency between thermodynamic and apparent constants of calcite and aragonite does not support a hypothesis of stable Mg-calcite coatings on calcite or aragonite surfaces in seawater, and suggests that the calcite critical carbonate ion curve of Broecker and Takahashi (1978,Deep-Sea Research25, 65–95) defines the calcite equilibrium boundary in the oceans, within the uncertainty of the data.
Seismic refraction data with a dense areal distribution were collected to study the seismic structure of Mount Hood and the surrounding region. This area is typical of Cascade volcanoes and is geologically quite complex. The prime goals of this project were to search for velocity variations in the upper crustal rocks and to determine if the velocity of these rocks is anisotropic. A new system, including 100 remote recording units, was developed to facilitate the collection of data in this type of survey. The data collected in this study reveal a large variation in velocity and thickness of the uppermost crustal rocks that is probably typical of the High Cascade province. A regional structural pattern surrounding Mount Hood, where there is a marked thinning of low-velocity near-surface rocks, suggests that the present edifice of Mount Hood lies on top of a much larger structure, possibly the roof of a large batholith that was emplaced prior to the eruption of the volcanic rocks that form the modern mountain. A straightforward time term analysis of the data reveals this structure. When the time terms are used to correct the travel time observations for the variation in structure under each station, the remaining set of residuals indicates a variation of travel time with azimuth. While a systematic error in the time term reduction cannot be ruled out, this variation is probably the result of anisotropic velocity structure in the underlying refractor. The alignment of the direction of maximum velocity with the direction of maximum principal stress and the decrease in anisotropy with depth suggest that the anisotropic velocity structure is related to the opening and closing of fractures in the present stress field. The direction of maximum velocity is about N25°W, and the degree of anisotropy appears to vary with depth from about 3% near the surface to zero at depths below 8 km.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/JB087iB01p00339","issn":"01480227","usgsCitation":"Kohler, W., Healy, J.H., and Wegener, S., 1982, Upper crustal structure of the Mount Hood, Oregon, region as revealed by time term analysis: Journal of Geophysical Research Solid Earth, v. 87, no. B1, p. 339-355, https://doi.org/10.1029/JB087iB01p00339.","productDescription":"17 p.","startPage":"339","endPage":"355","numberOfPages":"17","costCenters":[],"links":[{"id":221135,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"87","issue":"B1","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"505bbd56e4b08c986b328f8e","contributors":{"authors":[{"text":"Kohler, W.M.","contributorId":62999,"corporation":false,"usgs":true,"family":"Kohler","given":"W.M.","email":"","affiliations":[],"preferred":false,"id":362190,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Healy, J. H.","contributorId":48968,"corporation":false,"usgs":true,"family":"Healy","given":"J.","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":362189,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Wegener, S.S.","contributorId":67654,"corporation":false,"usgs":true,"family":"Wegener","given":"S.S.","email":"","affiliations":[],"preferred":false,"id":362191,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70011242,"text":"70011242 - 1982 - Assessment of models proposed for the 1981 revision of the IGRF","interactions":[],"lastModifiedDate":"2024-04-25T11:20:18.426624","indexId":"70011242","displayToPublicDate":"1982-01-01T00:00:00","publicationYear":"1982","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2310,"text":"Journal of Geomagnetism & Geoelectricity","active":true,"publicationSubtype":{"id":10}},"title":"Assessment of models proposed for the 1981 revision of the IGRF","docAbstract":"For the second revision of the International Geomagnetic Reference Field (IGRF), the U. S. National Aeronautics and Space Administration (NASA), the U. K. Institute of Geological Sciences (IGS), and the U. S. Geological Survey (USGS) submitted proposed models of the Earth's main magnetic field at 1965.0, 1970.0, 1975.0, and 1980.0, and its secular variation during 1980-1985. We assessed the proposed models by comparing them with annual mean values from worldwide magnetic observatories, data for 1978-1980 from 63 U. S. magnetic repeat stations, and rates-of-change values for worldwide magnetic observatories for 1965-1985 that were derived from straight lines fitted to annual means for five-year intervals. We also mutually compared the 1980 models.
The relative displacements of the walls of many veins, joints, and dikes demonstrate that these structures are dilatant cracks. We infer that dilatant cracks propagate in a principal stress plane, normal to the maximum tensile or least compressive stress. Arrays of echelon crack segments appear to emerge from the peripheries of some dilatant cracks. Breakdown of a parent crack into an echelon array may be initiated by a spatial or temporal rotation of the remote principal stresses about an axis parallel to the crack propagation direction. Near the parent-crack tip, a rotation of the local principal stresses is induced in the same sense, but not necessarily through the same angle. Incipient echelon cracks form at the parent-crack tip normal to the local maximum tensile stress. Further longitudinal growth along surfaces that twist about axes parallel to the propagation direction realigns each echelon crack into a remote principal stress plane. The walls of these twisted cracks may be idealized as helicoidal surfaces. An array of helicoidal cracks sweeps out less surface area than one parent crack twisting through the same angle. Thus, many echelon cracks grow from a single parent because the work done in creating the array, as measured by its surface area, decreases as the number of cracks increases. In cross sections perpendicular to the propagation direction, echelon cracks grow laterally, each crack overlapping its neighbors, until the mechanical interaction of adjacent cracks limits this growth. Dilation of each crack pinches the tips of adjacent cracks into an asymmetrical form and introduces local stresses that can cause lateral growth along a curving, sigmoidal path. Sigmoidal echelon cracks may link at tip-to-plane intersections, leaving a step in the through-going crack wall. The geometry of dilatant echelon cracks may be used to infer spatial or temporal changes in the orientation of principal stresses in the Earth.
Analyses of Sm-Nd and U-Th-Pb systematics, REE, Ba, Sr, Rb and K concentrations were carried out for whole rock and mineral separates from the Nakhla meteorite. The 1.26 ±.07 b.y. Sm-Nd age obtained in this work is in good agreement with those previously obtained by the Rb-Sr and Ar-Ar methods. The high initial ϵNd value of +16 suggests that Nakhla was derived from a light REE-depleted, old planetary mantle source. U-Th-Pb data, after correction for pre-analytical terrestrial Pb contamination assuming an age of 1.26 b.y., suggest that the age of the Nakhla source is ⩽4.33 b.y. The agreement in the age determined by three independent radiometric methods and the high initial ϵNd value strongly suggest that the 1.3 b.y. age dates one thorough igneous event in the parent body which not only reset these isotopic systems but also established the chemical and petrologic characteristics observed for the Nakhla meteorite.
Using a three-stage Sm-Nd evolution model in combination with LIL element data and estimated partition coefficients, we have tested partial melting and fractional crystallization models to estimate LIL element abundances in a possible Nakhla source. Our model calculations suggest that partial melting of the light REE-depleted source followed by extensive fractional crystallization (⩾50%) of the partial melt could account for the REE abundances in the Nakhla constituent minerals. The estimated source is depleted in the light REE, Ba, Rb and K and therefore may resemble the MORB source in the earth's upper mantle or the upper 60–300 km of the moon.
The significantly younger age of Nakhla than the youngest lunar rock; the young differentiation age inferred from the U-Th-Pb data, and the estimated LIL element abundances (including those of K, U and Th) in the source suggest that the Nakhla meteorite may have been derived from a relatively large, well-differentiated planetary body such as Mars.
","language":"English","publisher":"Elsevier","doi":"10.1016/0016-7037(82)90314-3","issn":"00167037","usgsCitation":"Nakamura, N., Unruh, D., Tatsumoto, M., and Hutchison, R., 1982, Origin and evolution of the Nakhla meteorite inferred from the Sm-Nd and U-Pb systematics and REE, Ba, Sr, Rb and K abundances: Geochimica et Cosmochimica Acta, v. 46, no. 9, p. 1555-1573, https://doi.org/10.1016/0016-7037(82)90314-3.","productDescription":"19 p.","startPage":"1555","endPage":"1573","numberOfPages":"19","costCenters":[],"links":[{"id":220785,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"46","issue":"9","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a70b1e4b0c8380cd7619b","contributors":{"authors":[{"text":"Nakamura, N.","contributorId":94034,"corporation":false,"usgs":true,"family":"Nakamura","given":"N.","email":"","affiliations":[],"preferred":false,"id":361688,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Unruh, D.M.","contributorId":8498,"corporation":false,"usgs":true,"family":"Unruh","given":"D.M.","email":"","affiliations":[],"preferred":false,"id":361685,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Tatsumoto, M.","contributorId":76798,"corporation":false,"usgs":true,"family":"Tatsumoto","given":"M.","email":"","affiliations":[],"preferred":false,"id":361687,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Hutchison, R.","contributorId":64386,"corporation":false,"usgs":true,"family":"Hutchison","given":"R.","email":"","affiliations":[],"preferred":false,"id":361686,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70011696,"text":"70011696 - 1982 - The chemical and isotopic record of rock-water interaction in the Sherman Granite, Wyoming and Colorado","interactions":[],"lastModifiedDate":"2012-03-12T17:18:27","indexId":"70011696","displayToPublicDate":"1982-01-01T00:00:00","publicationYear":"1982","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1336,"text":"Contributions to Mineralogy and Petrology","active":true,"publicationSubtype":{"id":10}},"title":"The chemical and isotopic record of rock-water interaction in the Sherman Granite, Wyoming and Colorado","docAbstract":"Chemical, isotopic, radiographic, and rock-leaching data are combined to describe the effects of rock-water interactions in core samples of petrographically fresh, 1.43 b.y.-old Sherman Granite. The data serve to identify sensitive indicators of incipient alteration and to estimate the degree, pathways, and timing of element mobilization. Unfractured core samples of Sherman Granite are remarkably fresh by most chemical or isotopic criteria, but incipient alteration is indicated by the abundance and distribution of uranium and the degree of radioactive equilibration of uranium with its decay products. Uranium abundances which are out of equilibrium with lead decay products indicate remobilization of a portion (3 to 60 percent) of original uranium in late Phanerozoic time. Association of uranium with minor but pervasive secondary alteration products also indicates some remobilization. The amount of apparent uranium mobility in unfractured Sherman Granite (3 to 60 percent) is small compared to the results of similar studies of Archean granites from nearby localities. Chemical and isotopic data evaluated as a function of core-sample depth suggest a uranium migrational pathway involving near-surface leaching and reconcentration at depth. Movement of solutions through the upper 200 ft (60 m) of Sherman Granite is fracture controlled, and brecciated granite shows more obvious petrographic, chemical, and isotopic evidence of alteration and multi-element redistribution. Laboratory experiments using freshly crushed Sherman Granite confirm that uranium is leached in preference to elements such as Si, Mg, Ca, and K, and that leachable uranium is situated close to the solid-liquid interface; perhaps as uranium along grain boundaries, in crystal defects, or on cleavage traces of minerals that exclude uranium from their structure. ?? 1981 Springer-Verlag.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Contributions to Mineralogy and Petrology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisherLocation":"Springer-Verlag","doi":"10.1007/BF00398915","issn":"00107999","usgsCitation":"Zielinski, R.A., Peterman, Z.E., Stuckless, J., Rosholt, J., and Nkomo, I.T., 1982, The chemical and isotopic record of rock-water interaction in the Sherman Granite, Wyoming and Colorado: Contributions to Mineralogy and Petrology, v. 78, no. 3, p. 209-219, https://doi.org/10.1007/BF00398915.","startPage":"209","endPage":"219","numberOfPages":"11","costCenters":[],"links":[{"id":221129,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":205089,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/BF00398915"}],"volume":"78","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505baa28e4b08c986b322730","contributors":{"authors":[{"text":"Zielinski, R. A. 0000-0002-4047-5129","orcid":"https://orcid.org/0000-0002-4047-5129","contributorId":106930,"corporation":false,"usgs":true,"family":"Zielinski","given":"R.","email":"","middleInitial":"A.","affiliations":[{"id":164,"text":"Central Energy Resources Science Center","active":true,"usgs":true}],"preferred":false,"id":361735,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Peterman, Z. E.","contributorId":63781,"corporation":false,"usgs":true,"family":"Peterman","given":"Z.","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":361734,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Stuckless, J. S.","contributorId":6060,"corporation":false,"usgs":true,"family":"Stuckless","given":"J. S.","affiliations":[],"preferred":false,"id":361731,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Rosholt, J.N.","contributorId":37749,"corporation":false,"usgs":true,"family":"Rosholt","given":"J.N.","email":"","affiliations":[],"preferred":false,"id":361732,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Nkomo, Ignatius T.","contributorId":61044,"corporation":false,"usgs":true,"family":"Nkomo","given":"Ignatius","email":"","middleInitial":"T.","affiliations":[],"preferred":false,"id":361733,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70011763,"text":"70011763 - 1982 - Unroofing history of a suture zone in the Himalaya of Pakistan by means of fission-track annealing ages","interactions":[],"lastModifiedDate":"2023-12-12T23:16:46.276496","indexId":"70011763","displayToPublicDate":"1982-01-01T00:00:00","publicationYear":"1982","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1427,"text":"Earth and Planetary Science Letters","active":true,"publicationSubtype":{"id":10}},"title":"Unroofing history of a suture zone in the Himalaya of Pakistan by means of fission-track annealing ages","docAbstract":"The uplift history of the Swat Valley and Hazara region of northwestern Pakistan has been established using 22 fission-track dates on apatite, zircon and sphene. A major fault, the Main Mantle Thrust (MMT) strikes east-west across the Swat Valley, separates regions of markedly differing fission-track age regimesm, and may be a suture zone separating an extinct island arc terrane on the north from the Indian plate to the south. Fission-track ages ranging from about 55 to 58 m.y. for sphene, 18 to 53 m.y. for zircon, and 9 to 17 m.y. for apatite were obtained from the region north of the MMT. To the south the fission-track age ranges are 20 to 25 m.y. for sphene, 17 to 26 m.y. for zircon, and 16 to 23 m.y. for apatite. Disparate zircon and sphene ages on each side of the MMT imply different cooling histories for each side of the fault prior to 15 m.y. Similar apatite ages on both sides of the fault imply similar cooling histories during the past 15 m.y. This may indicate that faulting ceased by 15 m.y. Mean uplift rates have been derived from the fission-track data using mainly the mineral-pair method. Uplift rates in the region north of the MMT increased from 0.07 to 0.20 mm/yr during the period 55 to 15 m.y. South of the fault, uplift rates averaged in excess of 0.70 mm/yr for the period 25 to 15 m.y. During the past 15 m.y. uplift across the MMT in the Swat Valley showsno discontinuities, ranging from 0.16 mm/yr in the south to 0.39 mm/yr in the north. A plausible interpretation for the fission-track uplift data has the MMT verging to the south with overthrusting taking place at a depth between 3.5 and 6.0 km, juxtaposing two terranes that were originally separated by a substantial, but unknown distance. In this model, regional uplift followed cessation of faulting just prior to 15 m.y.
The 210 Pb distribution, the clay mineralogy distribution, and the distribution of three trace metals, barium, lead, and manganese, in the sediments of the south Texas shelf are related to the dynamics of the sedimentary transport process. 210 Pb, whose concentration is time dependent, defines three loci of recent sediment accumulations. In addition, the variation of 210 Pb activity at the sediment-water interface delineates areas of terrestrial sedimentation from hemipelagic sedimentation. The clay mineralogy composition of the bottom and suspended sediments assists in defining the origin of the persistent nepheloid layer and bottom sediment. Barium, a major element used in drilling mud, tags sediment movement from areas of hydrocarbon exploration. Lead concentrations, anthropogenically introduced from urban areas, tag the sediment derived from the metropolitan complexes of coastal Texas. Manganese, because of diagenic mobilization, is concentrated in areas of very slow sediment accumulation. The distribution of these geochemical properties of the sediment are in direct response to the sediment regime of the shelf. Based on this data, a model of sediment transport and deposition which relates currents, wind, tides, sediment flux, and precipitation has been formulated. This model differs from the \"advective\" transport or convergent current schemes previously proposed for this shelf.