Random tilting of a single paleomagnetic vector produces a distribution of vectors which is not rotationally symmetric about the original vector and therefore not Fisherian. Monte Carlo simulations were performed on two types of vector distributions: (1) distributions of vectors formed by perturbing a single original vector with a Fisher distribution of bedding poles (each defining a tilt correction) and (2) standard Fisher distributions. These simulations demonstrate that inclinations of vectors drawn from both distributions are biased toward shallow inclinations. There is a greater likelihood of statistically “drawing” a vector shallower than the true mean vector than of drawing one that is steeper. The estimated probability increases as a function of angular dispersion and inclination of the true mean vector. Consequently, the interpretation of inclination-only data from either type of distribution is not straightforward, especially when the expected paleolatitude is greater than about 50°. Because of the symmetry of the two distributions, declinations of vectors in each distribution are unbiased. The Fisher mean direction of the distribution of vectors formed by perturbing a single vector with random undetected tilts is biased toward shallow inclinations, but this bias is insignificant for angular dispersions of bedding poles less than 20°. This observation implies that the mean pole calculated from a large set of paleomagnetic directions obtained for coeval rocks over a region will be effectively unbiased by random undetected tilts of those rocks provided the angular dispersion of the undetected tilts is less than about 20°. However, the bias of the mean can be significant for large (>20°) angular dispersion of tilts. The amount of bias of the mean direction maximizes at about 10°–12° in mid-latitude regions but is usually less than 8°. Consequently, large (>12°) inclination discordances are probably not the result of random undetected tilts, even if the angular dispersion of the tilts exceeds 20°.
An iterative least-squares technique is used to simultaneously invert the strong-motion records and teleseismic P waveforms for the 1978 Tabas, Iran, earthquake to deduce the rupture history. The effects of using different data sets and different parametrizations of the problem (linear versus nonlinear) are considered. A consensus of all the inversion runs indicates a complex, multiple source for the Tabas earthquake, with four main source regions over a fault length of 90 km and an average rupture velocity of 2.5 km/sec.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0810020305","usgsCitation":"Hartzell, S., and Mendoza, C., 1991, Application of an iterative least-squares waveform inversion of strong-motion and teleseismic records to the 1978 Tabas, Iran, earthquake: Bulletin of the Seismological Society of America, v. 81, no. 2, p. 305-331, https://doi.org/10.1785/BSSA0810020305.","productDescription":"27 p.","startPage":"305","endPage":"331","numberOfPages":"27","costCenters":[],"links":[{"id":422104,"rank":2,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.geoscienceworld.org/ssa/bssa/article/81/2/305/119398/Application-of-an-iterative-least-squares-waveform"},{"id":225068,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Iran","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n 55.959619141672704,\n 35.59561293693908\n ],\n [\n 55.959619141672704,\n 32.76041757496367\n ],\n [\n 59.65102539167262,\n 32.76041757496367\n ],\n [\n 59.65102539167262,\n 35.59561293693908\n ],\n [\n 55.959619141672704,\n 35.59561293693908\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"81","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059ec96e4b0c8380cd49370","contributors":{"authors":[{"text":"Hartzell, S.","contributorId":12603,"corporation":false,"usgs":true,"family":"Hartzell","given":"S.","email":"","affiliations":[],"preferred":false,"id":374069,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Mendoza, C.","contributorId":82059,"corporation":false,"usgs":true,"family":"Mendoza","given":"C.","email":"","affiliations":[],"preferred":false,"id":374070,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70016748,"text":"70016748 - 1991 - Lower Paleozoic host rocks in the Getchell gold belt: Several distinct allochthons or a sequence of continuous sedimentation?","interactions":[],"lastModifiedDate":"2024-01-24T01:09:20.227214","indexId":"70016748","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1796,"text":"Geology","active":true,"publicationSubtype":{"id":10}},"title":"Lower Paleozoic host rocks in the Getchell gold belt: Several distinct allochthons or a sequence of continuous sedimentation?","docAbstract":"The lower Paleozoic rocks that host gold deposits along the Getchell gold belt in Humboldt County, Nevada, represent several allochthonous terranes rather than a sequence of continuous deposition. The term \"terrane\" is used only in a descriptive sense. Evidence for allochthonous terranes in this area includes fault boundaries and differences in age, lithology, and structural style among several rock sequences. The two most widespread and distinct terranes in the area are (1) the Osgood terrane, which consists of intensely deformed, regionally metamorphosed, marine rocks (Lower Cambrian Osgood Mountain Quartzite, Lower Cambrian to Lower Ordovician Preble Formation, and some rocks currently mapped as Comus Formation) and (2) the Getchell terrane, which consists of less deformed chert, clastic sedimentary rocks, and volcanic rocks (rocks mapped as Valmy and Vinini Formations, including Lower and Upper Ordovician and Lower Silurian strata in this region). Osgood-terrane bedding and foliation dip predominantly eastward, and folds verge westward. Getchell-terrane folds verge southeastward. The Comus Formation, which is Middle Ordovician at its type locality on Edna Mountain, represents a third terrane (Iron Point terrane) situated structurally between the Osgood and Getchell terranes. Use of the unit name Comus Formation outside the type locality has created confusion and needs reexamination. Some of the rocks currently mapped as Comus Formation might really be part of the other terranes.
Jasper Seamount is a young, mid-sized (690 km3) oceanic intraplate volcano located about 500 km west-southwest of San Diego, California. Reliable 40Ar/39Ar age data were obtained for several milligram-sized samples of 4 to 10 Ma plagioclase by using a defocused laser beam to clean the samples before fusion. Gee and Staudigel suggested that Jasper Seamount consists of a transitional to tholeiitic shield volcano formed by flank transitional series lavas, overlain by flank alkalic series lavas and summit alkalic series lavas. Twenty-nine individual 40Ar/39Ar laser fusion analyses on nine samples confirm the stratigraphy:10.3-10.0 Ma for the flank transitional series, 8.7-7.5 Ma for the flank alkalic series, and 4.8-4.1 Ma for the summit alkalic series. The alkalinity of the lavas clearly increases with time, and there appear to be 1 to 3 m.y. hiatuses between each series. The age data are consistent with the complex magnetic anomaly of Jasper; however, the dominant reversed polarity inferred from the anomaly suggests that most of the seamount formed at ca. 11 Ma, prior to the onset of Chron C5N. The duration of volcanism of Jasper Seamount is slightly longer than the duration of volcanism at Hawaiian volcanoes, suggesting that individual age data from seamounts may constrain the age of a seamount only to within about 7 m.y. unless the stage of volcanism can be unambiguously determined. Extrapolating from the results of our study, similar precision in age determinations should be possible on 50 mg of 1 Ma plagioclase from mid-ocean ridge basalt, opening new possibilities in the geochronology of young, low-potassium volcanic rocks.
Several international programs have identified the need for a global 1-kilometer spatial database for land cover and land characterization studies. In 1992, the US Geological Survey (USGS) EROS Data Center (EDC), the European Space Agency (ESA), the National Oceanic and Atmospheric Administration (NOAA) and the National Aeronautics and Space Administration (NASA) will collect and archive all 1-kilometer Advanced Very High Resolution Radiometer (AVHRR) data acquired during afternoon orbital passes over land.
The Wasatch fault zone (WFZ) forms the eastern boundary of the Basin and Range province and is the longest continuous, active normal fault (343 km) in the United States. It underlies an urban corridor of 1.6 million people (80% of Utah's population) representing the largest earthquake risk in the interior of the western United States.
We have used paleoseismological data to identify 10 discrete segments of the WFZ. Five are active, medial segments with Holocene slip rates of 1–2 mm a−1, recurrence intervals of 2000–4000 years and average lengths of about 50 km. Five are less active, distal segments with mostly pre-Holocene surface ruptures, late Quaternary slip rates of <0.5 mm a−1 recurrence intervals of ≥10,000 years and average lengths of about 20 km. Surface-faulting events on each of the medial segments of the WFZ formed 2–4-m-high scarps repeatedly during the Holocene; latest Pleistocene (14–15 ka) deposits commonly have scarps as much as 15–20 m in height. Segments identified from paleoseismological studies of other major late Quaternary normal faults in the northern Basin and Range province are 20–25 km long, or about half of that proposed for the medial segments of the WFZ.
","language":"English","publisher":"Elsevier","doi":"10.1016/0191-8141(91)90062-N","issn":"01918141","usgsCitation":"Machette, M.N., Personius, S., Nelson, A., Schwartz, D.P., and Lund, W., 1991, The Wasatch fault zone, utah-segmentation and history of Holocene earthquakes: Journal of Structural Geology, v. 13, no. 2, p. 137-149, https://doi.org/10.1016/0191-8141(91)90062-N.","productDescription":"13 p.","startPage":"137","endPage":"149","numberOfPages":"13","costCenters":[],"links":[{"id":223465,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"13","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505ba97be4b08c986b3222c3","contributors":{"authors":[{"text":"Machette, M. N.","contributorId":19561,"corporation":false,"usgs":true,"family":"Machette","given":"M.","email":"","middleInitial":"N.","affiliations":[],"preferred":false,"id":373292,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Personius, S. F. 0000-0001-8347-7370","orcid":"https://orcid.org/0000-0001-8347-7370","contributorId":31408,"corporation":false,"usgs":true,"family":"Personius","given":"S. F.","affiliations":[],"preferred":false,"id":373293,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Nelson, A.R. 0000-0001-7117-7098","orcid":"https://orcid.org/0000-0001-7117-7098","contributorId":55078,"corporation":false,"usgs":true,"family":"Nelson","given":"A.R.","affiliations":[],"preferred":false,"id":373295,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Schwartz, David P. 0000-0001-5193-9200","orcid":"https://orcid.org/0000-0001-5193-9200","contributorId":52968,"corporation":false,"usgs":true,"family":"Schwartz","given":"David","middleInitial":"P.","affiliations":[],"preferred":false,"id":373294,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Lund, W.R.","contributorId":58781,"corporation":false,"usgs":true,"family":"Lund","given":"W.R.","email":"","affiliations":[],"preferred":false,"id":373296,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70184475,"text":"70184475 - 1991 - Birds of the Kilbuck and Ahklun mountain region, Alaska","interactions":[],"lastModifiedDate":"2018-07-15T11:02:21","indexId":"70184475","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":1,"text":"Federal Government Series"},"seriesTitle":{"id":58,"text":"North American Fauna","active":false,"publicationSubtype":{"id":1}},"title":"Birds of the Kilbuck and Ahklun mountain region, Alaska","docAbstract":"Between 1952 and 1988, we studied the abundance, distribution, occurrence, and habitats used by birds in the northwest portion of Bristol Bay and the adjacent Kilbuck and Ahklun mountains. In the 809 days we were present, we conducted 53 studies or surveys of birds in the region. We gathered information on 185 species, of which 65% (121) nested, 10% (19) probably nested, and 11% (21) were permanent residents in the region. Most breeding or probably breeding forms were of North American (58%; 81) or Beringian (24%; 33) affinity, while the remainder of the species were of Panboreal (17%; 24) and Old World (1%; 2) affinity. Similarly, most of the 44 migrants and visitants were of North American (41%; 18) affinity, while the remainder were of Beringian (32%; 14) and Panboreal (27%; 12) affinity. Of the 140 species that nested or probably nested, 53% (73) were abundant to fairly common, 29% (40) were uncommon to very rare, and 20% (27) were localized. Shrub thicket, dwarf shrub mat, coniferous forest, deciduous forest, mixed deciduous-coniferous forest, and fluviatile water and shoreline habitats supported the greatest diversity of species breeding and suspected of breeding. The highest concentrations of birds occurred in the estuaries of Nanvak, Chagvan, and Goodnews bays during spring and fall migrations and on the coastal and island cliffs during the breeding season.
The information presented here provides the basis for range extensions of several species. Our records further clarify the known or probable Alaska breeding ranges of 11 species (fork-tailed storm-petrel, Oceanodroma furcata; double-crested cormorant, Phalacrocorax auritus; red-faced cormorant, Phatacrocorax utile, brant, Branta bernicla; king eider, Somateria spectabilis; white-tailed ptarmigan, Lagopus leucurus; black-bellied plover, Pluvialis squatarola; Pacific golden-plover, Pluvialis fulva; lesser yellowlegs, Tringa flavipes; Say's phoebe, Sayomis saya; and Bohemian waxwing, Bombycilla garrulus). We also provide further information on distributions or documentation of unusual occurrences for nine taxa (frigatebird, Fregata spp.; Baikal teal, Anas formosa; American kestrel, Falco sparverius; Terek sandpiper, Xenus cinereus; bristle-thighed curlew, Numenius tahitiensis; slaty-backed gull, Larus schistisagus; rufous hummingbird, Selasphorus rufus; song sparrow, Melospiza melodia; and red-winged blackbird, Agelaius phoeniceus). We provide quantitative data on the coastal migration of 11 species along Bristol Bay (red-throated loon, Gavia stellata; Pacific loon, Gavia pacifica; pelagic cormorant, Phalacrocorax pelagicus; emperor goose, Chen canagica; brant; Steller's eider, Polysticta stellen; common eider, Somateria mollissima; king eider; black scoter, Melanina nigra; white-winged scoter, Melanina fusca; and surf scoter, Melanina perspicillatd). We document changes in nesting densities, differences in numbers, or habitat variations of 32 species in response to human activities (e.g., semipalmated plover, Charadrius semipalmatus; arctic tern, Sterna paradisaea; tree swallow, Tachycineta bicolor, varied thrush, Ixoreus naevius; yellow-rumped warbler, Dendroica coronata; and American tree sparrow, Spizella arborea). We report the changes in a major colony of Aleutian terns (Sterna aleatico) at irregular intervals over 50 years.
","language":"English","publisher":"U.S. Fish and Wildlife Service","doi":"10.3996/nafa.76.0001","usgsCitation":"Petersen, M.R., Weir, D.N., and Dick, M.H., 1991, Birds of the Kilbuck and Ahklun mountain region, Alaska: North American Fauna, v. 76, 158 p., https://doi.org/10.3996/nafa.76.0001.","productDescription":"158 p.","numberOfPages":"158","costCenters":[{"id":114,"text":"Alaska Science Center","active":true,"usgs":true}],"links":[{"id":488553,"rank":0,"type":{"id":41,"text":"Open Access External Repository Page"},"url":"https://digital.library.unt.edu/ark:/67531/metadc700997/","text":"External Repository"},{"id":337278,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Alaska","otherGeospatial":"Ahklun mountains, Bristol Bay, Kilbuck mountains","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -162.98217773437497,\n 58.29217023514878\n ],\n [\n -157.752685546875,\n 58.29217023514878\n ],\n [\n -157.752685546875,\n 61.93378188781818\n ],\n [\n -162.98217773437497,\n 61.93378188781818\n ],\n [\n -162.98217773437497,\n 58.29217023514878\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"76","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"58c3c951e4b0f37a93ee9b86","contributors":{"authors":[{"text":"Petersen, Margaret R. 0000-0001-6082-3189 mrpetersen@usgs.gov","orcid":"https://orcid.org/0000-0001-6082-3189","contributorId":167729,"corporation":false,"usgs":true,"family":"Petersen","given":"Margaret","email":"mrpetersen@usgs.gov","middleInitial":"R.","affiliations":[{"id":117,"text":"Alaska Science Center Biology WTEB","active":true,"usgs":true}],"preferred":true,"id":681636,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Weir, Douglas N.","contributorId":187773,"corporation":false,"usgs":false,"family":"Weir","given":"Douglas","email":"","middleInitial":"N.","affiliations":[],"preferred":false,"id":681637,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Dick, Matthew H.","contributorId":187774,"corporation":false,"usgs":false,"family":"Dick","given":"Matthew","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":681638,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70016543,"text":"70016543 - 1991 - Use of the Priestley-Taylor evaporation equation for soil water limited conditions in a small forest clearcut","interactions":[],"lastModifiedDate":"2018-10-16T16:31:33","indexId":"70016543","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":681,"text":"Agricultural and Forest Meteorology","active":true,"publicationSubtype":{"id":10}},"title":"Use of the Priestley-Taylor evaporation equation for soil water limited conditions in a small forest clearcut","docAbstract":"The Priestley-Taylor equation, a simplification of the Penman equation, was used to allow calculations of evapotranspiration under conditions where soil water supply limits evapotranspiration. The Priestley-Taylor coefficient, α, was calculated to incorporate an exponential decrease in evapotranspiration as soil water content decreases. The method is appropriate for use when detailed meteorological measurements are not available. The data required to determine the parameter for the α coefficient are net radiation, soil heat flux, average air temperature, and soil water content. These values can be obtained from measurements or models.
The dataset used in this report pertains to a partially vegetated clearcut forest site in southwest Oregon with soil depths ranging from 0.48 to 0.70 m and weathered bedrock below that. Evapotranspiration was estimated using the Bowen ratio method, and the calculated Priestley-Taylor coefficient was fitted to these estimates by nonlinear regression. The calculated Priestley-Taylor coefficient (α′) was found to be approximately 0.9 when the soil was near field capacity (0.225 cm3 cm−3). It was not until soil water content was less than 0.14 cm3 cm−3 that soil water supply limited evapotranspiration. The soil reached a final residual water content near 0.05 cm3 cm−3 at the end of the growing season.
","language":"English","publisher":"Elsevier","doi":"10.1016/0168-1923(91)90094-7","issn":"01681923","usgsCitation":"Flint, A.L., and Childs, S., 1991, Use of the Priestley-Taylor evaporation equation for soil water limited conditions in a small forest clearcut: Agricultural and Forest Meteorology, v. 56, no. 3-4, p. 247-260, https://doi.org/10.1016/0168-1923(91)90094-7.","productDescription":"14 p.","startPage":"247","endPage":"260","costCenters":[{"id":154,"text":"California Water Science Center","active":true,"usgs":true}],"links":[{"id":222856,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"56","issue":"3-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bbf9be4b08c986b329c64","contributors":{"authors":[{"text":"Flint, Alan L. 0000-0002-5118-751X aflint@usgs.gov","orcid":"https://orcid.org/0000-0002-5118-751X","contributorId":1492,"corporation":false,"usgs":true,"family":"Flint","given":"Alan","email":"aflint@usgs.gov","middleInitial":"L.","affiliations":[{"id":657,"text":"Western Geographic Science Center","active":true,"usgs":true},{"id":154,"text":"California Water Science Center","active":true,"usgs":true}],"preferred":true,"id":373856,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Childs, S.W.","contributorId":26449,"corporation":false,"usgs":true,"family":"Childs","given":"S.W.","email":"","affiliations":[],"preferred":false,"id":373855,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70016541,"text":"70016541 - 1991 - Sources and magnitude of bias associated with determination of polychlorinated biphenyls in environmental samples","interactions":[],"lastModifiedDate":"2023-03-08T17:48:35.000803","indexId":"70016541","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":761,"text":"Analytical Chemistry","active":true,"publicationSubtype":{"id":10}},"title":"Sources and magnitude of bias associated with determination of polychlorinated biphenyls in environmental samples","docAbstract":"Recently compiled data on the composition of commercial Aroclor mixtures and ECD (electron capture detector) response factors for all 209 PCB congeners are used to develop estimates of the bias associated with determination of polychlorinated blphenyis. During quantitation of multlcomponent peaks by congener-specific procedures error is introduced because of variable ECD response to isomeric PCBs. Under worst case conditions, the magnitude of this bias can range from less than 2% to as much as 600%. Multicomponent peaks containing the more highly and the lower chlorinated congeners experience the most bias. For this reason, quantitation of ΣPCB in Aroclor mixtures dominated by these species (e.g. 1016) are potentially subject to the greatest error. Comparison of response factor data for ECDs from two laboratories shows that the sign and magnitude of calibration bias for a given multicomponent peak is variable and depends, in part, on the response characteristics of individual detectors. By using the most abundant congener (of each multicomponent peak) for purposes of calibration, one can reduce the maximum bias to less than 55%. Moreover, due to cancellation of errors, the bias resulting from summation of all peak concentrations (i.e. ΣPCB) becomes vanishingly small (<1.2%). In contrast, bias associated with determination of ΣPCB as Aroclor equivalents by the traditional Aroclor method is potentially large (>200%) and highly variable in sign and magnitude. In this case, bias originates not only from the incomplete chromatographic resolution of PCB congeners but also the overlapping patterns of the Aroclor mixtures. Together these results illustrate the advantages of the congener-specific method of PCB quantitation over the traditional Aroclor Method and the extreme difficulty of estimating bias incurred by the latter procedure on a post hoc basis.
","language":"English","publisher":"ACS Publications","doi":"10.1021/ac00019a012","usgsCitation":"Eganhouse, R., and Gossett, R.W., 1991, Sources and magnitude of bias associated with determination of polychlorinated biphenyls in environmental samples: Analytical Chemistry, v. 63, no. 19, p. 2130-2137, https://doi.org/10.1021/ac00019a012.","productDescription":"8 p.","startPage":"2130","endPage":"2137","numberOfPages":"8","costCenters":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true}],"links":[{"id":222854,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"63","issue":"19","noUsgsAuthors":false,"publicationDate":"2002-05-01","publicationStatus":"PW","scienceBaseUri":"505b9357e4b08c986b31a43e","contributors":{"authors":[{"text":"Eganhouse, Robert P. eganhous@usgs.gov","contributorId":2031,"corporation":false,"usgs":true,"family":"Eganhouse","given":"Robert P.","email":"eganhous@usgs.gov","affiliations":[{"id":436,"text":"National Research Program - Eastern Branch","active":true,"usgs":true}],"preferred":true,"id":373850,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gossett, R. W.","contributorId":47086,"corporation":false,"usgs":true,"family":"Gossett","given":"R.","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":373849,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70016538,"text":"70016538 - 1991 - Seismicity and detection/location threshold in the southern Great Basin seismic network","interactions":[],"lastModifiedDate":"2024-04-26T11:30:11.373037","indexId":"70016538","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2312,"text":"Journal of Geophysical Research","active":true,"publicationSubtype":{"id":10}},"title":"Seismicity and detection/location threshold in the southern Great Basin seismic network","docAbstract":"A spatially varying model of the detection/location capabilities of the Southern Great Basin seismic network (SGBSN) has been derived that is based on simple empirical relations and statistics. This permits use of almost all the catalog data gathered; instead of ignoring data that are below the threshold of completeness, a spatially varying threshold model is developed so that subregions having lower completeness levels than the network as a whole can be outlined and the completeness level of each sub-region determined. Such a model is required to unambiguously identify regions that are aseismic due to natural processes rather than to limited detection and/or location capabilities. Accounting for spatial variations in detection/location threshold is also important for studies in which magnitude-frequency distributions are interpreted in terms of source scaling properties. The characteristics of the spatial distribution of earthquakes, where earthquake clusters and aseismic regions locate, appear to be stable at all magnitude levels so that inferences about where strain is being accommodated will be the same whether numbers of earthquakes or strain estimated from seismic moments are examined. For the southern Great Basin region these principal characteristics include clusters at the northern end of the Furnace Creek fault and in the Pahranagat Shear Zone, and a relatively large number of earthquakes in the northern and southeastern portions of the Nevada Test Site. These clusters cover regions much larger than the surface projections of any of the mapped faults. The extent to which seismicity is induced by nuclear testing is unclear. The predominantly aseismic regions include the area west of the Death Valley/Furnace Creek fault system and an almost complete absence of events at Yucca Mountain. Finally, a considerable number of isolated events in the SGBSN catalog cannot be correlated with mapped faults.
Methods of measuring volumes of water withdrawn from the Snake River and its tributaries and pumped through closed‐conduit irrigation systems were needed for equitable management of and resolution of conflicts over water use. On the basis of evaluations and field tests by researchers from the University of Idaho, Water Resources Research Institute, Moscow, Idaho, an impeller meter was selected to monitor pumpage through closed‐conduit systems. In 1988, impeller meters were installed at 20 pumping stations along the Snake River between the Upper Salmon Falls and C.J. Strike Dams. Impeller‐derived pumpage data were adjusted if they differed substantially from ultrasonic flow‐meter‐ or current‐meter‐derived values. Comparisons of pumpage data obtained by ultrasonic flow‐meter and current‐meter measurements indicated that the ultrasonic flow meter was a reliable means to check operation of impeller meters. The equipment generally performed satisfactorily, and reliable pumpage data could be obtained using impeller meters in closed‐conduit irrigation systems. Many pumping stations that divert water from the Snake River for irrigation remain unmeasured; however, regression analyses indicate that total pumpage can be reasonably estimated on the basis of electrical power consumption data, an approximation of total head at a pumping station, and a derived coefficient.
","language":"English","publisher":"ASCE","doi":"10.1061/(ASCE)0733-9437(1991)117:5(748)","issn":"07339437","usgsCitation":"Kjelstrom, L., 1991, Methods of measuring pumpage through closed-conduit irrigation systems: Journal of Irrigation and Drainage Engineering, v. 117, no. 5, p. 748-757, https://doi.org/10.1061/(ASCE)0733-9437(1991)117:5(748).","productDescription":"10 p.","startPage":"748","endPage":"757","numberOfPages":"10","costCenters":[],"links":[{"id":223370,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"117","issue":"5","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a5603e4b0c8380cd6d31b","contributors":{"authors":[{"text":"Kjelstrom, L.C.","contributorId":89104,"corporation":false,"usgs":true,"family":"Kjelstrom","given":"L.C.","email":"","affiliations":[],"preferred":false,"id":373705,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70016532,"text":"70016532 - 1991 - Low intensity of the geomagnetic field in early Jurassic time","interactions":[],"lastModifiedDate":"2024-04-26T12:25:06.929138","indexId":"70016532","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2312,"text":"Journal of Geophysical Research","active":true,"publicationSubtype":{"id":10}},"title":"Low intensity of the geomagnetic field in early Jurassic time","docAbstract":"From a large collection of Jurassic continental tholeiites cropping out in Europe and Africa, we selected 90 samples for paleointensity determinations. The samples were carefully selected to avoid any secondary magnetizations, especially viscous magnetization. Use of the Thellier method reveals that magnetic property changes due to heating begin often at quite low temperatures but fortunately without modifying noticeably their natural remanent magnetization-thermoremanent magnetization ratio. Twenty-eight well-clustered paleointensity estimates were obtained from two European dikes that were emplaced during Early Jurassic time: the Kerforne dike at Brenterc'h in Brittany (northwestern France) and the Messejana dike on the Iberian Peninsula (Spain and Portugal). Virtual dipole moments calculated from both magmatic units are similar and only about one-third of present-day values. These new data lend support to the recently postulated low dipole moment of the Mesozoic geomagnetic field.
Little field-scale research has been done to evaluate the effectiveness of compacted soil barriers in retarding the movement of water and leachates. In response to this need, the Illinois State Geological Survey constructed and instrumented an experimental compacted soil liner. Infiltration of water into the liner has been monitored for two years. The objectives of this investigation were to determine whether a soil liner could be constructed to meet the U.S. EPA's requirement for a saturated hydraulic conductivity of less than or equal to 1.0×10−7 cm/s, to quantify the areal variability of the hydraulic properties of the liner, and to determine the transit time for water and tracers through the liner.
The liner measures 8 m×15 m×0.9 m and was designed and constructed to simulate compacted soil liners built at waste disposal facilities. The surface of the liner was flooded to form a pond on April 12, 1988. Since flooding, infiltration has been monitored with four large-ring (LR) and 32 small-ring (SR) infiltrometers, and a water-balance (WB) method that accounted for total infiltration and evaporation. Ring-infiltrometer and WB data were analyzed using cumulative-infiltration curves to determine infiltration fluxes. The SR data are lognormally distributed, and the SR and LR data form two statistically distinct populations. Small-ring data are nearly identical with WB data; because there is evidence of leakage in the LRs, the SR and WB data are considered more reliable.
Geostatistical analysis of the SR infiltration data revealed that the infiltration-flux data were unstructured (random) at scales greater than 0.8 m. This analysis shows that it is possible to construct a compacted soil liner with a uniformly low saturated hydraulic conductivity, and that classical statistics should adequately estimate the mean infiltration flux of the liner and the associated uncertainty in that value.
Saturated hydraulic conductivity of the liner was estimated using Darcy's Law and the Green-Ampt Approximation; the average values for these calculations, based on the first and second years of SR data, were 4.0×10−8 and 3.4×10−8 cm/s, respectively. Breakthrough of water at the liner's bottom is expected to occur approximately six years after the initial ponding of the liner.
The Coastal Plain of the eastern United States is a low-latitude, low-altitude, low-relief terrain composed primarily of gently dipping marine and marginal-marine sediments that range in age from Cretaceous to Quaternary. Population density of the area is moderate, and most of the population is concentrated along the coast. Inland of the coast, agriculture, including growing trees for pulp, is the dominant economy. In this region, soils have developed along two different pathways. One pathway is dominated by the dissolution and movement of oxyhydroxides and the accumulation of organic matter; the other by the accumulation of clays and oxyhydroxyides and the adsorption or oxidation of organic matter. The first pathway has resulted in the formation of Spodosols; the second, in the development of Ultisols. No clearly distinguishable age trends have been identified in the Spodosols, but the properties of Ultisols can be measured to quantify surface material alteration through time. Ultisols are, therefore, suited to order-of-magnitude chronostratigraphic interpretations. Potentially, data derived through the study of Ultisols can be used to develop models that predict how surface processes will change due to continued weathering and pedogenesis or as the result of climate change.
","language":"English","publisher":"Elsevier","doi":"10.1016/0016-7061(91)90072-2","issn":"00167061","usgsCitation":"Markewich, H.W., and Pavich, M., 1991, Soil chronosequence studies in temperate to subtropical, low-latitude, low-relief terrain with data from the eastern United States: Geoderma, v. 51, no. 1-4, p. 213-239, https://doi.org/10.1016/0016-7061(91)90072-2.","productDescription":"27 p.","startPage":"213","endPage":"239","costCenters":[],"links":[{"id":223072,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Alabama, Delaware, Florida, Georgia, Maryland, New Jersey, New York, North Carolina, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -83.65740498515868,\n 29.56073216248066\n ],\n [\n -81.04209111575037,\n 29.70294791375342\n ],\n [\n -81.32008465430667,\n 30.336573155280433\n ],\n [\n -81.28926863352359,\n 30.839173001811446\n ],\n [\n -81.10795333948283,\n 31.675802100881526\n ],\n [\n -80.41054135680525,\n 32.2155811685203\n ],\n [\n -79.35141323445242,\n 32.88262853802331\n ],\n [\n -78.9951818009355,\n 33.080517055495775\n ],\n [\n -78.95338088751612,\n 33.44486091823089\n ],\n [\n -78.43340354833373,\n 33.73958574559721\n ],\n [\n -77.95669806937994,\n 33.63505845729995\n ],\n [\n -77.625425186773,\n 34.193993116921305\n ],\n [\n -77.05536053640651,\n 34.44958955891752\n ],\n [\n -76.27800212167642,\n 34.6980372864103\n ],\n [\n -75.66034727003597,\n 35.679759013216795\n ],\n [\n -75.63024711439672,\n 36.24611046119435\n ],\n [\n -75.75291815153346,\n 37.05242613609788\n ],\n [\n -75.64382189128256,\n 37.48612546856154\n ],\n [\n -75.04061840870713,\n 38.24571164914883\n ],\n [\n -74.54606120086645,\n 39.04666102268308\n ],\n [\n -74.16065699691825,\n 39.44510284389685\n ],\n [\n -73.91123229815838,\n 39.7461249726409\n ],\n [\n -73.98987192172642,\n 40.300395445354866\n ],\n [\n -73.67383075027301,\n 41.16024579379487\n ],\n [\n -73.45562020409652,\n 42.246377813940796\n ],\n [\n -73.24874940925498,\n 42.77550842067669\n ],\n [\n -77.29144540745926,\n 42.927755716296105\n ],\n [\n -77.37766959325147,\n 42.007514196380015\n ],\n [\n -79.64501061925347,\n 41.94853624470812\n ],\n [\n -79.6460568639244,\n 42.335962204424845\n ],\n [\n -80.50438839794788,\n 41.91098127866414\n ],\n [\n -80.5741585555397,\n 40.899542931395075\n ],\n [\n -80.73285291549277,\n 40.590263414786904\n ],\n [\n -80.69694400260454,\n 40.31039863298716\n ],\n [\n -80.96570253434754,\n 39.652857933995165\n ],\n [\n -81.418963558928,\n 39.414911863833964\n ],\n [\n -81.61948307147509,\n 39.43380229891457\n ],\n [\n -81.84637289319473,\n 39.14138287378918\n ],\n [\n -82.1359093662436,\n 39.02190171059155\n ],\n [\n -82.29219319714245,\n 38.798170410820376\n ],\n [\n -82.31564745443391,\n 38.52257047831131\n ],\n [\n -82.68922659569647,\n 38.45411056377512\n ],\n [\n -82.68906036545968,\n 38.195994304719164\n ],\n [\n -82.29806540311749,\n 37.645361355803544\n ],\n [\n -82.16905474335533,\n 37.455881280933184\n ],\n [\n -82.86080922721337,\n 37.11295010525521\n ],\n [\n -82.98927778322748,\n 36.92357308197964\n ],\n [\n -83.16094469814301,\n 36.871352448668105\n ],\n [\n -83.8447722119688,\n 36.59092866212001\n ],\n [\n -84.50260830666883,\n 36.25450391102903\n ],\n [\n -85.38289141785889,\n 35.59608738764305\n ],\n [\n -86.54619672147197,\n 34.68748424448863\n ],\n [\n -88.09453878295756,\n 34.65713328405975\n ],\n [\n -88.45882387865532,\n 32.28457646965607\n ],\n [\n -88.47957915470448,\n 30.412663603338416\n ],\n [\n -87.7830130061835,\n 30.251488905804294\n ],\n [\n -87.60687215829314,\n 30.11344712321747\n ],\n [\n -87.26815773703689,\n 30.224147044061937\n ],\n [\n -86.50464178478586,\n 30.3156419338991\n ],\n [\n -85.5675504699858,\n 29.927846128637057\n ],\n [\n -85.391940602425,\n 29.452508157008737\n ],\n [\n -84.43514465045406,\n 29.774246787668204\n ],\n [\n -84.14495900084188,\n 29.964033943908447\n ],\n [\n -83.76866227734911,\n 29.822433980986062\n ],\n [\n -83.65740498515868,\n 29.56073216248066\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"51","issue":"1-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b91f6e4b08c986b319be4","contributors":{"authors":[{"text":"Markewich, H. W.","contributorId":31426,"corporation":false,"usgs":true,"family":"Markewich","given":"H.","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":373560,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Pavich, M.J.","contributorId":70788,"corporation":false,"usgs":true,"family":"Pavich","given":"M.J.","email":"","affiliations":[],"preferred":false,"id":373561,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70016516,"text":"70016516 - 1991 - Implications for organic maturation studies of evidence of a geologically rapid increase and stabilization of vitrinite reflectance at peak temperature: Cerro Prieto geothermal system, Mexico","interactions":[],"lastModifiedDate":"2023-01-19T15:35:41.392266","indexId":"70016516","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","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":"Implications for organic maturation studies of evidence of a geologically rapid increase and stabilization of vitrinite reflectance at peak temperature: Cerro Prieto geothermal system, Mexico","docAbstract":"A short-term rapid heating and cooling of the rock in well M-94 below 1300 m was caused by a pulse of hot water passing through the edge of the Cerro Prieto, Mexico, geothermal system. Below 1300 m, the peak paleotemperatures were about 225-250 degrees C, but equilibrium well log temperatures indicate a decrease to 150-210 degrees C at present. This hot water pulse sharply increased vitrinite reflectance to levels comparable to those measured in the central part of the system, even though studies of apatite fission-track annealing indicate that the duration of heating was only 10{0}-10{1} yr in M-94, in contrast to 10{3}-10{4} yr in the central part of the system.
These data indicate that sedimentary organic matter chemically reacts quickly to temperature increases of about 125 degrees C above ambient, even when the higher temperature existed for only 10{0}-10{1} yr. The quick change of the vitrinite reflectance geothermometer indicates that thermal maturation reactions can stabilize, after a geologically short period of heating, to a level consistent with peak temperature under moderate to high-temperature diagenesis in open, fluid-rich, geothermal systems.
Cerro Prieto is one of the most intensively studied and well-known geothermal systems in the world. Thus, data from Cerro Prieto are a benchmark to compare with the predictions of published thermal maturation models such as those formulated by J. Karweil, N. V. Lopatin, and A. K. Burnham and J. J. Sweeney. These thermal maturation models inaccurately predict duration of heating at Cerro Prieto. The kinetic equations used in these models explicitly allow thermal maturation to continue indefinitely at peak temperature, which does not seem to be the case at Cerro Prieto.
","language":"English","publisher":"American Association of Petroleum Geologists","doi":"10.1306/0C9B2A51-1710-11D7-8645000102C1865D","usgsCitation":"Barker, C., 1991, Implications for organic maturation studies of evidence of a geologically rapid increase and stabilization of vitrinite reflectance at peak temperature: Cerro Prieto geothermal system, Mexico: American Association of Petroleum Geologists Bulletin, v. 75, no. 12, p. 1852-1863, https://doi.org/10.1306/0C9B2A51-1710-11D7-8645000102C1865D.","productDescription":"12 p.","startPage":"1852","endPage":"1863","numberOfPages":"12","costCenters":[],"links":[{"id":223474,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Mexico, United States","otherGeospatial":"Cerro Prieto fault","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -115.93369314042859,\n 33.27841604648326\n ],\n [\n -115.93369314042859,\n 31.617852838278367\n ],\n [\n -114.37067035754815,\n 31.617852838278367\n ],\n [\n -114.37067035754815,\n 33.27841604648326\n ],\n [\n -115.93369314042859,\n 33.27841604648326\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"75","issue":"12","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a3919e4b0c8380cd617d3","contributors":{"authors":[{"text":"Barker, C.E.","contributorId":69991,"corporation":false,"usgs":true,"family":"Barker","given":"C.E.","affiliations":[],"preferred":false,"id":373787,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70016521,"text":"70016521 - 1991 - MBSSAS: A code for the computation of margules parameters and equilibrium relations in binary solid-solution aqueous-solution systems","interactions":[],"lastModifiedDate":"2019-04-10T09:03:20","indexId":"70016521","displayToPublicDate":"1991-01-01T00:00:00","publicationYear":"1991","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1315,"text":"Computers & Geosciences","printIssn":"0098-3004","active":true,"publicationSubtype":{"id":10}},"title":"MBSSAS: A code for the computation of margules parameters and equilibrium relations in binary solid-solution aqueous-solution systems","docAbstract":"The computer code MBSSAS uses two-parameter Margules-type excess-free-energy of mixing equations to calculate thermodynamic equilibrium, pure-phase saturation, and stoichiometric saturation states in binary solid-solution aqueous-solution (SSAS) systems. Lippmann phase diagrams, Roozeboom diagrams, and distribution-coefficient diagrams can be constructed from the output data files, and also can be displayed by MBSSAS (on IBM-PC compatible computers). MBSSAS also will calculate accessory information, such as the location of miscibility gaps, spinodal gaps, critical-mixing points, alyotropic extrema, Henry's law solid-phase activity coefficients, and limiting distribution coefficients. Alternatively, MBSSAS can use such information (instead of the Margules, Guggenheim, or Thompson and Waldbaum excess-free-energy parameters) to calculate the appropriate excess-free-energy of mixing equation for any given SSAS system.