The peritrichous ciliate ‘Epistylis sp.’ involved in the‘red-sore’ disease of various North American freshwater fishes is identified as Heteropolaria colisarum Foissner & Schubert, 1977. Its morphology is redescribed from observations of living and silver-stained organisms and biometrically analysed individuals. Extended zooids can be easily identified by their highly characteristic (elongated) body. Silver impregnations show a very high number of silverlines and a band-like, irregularly formed macronucleus. The genus Heteropolaria belongs to the family Epistylididae and is characterized by the eccentric location of the scopula of the swarmer and a peculiar myoneme in the peristomal disc that branches off the myoneme of the peristomal collar. Autochthonous occurrences of this species are known only from North America. In Europe only the related species H. lwoffi has been found. Histological sections give some evidence that the terminal platelet of the stalk is embedded in the dermal epithelium. This suggests that H. colisarum could be a parasite rather than an epizoon and that the often associated bacterium Aeromonas hydrophila is a secondary invader. However, further studies are necessary. Experiments showed a high infectivity of the ciliate and no host specificity. These characteristics are supported by the observations of other researchers. Preliminary laboratory tests showed that a single treatment with salt solution (NaCl) at a rate of 1.5% for 3h controlled H. colisarum.
Water level observations from tide stations and current observations from current-meter moorings in South San Francisco Bay (South Bay), California have been harmonically analysed. At each tide station, 13 harmonic constituents have been computed by a least-squares regression without inference. Tides in South Bay are typically mixed; there is a phase lag of approximately 1 h and an amplification of 1·5 from north to south for a mean semi-diurnal tide. Because most of the current-meter records are between 14 and 29 days, only the five most important harmonics have been solved for east-west and north-south velocity components. The eccentricity of tidal-current ellipse is generally very small, which indicates that the tidal current in South Bay is strongly bidirectional. The analyses further show that the principal direction and the magnitude of tidal current are well correlated with the basin bathymetry. Patterns of Eulerian residual circulation deduced from the current-meter data show an anticlockwise gyre to the west and a clockwise gyre to the east of the main channel in the summer months due to the prevailing westerly wind. Opposite trends have been observed during winter when the wind was variable.
","language":"English","publisher":"Elsevier","doi":"10.1016/0272-7714(85)90006-X","issn":"02727714","usgsCitation":"Cheng, R.T., and Gartner, J.W., 1985, Harmonic analysis of tides and tidal currents in South San Francisco Bay, California: Estuarine, Coastal and Shelf Science, v. 21, no. 1, p. 57-74, https://doi.org/10.1016/0272-7714(85)90006-X.","productDescription":"18 p.","startPage":"57","endPage":"74","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":222272,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","otherGeospatial":"San Francisco Bay","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -122.31492171250483,\n 37.80882267928874\n ],\n [\n -122.40900839121292,\n 37.8029759392894\n ],\n [\n -122.39632254689272,\n 37.789610224027044\n ],\n [\n -122.39949400797269,\n 37.74866268048801\n ],\n [\n -122.38469385626583,\n 37.734451092534556\n ],\n [\n -122.40160831535962,\n 37.708528820279156\n ],\n [\n -122.40372262274627,\n 37.66502593191984\n ],\n [\n -122.38786531734608,\n 37.65414622325642\n ],\n [\n -122.3952653931994,\n 37.643264920279464\n ],\n [\n -122.38575100995917,\n 37.59888618867872\n ],\n [\n -122.35297924546545,\n 37.58548363043174\n ],\n [\n -122.32337894205173,\n 37.58129483600311\n ],\n [\n -122.29589294602467,\n 37.55280478393831\n ],\n [\n -122.2218921874901,\n 37.484887533061524\n ],\n [\n -122.16057727327573,\n 37.49159816068652\n ],\n [\n -122.14154850679554,\n 37.49830818545604\n ],\n [\n -122.12463404770176,\n 37.46139558943348\n ],\n [\n -122.10877674230159,\n 37.43118081381692\n ],\n [\n -122.04534752070057,\n 37.41858772281982\n ],\n [\n -121.97663253063288,\n 37.408511725080615\n ],\n [\n -121.9554894567658,\n 37.42950185739734\n ],\n [\n -121.93434638289895,\n 37.444611109469776\n ],\n [\n -121.92800346073872,\n 37.46391293655827\n ],\n [\n -121.93751784397895,\n 37.479015239389085\n ],\n [\n -122.01257575620684,\n 37.51172642627711\n ],\n [\n -122.0305473689937,\n 37.49411449062386\n ],\n [\n -122.06966205564764,\n 37.50669486859469\n ],\n [\n -122.05169044286079,\n 37.51927312685231\n ],\n [\n -122.05697621132744,\n 37.5301725692041\n ],\n [\n -122.06649059456765,\n 37.53268759898452\n ],\n [\n -122.08974797582141,\n 37.55196667627858\n ],\n [\n -122.09080512951473,\n 37.56034732873803\n ],\n [\n -122.07600497780788,\n 37.566213224637934\n ],\n [\n -122.0844622073545,\n 37.58548363043174\n ],\n [\n -122.08657651474141,\n 37.59888618867872\n ],\n [\n -122.11934827923513,\n 37.59553577540166\n ],\n [\n -122.13731989202198,\n 37.59469814851079\n ],\n [\n -122.13309127724867,\n 37.6223348571593\n ],\n [\n -122.14366281418222,\n 37.62317217286383\n ],\n [\n -122.15000573634218,\n 37.654983180527296\n ],\n [\n -122.15952011958241,\n 37.67841415370688\n ],\n [\n -122.17114881020927,\n 37.6876171549719\n ],\n [\n -122.18383465452948,\n 37.70351055855673\n ],\n [\n -122.1880632693028,\n 37.731942882017194\n ],\n [\n -122.2134349579432,\n 37.76454299081597\n ],\n [\n -122.26946410369092,\n 37.77624209074396\n ],\n [\n -122.31915032727817,\n 37.78793933959625\n ],\n [\n -122.31492171250483,\n 37.80882267928874\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"21","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a2f78e4b0c8380cd5cdf5","contributors":{"authors":[{"text":"Cheng, R. T.","contributorId":23138,"corporation":false,"usgs":false,"family":"Cheng","given":"R.","email":"","middleInitial":"T.","affiliations":[],"preferred":false,"id":364190,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gartner, J. W.","contributorId":81903,"corporation":false,"usgs":false,"family":"Gartner","given":"J.","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":364191,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70012688,"text":"70012688 - 1985 - Effects of the 1983 Coalinga, California, earthquake on creep along the San Andreas fault","interactions":[],"lastModifiedDate":"2022-12-23T14:57:03.555808","indexId":"70012688","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1135,"text":"Bulletin of the Seismological Society of America","onlineIssn":"1943-3573","printIssn":"0037-1106","active":true,"publicationSubtype":{"id":10}},"title":"Effects of the 1983 Coalinga, California, earthquake on creep along the San Andreas fault","docAbstract":"The M//L approximately equals 6. 5 earthquake that occurred near Coalinga, California, on May 2, 1983 induced changes in near-surface fault slip along the San Andreas fault. Coseismic steps were observed by creepmeters along a 200-km section of the San Andreas. some of the larger aftershocks induced additional steps, both right-lateral and left-lateral, and in general the sequence disrupted observed creep at several sites from preseismic long-term patterns. Static dislocation models can approximately explain the magnitudes and distribution of the larger coseismic steps on May 2. The smaller, more distant steps appear to be the abrupt release of accumulated slip, triggered by the coseismic strain changes, but independent of the strain change amplitudes.","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0750020475","issn":"00371106","usgsCitation":"Mavko, G.M., Schulz, S., and Brown, B.D., 1985, Effects of the 1983 Coalinga, California, earthquake on creep along the San Andreas fault: Bulletin of the Seismological Society of America, v. 75, no. 2, p. 475-489, https://doi.org/10.1785/BSSA0750020475.","productDescription":"15 p.","startPage":"475","endPage":"489","numberOfPages":"15","costCenters":[],"links":[{"id":222548,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":410995,"rank":2,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.geoscienceworld.org/ssa/bssa/article/75/2/475/118685/Effects-of-the-1983-Coalinga-California-earthquake","linkFileType":{"id":5,"text":"html"}}],"country":"United States","state":"California","city":"Coalinga","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -120.54473876953125,\n 35.98245135784044\n ],\n [\n -120.12176513671875,\n 35.98245135784044\n ],\n [\n -120.12176513671875,\n 36.28192129773192\n ],\n [\n -120.54473876953125,\n 36.28192129773192\n ],\n [\n -120.54473876953125,\n 35.98245135784044\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"75","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a045be4b0c8380cd5092b","contributors":{"authors":[{"text":"Mavko, Gerald M.","contributorId":40477,"corporation":false,"usgs":true,"family":"Mavko","given":"Gerald","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":364226,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Schulz, Sandra","contributorId":107701,"corporation":false,"usgs":true,"family":"Schulz","given":"Sandra","affiliations":[],"preferred":false,"id":364228,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Brown, Beth D.","contributorId":97770,"corporation":false,"usgs":true,"family":"Brown","given":"Beth","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":364227,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70012662,"text":"70012662 - 1985 - Geochemistry of great Salt Lake, Utah II: Pleistocene-Holocene evolution","interactions":[],"lastModifiedDate":"2020-01-19T11:15:38","indexId":"70012662","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","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":"Geochemistry of great Salt Lake, Utah II: Pleistocene-Holocene evolution","docAbstract":"Sedimentologic and biostratigraphic evidence is used to develop a geochemical model for Great Salt Lake, Utah, extending back some 30,000 yrs. B.P. Hydrologie conditions as defined by the water budget equation are characterized by a lake initially at a low, saline stage, rising by about 17,000 yrs. B.P. to fresh water basin-full conditions (Bonneville level) and then, after about 15,000 yrs. B.P., dropping rapidly to a saline stage again, as exemplified by the present situation. Inflow composition has changed through time in response to the hydrologie history. During fresh-water periods high discharge inflow is dominated by calcium bicarbonate-type river waters; during saline stages, low discharge, NaCl-rich hydrothermal springs are significant solute sources. This evolution in lake composition to NaCl domination is illustrated by the massive mirabilite deposition, free of halite, following the rapid drawdown until about 8,000 years ago, while historic droughts have yielded principally halite. Hydrologic history can be combined with inferred inflow composition to derive concentration curves with time for each major solute in the lake. Calcium concentrations before the drawdown were controlled by calcite solubility, and afterwards by aragonite. Significant amounts of solutes are removed from the lake by diffusion into the sediments. Na+, Cl- and SO42- are also involved in salt precipitation. By including pore fluid data, a surprisingly good fit has been obtained between solute input over the time period considered and the amounts actually found in lake brines, pore fluids, salt beds and sediments. Excess amounts are present for calcium, carbonate and silica, indicating detrital input.
","language":"English","publisher":"Elsevier","doi":"10.1016/0016-7037(85)90168-1","issn":"00167037","usgsCitation":"Spencer, R.J., Eugster, H., and Jones, B., 1985, Geochemistry of great Salt Lake, Utah II: Pleistocene-Holocene evolution: Geochimica et Cosmochimica Acta, v. 49, no. 3, p. 739-747, https://doi.org/10.1016/0016-7037(85)90168-1.","productDescription":"9 p.","startPage":"739","endPage":"747","numberOfPages":"9","costCenters":[{"id":589,"text":"Toxic Substances Hydrology Program","active":true,"usgs":true}],"links":[{"id":222156,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"Utah","otherGeospatial":"Great Salt Lake","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -113.22509765625,\n 40.6306300839918\n ],\n [\n -111.8792724609375,\n 40.6306300839918\n ],\n [\n -111.8792724609375,\n 41.713930073371294\n ],\n [\n -113.22509765625,\n 41.713930073371294\n ],\n [\n -113.22509765625,\n 40.6306300839918\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"49","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a16f7e4b0c8380cd55329","contributors":{"authors":[{"text":"Spencer, R. J.","contributorId":56664,"corporation":false,"usgs":true,"family":"Spencer","given":"R.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":364166,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Eugster, H.P.","contributorId":99992,"corporation":false,"usgs":true,"family":"Eugster","given":"H.P.","email":"","affiliations":[],"preferred":false,"id":364167,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Jones, B.F.","contributorId":52156,"corporation":false,"usgs":true,"family":"Jones","given":"B.F.","email":"","affiliations":[],"preferred":false,"id":364165,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70012674,"text":"70012674 - 1985 - Evaluation and use of a diffusion-controlled sampler for determining chemical and dissolved oxygen gradients at the sediment-water interface","interactions":[],"lastModifiedDate":"2012-03-12T17:19:01","indexId":"70012674","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1919,"text":"Hydrobiologia","onlineIssn":"1573-5117","printIssn":"0018-8158","active":true,"publicationSubtype":{"id":10}},"title":"Evaluation and use of a diffusion-controlled sampler for determining chemical and dissolved oxygen gradients at the sediment-water interface","docAbstract":"Field and laboratory evaluations were made of a simple, inexpensive diffusion-controlled sampler with ports on two sides at each interval which incorporates 0.2-??m polycarbonate membrane to filter samples in situ. Monovalent and divalent ions reached 90% of equilibrium between sampler contents and the external solution within 3 and 6 hours, respectively. Sediment interstitial water chemical gradients to depths of tens of centimeters were obtained within several days after placement. Gradients were consistent with those determined from interstitial water obtained by centrifugation of adjacent sediment. Ten milliliter sample volumes were collected at 1-cm intervals to determine chemical gradients and dissolved oxygen profiles at depth and at the interface between the sediment and water column. The flux of dissolved species, including oxygen, across the sediment-water interface can be assessed more accurately using this sampler than by using data collected from benthic cores. ?? 1985 Dr W. Junk Publishers.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Hydrobiologia","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisherLocation":"Kluwer Academic Publishers","doi":"10.1007/BF00008680","issn":"00188158","usgsCitation":"Simon, N., Kennedy, M., and Massoni, C., 1985, Evaluation and use of a diffusion-controlled sampler for determining chemical and dissolved oxygen gradients at the sediment-water interface: Hydrobiologia, v. 126, no. 2, p. 135-141, https://doi.org/10.1007/BF00008680.","startPage":"135","endPage":"141","numberOfPages":"7","costCenters":[],"links":[{"id":205224,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/BF00008680"},{"id":222317,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"126","issue":"2","noUsgsAuthors":false,"publicationDate":"1985-07-01","publicationStatus":"PW","scienceBaseUri":"505a0c09e4b0c8380cd529e6","contributors":{"authors":[{"text":"Simon, N.S.","contributorId":103272,"corporation":false,"usgs":true,"family":"Simon","given":"N.S.","email":"","affiliations":[],"preferred":false,"id":364196,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kennedy, M.M.","contributorId":10817,"corporation":false,"usgs":true,"family":"Kennedy","given":"M.M.","email":"","affiliations":[],"preferred":false,"id":364194,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Massoni, C.S.","contributorId":45461,"corporation":false,"usgs":true,"family":"Massoni","given":"C.S.","affiliations":[],"preferred":false,"id":364195,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70012658,"text":"70012658 - 1985 - Well bore breakouts and in situ stress","interactions":[],"lastModifiedDate":"2018-05-01T14:16:09","indexId":"70012658","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","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":"Well bore breakouts and in situ stress","docAbstract":"The detailed cross-sectional shape of stress induced well bore breakouts has been studied using specially processed ultrasonic borehole televiewer data. Breakout shapes are shown for a variety of rock types and introduce a simple elastic failure model which explains many features of the observations. Both the observations and calculations indicate that the breakouts define relatively broad and flat curvilinear surfaces which enlarge the borehole in the direction of minimum horizontal compression. Refs.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Journal of Geophysical Research","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1029/JB090iB07p05523 ","issn":"01480227","usgsCitation":"Zoback, M.D., Moos, D., Mastin, L., and Anderson, R.N., 1985, Well bore breakouts and in situ stress: Journal of Geophysical Research, v. 90, no. B7, p. 5523-5530, https://doi.org/10.1029/JB090iB07p05523 .","startPage":"5523","endPage":"5530","numberOfPages":"8","costCenters":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"links":[{"id":222093,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"90","issue":"B7","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"505bc395e4b08c986b32b269","contributors":{"authors":[{"text":"Zoback, Mark D.","contributorId":102455,"corporation":false,"usgs":true,"family":"Zoback","given":"Mark","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":364157,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Moos, Daniel","contributorId":48573,"corporation":false,"usgs":true,"family":"Moos","given":"Daniel","affiliations":[],"preferred":false,"id":364155,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mastin, Larry","contributorId":36124,"corporation":false,"usgs":true,"family":"Mastin","given":"Larry","affiliations":[],"preferred":false,"id":364154,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Anderson, Roger N.","contributorId":95618,"corporation":false,"usgs":true,"family":"Anderson","given":"Roger","email":"","middleInitial":"N.","affiliations":[],"preferred":false,"id":364156,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70012676,"text":"70012676 - 1985 - Origin and evolution of the alkalic ultramafic rocks in the Coyote Peak diatreme, Humboldt County, California","interactions":[],"lastModifiedDate":"2024-03-19T16:55:41.540911","indexId":"70012676","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","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":"Origin and evolution of the alkalic ultramafic rocks in the Coyote Peak diatreme, Humboldt County, California","docAbstract":"Instrumental-neutron-activation analyses are reported for two uncontaminated rocks, a phlogopite-rich clot, and two contaminated rocks from the Coyote Peak diatreme, northwestern California. These data, combined with Nd, Sr, and Pb isotopic evidence, have been modeled to a multi-stage evolution for the uncontaminated rocks. Fertile mantle material (refractory elements 2.5× chondritic abundances; Rb/Sr = 0.029 by weight) was depleted about 900 m.y. ago by congruent melting and removal of ~4% basaltic liquid; this depleted residue provided the source rock from which the Coyote Peak magma was ultimately derived. About 66 m.y. ago, the depleted mantle residue was incongruently melted in the presence of H2O and CO2 at a total pressure > 26 kb to yield ~0.5% of a Si-poor, Ca-rich melt. This melt then metasomatized depleted garnet-free harzburgite in the upper mantle at about 26 kb to produce a rock similar to phlogopite-bearing wehrlite. About 29 m.y. ago, this rock was subjected to an increase in pressure to >26 kb and incongruently melted to give ~0.5% of a second-stage melt resembling olivine melilitite in composition. Enroute to the surface, about 28% olivine and 2% titanomagnetite were lost from the highly fluid melt.
Coarse-grained phlogopite-rich clots in the uncontaminated rocks apparently crystallized from a latestage liquid derived from the uncontaminated melt. Contaminated rocks appear to be the result of partial assimilation of, and dilution by, ~14% Franciscan graywacke country rock.
The diatreme was emplaced near a converging plate margin where young hot oceanic mantle and crust of the Juan de Fuca plate was probably subducting obliquely beneath a thin lip of the North American plate. The unusual chemistry of the rocks may be the result of this complex tectonic setting which could also have included local strike-slip and extensional environments within the two plates pierced by the diatreme.
Analyses of sea level and current-meter data using digital filters and a variety of statistical methods show a variety of phenomena related to non-local coastal forcing and local tidal forcing in the northern reach of San Francisco Bay, a partially mixed estuary. Low-frequency variations in sea level are dominated by non-local variations in coastal sea level and also show a smaller influence from tidally induced fortnightly sea level variations. Low-frequency currents demonstrate a gravitational circulation which is modified by changes in tidal-current speed over the spring-neap tidal cycle. Transients in gravitational circulation induce internal oscillations with periods of two to four days.
","language":"English","publisher":"Elsevier","doi":"10.1016/0272-7714(85)90003-4","issn":"02727714","usgsCitation":"Walters, R.A., and Gartner, J.W., 1985, Subtidal sea level and current variations in the northern reach of San Francisco Bay: Estuarine, Coastal and Shelf Science, v. 21, no. 1, p. 17-32, https://doi.org/10.1016/0272-7714(85)90003-4.","productDescription":"16 p.","startPage":"17","endPage":"32","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":222316,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"California","otherGeospatial":"San Francisco Bay","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -122.49288365903871,\n 37.83365947740121\n ],\n [\n -122.47252439747213,\n 37.783616975293626\n ],\n [\n -122.40918447259784,\n 37.79255562354507\n ],\n [\n -122.39108735120529,\n 37.76752468391663\n ],\n [\n -122.30965030493846,\n 37.79613078009476\n ],\n [\n -122.28476676302354,\n 37.83187282919371\n ],\n [\n -122.30512602459041,\n 37.91044441089936\n ],\n [\n -122.3435824075495,\n 37.92650554655222\n ],\n [\n -122.39334949137933,\n 37.9443471390919\n ],\n [\n -122.37525236998678,\n 37.960400869467094\n ],\n [\n -122.35036882807188,\n 37.98714928977874\n ],\n [\n -122.31417458528654,\n 37.994280555594\n ],\n [\n -122.28702890319758,\n 38.0014111281601\n ],\n [\n -122.2576210809346,\n 38.03883525882202\n ],\n [\n -122.2417860997161,\n 38.04774294894307\n ],\n [\n -122.20106757658269,\n 38.04596149761244\n ],\n [\n -122.17392189449373,\n 38.0227986859378\n ],\n [\n -122.14451407223075,\n 38.015670193374916\n ],\n [\n -122.12415481066418,\n 38.01923452633122\n ],\n [\n -122.14225193205672,\n 38.05664955536099\n ],\n [\n -122.16713547397163,\n 38.07267871571531\n ],\n [\n -122.22368897832357,\n 38.08336287156371\n ],\n [\n -122.25309680058653,\n 38.117185732724664\n ],\n [\n -122.25535894076057,\n 38.1456559975872\n ],\n [\n -122.27571820232741,\n 38.16700140777752\n ],\n [\n -122.26893178180504,\n 38.23988440653355\n ],\n [\n -122.30965030493846,\n 38.23988440653355\n ],\n [\n -122.37751451016082,\n 38.20256320529367\n ],\n [\n -122.38656307085697,\n 38.15988696526969\n ],\n [\n -122.41144661277187,\n 38.16166564098279\n ],\n [\n -122.44764085555721,\n 38.12786338341408\n ],\n [\n -122.51324292060553,\n 38.12252475326176\n ],\n [\n -122.54038860269422,\n 38.07267871571531\n ],\n [\n -122.51550506077959,\n 38.03883525882202\n ],\n [\n -122.52907790182405,\n 38.01210568707435\n ],\n [\n -122.4680001171238,\n 37.98714928977874\n ],\n [\n -122.51098078043123,\n 37.978234232695755\n ],\n [\n -122.52681576165003,\n 37.94791493791199\n ],\n [\n -122.51324292060553,\n 37.912229154721274\n ],\n [\n -122.53812646252018,\n 37.87474044316498\n ],\n [\n -122.49288365903871,\n 37.83365947740121\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","volume":"21","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505b9d9ae4b08c986b31d941","contributors":{"authors":[{"text":"Walters, R. A.","contributorId":34174,"corporation":false,"usgs":true,"family":"Walters","given":"R.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":364192,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gartner, J. W.","contributorId":81903,"corporation":false,"usgs":false,"family":"Gartner","given":"J.","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":364193,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70185101,"text":"70185101 - 1985 - Diving depths of four alcids","interactions":[],"lastModifiedDate":"2017-03-15T09:46:31","indexId":"70185101","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3544,"text":"The Auk","onlineIssn":"1938-4254","printIssn":"0004-8038","active":true,"publicationSubtype":{"id":10}},"title":"Diving depths of four alcids","docAbstract":"Incidental catches of 12,243 Common Murres (Uria aalge), 875 Atlantic Puffins (Fratercula arctica), 36 Black Guillemots (Cepphus grylle), and 9 Razorbills (Alca torda) were recorded off Newfoundland during the summers of 1980-1982 (26,445 net-days of fishing effort). Most catch occurred in stationary gill nets set on the sea floor at depths of up to 180 m and revealed that murres, Razorbills, puffins, and guillemots can dive to depths of at least 180, 120, 60, and 50 m, respectively. Diving ability appeared to be directly correlated with body size.
","language":"English","publisher":"American Ornithological Society","doi":"10.2307/4086771 ","usgsCitation":"Piatt, J.F., and Nettleship, D.N., 1985, Diving depths of four alcids: The Auk, v. 102, no. 2, p. 293-297, https://doi.org/10.2307/4086771 .","productDescription":"5 p.","startPage":"293","endPage":"297","costCenters":[{"id":114,"text":"Alaska Science Center","active":true,"usgs":true}],"links":[{"id":337565,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"Canada","state":"Newfoundland","volume":"102","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"58c90130e4b0849ce97abd69","contributors":{"authors":[{"text":"Piatt, John F. 0000-0002-4417-5748 jpiatt@usgs.gov","orcid":"https://orcid.org/0000-0002-4417-5748","contributorId":3025,"corporation":false,"usgs":true,"family":"Piatt","given":"John","email":"jpiatt@usgs.gov","middleInitial":"F.","affiliations":[{"id":116,"text":"Alaska Science Center Biology MFEB","active":true,"usgs":true},{"id":114,"text":"Alaska Science Center","active":true,"usgs":true},{"id":117,"text":"Alaska Science Center Biology WTEB","active":true,"usgs":true}],"preferred":true,"id":684352,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Nettleship, David N.","contributorId":35374,"corporation":false,"usgs":false,"family":"Nettleship","given":"David","email":"","middleInitial":"N.","affiliations":[{"id":12590,"text":"Canadian Wildlife Service","active":true,"usgs":false}],"preferred":false,"id":684353,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70012689,"text":"70012689 - 1985 - Determination of elastic wave velocity and relative hypocenter locations using refracted waves. I. Methodology","interactions":[],"lastModifiedDate":"2023-10-29T15:46:39.969615","indexId":"70012689","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1135,"text":"Bulletin of the Seismological Society of America","onlineIssn":"1943-3573","printIssn":"0037-1106","active":true,"publicationSubtype":{"id":10}},"title":"Determination of elastic wave velocity and relative hypocenter locations using refracted waves. I. Methodology","docAbstract":"An arrival time difference method utilizing refracted arrivals from earthquakes in a homogeneous, layered earth model has been developed for the simultaneous determination of near-source (in situ) velocity and relative locations of earthquakes. The method is particularly applicable when analyzing data from arrays in which most of the recording stations are far (i.e., several focal depths) from a group of events. This iterative scheme locates earthquakes relative to a master event and performs an inversion for in situ velocity using a generalized inverseleast squares estimation procedure. Direct arrivals, when available, may be included to stabilize the inversion and increase the accuracy of the event locations. We tested this scheme on artificial data contaminated by random and systematic arrival time errors, gaps in azimuthal coverage, and inaccuracies in the assumed velocity model. As usual, depth is the least well-resolved hypocenter coordinate, but this scheme yielded accurate locations of most events while converging to the correct velocity model.
","language":"English","publisher":"Seismological Society of America","doi":"10.1785/BSSA0750020415","issn":"00371106","usgsCitation":"Shedlock, K.M., and Roecker, S.W., 1985, Determination of elastic wave velocity and relative hypocenter locations using refracted waves. I. Methodology: Bulletin of the Seismological Society of America, v. 75, no. 2, p. 415-426, https://doi.org/10.1785/BSSA0750020415.","productDescription":"12 p.","startPage":"415","endPage":"426","numberOfPages":"12","costCenters":[],"links":[{"id":222549,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"75","issue":"2","noUsgsAuthors":false,"publicationDate":"1985-04-01","publicationStatus":"PW","scienceBaseUri":"5059fd42e4b0c8380cd4e714","contributors":{"authors":[{"text":"Shedlock, Kaye M.","contributorId":61788,"corporation":false,"usgs":true,"family":"Shedlock","given":"Kaye","email":"","middleInitial":"M.","affiliations":[],"preferred":false,"id":364230,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Roecker, Steven W.","contributorId":34266,"corporation":false,"usgs":true,"family":"Roecker","given":"Steven","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":364229,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70012671,"text":"70012671 - 1985 - Recognition of interstitial anhydrite dissolution: A cause of secondary porosity, San Andres limestone, New Mexico, and Upper Minnelusa Formation, Wyoming","interactions":[],"lastModifiedDate":"2023-01-12T16:07:27.451364","indexId":"70012671","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","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":"Recognition of interstitial anhydrite dissolution: A cause of secondary porosity, San Andres limestone, New Mexico, and Upper Minnelusa Formation, Wyoming","docAbstract":"Rectangular and stair-step pore reentrants in carbonate mudstones have been recognized previously as indirect evidence for anhydrite dissolution. In this study, direct evidence for subsurface dissolution of interstitial anhydrite in both dolomite grainstones and quartz sandstones includes: (1) cleavage-related dissolution fringe on anhydrite crystal surfaces, and (2) isolated remnants of optically continuous (formerly poikilotopic) anhydrite. Influenced by the prominent cleavages, the dissolution fringe on the surfaces of the anhydrite crystals consists of a series of sharp, right-angled projections and reentrants. Experimentally etched anhydrite surfaces exhibit features that directly compare to the dissolution fringe, whereas experimentally grown anhydrite does not.
We deduced the following sequence of anhydrite dissolution within dolomite grainstones and quartz sandstones. Slow incipient dissolution began along the boundaries between anhydrite and adjacent minerals. From these intercrystalline boundaries, solutions penetrated anhydrite cleavages, leading to more rapid preferential dissolution perpendicular to the more prominent cleavage planes. The widened cleavage planes, together with intercrystalline boundaries, acted as conduits for the removal of dissolved ions. In the final stage, as dissolving anhydrite borders retreated toward pore throats, dissolution slowed and was, again, restricted to intercrystalline boundaries. This process was then repeated in adjacent interstices.
","language":"English","publisher":"American Association of Petroleum Geologists","doi":"10.1306/AD462B78-16F7-11D7-8645000102C1865D","usgsCitation":"Schenk, C.J., and Richardson, R.W., 1985, Recognition of interstitial anhydrite dissolution: A cause of secondary porosity, San Andres limestone, New Mexico, and Upper Minnelusa Formation, Wyoming: American Association of Petroleum Geologists Bulletin, v. 69, no. 7, p. 1064-1076, https://doi.org/10.1306/AD462B78-16F7-11D7-8645000102C1865D.","productDescription":"13 p.","startPage":"1064","endPage":"1076","numberOfPages":"13","costCenters":[{"id":164,"text":"Central Energy Resources Science Center","active":true,"usgs":true}],"links":[{"id":222271,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"69","issue":"7","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a9334e4b0c8380cd80c8a","contributors":{"authors":[{"text":"Schenk, Christopher J. 0000-0002-0248-7305 schenk@usgs.gov","orcid":"https://orcid.org/0000-0002-0248-7305","contributorId":826,"corporation":false,"usgs":true,"family":"Schenk","given":"Christopher","email":"schenk@usgs.gov","middleInitial":"J.","affiliations":[{"id":164,"text":"Central Energy Resources Science Center","active":true,"usgs":true},{"id":255,"text":"Energy Resources Program","active":true,"usgs":true}],"preferred":true,"id":364188,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Richardson, Randall W.","contributorId":26070,"corporation":false,"usgs":true,"family":"Richardson","given":"Randall","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":364189,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70013079,"text":"70013079 - 1985 - Comparison of aquifer characteristics derived from local and regional aquifer tests","interactions":[],"lastModifiedDate":"2024-03-20T22:56:52.610961","indexId":"70013079","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3825,"text":"Groundwater","active":true,"publicationSubtype":{"id":10}},"title":"Comparison of aquifer characteristics derived from local and regional aquifer tests","docAbstract":"A comparison of the aquifer parameter values obtained through the analysis of a local and a regional aquifer test involving the same area in southeast Georgia is made in order to evaluate the validity of extrapolating local aquifer-test results for use in large-scale flow simulations. Time-drawdown and time-recovery data were analyzed by using both graphical and least-squares fitting of the data to the Theis curve. Additionally, directional transmissivity, transmissivity tensor, and angle of anisotropy were computed for both tests.
","language":"English","publisher":"National Groundwater Association","issn":"0017467X","usgsCitation":"Randolph, R., Krause, R., and Maslia, M., 1985, Comparison of aquifer characteristics derived from local and regional aquifer tests: Groundwater, v. 23, no. 3, p. 309-316.","productDescription":"8 p.","startPage":"309","endPage":"316","numberOfPages":"8","costCenters":[],"links":[{"id":220566,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"23","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f850e4b0c8380cd4cffa","contributors":{"authors":[{"text":"Randolph, R.B.","contributorId":38606,"corporation":false,"usgs":true,"family":"Randolph","given":"R.B.","email":"","affiliations":[],"preferred":false,"id":365234,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Krause, R.E.","contributorId":73210,"corporation":false,"usgs":true,"family":"Krause","given":"R.E.","email":"","affiliations":[],"preferred":false,"id":365235,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Maslia, M.L.","contributorId":24090,"corporation":false,"usgs":true,"family":"Maslia","given":"M.L.","affiliations":[],"preferred":false,"id":365233,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70175631,"text":"70175631 - 1985 - Identification and tabulation of geological contacts in the Edwards aquifer, San Antonio area, Texas","interactions":[],"lastModifiedDate":"2016-08-17T13:50:47","indexId":"70175631","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":2,"text":"State or Local Government Series"},"seriesTitle":{"id":5176,"text":"Texas Department of Water Resources Report","active":true,"publicationSubtype":{"id":2}},"seriesNumber":"LP-199","title":"Identification and tabulation of geological contacts in the Edwards aquifer, San Antonio area, Texas","docAbstract":"No abstract available.
","language":"English","publisher":"Texas Department of Water Resources","usgsCitation":"Small, T.A., 1985, Identification and tabulation of geological contacts in the Edwards aquifer, San Antonio area, Texas: Texas Department of Water Resources Report LP-199, 54 p.","productDescription":"54 p.","onlineOnly":"N","additionalOnlineFiles":"N","costCenters":[{"id":583,"text":"Texas Water Science Center","active":true,"usgs":true}],"links":[{"id":326714,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"57b58b51e4b03bcb0104bc1a","contributors":{"authors":[{"text":"Small, T. A.","contributorId":105731,"corporation":false,"usgs":true,"family":"Small","given":"T.","email":"","middleInitial":"A.","affiliations":[],"preferred":false,"id":645894,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70197164,"text":"70197164 - 1985 - The Steens Mountain (Oregon) geomagnetic polarity transition, 2. Field intensity variations and discussion of reversal models","interactions":[],"lastModifiedDate":"2018-05-18T14:26:27","indexId":"70197164","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2314,"text":"Journal of Geophysical Research B: Solid Earth","active":true,"publicationSubtype":{"id":10}},"title":"The Steens Mountain (Oregon) geomagnetic polarity transition, 2. Field intensity variations and discussion of reversal models","docAbstract":"We carried out an extensive paleointensity study of the 15.5±0.3 m.y. Miocene reversed‐to‐normal polarity transition recorded in lava flows from Steens Mountain (south central Oregon). One hundred eighty‐five samples from the collection whose paleodirectional study is reported by Mankinen et al. (this issue) were chosen for paleointensity investigations because of their low viscosity index, high Curie point and reversibility, or near reversibility, of the strong field magnetization curve versus temperature. Application of the Thellier stepwise double heating method was very successful, yielding 157 usable paleointensity estimates corresponding to 73 distinct lava flows. After grouping successive lava flows that did not differ significantly in direction and intensity, we obtained 51 distinguishable, complete field vectors of which 10 are reversed, 28 are transitional, and 13 are normal. The record is complex, quite unlike that predicted by simple flooding or standing nondipole field models. It begins with an estimated several thousand years of reversed polarity with an average intensity of 31.5±8.5 μT, about one third lower than the expected Miocene intensity. This difference is interpreted as a long‐term reduction of the dipole moment prior to the reversal. When site directions and intensities are considered, truly transitional directions and intensities appear almost at the same time at the beginning of the transition, and they disappear simultaneously at the end of the reversal. Large deviations in declination occur during this approximately 4500±1000 year transition period that are compatible with roughly similar average magnitudes of zonal and nonzonal field components at the site. The transitional intensity is generally low, with an average of 10.9±4.9 μT for directions more than 45° away from the dipole field and a minimum of about 5 μT. The root‐mean‐square of the three field components X, Y, and Z are of the same order of magnitude for the transitional field and the historical nondipole field at the site latitude. However, a field intensity increase to pretransitional values occurs when the field temporarily reaches normal directions, which suggests that dipolar structure could have been briefly regenerated during the transition in an aborted attempt to reestablish a stationary field. Changes in the field vector are progressive but jerky, with at least two, and possibly three, large swings at astonishingly high rates. Each of those transitional geomagnetic impulses occurs when the field intensity is low (less than 10 μT) and is followed by an interval of directional stasis during which the magnitude of the field increases greatly. For the best documented geomagnetic impulse the rapid directional change corresponds to a vectorial intensity change of 6700±2700 nT yr−1, which is about 15–50 times larger than the maximum rate of change of the nondipole field observed during the last centuries. The occurrence of geomagnetic impulses seems to support reversal models assuming an increase in the level of turbulence within the liquid core during transitions. The record closes with an estimated several thousand years of normal polarity with an average intensity of 46.7±20.1 μT, agreeing with the expected Miocene value. However, the occurrence of rather large and apparently rapid intensity fluctuations accompanied by little change in direction suggests that the newly reestablished dipole was still somewhat unstable.
","language":"English","publisher":"AGU","doi":"10.1029/JB090iB12p10417","usgsCitation":"Prevot, M., Mankinen, E.A., Coe, R.S., and Gromme, C.S., 1985, The Steens Mountain (Oregon) geomagnetic polarity transition, 2. Field intensity variations and discussion of reversal models: Journal of Geophysical Research B: Solid Earth, v. 90, no. B12, p. 10417-10448, https://doi.org/10.1029/JB090iB12p10417.","productDescription":"32 p.","startPage":"10417","endPage":"10448","costCenters":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"links":[{"id":354331,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"90","issue":"B12","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"5aff3a76e4b0da30c1bfd9fd","contributors":{"authors":[{"text":"Prevot, M.","contributorId":75679,"corporation":false,"usgs":true,"family":"Prevot","given":"M.","email":"","affiliations":[],"preferred":false,"id":735876,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Mankinen, Edward A. 0000-0001-7496-2681 emank@usgs.gov","orcid":"https://orcid.org/0000-0001-7496-2681","contributorId":1054,"corporation":false,"usgs":true,"family":"Mankinen","given":"Edward","email":"emank@usgs.gov","middleInitial":"A.","affiliations":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"preferred":true,"id":735877,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Coe, Robert S.","contributorId":20477,"corporation":false,"usgs":true,"family":"Coe","given":"Robert","email":"","middleInitial":"S.","affiliations":[],"preferred":false,"id":735878,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Gromme, C. Sherman","contributorId":22236,"corporation":false,"usgs":true,"family":"Gromme","given":"C.","email":"","middleInitial":"Sherman","affiliations":[],"preferred":false,"id":735879,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70013217,"text":"70013217 - 1985 - GROUND-WATER DRAINAGE TO SURFACE MINES REFINED.","interactions":[],"lastModifiedDate":"2012-03-12T17:18:39","indexId":"70013217","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"GROUND-WATER DRAINAGE TO SURFACE MINES REFINED.","docAbstract":"Changes in seepage flux and hydraulic head (ground-water level) resulting from ground-water drainage into the first and subsequent cuts of a surface coal mine can be estimated by a technique that considers drainage from the unsaturated zone and drainage effects of the advancing mine. A 'single-layer' technique is used, in which each layer of a stratified aquifer system is considered separately. Use of the technique requires knowledge of some aquifer characteristics at the proposed mining site and an estimate of the rate of approach of the advancing surface mine.","conferenceTitle":"Hydraulics and Hydrology in the Small Computer Age, Proceedings of the Specialty Conference.","conferenceLocation":"Lake Buena Vista, FL, USA","language":"English","publisher":"ASCE","publisherLocation":"New York, NY, USA","isbn":"0872624749","usgsCitation":"Weiss, L.S., 1985, GROUND-WATER DRAINAGE TO SURFACE MINES REFINED., Hydraulics and Hydrology in the Small Computer Age, Proceedings of the Specialty Conference., Lake Buena Vista, FL, USA, p. 621-626.","startPage":"621","endPage":"626","numberOfPages":"6","costCenters":[],"links":[{"id":220024,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a1484e4b0c8380cd54a83","contributors":{"authors":[{"text":"Weiss, Linda S. lsweiss@usgs.gov","contributorId":2955,"corporation":false,"usgs":true,"family":"Weiss","given":"Linda","email":"lsweiss@usgs.gov","middleInitial":"S.","affiliations":[],"preferred":true,"id":365564,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70197165,"text":"70197165 - 1985 - The Steens Mountain (Oregon) geomagnetic polarity transition: 1. Directional history, duration of episodes, and rock magnetism","interactions":[],"lastModifiedDate":"2018-05-18T14:30:24","indexId":"70197165","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2314,"text":"Journal of Geophysical Research B: Solid Earth","active":true,"publicationSubtype":{"id":10}},"title":"The Steens Mountain (Oregon) geomagnetic polarity transition: 1. Directional history, duration of episodes, and rock magnetism","docAbstract":"The thick sequence of Miocene lava flows exposed on Steens Mountain in southeastern Oregon is well known for containing a detailed record of a reversed‐to‐normal geomagnetic polarity transition. Paleomagnetic samples were obtained from the sequence for a combined study of the directional and intensity variations recorded; the paleointensity study is reported in a companion paper. This effort has resulted in the first detailed history of total geomagnetic field behavior during a reversal of polarity. A comparison of the directional variation history of the reversed and normal polarity intervals on either side of the transition with the Holocene record has allowed an estimate of the duration of these periods to be made. These time estimates were then used to calculate accumulation rates for the volcanic sequence and thereby provide a means for estimating time periods within the transition itself. The polarity transition was found to consist of two phases, each with quite different characteristics. At the onset of the first phase, a one‐third decrease in magnetic field intensity may have preceded the first intermediate field directions by about 600 years. Changes in field direction were confined near the local north‐south vertical plane when the actual reversal in direction occurred and normal polarity directions may have been attained within 550±150 years. The end of the first phase of the transition was marked by a brief (possibly 100–300 years) period with normal polarity and a pretransitional intensity which suggests a quasi‐normal dipole field structure existed during this interval. The second phase of the transition was characterized by a return to very low field intensities with the changes in direction describing a long counterclockwise loop in contrast to the earlier narrowly constrained changes. This second phase lasted 2900±300 years, and both normal directions and intensities were recovered at the same time. Both directional and intensity data document very erratic geomagnetic field behavior during the polarity transition. Changes in magnetic field direction were variable and occurred either (1) in a regular, progressive manner, (2) with sudden, extremely rapid angular changes (58°±21°/year), or (3) with little or no movement for periods of the order of 600±200 years. Changes in magnetic intensity occurred in a like manner and were sometimes correlated with changes in direction, but during other periods both directional and intensity changes occurred independently. Directional changes following the polarity transition occurred in a seemingly normal manner, although intensity fluctuations attest to some instability of the newly reestablished dipole.
","language":"English","publisher":"AGU","doi":"10.1029/JB090iB12p10393","usgsCitation":"Mankinen, E.A., Prevot, M., Gromme, C.S., and Coe, R.S., 1985, The Steens Mountain (Oregon) geomagnetic polarity transition: 1. Directional history, duration of episodes, and rock magnetism: Journal of Geophysical Research B: Solid Earth, v. 90, no. B12, p. 10393-10416, https://doi.org/10.1029/JB090iB12p10393.","productDescription":"24 p.","startPage":"10393","endPage":"10416","costCenters":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"links":[{"id":354332,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"90","issue":"B12","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"5aff3a76e4b0da30c1bfd9fb","contributors":{"authors":[{"text":"Mankinen, Edward A. 0000-0001-7496-2681 emank@usgs.gov","orcid":"https://orcid.org/0000-0001-7496-2681","contributorId":1054,"corporation":false,"usgs":true,"family":"Mankinen","given":"Edward","email":"emank@usgs.gov","middleInitial":"A.","affiliations":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"preferred":true,"id":735880,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Prevot, M.","contributorId":75679,"corporation":false,"usgs":true,"family":"Prevot","given":"M.","email":"","affiliations":[],"preferred":false,"id":735881,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Gromme, C. Sherman","contributorId":22236,"corporation":false,"usgs":true,"family":"Gromme","given":"C.","email":"","middleInitial":"Sherman","affiliations":[],"preferred":false,"id":735882,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Coe, Robert S.","contributorId":20477,"corporation":false,"usgs":true,"family":"Coe","given":"Robert","email":"","middleInitial":"S.","affiliations":[],"preferred":false,"id":735883,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70013215,"text":"70013215 - 1985 - STREAMFLOW LOSSES, CONSEQUENT FLOW THROUGH A THICK UNSATURATED ZONE, AND RECHARGE TO AN UNCONFINED AQUIFER.","interactions":[],"lastModifiedDate":"2012-03-12T17:18:39","indexId":"70013215","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"STREAMFLOW LOSSES, CONSEQUENT FLOW THROUGH A THICK UNSATURATED ZONE, AND RECHARGE TO AN UNCONFINED AQUIFER.","docAbstract":"Two experiments were conducted in conjunction with a 23-day aquifer test made in south-central Arizona to determine (1) water loss from a natural channel and (2) flow through a 330-foot-thick unsaturated zone overlying an unconfined aquifer. The experiments provided control for the aquifer test plus results relative to arid land hydrology. The increases of soil moisture within the 330-foot-thick unsaturated zone and the consequent water-level rises show that recharge can occur quickly and that relatively large amounts of water can be recharged through thick sequences of unsaturated material.","conferenceTitle":"Development and Management Aspects of Irrigation and Drainage Systems.","conferenceLocation":"San Antonio, TX, USA","language":"English","publisher":"ASCE","publisherLocation":"New York, NY, USA","isbn":"0872624722","usgsCitation":"Marie, J., 1985, STREAMFLOW LOSSES, CONSEQUENT FLOW THROUGH A THICK UNSATURATED ZONE, AND RECHARGE TO AN UNCONFINED AQUIFER., Development and Management Aspects of Irrigation and Drainage Systems., San Antonio, TX, USA, p. 486-487.","startPage":"486","endPage":"487","numberOfPages":"2","costCenters":[],"links":[{"id":220022,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505aaf97e4b0c8380cd87694","contributors":{"authors":[{"text":"Marie, J.R.","contributorId":63416,"corporation":false,"usgs":true,"family":"Marie","given":"J.R.","email":"","affiliations":[],"preferred":false,"id":365561,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70012748,"text":"70012748 - 1985 - Uranium mineralization in the Smith Lake district of the Grants uranium region, New Mexico.","interactions":[],"lastModifiedDate":"2024-01-08T23:40:50.926431","indexId":"70012748","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1472,"text":"Economic Geology","active":true,"publicationSubtype":{"id":10}},"title":"Uranium mineralization in the Smith Lake district of the Grants uranium region, New Mexico.","docAbstract":"The Mariano Lake and Ruby 1 uranium orebodies, which together comprise much of the uranium ore in the Smith Lake district of the Grants uranium region, New Mexico, occur in sandstones in the lower part of the Brushy Basin Member of the Upper Jurassic Morrison Formation. The orebodies, which are offset by faults of Laramide age, are enriched in an amorphous organic material that was introduced into the host sandstone after deposition. The enrichment by this organic material, in ore, is an important characteristic of the primary uranium deposits in the Grants uranium region. However, the close proximity of the chemically reduced ore zones to oxidized rock is suggestive that the deposits represent accumulations of uranium redistributed by reduction-oxidation processes from preexisting primary deposits.Within the ores, whole-rock abundances of organic carbon correlate positively with uranium contents. This correlation is consistent with petrologic evidence which indicates that uranium is everywhere intimately admixed with the amorphous organic material. Ore zones are also enriched in vanadium (as ore-stage vanadiferous chlorite) and sulfur (as ore-stage iron disulfide minerals with delta 34 S values ranging from -29 to -42ppm).Petrographic observations demonstrate that Smith Lake uranium mineralization occurred early (before major burial compaction) in the paragenetic sequence of host-rock diagenetic alterations but was preceded by precipitation of authigenic iron disulfides (delta 34 S values ranging from -11 to -38ppm), mixed-layered smectite-illite clays, and potassium feldspars.Additional preore alterations included dissolution of detrital sanidine and plagioclase and the leaching of iron from detrital iron-titanium oxide grains. Following mineralization, varying amounts of authigenic calcite and barite formed, both of which were partly replaced by kaolinitc. Oxidation of some previously formed iron disulfide minerals occurred late in the paragenetic sequence, as did localized precipitation of native selenium, pyrite, and very minor amounts of uranium minerals.The positive correlation between contents of uranium and organic carbon and the admixture of uranium with the amorphous organic material indicates that the Mariano Lake and Ruby 1 deposits are primary-type uranium orebodies. The offset of orebodies by Laramide faults and radiometric age determinations of the ores are also consistent with a primary origin for the deposits. Late Tertiary oxygenated ground waters locally modified original chemical and mineralogical characteristics of the ores in part by leaching some uranium. Secondary uranium minerals precipitated from the partly leached primary ores are sparse in the mine area; such recycled uranium appears to represent an insignificant proportion of the total uranium in the Smith Lake district.
","language":"English","publisher":"Society of Economic Geologists","doi":"10.2113/gsecongeo.80.5.1348","issn":"03610128","usgsCitation":"Fishman, N., Reynolds, R.L., and Robertson, J., 1985, Uranium mineralization in the Smith Lake district of the Grants uranium region, New Mexico.: Economic Geology, v. 80, no. 5, p. 1348-1364, https://doi.org/10.2113/gsecongeo.80.5.1348.","productDescription":"17 p.","startPage":"1348","endPage":"1364","numberOfPages":"17","costCenters":[],"links":[{"id":222554,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"80","issue":"5","noUsgsAuthors":false,"publicationDate":"1985-08-01","publicationStatus":"PW","scienceBaseUri":"505bbdc2e4b08c986b3291eb","contributors":{"authors":[{"text":"Fishman, N.S.","contributorId":59441,"corporation":false,"usgs":true,"family":"Fishman","given":"N.S.","email":"","affiliations":[],"preferred":false,"id":364430,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Reynolds, R. L. 0000-0002-4572-2942","orcid":"https://orcid.org/0000-0002-4572-2942","contributorId":79885,"corporation":false,"usgs":true,"family":"Reynolds","given":"R.","middleInitial":"L.","affiliations":[{"id":318,"text":"Geosciences and Environmental Change Science Center","active":true,"usgs":true}],"preferred":true,"id":364431,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Robertson, J. F.","contributorId":11194,"corporation":false,"usgs":true,"family":"Robertson","given":"J. F.","affiliations":[],"preferred":false,"id":364429,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70013098,"text":"70013098 - 1985 - Regional setting and new information on some critical geologic features of the West Shasta district, California","interactions":[],"lastModifiedDate":"2024-01-08T23:32:02.199057","indexId":"70013098","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1472,"text":"Economic Geology","active":true,"publicationSubtype":{"id":10}},"title":"Regional setting and new information on some critical geologic features of the West Shasta district, California","docAbstract":"The West Shasta massive sulfide district is in the easternmost of a series of accreted island-arc and oceanic crust terranes that comprise the Klamath Mountains. A sequence of submarine volcanic rocks of predominantly Early Devonian age is the principal component of the island-arc terrane in which the sulfide deposits are hosted. The Copley Greenstone, consisting mainly of andesitic and basaltic pillow lavas and breccias totaling at least 1,800 m in thickness, is the oldest rock unit in the sequence. It is overlain and also intruded by dikes of the Balaklala Rhyolite. Northeast of the West Shasta district, greenstone also overlies the Balaklala Rhyolite, suggesting that a major greenstone unit may overlie potentially mineralized rhyolite east of the district. However, recent studies have shown that the complex relations in that area can be explained by folding.The Balaklala sequence consists of silicic flows, breccias, and tuffs having a maximum thickness somewhat in excess of 1,000 m. The Balaklala has been divided by Kinkel et al. (1956) into three units: a lower nonporphyritic to slightly porphyritic unit containing large amounts of breccia and tuff; a middle unit characterized by rhyolite containing quartz phenocrysts 1 to 4 mm in diameter but also containing a complex assortment of tuff, breccia, and pyritic massive sulfide bodies in its upper part; and an upper unit typically containing dark quartz phenocrysts in excess of 4 mm in diameter. Much of the lower part of the upper unit is pyroclastic material, whereas most of the upper part of the unit appears to be a massive volcanic-flow rock. At least half a dozen eruptive centers for the Balaklala Rhyolite are identified, three of them within an area measuring 17 X 3 km that constitutes the limits of the former mining district.The youngest unit in the arc sequence is the Kennett Formation consisting of black shale and chert containing radiolarians, which indicate fairly deep-water deposition in its lower part, and limestone containing a shallow water fauna of probable Middle Devonian age in the upper part. A 400-m.y.-old trondhjemite stock, named the Mule Mountain stock, intrudes the Copley Greenstone and Balaklala Rhyolite and is considered to be essentially coeval with these volcanic units.The pyritic massive sulfide deposits occur in clusters of individual bodies owing in large part to disruption by postmineral faults. The deposits are stratigraphically confined to the upper part of the subhorizontal middle unit of the Balaklala, and their horizontal distribution is here interpreted to have been controlled by an extensional tectonic regime that prevailed during Early Devonian time. The major geologic evidence for such a regime is the marked preferred elongations exhibited by the distribution of the afore-mentioned eruptive centers, the eight or nine massive sulfide clusters in the district, and the geometrically similar distribution of the clusters in relation to each other. The preferred directions of elongation in both the detailed and broader senses may be generalized to N 20 degrees to 25 degrees E, N 37 degrees E, N 60 degrees to 80 degrees E, and N 40 degrees to 60 degrees W. The three northeast trends dominate throughout the district, whereas the northwest trend is evident mainly in the northern part and is more speculative. The major deposit clusters fall at intersections of the major trends, some of which may have been grabens. Trend intersections having no known deposits may be good exploration targets in localities where the stratigraphically favorable middle unit of the Balaklala is still present.
","language":"English","publisher":"Society of Economic Geologists","doi":"10.2113/gsecongeo.80.8.2072","issn":"03610128","usgsCitation":"Albers, J.P., and Bain, J., 1985, Regional setting and new information on some critical geologic features of the West Shasta district, California: Economic Geology, v. 80, no. 8, p. 2072-2091, https://doi.org/10.2113/gsecongeo.80.8.2072.","productDescription":"20 p.","startPage":"2072","endPage":"2091","numberOfPages":"20","costCenters":[],"links":[{"id":219834,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"80","issue":"8","noUsgsAuthors":false,"publicationDate":"1985-12-01","publicationStatus":"PW","scienceBaseUri":"50e4a577e4b0e8fec6cdbe12","contributors":{"authors":[{"text":"Albers, J. P.","contributorId":81505,"corporation":false,"usgs":true,"family":"Albers","given":"J.","email":"","middleInitial":"P.","affiliations":[],"preferred":false,"id":365282,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Bain, J.H.C.","contributorId":84073,"corporation":false,"usgs":true,"family":"Bain","given":"J.H.C.","email":"","affiliations":[],"preferred":false,"id":365283,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70013050,"text":"70013050 - 1985 - SENSITIVITY OF STRUCTURAL RESPONSE TO GROUND MOTION SOURCE AND SITE PARAMETERS.","interactions":[],"lastModifiedDate":"2012-03-12T17:18:36","indexId":"70013050","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"SENSITIVITY OF STRUCTURAL RESPONSE TO GROUND MOTION SOURCE AND SITE PARAMETERS.","docAbstract":"Designing structures to withstand earthquakes requires an accurate estimation of the expected ground motion. While engineers use the peak ground acceleration (PGA) to model the strong ground motion, seismologists use physical characteristics of the source and the rupture mechanism, such as fault length, stress drop, shear wave velocity, seismic moment, distance, and attenuation. This study presents a method for calculating response spectra from seismological models using random vibration theory. It then investigates the effect of various source and site parameters on peak response. Calculations are based on a nonstationary stochastic ground motion model, which can incorporate all the parameters both in frequency and time domains. The estimation of the peak response accounts for the effects of the non-stationarity, bandwidth and peak correlations of the response.","conferenceTitle":"Soil Dynamics and Earthquake Engineering, Proceedings of the 2nd International Conference.","conferenceLocation":"Aboard the Queen Elizabeth 2, New York to Southampton","language":"English","publisher":"Computational Mechanics Ltd","publisherLocation":"Southampton, Engl","isbn":"0905451341","usgsCitation":"Safak, E., 1985, SENSITIVITY OF STRUCTURAL RESPONSE TO GROUND MOTION SOURCE AND SITE PARAMETERS., Soil Dynamics and Earthquake Engineering, Proceedings of the 2nd International Conference., Aboard the Queen Elizabeth 2, New York to Southampton.","costCenters":[],"links":[{"id":220173,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505aaf35e4b0c8380cd87453","contributors":{"editors":[{"text":"Brebbia, C.A.","contributorId":112425,"corporation":false,"usgs":true,"family":"Brebbia","given":"C.A.","affiliations":[],"preferred":false,"id":508473,"contributorType":{"id":2,"text":"Editors"},"rank":1},{"text":"Cakmak, A.S.","contributorId":114101,"corporation":false,"usgs":true,"family":"Cakmak","given":"A.S.","email":"","affiliations":[],"preferred":false,"id":508475,"contributorType":{"id":2,"text":"Editors"},"rank":2},{"text":"Ghaffar, Abdel","contributorId":113250,"corporation":false,"usgs":true,"family":"Ghaffar","given":"Abdel","email":"","affiliations":[],"preferred":false,"id":508474,"contributorType":{"id":2,"text":"Editors"},"rank":3}],"authors":[{"text":"Safak, Erdal","contributorId":73984,"corporation":false,"usgs":true,"family":"Safak","given":"Erdal","email":"","affiliations":[],"preferred":false,"id":365172,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70013052,"text":"70013052 - 1985 - A nomogram for interpreting slope stability of fine-grained deposits in modern and ancient-marine environments.","interactions":[],"lastModifiedDate":"2024-05-21T11:17:03.144979","indexId":"70013052","displayToPublicDate":"1985-01-01T00:00:00","publicationYear":"1985","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2450,"text":"Journal of Sedimentary Petrology","active":true,"publicationSubtype":{"id":10}},"title":"A nomogram for interpreting slope stability of fine-grained deposits in modern and ancient-marine environments.","docAbstract":"Design of the nomogram is based on effective stress and combines consolidation theory as applicable to depositional environments with the infinite-slope model of slope-stability analysis. The link between the two combined theories is a term representing the effective overburden stress, which may be predicted from consolidation theory and a knowledge of sedimentation rate, time, and the coefficient of consolidation. In turn, if infinite-slope conditions are assumed to exist, the effective overburden stress can be used to derive a factor of safety against static slope failure by using the angle of internal friction and the slope angle. The nomogram applies to depostitional settings in which fine-grained sediment has accumulated at a relatively constant rate upon a base that is essentially impermeable. The model further assumes that the lateral extent of sediment affected by any mass movement will be great compared to its thickness and that no outside agents (e.g., cements, gas) are influencing the section. The nomogram is applicable to static conditions (inherent stability of the slope) and certain dynamic conditions (such as earthquakes). It may be used to investigate mass movements in the geologic past as well as those in modern environments.--Modified journal abstract.
Seven Bonneterre and Davis Formation glauconite samples from the Magmont mine area, Viburnum Trend, southeast Missouri, yield a 359 + or - 22-m.y. Rb-Sr isochron with an initial 87 Sr/ 86 Sr ratio of 0.7234 + or - 0.0273 (2 sigma). Gangue calcite from the ore zone has an 87 Sr/ 86 Sr ratio of approximately 0.7112. The isochron age for the Magmont glauconite samples is about 30 percent younger than the age of their Cambrian host rocks.The Rb/Sr ratios for Magmont glauconite samples are typical of many early Paleozoic glauconites but distinctly lower than ratios for glauconites from unmineralized localities in basinal Bonneterre facies, some distance from the Vibrunum Trend. Because the Rb-Sr data from Magmont glauconite samples define an isochron, it appears that the glauconites behaved as a cogenetic suite which was isotopically homogenized 359 m.y. ago. It is very unlikely that episodic or incomplete loss or exchange of radiogenic strontium, or the addition of rubidium, would result in the formation of an isochron. Addition of common strontium (mixing) will lower and produce a greater spread in Rb/Sr ratios but will not significantly change the calculated Rb-Sr isochron age for the glauconites. Because the total thickness of stratigraphic cover in the southeast Missouri region has never exceeded a kilometer, it is unlikely that the anomalously young glauconite isochron age resulted from heating associated with deep burial. Mississippi Valley-type ore fluids offer a hot, chemically reactive medium which could promote isotopic homogenization in glauconites. Therefore, the 359-m.y. age probably reflects a real geologic event, most likely the time of ore formation in southeast Missouri. A review of other attempts at dating early Paleozoic glauconites from the midcontinental United States indicates that all Rb-Sr and K-Ar glauconite ages are 10 to greater than 30 percent younger than their known stratigraphic ages. These glauconites are from Paleozoic formations on the stable craton, and again, resetting due to burial metamorphism is unlikely. Because there was no immediately obvious explanation for the discordant young ages, early Paleozoic glauconites were simply considered to be unsuitable geochronometers. It is suggested that the anomalously young radiometric ages for early Paleozoic glauconites record disturbances in the Rb-Sr and K-Ar isotopic systems, the result of Mississippi Valley-type fluid migration in the midcontinent region.
","language":"English","publisher":"Society of Economic Geologists","doi":"10.2113/gsecongeo.80.3.739","issn":"03610128","usgsCitation":"Stein, H.J., and Kish, S., 1985, The timing of ore formation in southeast Missouri: Rb-Sr glauconite dating at the Magmont mine, Viburnum trend: Economic Geology, v. 80, no. 3, p. 739-753, https://doi.org/10.2113/gsecongeo.80.3.739.","productDescription":"15 p.","startPage":"739","endPage":"753","numberOfPages":"15","costCenters":[],"links":[{"id":220124,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"80","issue":"3","noUsgsAuthors":false,"publicationDate":"1985-05-01","publicationStatus":"PW","scienceBaseUri":"505bb102e4b08c986b3251bc","contributors":{"authors":[{"text":"Stein, H. J.","contributorId":98748,"corporation":false,"usgs":true,"family":"Stein","given":"H.","email":"","middleInitial":"J.","affiliations":[],"preferred":false,"id":365337,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kish, S.A.","contributorId":21685,"corporation":false,"usgs":true,"family":"Kish","given":"S.A.","email":"","affiliations":[],"preferred":false,"id":365336,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ]}