A strong test of our understanding of the earthquake cycle is the ability to reproduce extant fault-bounded geological structures, such as basins and ranges, which are built by repeated cycles of deformation. Along strike-slip faults, the coseismic and interseismic deformation can be nearly equal in magnitude and opposite in sign, resulting in little permanent deformation except for the fault offset. For dip-slip faults, portions of the crust are lifted and dropped, and so buoyancy forces are exerted. The seismic and interseismic deformations do not balance, and structures grow and become subject to erosion and deposition. We consider three examples for which the structure and fault geometry are well known: the White Wolf reverse fault in California, site of the 1952 Kern County M=7.3 earthquake, the Lost River normal fault in Idaho, site of the 1983 Borah Peak M=7.0 earthquake, and the Cricket Mountain normal fault in Utah, site of Quaternary slip events. Basin stratigraphy and seismic reflection records are used to profile the structure, and coseismic deformation measured by leveling surveys is used to estimate the fault geometry. To reproduce these structures, we add the deformation associated with the earthquake cycle (the coseismic slip and postseismic relaxation) to the flexure caused by the observed sediment load, treating the crust as a thin elastic plate overlying a fluid substrate. The cumulative deformation is principally dependent on the elastic plate thickness, modestly sensitive to the sediment-substrate density difference, and insensitive to the fluid viscosity for the 4- to 8-Ma structures. We deduce a longterm flexural rigidity of 2–15 × 1019 Nm; this is equivalent to an elastic plate thickness of 2–4 km for a Young's modulus of 2.5 × 1010 Nm−2. This value is found where independent estimates of the elastic thickness from the coherence between surface topography and gravity yield values of about 4 km, but where coseismic fault slip extends to a depth of 10–15 km. Thus much of the seismogenic crust must weaken substantially during the life of active faults, causing the fault-bounded basins to narrow over time.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/JB093iB11p13319","issn":"01480227","usgsCitation":"Stein, R., King, G., and Rundle, J.B., 1988, The growth of geological structures by repeated earthquakes: 2, Field examples of continental dip-slip faults: Journal of Geophysical Research Solid Earth, v. 93, no. B11, p. 13319-13331, https://doi.org/10.1029/JB093iB11p13319.","productDescription":"13 p.","startPage":"13319","endPage":"13331","costCenters":[],"links":[{"id":225835,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"93","issue":"B11","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"505baca9e4b08c986b32364a","contributors":{"authors":[{"text":"Stein, R.S.","contributorId":8875,"corporation":false,"usgs":true,"family":"Stein","given":"R.S.","email":"","affiliations":[],"preferred":false,"id":368441,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"King, G.C.P.","contributorId":18510,"corporation":false,"usgs":true,"family":"King","given":"G.C.P.","email":"","affiliations":[],"preferred":false,"id":368443,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Rundle, J. B.","contributorId":17766,"corporation":false,"usgs":false,"family":"Rundle","given":"J.","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":368442,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70014401,"text":"70014401 - 1988 - Electrical structure of Newberry Volcano, Oregon","interactions":[],"lastModifiedDate":"2024-06-05T15:29:47.942329","indexId":"70014401","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":6453,"text":"Journal of Geophysical Research Solid Earth","active":true,"publicationSubtype":{"id":10}},"title":"Electrical structure of Newberry Volcano, Oregon","docAbstract":"From the interpretation of magnetotelluric, transient electromagnetic, and Schlumberger resistivity soundings, the electrical structure of Newberry Volcano in central Oregon is found to consist of four units. From the surface downward, the geoelectrical units are (1) very resistive, young, unaltered volcanic rock, (2) a conductive layer of older volcanic material composed of altered tuffs, (3) a thick resistive layer thought to be in part intrusive rocks, and (4) a lower-crustal conductor. This model is similar to the regional geoelectrical structure found throughout the Cascade Range. Inside the caldera, the conductive second layer corresponds to the steep temperature gradient and alteration minerals observed in the USGS Newberry 2 test hole. Drill hole information on the south and north flanks of the volcano (test holes GEO N-1 and GEO N-3, respectively) indicates that outside the caldera the conductor is due to alteration minerals (primarily smectite) and not high-temperature pore fluids. On the flanks of Newberry the conductor is generally deeper than inside the caldera, and it deepens with distance from the summit. A notable exception to this pattern is seen just west of the caldera rim, where the conductive zone is shallower than at other flank locations. The volcano sits atop a rise in the resistive layer, interpreted to be due to intrusive rocks. The intrusive material has served as a heat source to produce enhanced hydrothermal alteration and, perhaps in the case of the west-flank anomaly, elevated fluid temperatures. While no public drill hole information is available to confirm this hypothesis, the west-flank anomaly appears to be a good geothermal target. In addition to the possibility that a region on the west side of the volcano could be favorable for prospecting, part of the resistive structure under the center of the volcano could be due to a vapor-dominated environment with temperatures above 300°C. In other parts of the Cascades, pervasive alteration has produced mixed layer clays and zeolites, resulting in low-resistivity anomalies. Low resistivities cannot be assumed to indicate high-temperature pore fluids. The use of electrical methods that measure resistivity as a function of excitation frequency, such as spectral induced polarization, may provide a way of obtaining information about the type and extent of alteration.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/JB093iB09p10119","issn":"01480227","usgsCitation":"Fitterman, D., Stanley, W.D., and Bisdorf, R., 1988, Electrical structure of Newberry Volcano, Oregon: Journal of Geophysical Research Solid Earth, v. 93, no. B9, p. 10119-10134, https://doi.org/10.1029/JB093iB09p10119.","productDescription":"16 p.","startPage":"10119","endPage":"10134","costCenters":[],"links":[{"id":225895,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"93","issue":"B9","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"505a0898e4b0c8380cd51ba7","contributors":{"authors":[{"text":"Fitterman, D.V. 0000-0001-5600-3401","orcid":"https://orcid.org/0000-0001-5600-3401","contributorId":70386,"corporation":false,"usgs":true,"family":"Fitterman","given":"D.V.","email":"","affiliations":[],"preferred":false,"id":368323,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Stanley, W. D.","contributorId":86756,"corporation":false,"usgs":true,"family":"Stanley","given":"W.","email":"","middleInitial":"D.","affiliations":[],"preferred":false,"id":368324,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Bisdorf, R.J.","contributorId":42960,"corporation":false,"usgs":true,"family":"Bisdorf","given":"R.J.","email":"","affiliations":[],"preferred":false,"id":368322,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70014455,"text":"70014455 - 1988 - Vapor-dominated zones within hydrothermal systems: Evolution and natural state","interactions":[],"lastModifiedDate":"2024-06-05T14:53:15.43716","indexId":"70014455","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":6453,"text":"Journal of Geophysical Research Solid Earth","active":true,"publicationSubtype":{"id":10}},"title":"Vapor-dominated zones within hydrothermal systems: Evolution and natural state","docAbstract":"Three conceptual models illustrate the range of hydrothermal systems in which vapor-dominated conditions are found. The first model (model I) represents a system with an extensive near-vaporstatic vapor-dominated zone and limited liquid throughflow and is analogous to systems such as The Geysers, California. Such systems can evolve within low-permeability barriers without changes in boundary conditions or rock properties, given an adequate supply of heat. Their scarcity in nature may be due to the need for a long-lived, potent heat source and for a low-permeability aureole that remains intact for significant lengths of time. Models II and III represent systems with significant liquid throughflow and include steam-heated discharge features at higher elevations and high-chloride springs at lower elevations, connected to and fed by a single circulation system at depth. In model II, as in model I, the vapor-dominated zone has a near-vaporstatic vertical pressure gradient and is generally underpressured with respect to local hydrostatic pressure. The vapor-dominated zone in model III is quite different, in that phase separation takes place at pressures close to local hydrostatic and the overall pressure gradient is near hydrostatic. A relatively large number of high-temperature systems in regions of moderate to great topographic relief are similar to either model II or model III; however, in most cases there are insufficient data to establish a single preferred model.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/JB093iB11p13635","issn":"01480227","usgsCitation":"Ingebritsen, S.E., and Sorey, M., 1988, Vapor-dominated zones within hydrothermal systems: Evolution and natural state: Journal of Geophysical Research Solid Earth, v. 93, no. B11, p. 13635-13655, https://doi.org/10.1029/JB093iB11p13635.","productDescription":"21 p.","startPage":"13635","endPage":"13655","costCenters":[],"links":[{"id":225776,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"93","issue":"B11","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"505bc120e4b08c986b32a461","contributors":{"authors":[{"text":"Ingebritsen, S. E.","contributorId":8078,"corporation":false,"usgs":true,"family":"Ingebritsen","given":"S.","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":368433,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Sorey, M.L.","contributorId":73185,"corporation":false,"usgs":true,"family":"Sorey","given":"M.L.","affiliations":[],"preferred":false,"id":368434,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70014402,"text":"70014402 - 1988 - MAGMIX: a basic program to calculate viscosities of interacting magmas of differing composition, temperature, and water content","interactions":[],"lastModifiedDate":"2013-01-21T15:34:37","indexId":"70014402","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","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":"MAGMIX: a basic program to calculate viscosities of interacting magmas of differing composition, temperature, and water content","docAbstract":"MAGMIX is a BASIC program designed to predict viscosities at thermal equilibrium of interacting magmas of differing compositions, initial temperatures, crystallinities, crystal sizes, and water content for any mixing proportion between end members. From the viscosities of the end members at thermal equilibrium, it is possible to predict the styles of magma interaction expected for different initial conditions. The program is designed for modeling the type of magma interaction between hypersthenenormative magmas at upper crustal conditions. Utilization of the program to model magma interaction at pressures higher than 200 MPa would require modification of the program to account for the effects of pressure on heat of fusion and magma density. ?? 1988.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Computers and Geosciences","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisher":"Elsevier","publisherLocation":"Amsterdam, Netherlands","doi":"10.1016/0098-3004(88)90005-2","issn":"00983004","usgsCitation":"Frost, T.P., and Lindsay, J., 1988, MAGMIX: a basic program to calculate viscosities of interacting magmas of differing composition, temperature, and water content: Computers & Geosciences, v. 14, no. 2, p. 213-228, https://doi.org/10.1016/0098-3004(88)90005-2.","startPage":"213","endPage":"228","numberOfPages":"16","costCenters":[],"links":[{"id":266180,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/0098-3004(88)90005-2"},{"id":225953,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"14","issue":"2","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a4aade4b0c8380cd68f57","contributors":{"authors":[{"text":"Frost, T. P.","contributorId":49797,"corporation":false,"usgs":true,"family":"Frost","given":"T.","email":"","middleInitial":"P.","affiliations":[],"preferred":false,"id":368326,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Lindsay, J.R.","contributorId":45452,"corporation":false,"usgs":true,"family":"Lindsay","given":"J.R.","email":"","affiliations":[],"preferred":false,"id":368325,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70014453,"text":"70014453 - 1988 - Coastal geomorphology of arctic Alaska","interactions":[],"lastModifiedDate":"2012-03-12T17:19:31","indexId":"70014453","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3519,"text":"Technical Council on Cold Regions Engineering Monograph","active":true,"publicationSubtype":{"id":10}},"title":"Coastal geomorphology of arctic Alaska","docAbstract":"The treeless, tundra-plain of northern Alaska merges with the Arctic Ocean along a coastal area characterized by low tundra bluffs, and sparse coastal and delta dunes. Coastal engineering projects that aggrade or degrade permafrost will alter the geomorphology and rates of coastal processes by changing coastal stability. Similarly, projects that modify the ice environment (artificial islands) or the coastal configuration (causeways) will cause nature to readjust to the new process regime, resulting in modification of the coast. In this paper the authors describe the coastal geomorphology from Barrow to the Canadian border. In addition, they provide a general outline and extensive references of the major coastal processes operating in this environment that will be useful on coastal environments elsewhere in the Arctic.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Technical Council on Cold Regions Engineering Monograph","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","isbn":"0872626393; 0872626393","usgsCitation":"Barnes, P.W., Rawlinson, S.E., and Reimnitz, E., 1988, Coastal geomorphology of arctic Alaska: Technical Council on Cold Regions Engineering Monograph, p. 3-30.","startPage":"3","endPage":"30","numberOfPages":"28","costCenters":[],"links":[{"id":225774,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f782e4b0c8380cd4cb63","contributors":{"authors":[{"text":"Barnes, Peter W.","contributorId":6042,"corporation":false,"usgs":true,"family":"Barnes","given":"Peter","email":"","middleInitial":"W.","affiliations":[],"preferred":false,"id":368427,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Rawlinson, Stuart E.","contributorId":99708,"corporation":false,"usgs":true,"family":"Rawlinson","given":"Stuart","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":368429,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Reimnitz, Erk","contributorId":17963,"corporation":false,"usgs":true,"family":"Reimnitz","given":"Erk","email":"","affiliations":[],"preferred":false,"id":368428,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70013813,"text":"70013813 - 1988 - Fluid inclusions in vadose cement with consistent vapor to liquid ratios, Pleistocene Miami Limestone, southeastern Florida","interactions":[],"lastModifiedDate":"2024-04-03T16:11:14.614081","indexId":"70013813","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","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":"Fluid inclusions in vadose cement with consistent vapor to liquid ratios, Pleistocene Miami Limestone, southeastern Florida","docAbstract":"Vadose cements in the Late Pleistocene Miami Limestone contain regions with two-phase aqueous fluid inclusions that have consistent vapor to liquid (V-L) ratios. When heated, these seemingly primary inclusions homogenize to a liquid phase in a range between 75°C and 130°C (mean = 100°C) and have final melting temperatures between −0.3° and 0.0°C. The original distribution of Th was broadened during measurements because of fluid inclusion reequilibration. The narrow range of Th in these fluid inclusions suggest unusually consistent V-L ratios. They occur with small, obscure, single phase liquid-filled inclusions, which infer a low temperature origin (less than 60°C), and contradict the higher temperature origin implied by the two phase inclusions.
The diagenetic environment producing these seemingly primary fluid inclusions can be inferred from the origin of the host calcite enclosing them. The δ18O composition of these cements (−4 to−5.5%., PDB) and the fresh water in the fluid inclusions are consistent with precipitation from low-temperature meteoric water. The carbon-isotope composition of the vadose cements that contain only rare two-phase fluid inclusions are comparable to the host rock matrix (δ13C between 0 and +4%., PDB). Cements that contain common two-phase fluid-inclusions have a distinctly lighter carbon isotopic composition of −3 to −5%.. The carbon isotope composition of cements that contain common two-phase inclusions are about 6%. lighter than those of other vadose cements; models of early meteoric diagenesis indicate that this is the result of precipitation from water that has been influenced by soil gas CO2.
Our hypothesis is that the primary fluid inclusions, those with consistent V-L ratios and the single-phase liquid inclusions, form at near-surface temperature (25°C) and pressure when consistent proportions of soil gas and meteoric water percolating through the vadose zone are trapped within elongate vacuoles.
This study corroborates that Th measurements on two phase inclusions in vadose cements can be misleading evidence of thermal diagenesis, even if the measurements are well grouped.
","language":"English","publisher":"Elsevier","doi":"10.1016/0016-7037(88)90256-6","issn":"00167037","usgsCitation":"Barker, C., and Halley, R.B., 1988, Fluid inclusions in vadose cement with consistent vapor to liquid ratios, Pleistocene Miami Limestone, southeastern Florida: Geochimica et Cosmochimica Acta, v. 52, no. 5, p. 1019-1025, https://doi.org/10.1016/0016-7037(88)90256-6.","productDescription":"7 p.","startPage":"1019","endPage":"1025","numberOfPages":"7","costCenters":[],"links":[{"id":220668,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"52","issue":"5","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a1277e4b0c8380cd542fc","contributors":{"authors":[{"text":"Barker, C.E.","contributorId":69991,"corporation":false,"usgs":true,"family":"Barker","given":"C.E.","affiliations":[],"preferred":false,"id":366918,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Halley, R. B.","contributorId":87941,"corporation":false,"usgs":true,"family":"Halley","given":"R.","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":366919,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70013784,"text":"70013784 - 1988 - Forecast model for great earthquakes at the Nankai Trough subduction zone","interactions":[],"lastModifiedDate":"2012-03-12T17:18:37","indexId":"70013784","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3209,"text":"Pure and Applied Geophysics PAGEOPH","active":true,"publicationSubtype":{"id":10}},"title":"Forecast model for great earthquakes at the Nankai Trough subduction zone","docAbstract":"An earthquake instability model is formulated for recurring great earthquakes at the Nankai Trough subduction zone in southwest Japan. The model is quasistatic, two-dimensional, and has a displacement and velocity dependent constitutive law applied at the fault plane. A constant rate of fault slip at depth represents forcing due to relative motion of the Philippine Sea and Eurasian plates. The model simulates fault slip and stress for all parts of repeated earthquake cycles, including post-, inter-, pre- and coseismic stages. Calculated ground uplift is in agreement with most of the main features of elevation changes observed before and after the M=8.1 1946 Nankaido earthquake. In model simulations, accelerating fault slip has two time-scales. The first time-scale is several years long and is interpreted as an intermediate-term precursor. The second time-scale is a few days long and is interpreted as a short-term precursor. Accelerating fault slip on both time-scales causes anomalous elevation changes of the ground surface over the fault plane of 100 mm or less within 50 km of the fault trace. ?? 1988 Birkha??user Verlag.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Pure and Applied Geophysics PAGEOPH","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisherLocation":"Birkha??user-Verlag","doi":"10.1007/BF00879012","issn":"00334553","usgsCitation":"Stuart, W., 1988, Forecast model for great earthquakes at the Nankai Trough subduction zone: Pure and Applied Geophysics PAGEOPH, v. 126, no. 2-4, p. 619-641, https://doi.org/10.1007/BF00879012.","startPage":"619","endPage":"641","numberOfPages":"23","costCenters":[],"links":[{"id":205016,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/BF00879012"},{"id":220221,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"126","issue":"2-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a1312e4b0c8380cd544ea","contributors":{"authors":[{"text":"Stuart, W.D.","contributorId":65865,"corporation":false,"usgs":true,"family":"Stuart","given":"W.D.","email":"","affiliations":[],"preferred":false,"id":366864,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70014809,"text":"70014809 - 1988 - A magmatic model of Medicine Lake Volcano, California","interactions":[],"lastModifiedDate":"2024-05-30T16:28:28.825029","indexId":"70014809","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":6453,"text":"Journal of Geophysical Research Solid Earth","active":true,"publicationSubtype":{"id":10}},"title":"A magmatic model of Medicine Lake Volcano, California","docAbstract":"Medicine Lake volcano is a Pleistocene and Holocene shield volcano of the southern Cascade Range. It is located behind the main Cascade arc in an extensional tectonic setting where high-alumina basalt is the most commonly erupted lava. This basalt is parental to the higher-silica calc-alkaline and tholeiitic lavas that make up the bulk of the shield. The presence of late Holocene, chemically identical rhyolites on opposite sides of the volcano led to hypotheses of a large shallow silicic magma chamber and of a small, deep chamber that fed rhyolites to the surface via cone sheets. Subsequent geophysical work has been unable to identify a large silicic magma body, and instead a small one has apparently been recognized. Some geologic data support the geophysical results. Tectonic control of vent alignments and the dominance of mafic eruptions both in number of events and volume throughout the history of the volcano indicate that no large silicic magma reservoir exists. Instead, a model is proposed that includes numerous dikes, sills, and small magma bodies, most of which are too small to be recognized by present geophysical methods.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/JB093iB05p04412","issn":"01480227","usgsCitation":"Donnelly-Nolan, J., 1988, A magmatic model of Medicine Lake Volcano, California: Journal of Geophysical Research Solid Earth, v. 93, no. B5, p. 4412-4420, https://doi.org/10.1029/JB093iB05p04412.","productDescription":"9 p.","startPage":"4412","endPage":"4420","numberOfPages":"9","costCenters":[],"links":[{"id":226046,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"93","issue":"B5","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"5059e444e4b0c8380cd46537","contributors":{"authors":[{"text":"Donnelly-Nolan, J.M.","contributorId":104936,"corporation":false,"usgs":false,"family":"Donnelly-Nolan","given":"J.M.","email":"","affiliations":[],"preferred":false,"id":369345,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70014425,"text":"70014425 - 1988 - Icebergs rework shelf sediments to 500 m off Antarctica","interactions":[],"lastModifiedDate":"2024-01-24T12:32:57.237036","indexId":"70014425","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1796,"text":"Geology","active":true,"publicationSubtype":{"id":10}},"title":"Icebergs rework shelf sediments to 500 m off Antarctica","docAbstract":"Icebergs and sea ice rework the sediments of high-latitude shelves, producing modern diamicts (ice-keel turbates) unrelated to glacial proximity. Off Antarctica, sidescan sonar data indicate the presence of ice-gouge features formed by the physical interaction between ice keels and the sea bed. These are recognized as incisions a few metres deep and tens of metres wide, in water depths up to 500 m. On the submarine bank tops and slopes off Wilkes Land and in the Weddell Sea, subcircular depressions 30 to 150 m in diameter, a washboard pattern, and hummocky bed features also represent iceberg-resting sites. The freshness of sea-bed morphology, nearby Holocene sediment ponding, and active hydraulic sedimentary processes indicate that the sea floor is being reworked by iceberg keels. Tabular iceberg drafts in excess of 330 m have been measured, and modeling studies suggest that nontabular iceberg drafts of 500 m are possible. We conclude that a modern ice-keel turbate deposit in the form of a poorly stratified diamicton is probably widespread on that part (54%) of the Antarctic shelf less than 500 m deep.
Sensitivities of solute concentration to parameters associated with first-order chemical decay, boundary conditions, initial conditions, and multilayer transport are examined in one-dimensional analytical models of transient solute transport in porous media. A sensitivity is a change in solute concentration resulting from a change in a model parameter. Sensitivity analysis is important because minimum information required in regression on chemical data for the estimation of model parameters by regression is expressed in terms of sensitivities. Nonlinear regression models of solute transport were tested on sets of noiseless observations from known models that exceeded the minimum sensitivity information requirements. Results demonstrate that the regression models consistently converged to the correct parameters when the initial sets of parameter values substantially deviated from the correct parameters. On the basis of the sensitivity analysis, several statements may be made about design of sampling for parameter estimation for the models examined: (1) estimation of parameters associated with solute transport in the individual layers of a multilayer system is possible even when solute concentrations in the individual layers are mixed in an observation well; (2) when estimating parameters in a decaying upstream boundary condition, observations are best made late in the passage of the front near a time chosen by adding the inverse of an hypothesized value of the source decay parameter to the estimated mean travel time at a given downstream location; (3) estimation of a first-order chemical decay parameter requires observations to be made late in the passage of the front, preferably near a location corresponding to a travel time of √2 times the half-life of the solute; and (4) estimation of a parameter relating to spatial variability in an initial condition requires observations to be made early in time relative to passage of the solute front.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/WR024i002p00225","usgsCitation":"Knopman, D.S., and Voss, C.I., 1988, Further comments on sensitivities, parameter estimation, and sampling design in one-dimensional analysis of solute transport in porous media: Water Resources Research, v. 24, no. 2, p. 225-238, https://doi.org/10.1029/WR024i002p00225.","productDescription":"14 p.","startPage":"225","endPage":"238","costCenters":[],"links":[{"id":226110,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"24","issue":"2","noUsgsAuthors":false,"publicationDate":"2010-07-09","publicationStatus":"PW","scienceBaseUri":"505a1421e4b0c8380cd5490c","contributors":{"authors":[{"text":"Knopman, Debra S.","contributorId":51472,"corporation":false,"usgs":true,"family":"Knopman","given":"Debra","email":"","middleInitial":"S.","affiliations":[],"preferred":false,"id":369347,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Voss, Clifford I. 0000-0001-5923-2752 cvoss@usgs.gov","orcid":"https://orcid.org/0000-0001-5923-2752","contributorId":1559,"corporation":false,"usgs":true,"family":"Voss","given":"Clifford","email":"cvoss@usgs.gov","middleInitial":"I.","affiliations":[{"id":438,"text":"National Research Program - Western Branch","active":true,"usgs":true}],"preferred":true,"id":369348,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70013777,"text":"70013777 - 1988 - Assimilation of granite by basaltic magma at Burnt Lava flow, Medicine Lake volcano, northern California: Decoupling of heat and mass transfer","interactions":[],"lastModifiedDate":"2012-03-12T17:18:37","indexId":"70013777","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1336,"text":"Contributions to Mineralogy and Petrology","active":true,"publicationSubtype":{"id":10}},"title":"Assimilation of granite by basaltic magma at Burnt Lava flow, Medicine Lake volcano, northern California: Decoupling of heat and mass transfer","docAbstract":"At Medicine Lake volcano, California, andesite of the Holocene Burnt Lava flow has been produced by fractional crystallization of parental high alumina basalt (HAB) accompanied by assimilation of granitic crustal material. Burnt Lava contains inclusions of quenched HAB liquid, a potential parent magma of the andesite, highly melted granitic crustal xenoliths, and xenocryst assemblages which provide a record of the fractional crystallization and crustal assimilation process. Samples of granitic crustal material occur as xenoliths in other Holocene and Pleistocene lavas, and these xenoliths are used to constrain geochemical models of the assimilation process. A large amount of assimilation accompanied fractional crystallization to produce the contaminated Burnt lava andesites. Models which assume that assimilation and fractionation occurred simultaneously estimate the ratio of assimilation to fractional crystallization (R) to be >1 and best fits to all geochemical data are at an R value of 1.35 at F=0.68. Petrologic evidence, however, indicates that the assimilation process did not involve continuous addition of granitic crust as fractionation occurred. Instead, heat and mass transfer were separated in space and time. During the assimilation process, HAB magma underwent large amounts of fractional crystallization which was not accompanied by significant amounts of assimilation. This fractionation process supplied heat to melt granitic crust. The models proposed to explain the contamination process involve fractionation, replenishment by parental HAB, and mixing of evolved and parental magmas with melted granitic crust. ?? 1988 Springer-Verlag.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Contributions to Mineralogy and Petrology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisherLocation":"Springer-Verlag","doi":"10.1007/BF00375365","issn":"00107999","usgsCitation":"Grove, T., Kinzler, R., Baker, M.B., Donnelly-Nolan, J., and Lesher, C., 1988, Assimilation of granite by basaltic magma at Burnt Lava flow, Medicine Lake volcano, northern California: Decoupling of heat and mass transfer: Contributions to Mineralogy and Petrology, v. 99, no. 3, p. 320-343, https://doi.org/10.1007/BF00375365.","startPage":"320","endPage":"343","numberOfPages":"24","costCenters":[],"links":[{"id":205005,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/BF00375365"},{"id":220115,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"99","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059ee8ce4b0c8380cd49dfa","contributors":{"authors":[{"text":"Grove, T.L.","contributorId":22088,"corporation":false,"usgs":true,"family":"Grove","given":"T.L.","email":"","affiliations":[],"preferred":false,"id":366847,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Kinzler, R.J.","contributorId":47909,"corporation":false,"usgs":true,"family":"Kinzler","given":"R.J.","email":"","affiliations":[],"preferred":false,"id":366849,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Baker, M. B.","contributorId":76068,"corporation":false,"usgs":true,"family":"Baker","given":"M.","email":"","middleInitial":"B.","affiliations":[],"preferred":false,"id":366850,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Donnelly-Nolan, J.M.","contributorId":104936,"corporation":false,"usgs":false,"family":"Donnelly-Nolan","given":"J.M.","email":"","affiliations":[],"preferred":false,"id":366851,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Lesher, C.E.","contributorId":28217,"corporation":false,"usgs":true,"family":"Lesher","given":"C.E.","email":"","affiliations":[],"preferred":false,"id":366848,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70014395,"text":"70014395 - 1988 - Pb, Nd, and Sr isotopic evidence for a multicomponent source for rocks of Cook-Austral Islands and heterogeneities of mantle plumes","interactions":[],"lastModifiedDate":"2024-04-03T16:29:42.944394","indexId":"70014395","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","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":"Pb, Nd, and Sr isotopic evidence for a multicomponent source for rocks of Cook-Austral Islands and heterogeneities of mantle plumes","docAbstract":"Sr, Nd, and Pb isotopic compositions were measured in alkaline volcanic rocks (alkali basalt, ankaramite, nephelinite, phonolite, and trachyte) from the South Cook Islands (Aitutaki, Mauke, Rarotonga, Atiu, and Mangaia) and the Austral Islands (Rimatara and Rurutu). The results show that the Cook-Austral rocks have an extremely wide range in isotopic compositions of Pb:
The Aitutaki group could have been derived from heterogeneous mantle plumes, which rose from the enriched deep mantle (the almost primitive lower mantle or recycled continental and oceanic slabs). On the other hand, the Mangaia component could have been derived from the depleted upper mantle which may have been metasomatized with a CO2-rich fluid, as indicated by the near-MORB values of Sr and Nd isotopes. Although Pb isotopic data of the two groups cannot be distinguished from each other statistically, the end components of the Pb-Pb system do not match with those of the Nd-Sr system. Thus, the data must be explained by a multi-, at least three, component mixing model: the mantle plumes (Dupal component and a recycled oceanic slab), metasomatized upper mantle, and lithosphere. The K-Ar ages and isotopic characteristics of the Cook-Austral rocks indicate that if one mantle plume rises from the deep mantle in this region, it has separated into at least two segments on the way to the surface.
","language":"English","publisher":"Elsevier","doi":"10.1016/0016-7037(88)90157-3","issn":"00167037","usgsCitation":"Nakamura, Y., and Tatsumoto, M., 1988, Pb, Nd, and Sr isotopic evidence for a multicomponent source for rocks of Cook-Austral Islands and heterogeneities of mantle plumes: Geochimica et Cosmochimica Acta, v. 52, no. 12, p. 2909-2924, https://doi.org/10.1016/0016-7037(88)90157-3.","productDescription":"16 p.","startPage":"2909","endPage":"2924","numberOfPages":"16","costCenters":[],"links":[{"id":225772,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"52","issue":"12","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a75fae4b0c8380cd77e5c","contributors":{"authors":[{"text":"Nakamura, Y.","contributorId":70117,"corporation":false,"usgs":true,"family":"Nakamura","given":"Y.","email":"","affiliations":[],"preferred":false,"id":368304,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Tatsumoto, M.","contributorId":76798,"corporation":false,"usgs":true,"family":"Tatsumoto","given":"M.","email":"","affiliations":[],"preferred":false,"id":368305,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70014397,"text":"70014397 - 1988 - The hydrothermal system at Newberry Volcano, Oregon","interactions":[],"lastModifiedDate":"2024-06-05T15:31:30.70872","indexId":"70014397","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":6453,"text":"Journal of Geophysical Research Solid Earth","active":true,"publicationSubtype":{"id":10}},"title":"The hydrothermal system at Newberry Volcano, Oregon","docAbstract":"Results of recent geological and geophysical studies at Newberry Volcano have been incorporated into conceptual and numerical models of a magma-based hydrothermal system. Numerical simulations begin with emplacement of a small magma body, the presumed source of silicic eruptions at Newberry that began about 10,000 B.P., into a thermal regime representing 100,000 years of cooling of a large underlying intrusion. Simulated flow patterns and thermal histories for three sets of hypothetical permeability values are compatible with data from four geothermal drill holes on the volcano. Meteoric recharge cools the caldera-fill deposits, but thermal water moving up a central conduit representing a permeable volcanic vent produces temperatures close to those observed in drill holes within the caldera. Meteoric recharge from the caldera moves down the flanks and creates a near-isothermal zone that extends several hundred meters below the water table, producing temperature profiles similar to those observed in drill holes on the flanks. The temperatures observed in drill holes on the flanks are not influenced by the postulated Holocene magma body. The elevated temperature gradients measured in the lower portions of these holes may be related to the cumulative effect of older intrusions. The models also indicate that meteoric recharge to the deep hydrothermal system probably originates within or near the caldera. Relatively low fluid velocities at depth suggest that at least a significant fraction of the thermal fluid may be very old.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/JB093iB09p10149","issn":"01480227","usgsCitation":"Sammel, E., Ingebritsen, S.E., and Mariner, R.H., 1988, The hydrothermal system at Newberry Volcano, Oregon: Journal of Geophysical Research Solid Earth, v. 93, no. B9, p. 10149-10162, https://doi.org/10.1029/JB093iB09p10149.","productDescription":"14 p.","startPage":"10149","endPage":"10162","numberOfPages":"14","costCenters":[],"links":[{"id":225831,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"93","issue":"B9","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"505baccee4b08c986b32375c","contributors":{"authors":[{"text":"Sammel, E.A.","contributorId":59480,"corporation":false,"usgs":true,"family":"Sammel","given":"E.A.","affiliations":[],"preferred":false,"id":368309,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Ingebritsen, S. E.","contributorId":8078,"corporation":false,"usgs":true,"family":"Ingebritsen","given":"S.","email":"","middleInitial":"E.","affiliations":[],"preferred":false,"id":368308,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Mariner, Robert H.","contributorId":81075,"corporation":false,"usgs":true,"family":"Mariner","given":"Robert","email":"","middleInitial":"H.","affiliations":[],"preferred":false,"id":368310,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70014816,"text":"70014816 - 1988 - New trend- trigonometric model for interpolation and prediction of the geomagnetic field utilizing the new DGRF models","interactions":[],"lastModifiedDate":"2024-04-25T00:03:54.520529","indexId":"70014816","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2310,"text":"Journal of Geomagnetism & Geoelectricity","active":true,"publicationSubtype":{"id":10}},"title":"New trend- trigonometric model for interpolation and prediction of the geomagnetic field utilizing the new DGRF models","docAbstract":"At the IUGG Assembly at Vancouver during August 1987 new definitive geomagnetic reference field (DGRF) models to degree 10 for 1945, 1950, 1955, and 1960 were adopted by IAGA. Before these new DGRF models were accepted, the author developed a trend and trigonometric model (old trig model) based on the models IGRF 1945, IGRF 1950, IGRF 1955, IGRF 1960, DGRF 1965, DGRF 1970, DGRF 1975, DGRF 1980, and IGRF 1985, which were all approved by IAGA in Prague in August 1985. The old trig model consists of 720 trend and trigonometric coefficients for the calculation of spherical harmonic coefficients (SHC) only to degree eight because the early IGRF models were truncated there. These trend and Fourier sine coefficients can replace the equal number of SHC contained in the 9 DGRF-IGRF models.
","language":"English","publisher":"J-STAGE","doi":"10.5636/jgg.40.749","usgsCitation":"Alldredge, L., 1988, New trend- trigonometric model for interpolation and prediction of the geomagnetic field utilizing the new DGRF models: Journal of Geomagnetism & Geoelectricity, v. 40, no. 6, p. 749-759, https://doi.org/10.5636/jgg.40.749.","productDescription":"11 p.","startPage":"749","endPage":"759","numberOfPages":"11","costCenters":[],"links":[{"id":480023,"rank":2,"type":{"id":40,"text":"Open Access Publisher Index Page"},"url":"https://doi.org/10.5636/jgg.40.749","text":"Publisher Index Page"},{"id":226182,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"40","issue":"6","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a661ce4b0c8380cd72d18","contributors":{"authors":[{"text":"Alldredge, L.R.","contributorId":53457,"corporation":false,"usgs":true,"family":"Alldredge","given":"L.R.","email":"","affiliations":[],"preferred":false,"id":369356,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70014817,"text":"70014817 - 1988 - The mechanics and three-dimensional internal structure of active magmatic systems: Kilauea volcano, Hawaii","interactions":[],"lastModifiedDate":"2024-05-30T16:53:03.963401","indexId":"70014817","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":6453,"text":"Journal of Geophysical Research Solid Earth","active":true,"publicationSubtype":{"id":10}},"title":"The mechanics and three-dimensional internal structure of active magmatic systems: Kilauea volcano, Hawaii","docAbstract":"Interpretation of abundant seismic data suggests that Kilauea's primary conduit within the upper mantle is concentrically zoned to about 34-km depth. This zoned structure is inferred to contain a central core region of relatively higher permeability, surrounded by numerous dikes that are in intermittent hydraulic communication with each other and with the central core. During periods of relatively high magma transport, the entire cross section of the conduit is utilized. During periods of relatively low to moderate transport, however, only the central core is active. As the conduit penetrates the oceanic crust and enters the volcanic shield, it simultaneously supplies the deeper sections of the rift zones (6-to 10-km depth) and the roots of the summit reservoir with picritic magma. The rift zones at depth are inferred to be almost wholly molten and to possess a high degree of fluid continuity from Heiheiahulu in the East Rift Zone, 45 km westward through the roots of the summit magma reservoir, and well into the Southwest Rift Zone. Higher in the shield, the subcaldera magma reservoir and the shallow rift zones occupy the 2-to 4-km depth interval. Summit-differentiated olivine tholeiite (ρ ≈ 2.62 g cm−3) is periodically injected laterally along a horizon of neutral buoyancy within the rift zones, where the density of the magma is just balanced by the in situ density of the shield (Ryan, 1987a, b). Deep rift zone intrusions push seaward the deep tectonic blocks of the volcano's south flank. Shallow rift intrusions build a sheeted dike complex, inferred to be in isostatic equilibrium with the higher-density deep rift cores below. General finite element analyses are presented for the deformation and stress fields surrounding such dikes in the horizontal and vertical planes. The dike tip in two and three dimensions is surrounded by a tubular core of tensile (σ1, σ2) and shear stress (τmax). The displacement field is characterized by counterrotating cells on either side of the dike tip which, in vertical orientation, produce the characteristic subsidence above the dike complex, with uplift on either side, forming a ridge-trough-ridge structure. A finite element model of Kilauea's shield computes the displacement fields and principal stress (σ1) distributions resulting from intrusive activity on each or both of the rift zones. Within the summit region, tensile stress lobes produced by the three-dimensional upward extension of the intrusions superpose constructively to produce calderawide regimes of tensile stress, conducive to caldera development. Parametric studies of (1) intrusion in the East Rift Zone only, (2) intrusion in the Southwest Rift Zone only, and (3) intrusion in both rift zones demonstrate their unique kinematic contributions. For case 1, the caldera undergoes a counterclockwise rotation (torque up state) conducive to the development of rightstepping en echelon eruptive fissures, as exemplified by the August 14, 1971, eruption. For case 2, the caldera undergoes a clockwise rotation (torque down state) conducive to the development of left-stepping eruptive fissures, as occurred during the December 31, 1974, eruption. For case 3, the caldera substructure is driven due southward, producing the southward migration of the upper portions of the summit magma reservoir.
","language":"English","publisher":"American Geophysical Union","doi":"10.1029/JB093iB05p04213","issn":"01480227","usgsCitation":"Ryan, M., 1988, The mechanics and three-dimensional internal structure of active magmatic systems: Kilauea volcano, Hawaii: Journal of Geophysical Research Solid Earth, v. 93, no. B5, p. 4213-4248, https://doi.org/10.1029/JB093iB05p04213.","productDescription":"36 p.","startPage":"4213","endPage":"4248","numberOfPages":"36","costCenters":[],"links":[{"id":226183,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"93","issue":"B5","noUsgsAuthors":false,"publicationDate":"2012-09-20","publicationStatus":"PW","scienceBaseUri":"505badc3e4b08c986b323dd3","contributors":{"authors":[{"text":"Ryan, M.P.","contributorId":30754,"corporation":false,"usgs":true,"family":"Ryan","given":"M.P.","email":"","affiliations":[],"preferred":false,"id":369357,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70014847,"text":"70014847 - 1988 - Characterization of humic acid fractions by C-13 nuclear magnetic resonance spectroscopy","interactions":[],"lastModifiedDate":"2023-10-26T15:27:20.583113","indexId":"70014847","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1569,"text":"Environmental Technology Letters","active":true,"publicationSubtype":{"id":10}},"title":"Characterization of humic acid fractions by C-13 nuclear magnetic resonance spectroscopy","docAbstract":"Soil humic acids from different environments were fractionated by adsorption chromatography on Sephadex and characterized by C‐13 nuclear magnetic resonance (NMR) spectroscopy. The C‐13 NMR spectra of the fractions consist of some sharp, well‐resolved lines and some broad bands in contrast to the spectra of the unfractionated humic acids, where the bands are broader and less well‐resolved. The marked increase in resolution is apparently due to increased homogeneity of the fractions. These spectra are compared to the spectra of model compounds.
","language":"English","publisher":"Taylor & Francis","doi":"10.1080/09593338809384538","usgsCitation":"Wershaw, R.L., Thorn, K.A., and Pinckney, D., 1988, Characterization of humic acid fractions by C-13 nuclear magnetic resonance spectroscopy: Environmental Technology Letters, v. 9, no. 1, p. 53-62, https://doi.org/10.1080/09593338809384538.","productDescription":"10 p.","startPage":"53","endPage":"62","numberOfPages":"10","costCenters":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"links":[{"id":225603,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"9","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5059f4cbe4b0c8380cd4bf0a","contributors":{"authors":[{"text":"Wershaw, Robert L. rwershaw@usgs.gov","contributorId":4856,"corporation":false,"usgs":true,"family":"Wershaw","given":"Robert","email":"rwershaw@usgs.gov","middleInitial":"L.","affiliations":[],"preferred":true,"id":369440,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Thorn, Kevin A. 0000-0003-2236-5193 kathorn@usgs.gov","orcid":"https://orcid.org/0000-0003-2236-5193","contributorId":3288,"corporation":false,"usgs":true,"family":"Thorn","given":"Kevin","email":"kathorn@usgs.gov","middleInitial":"A.","affiliations":[{"id":5044,"text":"National Research Program - Central Branch","active":true,"usgs":true}],"preferred":true,"id":369439,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Pinckney, D.J.","contributorId":23175,"corporation":false,"usgs":true,"family":"Pinckney","given":"D.J.","affiliations":[],"preferred":false,"id":369438,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70014334,"text":"70014334 - 1988 - Precursory seismic quiescence: A preliminary assessment of the hypothesis","interactions":[],"lastModifiedDate":"2012-03-12T17:19:30","indexId":"70014334","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3209,"text":"Pure and Applied Geophysics PAGEOPH","active":true,"publicationSubtype":{"id":10}},"title":"Precursory seismic quiescence: A preliminary assessment of the hypothesis","docAbstract":"Numerous cases of precursory seismic quiescence have been reported in recent years. Some investigators have interpreted these observations as evidence that seismic quiescence is a somewhat reliable precursor to moderate or large earthquakes. However, because failures of the pattern to predict earthquakes may not, in general, be reported, and because numerous earthquakes are not preceded by quiescence, the validity and reliability of the quiescence precursor have not been established. We have analyzed the seismicity rate prior to, and in the source region of, 37 shallow earthquakes (M 5.3-7.0) in central California and Japan for patterns of rate fluctuation, especially precursory quiescence. Nonuniformity in rate for these pre-mainshock sequences is relatively high, and numerous intervals with significant (p<0.10) extrema in rate are observed in some of the sequences. In other sequences, however, the rate remains within normal limits up to the time of the mainshock. Overall, in terms of an observational basis for intermediate-term earthquake prediction, no evidence is found in the cases studied for a systematic, widespread or reliable pattern of quiescence prior to the mainshocks. In earthquake sequences comprising full seismic cycles for 5 sets of (M 3.7-5.1) repeat earthquakes on the San Andreas fault near Bear Valley, California, the seismicity rates are found to be uniform. A composite of the estimated rate fluctuations for the sequences, normalized to the length of the seismic cycle, reveals a weak pattern of a low rate in the first third of the cycle, and a high rate in the last few months. While these observations are qualitative, they may represent weak expressions of physical processes occurring in the source region over the seismic cycle. Re-examination of seismicity rate fluctuations in volumes along the creeping section of the San Andreas fault specified by Wyss and Burford (1985) qualitatively confirms the existence of low-rate intervals in volumes 361, 386, 382, 372 and 401. However, only the quiescence in volume 386 is found by the present study to be statistically significant. ?? 1988 Birkha??user Verlag.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Pure and Applied Geophysics PAGEOPH","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisherLocation":"Birkha??user-Verlag","doi":"10.1007/BF00879004","issn":"00334553","usgsCitation":"Reasenberg, P., and Matthews, M., 1988, Precursory seismic quiescence: A preliminary assessment of the hypothesis: Pure and Applied Geophysics PAGEOPH, v. 126, no. 2-4, p. 373-406, https://doi.org/10.1007/BF00879004.","startPage":"373","endPage":"406","numberOfPages":"34","costCenters":[],"links":[{"id":205648,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/BF00879004"},{"id":225699,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"126","issue":"2-4","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a814ce4b0c8380cd7b463","contributors":{"authors":[{"text":"Reasenberg, P.A.","contributorId":19959,"corporation":false,"usgs":true,"family":"Reasenberg","given":"P.A.","email":"","affiliations":[],"preferred":false,"id":368148,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Matthews, M.V.","contributorId":70920,"corporation":false,"usgs":true,"family":"Matthews","given":"M.V.","email":"","affiliations":[],"preferred":false,"id":368149,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":70014699,"text":"70014699 - 1988 - Gravity-induced stresses in stratified rock masses","interactions":[],"lastModifiedDate":"2012-03-12T17:19:35","indexId":"70014699","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3306,"text":"Rock Mechanics and Rock Engineering","active":true,"publicationSubtype":{"id":10}},"title":"Gravity-induced stresses in stratified rock masses","docAbstract":"This paper presents closed-form solutions for the stress field induced by gravity in anisotropic and stratified rock masses. These rocks are assumed to be laterally restrained. The rock mass consists of finite mechanical units, each unit being modeled as a homogeneous, transversely isotropic or isotropic linearly elastic material. The following results are found. The nature of the gravity induced stress field in a stratified rock mass depends on the elastic properties of each rock unit and how these properties vary with depth. It is thermodynamically admissible for the induced horizontal stress component in a given stratified rock mass to exceed the vertical stress component in certain units and to be smaller in other units; this is not possible for the classical unstratified isotropic solution. Examples are presented to explore the nature of the gravity induced stress field in stratified rock masses. It is found that a decrease in rock mass anisotropy and a stiffening of rock masses with depth can generate stress distributions comparable to empirical hyperbolic distributions previously proposed in the literature. ?? 1988 Springer-Verlag.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Rock Mechanics and Rock Engineering","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisherLocation":"Springer-Verlag","doi":"10.1007/BF01019673","issn":"07232632","usgsCitation":"Amadei, B., Swolfs, H., and Savage, W.Z., 1988, Gravity-induced stresses in stratified rock masses: Rock Mechanics and Rock Engineering, v. 21, no. 1, p. 1-20, https://doi.org/10.1007/BF01019673.","startPage":"1","endPage":"20","numberOfPages":"20","costCenters":[],"links":[{"id":205626,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/BF01019673"},{"id":225397,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"21","issue":"1","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a2a43e4b0c8380cd5b017","contributors":{"authors":[{"text":"Amadei, B.","contributorId":86902,"corporation":false,"usgs":true,"family":"Amadei","given":"B.","affiliations":[],"preferred":false,"id":369033,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Swolfs, H.S.","contributorId":70759,"corporation":false,"usgs":true,"family":"Swolfs","given":"H.S.","affiliations":[],"preferred":false,"id":369032,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Savage, W. Z.","contributorId":106481,"corporation":false,"usgs":true,"family":"Savage","given":"W.","email":"","middleInitial":"Z.","affiliations":[],"preferred":false,"id":369034,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70014461,"text":"70014461 - 1988 - The global distribution, abundance, and stability of SO2 on Io","interactions":[],"lastModifiedDate":"2012-03-12T17:19:30","indexId":"70014461","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1963,"text":"Icarus","active":true,"publicationSubtype":{"id":10}},"title":"The global distribution, abundance, and stability of SO2 on Io","docAbstract":"Sulfur dioxide distribution and abundances, bolometric hemispheric albedos, and passive surface temperatures on Io are modeled and mapped globally from Voyager multispectral mosaics, Earth-based spectra, and photometric descriptions. Photometric models indicate global average values for regolith porosity of 75-95% and macroscopic roughness with a mean slope angle of ~30??. Abundances of SO2 suggested by observations at uv-visible wavelengths and at 4.08 ??m are partially reconciled by intimate-mixing models; 30-50% SO2 coverage of the integral disk is indicated. Three major spectral end members, with continuous mixing, are recognized from the Voyager multispectral mosaics; one of these end members is identified as SO2. Intimate-mixing models with the three spectal end members are used to produce abundance maps for the optical surface; ~30% of Io's total optical surface consists of SO2. The SO2 is concentrated in the bright equatorial band and is relatively deficient in the region of Pele-type volcanic reuptions (long 240??-360??) and the polar regions. Temperatures are computed to vary over a 40??K range, at the same illumination angle, according to variations in surface bolometric hemispheric albedo. The brightest (and locally coldest) areas correspond to areas rich in SO2 and are concentrated in an equatorial band (??30?? lat), but many small cold patches occur elsewhere. These cold patches have radiative equilibrium temperatures ???120??K at the subsolar point, resulting in SO2 saturation vapor pressures ???10-8 bar. Midlatitude areas and the region of Pele-type plume eruptions are generally warmer (due to lower albedos). These results for surface temperatures and SO2 abundances and distribution support the regional coldtrapping model for the surface and atmospheric SO2 presented by F.P. Fanale, W.B. Banerdt, L.S. Elson, T.V. Johnson, and R.W. Zurek (1982, In Satellites of Jupiter (D. Morrison, Ed.), pp. 756-781, Univ. of Arizona Press, Tucson), although the region of Pele-type volcanic eruptions may be better characterized by the regolith condtrapping/volcanic-venting model of D.L. Matson and D.B. Nash (1983, J. Geophys. Res. 88, 4771-4783). The bright equatorial band is especially effective at slowing the formation of polar caps of SO2, both by reducing the sublimation rate near the subsolar point and by coldtrapping the SO2 in the equatorial region, so that competing processes of sputtering and volcanic resurfacing may prevent the formation of polar SO2 caps.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Icarus","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","doi":"10.1016/0019-1035(88)90157-1","issn":"00191035","usgsCitation":"McEwen, A.S., Johnson, T.V., Matson, D.L., and Soderblom, L., 1988, The global distribution, abundance, and stability of SO2 on Io: Icarus, v. 75, no. 3, p. 450-478, https://doi.org/10.1016/0019-1035(88)90157-1.","startPage":"450","endPage":"478","numberOfPages":"29","costCenters":[],"links":[{"id":205665,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1016/0019-1035(88)90157-1"},{"id":225897,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"75","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bac8ae4b08c986b32357f","contributors":{"authors":[{"text":"McEwen, A. S.","contributorId":11317,"corporation":false,"usgs":true,"family":"McEwen","given":"A.","email":"","middleInitial":"S.","affiliations":[],"preferred":false,"id":368449,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Johnson, T. V.","contributorId":79619,"corporation":false,"usgs":false,"family":"Johnson","given":"T.","email":"","middleInitial":"V.","affiliations":[],"preferred":false,"id":368451,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Matson, D. L.","contributorId":59940,"corporation":false,"usgs":false,"family":"Matson","given":"D.","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":368450,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Soderblom, L.A. 0000-0002-0917-853X","orcid":"https://orcid.org/0000-0002-0917-853X","contributorId":6139,"corporation":false,"usgs":true,"family":"Soderblom","given":"L.A.","affiliations":[],"preferred":false,"id":368448,"contributorType":{"id":1,"text":"Authors"},"rank":4}]}} ,{"id":70013778,"text":"70013778 - 1988 - The geometric signature: Quantifying landslide-terrain types from digital elevation models","interactions":[],"lastModifiedDate":"2012-03-12T17:18:38","indexId":"70013778","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2700,"text":"Mathematical Geology","active":true,"publicationSubtype":{"id":10}},"title":"The geometric signature: Quantifying landslide-terrain types from digital elevation models","docAbstract":"Topography of various types and scales can be fingerprinted by computer analysis of altitude matrices (digital elevation models, or DEMs). The critical analytic tool is the geometric signature, a set of measures that describes topographic form well enough to distinguish among geomorphically disparate landscapes. Different surficial processes create topography with diagnostic forms that are recognizable in the field. The geometric signature abstracts those forms from contour maps or their DEMs and expresses them numerically. This multivariate characterization enables once-in-tractable problems to be addressed. The measures that constitute a geometric signature express different but complementary attributes of topographic form. Most parameters used here are statistical estimates of central tendency and dispersion for five major categories of terrain geometry; altitude, altitude variance spectrum, slope between slope reversals, and slope and its curvature at fixed slope lengths. As an experimental application of geometric signatures, two mapped terrain types associated with different processes of shallow landsliding in Marin County, California, were distinguished consistently by a 17-variable description of topography from 21??21 DEMs (30-m grid spacing). The small matrix is a statistical window that can be used to scan large DEMs by computer, thus potentially automating the mapping of contrasting terrain types. The two types in Marin County host either (1) slow slides: earth flows and slump-earth flows, or (2) rapid flows: debris avalanches and debris flows. The signature approach should adapt to terrain taxonomy and mapping in other areas, where conditions differ from those in Central California. ?? 1988 International Association for Mathematical Geology.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Mathematical Geology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisherLocation":"Kluwer Academic Publishers-Plenum Publishers","doi":"10.1007/BF00890333","issn":"08828121","usgsCitation":"Pike, R., 1988, The geometric signature: Quantifying landslide-terrain types from digital elevation models: Mathematical Geology, v. 20, no. 5, p. 491-511, https://doi.org/10.1007/BF00890333.","startPage":"491","endPage":"511","numberOfPages":"21","costCenters":[],"links":[{"id":205010,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1007/BF00890333"},{"id":220163,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"20","issue":"5","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505bac7fe4b08c986b32352b","contributors":{"authors":[{"text":"Pike, R.J.","contributorId":72814,"corporation":false,"usgs":true,"family":"Pike","given":"R.J.","email":"","affiliations":[],"preferred":false,"id":366852,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70014336,"text":"70014336 - 1988 - Power formula for open-channel flow resistance","interactions":[],"lastModifiedDate":"2012-03-12T17:19:30","indexId":"70014336","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":24,"text":"Conference Paper"},"publicationSubtype":{"id":19,"text":"Conference Paper"},"title":"Power formula for open-channel flow resistance","docAbstract":"This paper evaluates various power formulas for flow resistance in open channels. Unlike the logarithmic resistance equation that can be theoretically derived either from Prandtl's mixing-length hypothesis or von Karman's similarity hypothesis, the power formula has long had an appearance of empiricism. Nevertheless, the simplicity in the form of the power formula has made it popular among the many possible forms of flow resistance formulas. This paper reexamines the concept and rationale of the power formulation, thereby addressing some critical issues in the modeling of flow resistance.","conferenceTitle":"Hydraulic Engineering: Proceedings of the 1988 National Conference on Hydraulic Engineering","conferenceDate":"8 August 1988 through 12 August 1988","conferenceLocation":"Colorado Springs, CO, USA","language":"English","publisher":"Publ by ASCE","publisherLocation":"New York, NY, United States","isbn":"0872626709; 0872626709","usgsCitation":"Chen, C., 1988, Power formula for open-channel flow resistance, Hydraulic Engineering: Proceedings of the 1988 National Conference on Hydraulic Engineering, Colorado Springs, CO, USA, 8 August 1988 through 12 August 1988, p. 25-35.","startPage":"25","endPage":"35","numberOfPages":"11","costCenters":[],"links":[{"id":225701,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"505a80a0e4b0c8380cd7b0ed","contributors":{"authors":[{"text":"Chen, Cheng-lung","contributorId":30752,"corporation":false,"usgs":true,"family":"Chen","given":"Cheng-lung","email":"","affiliations":[],"preferred":false,"id":368152,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70014700,"text":"70014700 - 1988 - Analytical approach to calculation of response spectra from seismological models of ground motion","interactions":[],"lastModifiedDate":"2013-03-13T15:26:08","indexId":"70014700","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1434,"text":"Earthquake Engineering and Structural Dynamics","active":true,"publicationSubtype":{"id":10}},"title":"Analytical approach to calculation of response spectra from seismological models of ground motion","docAbstract":"An analytical approach to calculate response spectra from seismological models of ground motion is presented. Seismological models have three major advantages over empirical models: (1) they help in an understanding of the physics of earthquake mechanisms, (2) they can be used to predict ground motions for future earthquakes and (3) they can be extrapolated to cases where there are no data available. As shown with this study, these models also present a convenient form for the calculation of response spectra, by using the methods of random vibration theory, for a given magnitude and site conditions. The first part of the paper reviews the past models for ground motion description, and introduces the available seismological models. Then, the random vibration equations for the spectral response are presented. The nonstationarity, spectral bandwidth and the correlation of the peaks are considered in the calculation of the peak response.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Earthquake Engineering and Structural Dynamics","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisher":"Wiley","doi":"10.1002/eqe.4290160109","issn":"03756297","usgsCitation":"Safak, E., 1988, Analytical approach to calculation of response spectra from seismological models of ground motion: Earthquake Engineering and Structural Dynamics, v. 16, no. 1, p. 121-134, https://doi.org/10.1002/eqe.4290160109.","startPage":"121","endPage":"134","numberOfPages":"14","costCenters":[],"links":[{"id":225461,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":269246,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1002/eqe.4290160109"}],"volume":"16","issue":"1","noUsgsAuthors":false,"publicationDate":"2006-12-18","publicationStatus":"PW","scienceBaseUri":"5059e62ee4b0c8380cd47204","contributors":{"authors":[{"text":"Safak, Erdal","contributorId":73984,"corporation":false,"usgs":true,"family":"Safak","given":"Erdal","email":"","affiliations":[],"preferred":false,"id":369035,"contributorType":{"id":1,"text":"Authors"},"rank":1}]}} ,{"id":70014863,"text":"70014863 - 1988 - The origin of Chubutolithes Ihering, ichnofossils from the Eocene and Oligocene of Chubut Province, Argentina.","interactions":[],"lastModifiedDate":"2024-06-20T11:44:16.835536","indexId":"70014863","displayToPublicDate":"1988-01-01T00:00:00","publicationYear":"1988","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":2412,"text":"Journal of Paleontology","active":true,"publicationSubtype":{"id":10}},"title":"The origin of Chubutolithes Ihering, ichnofossils from the Eocene and Oligocene of Chubut Province, Argentina.","docAbstract":"The distinctive trace fossil Chubutolithes gaimanensis n. ichnosp. occurs in Casamayoran (early Eocene) and Colhuéhaupian (late Oligocene) alluvial rocks of the Sarmiento Formation in eastern Chubut Province, Argentina. Though known for nearly 70 years, its origin has remained obscure. Examination of new specimens and comparisons with modern analogs demonstrate that specimens of Chubutolithes represent the fossil nests of a mud-dauber (Hymenoptera: Sphecidae). Virtually identical nests are constructed today by mud-daubers in areas as disparate as southern Santa Cruz Province, Argentina, and Nebraska, confirming that quite similar trace fossils can be produced by several different taxa in a higher taxonomic clade. No satisfactory ethological term exists for trace fossils that, like Chubutolithes, were constructed by organisms above, rather than within, a substrate or medium. The new term aedificichnia is proposed.
Chubutolithes occurs in alluvial paleosols and is associated with a large terrestrial ichnofauna. These trace fossils include the nests of scarab beetles, compound nests of social insects, and burrows of earthworms.
Large Cenozoic clockwise rotations defined by paleomagnetic data are an established fact in the Pacific Northwest, and many tectonic models have been proposed to explain them, including (1) rotation of accreted oceanic microplates during docking, (2) dextral shear between North America and northward-moving oceanic plates to the west, and (3) microplate rotation in front of an expanding Basin and Range province. Stratigraphic onlap relations and local structure indicate that microplate rotation during docking was not a major contributor to the observed rotations. Coast Range structures, Basin and Range extension, and paleomagnetic data from middle Miocene (15 Ma) Coast Range rocks indicate that dextral shear is responsible for at least 40% of the post-15 Ma rotation of the Coast Range and that Basin and Range extension is responsible for the remainder. Reconstructions based on extrapolation of this ratio back to 37 and 50 Ma are consistent with reconstructions based on paleomagnetic and stratigraphic relations in older rocks and suggest that dextral shear has, been a significant contributor to rotation during most of Tertiary time. Changes in the dextral-shear rotation rate over the past 50 m.y. correlate directly with changes in the velocity of the Farallon plate parallel to the coast and provide a strong argument for oblique subduction as the driving mechanism. Continental reconstructions incorporating shear may provide constraints on the rate of extension in the northernmost Basin and Range region and suggest 17% extension since 15 Ma, 39% since 37 Ma, and 72% since 50 Ma near latitude 42°N.
","language":"English","publisher":"Geological Society of America","doi":"10.1130/0016-7606(1988)100<0325:TRCOAS>2.3.CO;2","usgsCitation":"Wells, R., and Heller, P.L., 1988, The relative contribution of accretion, shear, and extension to Cenozoic tectonic rotation in the Pacific Northwest: GSA Bulletin, v. 100, no. 3, p. 325-338, https://doi.org/10.1130/0016-7606(1988)100<0325:TRCOAS>2.3.CO;2.","productDescription":"14 p.","startPage":"325","endPage":"338","costCenters":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"links":[{"id":354840,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"volume":"100","issue":"3","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"5c113026e4b034bf6a824e4b","contributors":{"authors":[{"text":"Wells, Ray E. 0000-0002-7796-0160 rwells@usgs.gov","orcid":"https://orcid.org/0000-0002-7796-0160","contributorId":2692,"corporation":false,"usgs":true,"family":"Wells","given":"Ray E.","email":"rwells@usgs.gov","affiliations":[{"id":312,"text":"Geology, Minerals, Energy, and Geophysics Science Center","active":true,"usgs":true}],"preferred":false,"id":737478,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Heller, Paul L.","contributorId":83924,"corporation":false,"usgs":true,"family":"Heller","given":"Paul","email":"","middleInitial":"L.","affiliations":[],"preferred":false,"id":737479,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ]}