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USGS2020

The community code verification exercise for simulating sequences of earthquakes and aseismic slip (SEAS)

Numerical simulations of sequences of earthquakes and aseismic slip (SEAS) have made great progress over past decades to address important questions in earthquake physics. However, significant challenges in SEAS modeling remain in resolving multiscale interactions between earthquake nucleation, dynamic rupture, and aseismic slip, and understanding physical factors controlling observables such as seismicity and ground deformation. The increasing complexity of SEAS modeling calls for extensive efforts to verify codes and advance these simulations with rigor, reproducibility, and broadened impact. In 2018, we initiated a community code-verification exercise for SEAS simulations, supported by the Southern California Earthquake Center. Here, we report the findings from our first two benchmark problems (BP1 and BP2), designed to verify different computational methods in solving a mathematically well-defined, basic faulting problem. We consider a 2D antiplane problem, with a 1D planar vertical strike-slip fault obeying rate-and-state friction, embedded in a 2D homogeneous, linear elastic halfspace. Sequences of quasi-dynamic earthquakes with periodic occurrences (BP1) or bimodal sizes (BP2) and their interactions with aseismic slip are simulated. The comparison of results from 11 groups using different numerical methods show excellent agreements in long-term and coseismic fault behavior. In BP1, we found that truncated domain boundaries influence interseismic stressing, earthquake recurrence, and coseismic rupture, and that model agreement is only achieved with sufficiently large domain sizes. In BP2, we found that complexity of fault behavior depends on how well physical length scales related to spontaneous nucleation and rupture propagation are resolved. Poor numerical resolution can result in artificial complexity, impacting simulation results that are of potential interest for characterizing seismic hazard such as earthquake size distributions, moment release, and recurrence times. These results inform the development of more advanced SEAS models, contributing to our further understanding of earthquake system dynamics.

Seismological Research Letters↗
USGS2004

Digital mapping techniques '04, workshop proceedings : May 16-19, 2004, Portland, Oregon

The Digital Mapping Techniques ‘04 (DMT’04) workshop was attended by about 100 technical experts from 40 agencies, universities, and private companies, including representatives from 22 state geological surveys (see Appendix A). This workshop was similar in nature to the previous seven meetings, held in Lawrence, Kansas (Soller, 1997), in Champaign, Illinois (Soller, 1998), in Madison, Wisconsin (Soller, 1999), in Lexington, Kentucky (Soller, 2000), in Tuscaloosa, Alabama (Soller, 2001), in Salt Lake City, Utah (Soller, 2002), and in Millersville, Pennsylvania (Soller, 2003). This year’s meeting was hosted by the Oregon Department of Geology and Mineral Industries, from May 16–19, 2004, on the Portland State University campus in Portland, Oregon. As in the previous meetings, the objective was to foster informal discussion and exchange of technical information. This objective was well met, as attendees continued to share and exchange knowledge and information, and to renew friendships and collegial work begun at past DMT workshops. All the DMT workshops have been coordinated by the Association of American State Geologists (AASG) and U.S. Geological Survey (USGS) Data Capture Working Group, which was formed in August 1996, to support the AASG and the USGS in their effort to build a National Geologic Map Database (see Soller, Berg, and Stamm, this volume, and http://ngmdb.usgs.gov/info/standards/datacapt/ ). The Working Group was formed because increased production efficiencies, standardization, and quality of digital map products were needed for the National database—and for the State and Federal geological surveys—to provide more high-quality digital maps to the public. At the 2004 meeting, oral and poster presentations and special discussion sessions emphasized: 1) methods for creating and publishing map products (here, “publishing” includes Web-based release); 2) field data capture software and techniques; 3) digital cartographic techniques; 4) migration of digital maps into ArcGIS Geodatabase format; 5) analytical GIS techniques; 6) continued development of the National Geologic Map Database; and 7) progress toward building and implementing a standard geologic map data model and standard science language for the U.S. and for North America.

Open-File Report↗
USGS2001

Leaping lopsided: a review of the current hypotheses regarding etiologies of limb malformations in frogs

Recent progress in the investigation of limb malformations in free-living frogs has underlined the wide range in the types of limb malformations and the apparent spatiotemporal clustering of their occurrence. Here, we review the current understanding of normal and abnormal vertebrate limb development and regeneration and discuss some of the molecular events that may bring about limb malformation. Consideration of the differences between limb development and regeneration in amphibians has led us to the hypothesis that some of the observed limb malformations come about through misdirected regeneration. We report the results of a pilot study that supports this hypothesis. In this study, the distal aspect of the right hindlimb buds of X. laevis tadpoles was amputated at the pre-foot paddle stage. The tadpoles were raised in water from a pond in Minnesota at which 7% of surveyed newly metamorphosed feral frogs had malformations. Six percent (6 of 100) of the right limbs of the tadpoles raised in pond water developed abnormally. One truncated right limb was the only malformation in the control group, which was raised in dechlorinated municipal water. All unamputated limbs developed normally in both groups. Three major factors under consideration for effecting the limb malformations are discussed. These factors include environmental chemicals (primarily agrichemicals), encysted larvae (metacercariae) of trematode parasites, and increased levels of ultraviolet light. Emphasis is placed on the necessary intersection of environmental stressors and developmental events to bring about the specific malformations that are observed in free-living frog populations.

California, Maine, Minnesota, Quebec, Vermont↗
USGS2011

Paleomagnetic correlation of surface and subsurface basaltic lava flows and flow groups in the southern part of the Idaho National Laboratory, Idaho, with paleomagnetic data tables for drill cores

Paleomagnetic inclination and polarity studies have been conducted on thousands of subcore samples from 51 coreholes located at and near the Idaho National Laboratory. These studies are used to paleomagnetically characterize and correlate successive stratigraphic intervals in each corehole to similar depth intervals in adjacent coreholes. Paleomagnetic results from 83 surface paleomagnetic sites, within and near the INL, are used to correlate these buried lava flow groups to basaltic shield volcanoes still exposed on the surface of the eastern Snake River Plain. Sample handling and demagnetization protocols are described as well as the paleomagnetic data averaging process. Paleomagnetic inclination comparisons between coreholes located only kilometers apart show comparable stratigraphic successions of mean inclination values over tens of meters of depth. At greater distance between coreholes, comparable correlation of mean inclination values is less consistent because flow groups may be missing or additional flow groups may be present and found at different depth intervals. Two shallow intersecting cross-sections, A-A- and B-B- (oriented southwest-northeast and northwest-southeast, respectively), drawn through southwest Idaho National Laboratory coreholes show the corehole to corehole or surface to corehole correlations derived from the paleomagnetic inclination data. From stratigraphic top to bottom, key results included the (1) Quaking Aspen Butte flow group, which erupted from Quaking Aspen Butte southwest of the Idaho National Laboratory, flowed northeast, and has been found in the subsurface in corehole USGS 132; (2) Vent 5206 flow group, which erupted near the southwestern border of the Idaho National Laboratory, flowed north and east, and has been found in the subsurface in coreholes USGS 132, USGS 129, USGS 131, USGS 127, USGS 130, USGS 128, and STF-AQ-01; and (3) Mid Butte flow group, which erupted north of U.S. Highway 20, flowed northwest, and has been found in the subsurface at coreholes ARA-COR-005 and STF-AQ-01. The high K20 flow group erupted from a vent that may now be buried south of U.S. Highway 20 near Middle Butte, flowed north, and is found in the subsurface in coreholes USGS 131, USGS 127, USGS 130, USGS 128, USGS 123, STF-AQ-01, and ARA-COR-005 ending near the Idaho Nuclear Technology and Engineering Center. The vent 5252 flow group erupted just south of U.S. Highway 20 near Middle and East Buttes, flowed northwest, and is found in the subsurface in coreholes ARA-COR-005, STF-AQ-01, USGS 130, USGS 128, ICPP 214, USGS 123, ICPP 023, USGS 121, USGS 127, and USGS 131. The Big Lost flow group erupted from a now-buried vent near the Radioactive Waste Management Complex, flowed southwest to corehole USGS 135, and northeast to coreholes USGS 132, USGS 129, USGS 131, USGS 127, USGS 130, STF-AQ-01, and ARA-COR-005. The AEC Butte flow group erupted from AEC Butte near the Advanced Test Reactor Complex and flowed south to corehole Middle 1823, northwest to corehole USGS 134, northeast to coreholes USGS 133 and NRF 7P, and south to coreholes USGS 121, ICPP 023, USGS 123, and USGS 128. Evidence of progressive subsidence of the axial zone of the ESRP is shown in these cross-sections, distorting the original attitudes of the lava flow groups and interbedded sediments. A deeper cross-section, C-C- (oriented west to east), spanning the entire southern Idaho National Laboratory shows correlations of the lava flow groups in the saturated part of the ESRP aquifer. Areally extensive flow groups in the deep subsurface (from about 100-800 meters below land surface) can be traced over long distances. In cross-section C-C-, the flow group labeled "Matuyama" can be correlated from corehole USGS 135 to corehole NPR Test/W-02, a distance of about 28 kilometers (17 miles). The flow group labeled "Matuyama 1.21 Ma" can be correlated from corehole Middle 1823 to corehole ANL-OBS-A-001, a distance of 26 kilometers (16 miles). Other flo

Idaho↗
USGS2002

Digital mapping techniques '02, workshop proceedings : May 19-22, 2002, Salt Lake City, Utah

The Digital Mapping Techniques '02 (DMT'02) workshop was attended by 101 technical experts from 43 agencies, universities, and private companies, including representatives from 25 state geological surveys (see Appendix A). This workshop was similar in nature to the previous five meetings, held in Lawrence, Kansas (Soller, 1997), in Champaign, Illinois (Soller, 1998a), in Madison, Wisconsin (Soller, 1999), in Lexington, Kentucky (Soller, 2000), and in Tuscaloosa, Alabama (Soller, 2001). This year's meeting was hosted by the Utah Geological Survey, from May 19 to 22, 2002, on the University of Utah campus in Salt Lake City. As in the previous meetings, the objective was to foster informal discussion and exchange of technical information. When an attendee adopts or modifies a newly learned technique on the basis of discussions at the workshop, the workshop clearly has met that objective. Evidence of learning and cooperation among participating agencies continued to be a highlight of the DMT workshops (see example in Soller, 1998b, and various papers in this volume). All the DMT workshops have been coordinated by the Association of American State Geologists (AASG) and the U.S. Geological Survey (USGS) Data Capture Working Group, which was formed in August 1996 to support the AASG and the USGS in their effort to build a National Geologic Map Database (see Soller and Berg, this volume, and http://ncgmp.usgs.gov/ngmdbproject/standards/datacapt/ ). The Working Group was formed because increased production efficiencies, standardization, and quality of digital map products were needed for the database--and the State and Federal geological surveys--to provide more high-quality digital maps to the public. At the 2002 meeting, oral and poster presentations and special discussion sessions emphasized (1) methods for creating and publishing map products (here, "publishing" includes Web-based release); (2) techniques for scanning already published maps and managing and delivering them on the Web; (3) continued development of the National Geologic Map Database; and (4) progress toward building a standard geologic map data model. In addition, special presentations were provided on building a statewide GIS council, incorporating geology as a NSDI Framework layer, and resolving the roles of surveyors and GIS professionals.

Open-File Report↗
USGS2005

Digital Mapping Techniques '05--Workshop Proceedings, Baton Rouge, Louisiana, April 24-27, 2005

Introduction: The Digital Mapping Techniques '05 (DMT'05) workshop was attended by more than 100 technical experts from 47 agencies, universities, and private companies, including representatives from 25 state geological surveys (see Appendix A). This workshop was similar in nature to the previous eight meetings, held in Lawrence, Kansas (Soller, 1997), in Champaign, Illinois (Soller, 1998), in Madison, Wisconsin (Soller, 1999), in Lexington, Kentucky (Soller, 2000), in Tuscaloosa, Alabama (Soller, 2001), in Salt Lake City, Utah (Soller, 2002), in Millersville, Pennsylvania (Soller, 2003), and in Portland, Oregon (Soller, 2004). This year's meeting was hosted by the Louisiana Geological Survey, from April 24-27, 2005, on the Louisiana State University campus in Baton Rouge, Louisiana. As in the previous meetings, the objective was to foster informal discussion and exchange of technical information. It is with great pleasure I note that the objective was successfully met, as attendees continued to share and exchange knowledge and information, and to renew friendships and collegial work begun at past DMT workshops. Each DMT workshop has been coordinated by the Association of American State Geologists (AASG) and U.S. Geological Survey (USGS) Data Capture Working Group, which was formed in August 1996, to support the AASG and the USGS in their effort to build a National Geologic Map Database (see Soller and Berg, this volume, and http://ngmdb.usgs.gov/info/standards/datacapt/). The Working Group was formed because increased production efficiencies, standardization, and quality of digital map products were needed for the database?and for the State and Federal geological surveys?to provide more high-quality digital maps to the public. At the 2005 meeting, oral and poster presentations and special discussion sessions emphasized: 1) methods for creating and publishing map products (here, 'publishing' includes Web-based release); 2) field data capture software and techniques, including the use of LIDAR; 3) digital cartographic techniques; 4) migration of digital maps into ArcGIS Geodatabase format; 5) analytical GIS techniques; 6) continued development of the National Geologic Map Database; and 7) progress toward building and implementing a standard geologic map data model and standard science language for the U.S. and for North America.

Open-File Report↗
USGS1979

Directory to Federal, State, and local OCS-related activities and contacts

This directory identifies specific Federal, state, and local agencies involved with oil and gas activities on the Outer Continental Shelf (OCS). Current agency responsibilities and the mechanisms used for interacting with OCS activities are outlined in three groupings: (a) an overview of major Federal activities (Chapter 2) and the mechanisms used for controlling, regulating, and monitoring OCS activities, (b) a review of major state government programs (Chapter 3) pertaining to the OCS, both the supportive activities in response to Federal initiatives as well as those activities for which the states have direct responsibility, and (c) a description of county and municipal participation (Chapter 4) in local and sub-state programs which can affect the OCS process. Appendix A is a bibliography and Appendix B is a telephone directory of agency contacts arranged alphabetically by state and region. The directory progresses from Federal to local information in Chapters two through four. The reader can then identify which level of interaction is of interest and obtain the appropriate government contact from the listings in Appendix B.

Open-File Report↗
USGS2005

Timing and development of the Heise volcanic field, Snake River Plain, Idaho, western USA

The Snake River Plain (SRP) developed over the last 16 Ma as a bimodal volcanic province in response to the southwest movement of the North American plate over a fixed melting anomaly. Volcanism along the SRP is dominated by eruptions of explosive high-silica rhyolites and represents some of the largest eruptions known. Basaltic eruptions represent the final stages of volcanism, forming a thin cap above voluminous rhyolitic deposits. Volcanism progressed, generally from west to east, along the plain episodically in successive volcanic fields comprised of nested caldera complexes with major caldera-forming eruptions within a particular field separated by ca. 0.5-1 Ma, similar to, and in continuation with, the present-day Yellowstone Plateau volcanic field. Passage of the North American plate over the melting anomaly at a particular point in time and space was accompanied by uplift, regional tectonism, massive explosive eruptions, and caldera subsidence, and followed by basaltic volcanism and general subsidence. The Heise volcan ic field in the eastern SRP, Idaho, represents an adjacent and slightly older field immediately to the southwest of the Yellowstone Plateau volcanic field. Five large-volume (>0.5 km3) rhyolitic ignimbrites constitute a time-stratigraphic framework of late Miocene to early Pliocene volcanism for the study region. Field relations and high-precision 40Ar/39Ar age determinations establish that four of these regional ignimbrites were erupted from the Heise volcanic field and form the framework of the Heise Group. These are the Blacktail Creek Tuff (6.62 ?? 0.03 Ma), Walcott Tuff (6.27 ?? 0.04 Ma), Conant Creek Tuff (5.51 ?? 0.13 Ma), and Kilgore Tuff (4.45 ?? 0.05 Ma; all errors reported at ?? 2??). The fifth widespread ignimbrite in the regions is the Arbon Valley Tuff Member of the Starlight Formation (10.21 ?? 0.03 Ma), which erupted from a caldera source outside of the Heise volcanic field. These results establish the Conant Creek Tuff as a distinct and widespread ignimbrite in the Heise volcanic field, eliminating former confusion resulting from previous discordant K/Ar and fission-track dates. New 40Ar/39Ar determinations, when combined wi th geochemical, lithologic geophysical, and field data, define the volcanic and tectonic history of the Heise volcanic field and surrounding areas. Volcanic units erupted from the Heise volcanic field also provide temporal control for tectonic events associated with late Cenozoic extension in the Snake Range and with uplift of the Teton Range, Wyoming. In the Snake Range, movement of large (???0.10 km3) slide blocks of Mississippian limestone exposed 50 km to the east of the Heise field occurred between 6.3 and 5.5 Ma and may have been catastrophically triggered by the caldera eruption of the 5.51 ?? 0.13-Ma Conant Creek Tuff. This slide block movement of ???300 vertical meters indicates that the Snake Range had significant relief by at least 5.5 Ma. In Jackson Hole, the distribution of outflow facies of the 4.45 ?? 0.05-Ma Kilgore caldera in the Heise volcanic field on the eastern SRP indicates that the northern Teton Range was not a significant topographic feature at this time. ?? 2005 Geological Society of America.

Geological Society of America Bulletin↗
USGS2012

Origin and diagenesis of K/T impact spherules - from Haiti to Wyoming and beyond

Impact spherules in Cretaceous/Tertiary (K/T) boundary clays and claystones consist of two types; each type is confined to its own separate layer of the boundary couplet in the Western Hemisphere. The form and composition of each of the spherule types result from its own unique mode of origin during the K/T event. Type 1 splash-form spherules occur only in the melt-ejecta (basal) layer of the K/T couplet. This layer was deposited from a ballistic ejecta curtain composed of melt-glass droplets transported mostly within the atmosphere. In contrast, Type 2 spherules are accreted, partially crystalline, spheroidal bodies that formed by condensation of vaporized bolide and target-rock materials in an expanding fireball cloud, from which they settled out of buoyant suspension to form the fireball layer. Dendritic and skeletal Ni-rich spinel crystals are unique to these Type 2 spherules in the fireball layer. Compositions of relict glasses found in Type 1 K/T spherules from Haiti indicate that they were derived from intermediate silicic target rocks. These melt-glass droplets were deposited into an aqueous environment at both continental and marine sites. We propose that the surfaces of the hot melt droplets hydrated rapidly in water and that these hydrated glass rims then altered to palagonite. Subsequent alteration of the palagonite rims to smectite, glauconite, chlorite, kaolinite, or goyazite occurred later during various modes of progressive diagenesis, accompanied by dissolution of some of the glass cores in spherules from continental sections and from marine sections that were subsequently raised above sea level. In many of the nonmarine sections in the Western Interior, the glass cores altered to kaolinite instead of dissolving. Directly comparable spherule morphologies (splash forms), textural features of the altered shells, and scalloping and grooving of relict glass cores or secondary casts demonstrate that the Haitian and Wyoming spherules are equivalent altered Type 1 melt-droplet bodies. The spherules at both locations were deposited in a melt-ejecta layer as part of the K/T impact event. Previously, two types of relict impact glasses had been identified in the Haitian spherule beds: black glass of andesitic composition and high-Ca yellow glass with an unusually high S content. Most workers agree that the latter probably formed by impact melting and mixing of surficial carbonate (and minor anhydrite) rocks with the more deeply-buried crystalline parent rocks of the black glasses. However, some workers have suggested that an intermediate compositional gap exists between the two groups of glasses, implying a different origin than simple mixing of end members during impact. We report glass compositional analyses with values extending throughout this intermediate range, lending support to the impact-mixing model. Inclusions of CaSO 4 found by us in relict yellow glasses further support this model.

Meteoritics↗
USGS1990

Trace-element and Sr, Nd, Pb, and O isotopic composition of Pliocene and Quaternary alkali basalts of the Patagonian Plateau lavas of southernmost South America

The Pliocene and Quaternary Patagonian alkali basalts of southernmost South America can be divided into two groups. The "cratonic" basalts erupted in areas of Cenozoic plateau volcanism and continental sedimentation and show considerable variation in 87Sr/86Sr (0.70316 to 0.70512), 143Nd/144Nd (e{open}Nd) and 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios (18.26 to 19.38, 15.53 to 15.68, and 38.30 to 39.23, respectively). These isotopic values are within the range of oceanic island basalts, as are the Ba/La, Ba/Nb, La/Nb, K/Rb, and Cs/Rb ratios of the "cratonic" basalts. In contrast, the "transitional" basalts, erupted along the western edge of the outcrop belt of the Pliocene and Quaternary plateau lavas in areas that were the locus of earlier Cenozoic Andean orogenic arc colcanism, have a much more restricted range of isotopic composition which can be approximated by 87Sr/86Sr=0.7039??0.0004, e{open}Nd, 206Pb/204Pb=18.60??0.08, 207Pb/204Pb=15.60??0.01, and 208Pb/204Pb=38.50??0.10. These isotopic values are similar to those of Andean orogenic are basalts and, compared to the "cratonic" basalts, are displaced to higher 87Sr/86Sr at a given 143Nd/144Nd and to higher 207Pb/204Pb at a given 208Pb/204Pb. The "transitional" basalts also have Ba/La, Ba/Nb, La/Nb, and Cs/Rb ratios higher than the "cratonic" and oceanic island basalts, although not as high as Andean orogenic are basalts. In contrast to the radiogenic isotopes, ??18O values for both groups of the Patagonian alkali basalts are indistinguishable and are more restricted than the range reported for Andean orogenic are basalts. Whole rock ??18O values calculated from mineral separates for both groups range from 5.3 to 6.5, while measured whole rock ??18O values range from 5.1 to 7.8. The trace element and isotopic data suggest that decreasing degrees of partial melting in association with lessened significance of subducted slabderived components are fundamental factors in the west to east transition from arc to back-arc volcanism in southern South America. The "cratonic" basalts do not contain the slab-derived components that impart the higher Ba/La, Ba/Nb, La/Nb, Cs/Rb, 87Sr/86Sr at a given 143Nd/144Nd, 207Pb/204Pb at a given 208Pb/204Pb, and ??18O to Andean orogenic arc basalts. Instead, these basalts are formed by relatively low degrees of partial melting of heterogeneous lower continental lithosphere and/or asthenosphere, probably due to thermal and mechanical pertubation of the mantle in response to subduction of oceanic lithosphere below the western margin of the continent. The "transitional" basalts do contain components added to their source region by either (1) active input of slab-derived components in amounts smaller than the contribution to the mantle below the arc and/or with lower Ba/La, Ba/Nb, La/Nb, and Cs/Rb ratios than below the arc due to progressive downdip dehydration of the subducted slab; or (2) subarc source region contamination processes which affected the mantle source of the "transitional" basalts earlier in the Cenozoic. ?? 1990 Springer-Verlag.

Contributions to Mineralogy and Petrology↗
USGS1982

Test well DO-CE 88 at Cambridge, Dorchester County, Maryland

Test well DO-CE 88 at Cambridge, Maryland, penetrated 3,299 feet of unconsolidated Quaternary, Tertiary and Cretaceous sediments and bottomed in quartz-monzonite gneiss. The well was drilled to provide data for a study of the aquifer system of the northern Atlantic Coastal Plain. Twenty-one core samples were collected. Six sand zones were tested for aquifer properties and sampled for ground-water chemistry. Point-water heads were measured at seven depths. Environmental heads (which ranged from -18.33 to +44.16 feet relative to sea level) indicate an upward component of flow. A temperature log showed a maximum temperature of 41.9 degrees Celsius and a mean temperature gradient of 0.00838 degrees Celsius per foot. The water analyses delineated the freshwater-saltwater transition zone between 2,650 and 3,100 feet. The ground water changes progressively downward from a sodium bicarbonate to a sodium chloride character. Clays in the analyzed core samples belong to the montmorillonite and kaolinite groups, and mean cation exchange capacity ranged from 8.3 to 38.9 milliequivalents per 100 grams. Vertical and horizontal hydraulic conductivities measured in cores ranged from 1.5 x 10-s to 1.3 feet per day and from 7.3 x 10-6 to 1.3 feet per day, respectively, but the most permeable sands were not cored. Porosity was 1.5 percent in the quartz monzonite bedrock and ranged from 22.4 to 41 percent in the overlying sediments. Transmissivities from aquifer tests ranged from 25 to 850 feet squared per day, horizontal hydraulic conductivities ranged from 2.5 to 85 feet squared per day, and intrinsic permeabilities ranged from 0.8 to 23 micrometers squared. Fossils identified in core samples include palynomorphs, dinoflagellates, and foraminifers.

Maryland↗
USGS1997

U.S. Geological Survey Middle Rio Grande Basin Study; Proceedings of the first annual workshop, Denver, Colorado, November 12-14, 1996

Approximately 40 percent (about 600,000 people) of the total population of New Mexico lives within the Middle Rio Grande Basin, which includes the City of Albuquerque. Ongoing analyses of the central portion of the Middle Rio Grande Basin by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque and other cooperators have shown that ground water in the basin is not as readily accessible as earlier studies indicated. A more complete characterization of the ground-water resources of the entire Middle Rio Grande Basin is hampered by a scarcity of data in the northern and southern areas of the basin. The USGS Middle Rio Grande Basin Study is a 5-year effort by the USGS and other agencies to improve the understanding of the hydrology, geology, and land-surface characteristics of the Middle Rio Grande Basin. The primary objective of this study is to improve the understanding of the water resources of the basin. Of particular interest is to determine the extent of hydrologic connection between the Rio Grande and the Santa Fe Group aquifer. Additionally, ground-water quality affects the availability of water supplies in the basin. Improving the existing USGS- constructed ground-water flow model of the Middle Rio Grande Basin will integrate all the various tasks that improve our knowledge of the various components of the Middle Rio Grande water budget. Part of this improvement will be accompanied by extended knowledge of the aquifer system beyond the Albuquerque area into the northern and southern reaches of the basin. Other improvements will be based on understanding gained through process-oriented research and improved geologic characterization of the deposits. The USGS will study the hydrology, geology, and land-surface characteristics of the basin to provide the scientific information needed for water- resources management and for managers to plan for water supplies needed for a growing population. To facilitate exchange of information among the many USGS scientists working in the Middle Rio Grande Basin, yearly technical meetings are planned for the anticipated 5-year study. These meetings provide an opportunity to present research results and plan new field efforts. This report documents the results of research presented at the first technical workshop held in Denver, Colorado, in November 1996. The report is organized into this introduction, five chapters that focus on USGS investigations in progress in the Middle Rio Grande Basin, and three appendixes with supplemental information. The first chapter provides an overview of the USGS program in the basin. The second chapter describes geographic data and analysis efforts in the basin. The third chapter details work being done on the hydrogeologic framework of the basin. The fourth chapter describes studies on ground-water availability in the basin and is divided into three areas of research: ground-water/surface-water interaction, ground-water flow and aquifer properties, and recharge. The fifth chapter is devoted to an overview of New Mexico District Cooperative Program studies in the basin. Finally, the appendixes list publications and presentations made during the first year of the study and 1996 workshop attendees. The report concludes with a list of selected references relevant to the study. The information in this report presents preliminary results of an evolving study. As the study progresses and individual projects publish their results in more detail, the USGS hopes to expand the scientific basis needed for management decisions regarding the Middle Rio Grande Basin.

Open-File Report↗
USGS2026

Improving offshore 3D splay fault geometries and slip histories using seismic data reprocessing and structural modeling

The goal of this project as written in the CRESCENT seed grant proposal was as follows: 1) reprocess selected profiles along strike from 45° to 48°N from the CASIE21 crustal-scale seismic data to obtain higher-resolution and higher-quality imaging of the uppermost 1-2 km of the accretionary wedge; 2) convert high-resolution USGS sparker seismic data from the time to depth domain to constrain near-surface fault geometries; 3) use kinematic modeling in the MOVE software to derive individual fault slip rates and per-event-displacements; and 4) work with the CFM group to create updated 3D models of identified faults based on the new data sources. At this stage, we have begun the reprocessing of the CASIE21 seismic reflection data (Carbotte et al., 2023). The time-migration reprocessing of the CASIE21 dataset has improved imaging of the near-surface structure by incorporating usable frequencies up to ~220 Hz, in contrast to the ~50 Hz maximum usable content in the currently available pre-stack depth migrated (PSDM) profiles (Fig. 1C). An example of the image quality gained through reprocessing is shown in Fig. 1, where the dominant wavelength of each reflector is reduced to ~10 m (Fig. 1B) from ~20 m in the existing PSDM product (Fig. 1A). The reprocessing work is still currently in progress. While the imaging in the shallow section has been much improved, reprocessing below the first multiple is still needed to create a seamless image from the plate boundary to the surface.

Final Report↗
USGS1983

Stratigraphy, structure, and palinspastic synthesis of the western Brooks Range, northwestern Alaska

This report is an effort to describe and decipher the mid-Paleozoic to Lower Cretaceous stratigraphy and the orogenic evolution of the western Brooks Range. The western Brooks Range primarily is composed of stacks of complexly deformed thrust sheets that contain mostly coeval sequences of rocks with slightly different lithologic facies. In order to simplify the thrust-faulted stratigraphy and palinspastic restoration, the rocks are grouped into eight principal structural levels. The lowest structural level is believed to be autochthonous or parautochthonous and above that, each succeeding level is designated allochthon one through seven. Allochthon seven is composed of the remnants of an extensive ophiolite sheet. Allochthon six is composed of pillow basalt with subordinate intermediate volcanic rocks, chert, and Devonian limestone. It is not certain whether this allochthon was formed in a continental or oceanic setting. Allochthons five through one consist of distinctive and coeval sequences of Devonian to Lower Cretaceous sedimentary rocks that were deposited in a continental setting. The present geographic distribution of each structural level is shown on the allochthon map of the western Brooks Range. The stratigraphy of the southern part of northern Alaska has been reconstructed by systematically unstacking lower allochthons to the north of higher allochthons. The palinspastic map that results from this procedure shows that the minimum thrust displacement between allochthon seven and the autochthon is approximately 700 to 800 km. Schematic cross sections drawn across the palinspastic map show how the stratigraphy of the southern part of northern. Alaska most likely appeared prior to the orogeny. During Devonian and Mississippian time, the sedimentary sequences that are now part of allochthons one to five are inferred to have been deposited in an ensialic basin with both northern and southern margins. During Pennsylvanian time, the sequences seem to have become part of a southward-sloping continental shelf when a southern land area moved away from northern Alaska by an inferred plate tectonic process of rifting or strike-slip motion. In Early Jurassic time just prior to the Brooks Range orogeny, northern Alaska probably was an extensive continental shelf with oceanic conditions to the south and land to the north. The Brooks Range orogeny seems to have begun in the Middle Jurassic as the Arctic Alaska plate was underthrust (subducted) southward beneath oceanic crust of allochthon seven. At progressively later stages in the underthrusting process, the upper parts of the continental shelf were detached from the subthrust basement on which they were deposited, resulting in the other allochthons of the western Brooks Range. The period of major thrusting ceased by Albian time in the Early Cretaceous. During middle and Late Cretaceous time, epeirogenic uplift in the Brooks Range caused large quantities of clastic detritus to be shed into successor basins to the north and south. Broad folds and reverse faults in Upper Cretaceous sediments north of the Brooks Range provide evidence for a later period(s) of less intense deformation in northern Alaska.

Open-File Report↗
USGS1999

U.S. Geological Survey middle Rio Grande basin study; proceedings of the third annual workshop, Albuquerque, New Mexico, February 24-25, 1999

Approximately 40 percent (about 600,000 people) of the total population of New Mexico lives within the Middle Rio Grande Basin, which includes the City of Albuquerque. Ongoing analyses of the central portion of the Middle Rio Grande Basin by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque and other agencies have shown that ground water in the basin is not as readily accessible as earlier studies indicated. A more complete characterization of the ground-water resources of the entire Middle Rio Grande Basin is hampered by a scarcity of data in the northern and southern areas of the basin. The USGS Middle Rio Grande Basin study is a 5-year effort by the USGS and other agencies to improve the understanding of the hydrology, geology, and land-surface characteristics of the Middle Rio Grande Basin. The primary objective of this study is to improve the understanding of the water resources of the basin. Of particular interest is to determine the extent of hydrologic connection between the Rio Grande and the Santa Fe Group aquifer. Additionally, ground-water quality affects the availability of water supplies in the basin. Improving the existing USGS-constructed ground-water flow model of the Middle Rio Grande Basin will integrate all the various tasks that improve our knowledge of the various components of the Middle Rio Grande water budget. Part of this improvement will be accompanied by extended knowledge of the aquifer system beyond the Albuquerque area into the northern and southern reaches of the basin. Other improvements will be based on understanding gained through process-oriented research and improved geologic characterization of the deposits. The USGS and cooperating agencies will study the hydrology, geology, and land-surface characteristics of the basin to provide the scientific information needed for water-resources management and for managers to plan for water supplies needed for a growing population. To facilitate exchange of information among the scientists working on the Middle Rio Grande Basin study, yearly technical meetings have been held for each of the first 3 years of the anticipated 5-year study. These meetings provide an opportunity to present research results and plan new field efforts. This report documents the results of research presented at the third annual technical workshop held in Albuquerque, New Mexico, February 24-25, 1999. The report is organized into this introduction and five chapters that focus on Middle Rio Grande Basin study investigations in progress in the Middle Rio Grande Basin. The first chapter describes geographic data and analysis efforts in the basin. The second chapter details work being done on the hydrogeologic and geologic framework of the basin. The third chapter describes studies on ground-water recharge in the basin. The fourth chapter provides details on the research on the ground-water flow system in the basin, including modeling efforts. The fifth chapter is devoted to an overview of New Mexico District Cooperative Program studies in the basin. The information in this report presents preliminary results of an evolving study. As the study progresses and individual projects publish their results in more detail, the USGS hopes to expand the scientific basis needed for management decisions regarding the Middle Rio Grande Basin.

Open-File Report↗
USGS1995

Physical and hydrologic properties of outcrop samples from a nonwelded to welded tuff transition, Yucca Mountain, Nevada

Quantitative material-property data are needed to describe lateral and vertical spatial variability of physical and hydrologic properties and to model ground-water flow and radionuclide transport at the potential Yucca Mountain nuclear-waste repository site in Nevada. As part of ongoing site characterization studies of Yucca Mountain directed toward this understanding of spatial variability, laboratory measurements of porosity, bull* and particle density, saturated hydraulic conductivity, and sorptivity have been obtained for a set of outcrop samples that form a systematic,two dimensional grid that covers a large exposure of the basal Tiva Canyon Tuff of the Paintbrush Group of Miocene age at Yucca Mountain. The samples form a detailed vertical grid roughly parallel to the transport direction of the parent ash flows, and they exhibit material-property varia- tions in an interval of major lithologic change overlying a potential nuclear-waste repository at Yucca Mountain. The observed changes in hydrologic properties were systematic and consistent with the changes expected for the nonwelded to welded transition at the base of a major ash-flow sequence. Porosity, saturated hydraulic conductivity, and sorptivity decreased upward from the base of the Tiva Canyon Tuff, indicating the progressive compaction of ash- rich volcanic debris and the onset of welding with increased overburden pressure from the accumulating ash-flow sheet. The rate of decrease in the values of these material properties varied with vertical position within the transition interval. In contrast, bulk-density values increased upward, a change that also is consistent with progressive compaction and the onset of welding. Particle-density values remained almost constant throughout the transition interval, probably indicating compositional (chemical) homogeneity.

Water-Resources Investigations Report↗
USGS2008

Environmental factors affecting mercury in Camp Far West Reservoir, California, 2001-03

This report documents water quality in Camp Far West Reservoir from October 2001 through August 2003. The reservoir, located at approximately 300 feet above sea level in the foothills of the northwestern Sierra Nevada, California, is a monomictic lake characterized by extreme drawdown in the late summer and fall. Thermal stratification in summer and fall is coupled with anoxic conditions in the hypolimnion. Water-quality sampling was done at approximately 3-month intervals on eight occasions at several stations in the reservoir, including a group of three stations along a flow path in the reservoir: an upstream station in the Bear River arm (principal tributary), a mid-reservoir station in the thalweg (prereservoir river channel), and a station in the deepest part of the reservoir, in the thalweg near Camp Far West Dam. Stations in other tributary arms of the reservoir included those in the Rock Creek arm of the reservoir, a relatively low-flow tributary, and the Dairy Farm arm, a small tributary that receives acidic, metal-rich drainage seasonally from the inactive Dairy Farm Mine, which produced copper, zinc, and gold from underground workings and a surface pit. Several water-quality constituents varied significantly by season at all sampling stations, including major cations and anions, total mercury (filtered and unfiltered samples), nitrogen (ammonia plus organic), and total phosphorus. A strong seasonal signal also was observed for the sulfurisotope composition of aqueous sulfate from filtered water. Although there were some spatial differences in water quality, the seasonal variations were more profound. Concentrations of total mercury (filtered and unfiltered water) were highest during fall and winter; these concentrations decreased at most stations during spring and summer. Anoxic conditions developed in deep parts of the reservoir during summer and fall in association with thermal stratification. The highest concentrations of methylmercury in unfiltered water were observed in samples collected during summer from deepwater stations in the anoxic hypolimnion. In the shallow (less than 14 meters depth) oxic epilimnion, concentrations of methylmercury in unfiltered water were highest during the spring and lowest during the fall. The ratio of methylmercury to total mercury (MeHg/HgT) increased systematically from winter to spring to summer, largely in response to the progressive seasonal decrease in total mercury concentrations, but also to some extent because of increases in MeHg concentrations during summer. Water-quality data for Camp Far West Reservoir are used in conjunction with data from linked studies of sediment and biota to develop and refine a conceptual model for mercury methylation and bioaccumulation in the reservoir and the lower Bear River watershed. It is hypothesized that MeHg is produced by sulfate-reducing bacteria in the anoxic parts of the water column and in shallow bed sediment. Conditions were optimal for this process during late summer and fall. Previous work has indicated that Camp Far West Reservoir is a phosphate-limited system - molar ratios of inorganic nitrogen to inorganic phosphorus in filtered water were consistently greater than 16 (the Redfield ratio), sometimes by orders of magnitude. Therefore, concentrations of orthophosphate were expectedly very low or below detection at all stations during all seasons. It is further hypothesized that iron-reducing bacteria facilitate release of phosphorus from iron-rich sediments during summer and early fall, stimulating phytoplankton growth in the fall and winter, and that the MeHg produced in the hypolimnion and metalimnion is released to the entire water column in the late fall during reservoir destratification (vertical mixing). Mercury bioaccumulation factors (BAF) were computed using data from linked studies of biota spanning a range of trophic position: zooplankton, midge larvae, mayfly nymphs, crayfish, threadfin shad, bluegill,

California↗
USGS1941

Geologic structure and occurrence of gas in part of southwestern New York. Part 1, Structure and gas possibilities of the Oriskany sandstone in Steuben, Yates, and parts of the adjacent counties

The area covered by this report is in southwestern New York and includes a little more than 3,000 square miles in Steuben and Yates counties and parts of the six adjacent counties. This area has been mapped to determine the structural attitude of the exposed rocks, so as to aid those interested in prospecting for natural gas in the Oriskany sandstone of Lower Devonian age. Because of the gentle regional dip toward the southwest, the youngest beds are exposed in the southwest corner of the area, and progressively older beds crop out northeastward in successive bands that strike generally northwest. All the exposed rocks are of Upper Devonian age except those in a narrow belt at the extreme north edge of the area, where a small thickness of Middle Devonian rocks crops out. The maximum thickness of beds so exposed is nearly 4,000 feet, of which the lower part is predominantly soft dark shale and the upper part predominantly fine-grained sandstone and gray shale. All the beds are marine except a few tongues of continental deposits red shale and sandstone and gray mudstone in the youngest beds. All the beds thicken southeastward, so that there is a northwestward convergence between any two lithologic units in the series. More than 30 key horizons that are persistent and distinctive were mapped, and altitudes on these key horizons served as a basis for constructing the structure contour map. Many of the key horizons are formation or member boundaries, but others are the tops or bottoms of limestone or sandstone beds within formations. All the stratigraphic units mapped are purely lithologic. (See pi. 2.) The Tully limestone, which crops out along the northern border of the area, is an easily recognizable and therefore valuable key bed for subsurface correlations in this part of the State. Below the Tully limestone is a thick body of Middle Devonian shales of the Hamilton group which rests on another valuable key bed, the hard, cherty Onondaga limestone, also of Middle Devonian age. Below the Onondaga limestone is the Lower Devonian Oriskany sandstone, which is the gas-producing bed. Unlike the Onondaga, the Oriskany is locally thin or absent. The structure of most of the area is shown by contour lines at 25-foot intervals, but where key horizons are lacking the structure is indicated by dip symbols. Upon the regional south and southwest dip are superposed numerous gentle folds whose axes trend approximately northeastward in the greater part of the area but more nearly eastward in the eastern part. The folds generally tend to become narrower and steeper, and therefore more closely spaced, southwestward. Many of the anticlines fork southwestward, whereas the synclines. tend to fork northeastward. All the folds have a westward or southwestward plunge. Throughout the area the rocks are jointed in two dominant sets one that trends northwest and the other east or northeast. No evident relation .between these joints, which were measured only in the hard, relatively brittle beds, and the individual folds or domes was discernible. The faults are concentrated in the northeastern and southwestern parts of the area and trend either northeastward or northwestward. Some are nearly vertical normal faults; others are steep reverse faults. Subsurface data show that most of the faults increase in throw downward and also that many subsurface faults do not reach the surface. A group of faults in the northwestern part of the Greenwood quadrangle and the southwestern part of the Hornell quadrangle were active during Upper Devonian time, while the Gowanda shale and overlying beds were being deposited. At this stratigraphic horizon the beds in a zone a few hundred feet thick are highly deformed in a wide belt on both sides of the faults. Sandstone layers are thinned out into long stringers or swollen into thick masses and in places are bent acutely without fracture. Thin layers of shale, coquina, and sand have flowed together into intricately plicated zones that lack cleavage and joints. These features show that the sediments were deformed while wet and plastic and buried only a little way below the sea floor. The beds that were laid down over these disturbed zones were not involved in this deformation. Many of the sharper flexures and most of the faults are not evident in the beds several hundred feet stratigraphically higher. Accordingly, broad, gentle folds in these higher beds in parts of the area south and west of the northwest corner of the Greenwood quadrangle may conceal, at considerable depths below them, narrow folds separated by abrupt flexures or faults. Several of the larger streams and rivers occupy strike valleys, and their j courses swing to follow the changing strike of the rocks where they cross ( successive folds. But, with few exceptions, the small streams are not adjusted to the bedrock structure. Domes likely to serve as traps for natural gas are concentrated in the northeastern and southwestern parts of the area. The Wayne-Dundee gas field is in the northeastern part. All the other potentially valuable domes in this part of the area have been drilled and found valueless except one small structural feature in the southern part of the Ovid quadrangle, which, if the Oriskany is present, may trap a small quantity of gas. In the Greenwood quadrangle in the southwestern part of the area there is one gas field and four well-defined domes, all of which may be productive if the Oriskany sandstone is present. In the northwest corner of the quadrangle the dips indicate at least two domes that can be adequately defined and evaluated only by geophysical prospecting. The State Line gas field is in tbe Wellsville quadrangle. In the southeast corner of this quadrangle there are three other domes of comparable size that may also be productive if underlain by the Oriskany sandstone. At other places in the Wellsville quadrangle the dips suggest several anticlinal axes on which analogous productive domes maybe found. The structural features in this quadrangle, however, are defined by contours only in the southeastern part. In the Woodhull quadrangle a large dome east of Jasper may be productive, and the western top of the large Woodhull dome in the southwestern part of the quadrangle seems to warrant drilling, despite the absence of the Oriskany in a well on the eastern top. Two wells drilled in 1936 and 1937 a little northeast of a broad, nearly flat-topped dome in the Hornell quadrangle, a few miles east of Hornell,, struck small flows of gas, suggesting that wells drilled higher on this dome may be productive. In much of the southwestern part of the area seismograph surveys should be of great value in determining the structure at the Tully and Onondaga horizons. Without abundant subsurface control of this sort, the danger of drilling into subsurface faults can hardly be overemphasized. Three closed or nearly closed synclines in the Greenwood and Wellsville quadrangles appear to be favorable places to drill for oil in the shallow sands presumably parts of the Dunkirk sandstone.

New York↗