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At least 19 recordsLinked to original sources
USGS2020

2018 U.S. Geological Survey–California Geological Survey fault-imaging surveys across the Hollywood and Santa Monica Faults, Los Angeles County, California

We acquired multiple types of seismic data across the Hollywood Fault in Hollywood, Calif., and the Santa Monica Fault in Beverly Hills, Calif., in May and June 2018. On the basis of our data, we infer near-surface locations of various traces of these faults. From two separate profiles across the Hollywood Fault, we evaluated multiple seismic datasets and models, including guided-wave data, tomographic V P data, tomographic V S data, V P /V S and Poisson’s ratio models derived from tomographic V P and V S data, Rayleigh-wave–based V S models, Love-wave–based V S models, V P /V S and Poisson’s ratio models (derived from combinations of tomographic-based V P and surface-wave–based V S models), P-wave reflection images, and S-wave reflection images. All of these data and models can be used to delineate near-surface faulting, and the data consistently infer near-surface fault traces of the Hollywood Fault in the same locations. Importantly, the combined data indicate more than one near-surface fault trace of the Hollywood Fault. Between North Bronson and North Gower Avenues, evidence exists for a near-surface trace of the Hollywood Fault slightly south of Carlos Avenue. Farther west, along Argyle Avenue, our data contain high levels of cultural noise, but we interpret near-surface faulting slightly south of the intersection of Carlos and Argyle Avenues and between Carlos Avenue and Yucca Street. For the Santa Monica Fault in Beverly Hills, we acquired guided-wave data only along Lasky Drive between Moreno Drive and South Santa Monica Boulevard, owing to limited access permissions. However, we used two separate source locations to generate the guided-wave data (SP1 and SP2). The data from more distant source location (relative to the recording array, SP1) were noisy, but on the basis of those data, we infer near-surface faulting at several locations along Lasky Drive, with concentrated near-surface faulting slightly south of the intersection of Lasky Drive and Charleville Boulevard. Guided-wave data generated at the closer source location (relative to recording array, SP2) more clearly show evidence for distributed near-surface faulting at several locations along Lasky Drive, with concentrated faulting near the intersection of Lasky Drive and Charleville Boulevard. Although the seismic surveys across both faults provide strong evidence for the locations of near-surface fault traces, the seismic data provide little or no information about the rupture history of the fault traces.

California↗
USGS2003

Geology of the Right Stepover region between the Rodgers Creek, Healdsburg, and Maacama faults, northern San Francisco Bay region: A contribution to Northern California Geological Society Field Trip Guide, June 6-8, 2003

This Open file report was written as part of a two-day field trip on June 7 and 8, 2003, conducted for the Northern California Geological Society. The first day of this field trip (June 7) was led by McLaughlin and Sarna-Wojcicki in the area of the right- step between the Rodgers Creek- Healdsburg fault zone and the Maacama fault. The second day of the trip (June 8), was led by David Wagner of the California Geological Survey and students having recently completed MS theses at San Jose State University (James Allen) and San Francisco State University (Carrie Randolph-Loar), as well as a student from San Francisco State University whose MS thesis was in progress in June 2003 (Eric Ford). The second day covered the Rodgers Creek fault zone and related faults of the Petaluma Valley area (the Tolay and Petaluma Valley fault zones).

California↗
USGS2003

A bibliography of Klamath Mountains geology, California and Oregon, listing authors from Aalto to Zucca for the years 1849 to Mid-2003

This bibliography of Klamath Mountains geology was begun, although not in a systematic or comprehensive way, when, in 1953, I was assigned the task of preparing a report on the geology and mineral resources of the drainage basins of the Trinity, Klamath, and Eel Rivers in northwestern California. During the following 40 or more years, I maintained an active interest in the Klamath Mountains region and continued to collect bibliographic references to the various reports and maps of Klamath geology that came to my attention. When I retired in 1989 and became a Geologist Emeritus with the Geological Survey, I had a large amount of bibliographic material in my files. Believing that a comprehensive bibliography of a region is a valuable research tool, I have expended substantial effort to make this bibliography of the Klamath Mountains as complete as is reasonably feasible. My aim was to include all published reports and maps that pertain primarily to the Klamath Mountains, as well as all pertinent doctoral and master's theses. In addition, I included reports in which the Klamath Mountains are of significance but not the primary focus; these latter kinds are mostly reports that correlate the Klamath terranes with those of other provinces, that compare the genesis of Klamath rocks with those elsewhere, or that include the Klamath Mountains in a continental framework. Reports describing the geology of the overlap sequences such as the Great Valley sequence, Hornbrook Formation, and Tertiary sediments and volcanics are included where those rocks lie within the limits of the Klamath Mountains province, but are only selectively included where the overlap sequences are mainly peripheral to the province. The alphabetical part of the bibliography consists of approximately 1700 entries. The list of primary references probably is virtually complete through 1994 and includes some 1995 references. The earliest reference is to James Dwight Dana in 1849. In order to restrict the size of the topical part of the bibliography to reasonable limits, each reference is listed under only one subject although many references may be applicable to two or more subjects. Titles in the topical section are abbreviated to conserve space and still retain identity. The bibliography was compiled from a variety of sources. Some of the references have not been checked against the original publications for accuracy. Caveat emptor! I would appreciate being informed of any errors or ommissions in order that a corrected and updated version of the bibliography may be prepared. I thank Nancy Blair for assistance in verifying some of the references, and thank Mary Donato and Robert Brown for helpful suggestions regarding the topical part of the bibliography. Since the first version of this bibliography was released in 1995, the total number of entries has increased from approximately 1700 to 1937, which indicates a continued high interest in the geology of the Klamath Mountains province. The total number of entries includes 73 Ph.D. theses and 123 Masters theses representing 26 universities.

Open-File Report↗
USGS1996

Resource assessment of the Bureau of Land Management's Winnemucca District and Surprise Resource Area, Northwest Nevada and Northeast California; geology and its relation to resource genesis

The U.S. Geological Survey (USGS) is a party to joint interagency Memorandum of Understandings (MOUs) with the Bureau of Land Management (BLM) and the U.S. Bureau of Mines (USBM) to coordinate resource assessments and evaluations of BLM administered lands. Resource assessments of BLM Resource Areas, that are conducted by the USGS under these MOUs, assist the BLM in meeting inventory and evaluation, resource-management planning, and other management requirements of the Federal Land Policy and Management Act of 1976 (FLPMA). This report is one of several to be generated as part of a resource assessment of BLMadministered lands in northwest Nevada and northeast California. The project area is composed of three contiguous BLM Resource Areas (RAs), totalling 13.5 million acres, in northwest Nevada and northeast California (figs. 1, 2). The SonomaGerlach and Paradise-Denio Resource Areas in northwest Nevada together comprise the BLM's Winnemucca District. The Surprise RA is located in extreme northwest Nevada and northeast California and is part of the BLM's Susanville District, which is administered by the BLM's California state office. Henceforth in this report, the project area will be referred to as the Winnemucca-Surprise Resource Assessment Area (WSRAA). Sources of geologic data used in this compilation include the state geologic maps of Nevada (Stewart and Carlson, 1978) and California (Jennings, 1977). Other regional, largerscale geologic maps of the area that were used include the 1:250,000 scale Nevada county geologic maps (Willden, 1964; Bonham, 1969; Willden and Speed, 1974; Johnson, 1977), l:125,000-scale geologic quadrangle maps (Ferguson and others, 1951, 1952; Muller and others, 1951), 1:62,500-scale geologic quadrangle maps (Gilluly, 1967; Silberling and Wallace, 1967; Wallace and others, 1969a, b) and several 1:48,000- and 1:24,000-scale geologic quadrangle maps (e.g., Erickson and Marsh, 1974 b, c; Vikre, 1985b; Theodore, 1991 a, b; 1994; Doebrich, 1994, 1995; Jones, in press a, b). The geology of the WSRAA records a complex history of Paleozoic and Mesozoic accretionary and plutonic events followed by Tertiary extensional tectonism and magmatism. This report chronologically outlines sedimentologic, magmatic, and tectonic events that shaped the geology of the WSRAA and relates these events to the genesis and distribution of the region's mineral and non-mineral resources. This is the initial report of several scheduled to be prepared on the WSRAA. Others reports include geochemistry, geophysics, hydrothermal alteration classification using Landsat Thematic Mapper imagery, assessment of metallic mineral resources, assessment of non-metallic mineral resources, and assessment of oil and gas resources.

Open-File Report↗
USGS2005

Net dextral slip, Neogene San Gregorio–Hosgri fault zone, coastal California: Geologic evidence and tectonic implications

Reinterpretation of onshore and offshore geologic mapping, examination of a key offshore well core, and revision of cross-fault ties indicate Neogene dextral strike slip of 156 ± 4 km along the San Gregorio–Hosgri fault zone, a major strand of the San Andreas transform system in coastal California. Delineating the full course of the fault, defining net slip across it, and showing its relationship to other major tectonic features of central California helps clarify the evolution of the San Andreas system. San Gregorio–Hosgri slip rates over time are not well constrained, but were greater than at present during early phases of strike slip following fault initiation in late Miocene time. Strike slip took place southward along the California coast from the western fl ank of the San Francisco Peninsula to the Hosgri fault in the offshore Santa Maria basin without significant reduction by transfer of strike slip into the central California Coast Ranges. Onshore coastal segments of the San Gregorio–Hosgri fault include the Seal Cove and San Gregorio faults on the San Francisco Peninsula, and the Sur and San Simeon fault zones along the flank of the Santa Lucia Range. Key cross-fault ties include porphyritic granodiorite and overlying Eocene strata exposed at Point Reyes and at Point Lobos, the Nacimiento fault contact between Salinian basement rocks and the Franciscan Complex offshore within the outer Santa Cruz basin and near Esalen on the flank of the Santa Lucia Range, Upper Cretaceous (Campanian) turbidites of the Pigeon Point Formation on the San Francisco Peninsula and the Atascadero Formation in the southern Santa Lucia Range, assemblages of Franciscan rocks exposed at Point Sur and at Point San Luis, and a lithic assemblage of Mesozoic rocks and their Tertiary cover exposed near Point San Simeon and at Point Sal, as restored for intrabasinal deformation within the onshore Santa Maria basin. Slivering of the Salinian block by San Gregorio–Hosgri displacements elongated its northern end and offset its western margin delineated by the older Nacimiento fault, a sinistral strike-slip fault of latest Cretaceous to Paleocene age. North of its juncture with the San Andreas fault, dextral slip along the San Gregorio–Hosgri fault augments net San Andreas displacement. Alternate restorations of the Gualala block imply that nearly half the net San Gregorio–Hosgri slip was accommodated along the offshore Gualala fault strand lying west of the Gualala block, which is bounded on the east by the current master trace of the San Andreas fault. With San Andreas and San Gregorio–Hosgri slip restored, there remains an unresolved proto–San Andreas mismatch of ∼100 km between the offset northern end of the Salinian block and the southern end of the Sierran-Tehachapi block. On the south, San Gregorio–Hosgri strike slip is transposed into crustal shortening associated with vertical-axis tectonic rotation of fault-bounded crustal panels that form the western Transverse Ranges, and with kinematically linked deformation within the adjacent Santa Maria basin. The San Gregorio–Hosgri fault serves as the principal link between transrotation in the western Transverse Ranges and strike slip within the San Andreas transform system of central California.

California↗
USGS2017

Fluid-driven uplift at Long Valley Caldera, California: Geologic perspectives

Since persistent seismicity began in the Sierra Nevada adjacent to Long Valley caldera in 1978–1980, intracaldera unrest has been marked by (1) episodes of uplift totaling ~ 83 cm, centered on the middle Pleistocene resurgent dome, and (2) recurrent earthquake swarms along a 12-km-long segment of the caldera's ring-fault zone that is contiguous with both the dome and the Sierran seismogenic domain. Others have attributed the recent unrest to magmatic intrusion(s), but it is argued here that evidence for new magma is lacking and that ongoing uplift and ring-fault-zone seismicity are both promoted by ascent of aqueous fluid released by second boiling of the residue of the enormous Pleistocene rhyolitic reservoir terminally crystallizing at depths ≥ 10 km. For 2 Myr, eruptive vent clusters migrated southwestward from Glass Mountain to Mammoth Mountain. There has been no eruption on the resurgent dome since 500 ka, and since 230 ka volcanism has been restricted to the caldera's west moat and contiguous Sierran terrain, both outside the structural caldera. High-temperature hydrothermal activity in the central caldera waned after ~ 300 ka, cooling the Pleistocene rhyolitic focus to the extent that drilling on the resurgent dome found mid-caldera temperature to be only 100 °C and isothermal at depths of 2–3 km. Beneath most of the resurgent dome, there is little seismicity at any depth, no emission of magmatic CO 2 or other magmatic gases, no elevated 3 He/ 4 He ratios, and only normal to below-normal heat flow. Most of the 75-km-long ring-fault zone is likewise aseismic, excepting only the 12-km segment contiguous with the extracaldera seismogenic domain in the Sierra. Since 1980, the Sierran seismicity has released 3.6 times more cumulative seismic energy than have intracaldera earthquakes. The caldera seismicity is not driven by stresses associated with the adjacent uplift but, instead, by the extracaldera tectonic stressfield. Sierran seismicity activated the directly contiguous south-moat segment of the ring-fault zone, which had originated in the caldera-forming eruption at 767 ka and everywhere else remains sealed. Hypocenter relocation studies of 1000s of earthquakes along the seismic segment have resolved recurrent upward-migrating swarms within networks of cryptic faults, apparently triggered by rapidly ascending pulses of high-pressure low-viscosity aqueous fluid. Entering the brittle crust at depths of 8–10 km, such fluid is just what should be expected from second boiling of the late-stage CO 2 -poor rhyolitic residue. The fluid provides the pressure source above the apex of the crystallizing caldera-wide pluton and then escapes laterally to the newly reactivated southern segment of the ring-fault zone, its only available permeable pathway, where it mediates the ongoing south-moat seismicity.

California↗
USGS1991

The Marina District, San Francisco, California: Geology, history, and earthquake effects

A northwest-trending valley in the bedrock surface is buried by firm Pleistocene bay clay, a dense Pleistocene sand layer, soft Holocene bay sediments, loose to dense Holocene beach and dune sands, and artificial fill that have an aggregate maximum thickness of about 90 m (300 ft). Artificial filling of a cove at the site of The Marina District proceeded gradually from the late 1860s to 1912, when major hydraulic filling was done for the Panama-Pacific International Exposition. The remains of thousands of piles driven for the Exposition very probably still exist and have had unknown effects on long-term ground settlement and earthquake-related ground displacements. Intensity maps of the 1906 earthquake, and seismic recordings and severe building damage in 1989, reported by others, indicate that ground motion was amplified on both natural and artificial ground. This suggests that the configuration of the bedrock surface and the location and thickness of various clay and sand deposits underlying the fill had an important effect on the shaking. However, most of the settlement and liquefaction and the damage to pipelines, building foundations, streets, side-walks, and curbs occurred in areas of artificial fill consisting mainly of loose sand.

California↗
USGS1945

Topographic and geologic maps of manganese deposits in California

Geologic and topographic maps of several manganese properties in California were released today by the Geological Survey according to an announcement made by Survey Director W. E. Wrather to Secretary of the Interior Harold L. Ickes. The maps have been placed on open file at the offices of the Geological Survey in Washington, D. C., and at the offices of the Geologic Branch, California Division of Mines, Ferry Building, San Francisco, where they may be consulted by persons directly interested in the properties. The recently increased demand for information regarding deposits of manganese silicates for new uses in connection with the war effort has indicated the desirability of releasing unpublished detailed maps of the California deposits, many of which carry manganese silicates. The maps were made as part of the strategic minerals investigations of the Geological Survey from 1941 to 1943. The deposits covered by the maps are in the following counties of California: Amador, Calaveras, Eldorado, Glenn, Humboldt, Los Angeles, Madera, Mariposa, Mendocino, Mono, Placer, Plumas, San Bernardino, San Benito, San Luis Obispo, San Joaquin, Sonoma, Stanislaus, Trinity, and Tuolumne.

California↗
USGS2011

Onshore and offshore geologic map of the Coal Oil Point area, southern California

Geologic maps that span the shoreline and include both onshore and offshore areas are potentially valuable tools that can lead to a more in depth understanding of coastal environments. Such maps can contribute to the understanding of shoreline change, geologic hazards, both offshore and along-shore sediment and pollutant transport. They are also useful in assessing geologic and biologic resources. Several intermediate-scale (1:100,000) geologic maps that include both onshore and offshore areas (herein called onshore-offshore geologic maps) have been produced of areas along the California coast (see Saucedo and others, 2003; Kennedy and others, 2007; Kennedy and Tan, 2008), but few large-scale (1:24,000) maps have been produced that can address local coastal issues. A cooperative project between Federal and State agencies and universities has produced an onshore-offshore geologic map at 1:24,000 scale of the Coal Oil Point area and part of the Santa Barbara Channel, southern California (fig. 1). As part of the project, the U.S. Geological Survey (USGS) and the California Geological Survey (CGS) hosted a workshop (May 2nd and 3rd, 2007) for producers and users of coastal map products (see list of participants) to develop a consensus on the content and format of onshore-offshore geologic maps (and accompanying GIS files) so that they have relevance for coastal-zone management. The USGS and CGS are working to develop coastal maps that combine geospatial information from offshore and onshore and serve as an important tool for addressing a broad range of coastal-zone management issues. The workshop was divided into sessions for presentations and discussion of bathymetry and topography, geology, and habitat products and needs of end users. During the workshop, participants reviewed existing maps and discussed their merits and shortcomings. This report addresses a number of items discussed in the workshop and details the onshore and offshore geologic map of the Coal Oil Point area. Results from this report directly address issues raised in the California Ocean Protection Act (COPA) Five Year Strategic Plan. For example, one of the guiding principles of the COPA five-year strategic plan is to 'Recognize the interconnectedness of the land and the sea, supporting sustainable uses of the coast and ensuring the health of ecosystems.' Results from this USGS report directly connect the land and sea with the creation of both a seamless onshore and offshore digital terrain model (DTM) and geologic map. One of the priority goals (and objectives) of the COPA plan is to 'monitor and map the ocean environment to provide data about conditions and trends.' Maps within this report provide land and sea geologic information for mapping and monitoring nearshore sediment processes, pollution transport, and sea-level rise and fall.

California↗
USGS2014

Introduction to the geologic and geophysical studies of Fort Irwin, California

Geologic and geophysical investigations in the vicinity of Fort Irwin National Training Center, California, have been completed in support of groundwater investigations, and are presented in eight chapters of this report. A generalized surficial geologic map along with field and borehole investigations conducted during 2010–11 provide a lithostratigraphic and structural framework for the area during the Cenozoic. Electromagnetic properties of resistivity were measured in the laboratory on hand and core samples, and compared to borehole geophysical resistivity data. These data were used in conjunction with ground-based time-domain and airborne data and interpretations to provide a framework for the shallow lithologic units and structure. Gravity and aeromagnetic maps cover areas ~4 to 5 times that of Fort Irwin. Each chapter includes hydrogeologic applications of the data or model results.

California↗
USGS2014

Geology and geophysics applied to groundwater hydrology at Fort Irwin, California

Geologic and geophysical investigations in the vicinity of Fort Irwin National Training Center, California, have been completed in support of groundwater investigations, and are presented in eight chapters of this report. A generalized surficial geologic map along with field and borehole investigations conducted during 2010–11 provide a lithostratigraphic and structural framework for the area during the Cenozoic. Electromagnetic properties of resistivity were measured in the laboratory on hand and core samples, and compared to borehole geophysical resistivity data. These data were used in conjunction with ground-based time-domain and airborne data and interpretations to provide a framework for the shallow lithologic units and structure. Gravity and aeromagnetic maps cover areas ~4 to 5 times that of Fort Irwin. Each chapter includes hydrogeologic applications of the data or model results.

Open-File Report↗
USGS2007

Data sources and compilation: Chapter 27 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

Geologic, production, and exploration/discovery-history data are used by the U.S. Geological Survey to aid in the assessment of petroleum resources. These data, as well as the broad knowledge and experience of the assessing geologists, are synthesized to provide, for each assessment unit, geologic and exploration models upon which estimates are made of the number and sizes of undiscovered accumulations for conventional assessment units or number and total recoverable volumes of untested cells for continuous assessment units (input data for resource calculations). Quantified geologic information and trends in production and exploration/discovery-history data with respect to time and exploration effort provide guides for the estimating parameters of variables recorded on the input-data forms (input data) used to calculate petroleum resources. An Assessment Review Team reviews proposed geologic and exploration models and input data for each assessment unit in formal assessment meetings. The Assessment Review Team maintains the accuracy and consistency of the assessment procedure during the formal assessment meetings.

Professional Paper↗
USGS2001

Geologic map and digital database of the San Rafael Mtn. 7.5-minute quadrangle, Santa Barbara County, California

Geologic mapping of the San Rafael Primitive Area (now the San Rafael Wilderness) by Gower and others (1966) and Vedder and others (1967) did not include all of the San Rafael Mtn. quadrangle, and the part that was mapped was done in reconnaissance fashion. To help resolve some of the structural and stratigraphic ambiguities of the earlier mapping and to complete the mapping of the quadrangle, additional field work was done during short intervals in 1980 and 1981 and from 1996 to 1998. Contacts within the belt of Franciscan rocks at the southwestern corner of the quadrangle were generalized from the detailed map by Wahl (1998). Because extensive areas were inaccessible owing to impenetrable chaparral, observations from several helicopter overflights (1965, 1980, 1981) and interpretations from aerial photographs were used as compilation aids. Consequently, some of the depicted contacts and faults are highly inferential, particularly within the Upper Cretaceous rocks throughout the middle part of the quadrangle.

California↗
USGS1985

An evaluation of temperature scales for silica diagenesis in diatomaceous sequences including a new approach based on the Miocene Monterey Formation, California

Geologic relations indicate that silica phases transformed in the Monterey Formation in two zones that persist over a narrow depth/temperature range and do not stratigraphically overlap. The wide and overlapping range of reported temperatures of these transformations is mainly a result of the many uncertainties inherent in the different methods used to estimate temperature and does not indicate that phases transform throughout these ranges. Our approach to a reliable temperature scale for silica diagenesis combines as empirical zonation of silica phases with temperature calibration from a sequence at maximum temperature and depth of burial. ?? 1985 Springer-Verlag New York Inc.

Geo-Marine Letters↗