Robert J Fleck (Former Employee)
Science and Products
Tabular geochronologic, geochemical, and isotopic data from igneous rocks in the Lane Mountain area, San Bernardino County, California
This dataset provides geochronologic, geochemical, and isotopic data for selected igneous rock samples collected in the Lane Mountain area about 20 kilometers northeast of Barstow, California. Uranium-lead (U-Pb) zircon geochronologic and whole-rock geochemical data were obtained for 62 samples of which 28 are from Permian to Triassic plutonic rocks and dikes, 24 are from Late Jurassic...
Data to accompany U.S. Geological Survey Data Series 1099: Petrographic, geochemical and geochronologic data for Cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
This dataset is the assembled analytical results of geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada. Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during...
Geologic map of the Beacon Rock quadrangle, Skamania County, Washington
The Beacon Rock 7.5′ quadrangle is located approximately 50 km east of Portland, Oregon, on the north side of the Columbia River Gorge, a scenic canyon carved through the axis of the Cascade Range by the Columbia River. Although approximately 75,000 people live within the gorge, much of the region remains little developed and is encompassed by the 292,500-acre Columbia River Gorge...
Geologic map of the Bodie Hills, California and Nevada
The Bodie Hills covers about 1,200 km2 straddling the California-Nevada state boundary just north of Mono Lake in the western part of the Basin and Range Province, about 20 km east of the central Sierra Nevada. The area is mostly underlain by the partly overlapping, middle to late Miocene Bodie Hills volcanic field and Pliocene to late Pleistocene Aurora volcanic field (John and others...
A tunnel runs through it — An inside view of the Tualatin Mountains, Oregon
The Tualatin Mountains form a northwest-striking ridge about 350 m high that separates Portland, Oregon, from the cities of the Tualatin Valley to the west. Known informally as the Portland Hills, the ridge is a late Cenozoic anticline, bounded by reverse faults that dip toward the anticlinal axis. The anticline is a broad, open fold consisting chiefly of Miocene Columbia River Basalt...
Filter Total Items: 41
Geochronologic, isotopic, and geochemical data from pre-Cretaceous plutonic rocks in the Lane Mountain area, San Bernardino County, California
Pre-Cretaceous, predominantly dioritic plutonic rocks in the Lane Mountain area, California, intrude metasedimentary and metavolcanic rocks considered part of the El Paso terrane. New geochronologic (uranium-lead zircon), geochemical, and isotopic data provide a reliable basis for dividing these pre-Cretaceous plutonic rocks into two mappable suites of Permian–Triassic and Late Jurassic...
Authors
Paul Stone, Howard J. Brown, M. Robinson Cecil, Robert J. Fleck, Jorge A. Vazquez, John A. Fitzpatrick
Characterization of the rhyolite of Bodie Hills and 40Ar/39Ar intercalibration with Ar mineral standards
The rhyolite of Bodie Hills (California) is characterized compositionally and the geochronology of selected phases is studied. Sanidine (BHs) from the rhyolite is well suited as a 40Ar/39Ar reference material with high K/Ca and radiogenic yield. Intercalibration with GA1550 biotite from the Dromedary igneous complex (New South Wales, Australia) yields an age of 9.7946 ± 0.0031 Ma for BHs...
Authors
Robert J. Fleck, Andrew T. Calvert, Matthew Coble, Joseph L. Wooden, Kip V. Hodges, Leslie A. Hayden, Matthijs C. van Soest, Edward A. du Bray, David A. John
Geochronologic, isotopic, and geochemical data from igneous rocks in the Lane Mountain area, San Bernardino County, California
We present new geochronologic, isotopic, and geochemical data for selected igneous rocks in the Lane Mountain area, California. We determined SHRIMP-RG U-Pb zircon ages for the following units: (1) Larrea complex (~253 Ma and ~149–146 Ma); (2) Daisy granodiorite (~151 Ma); (3) Jack Spring quartz monzonite (~85–82 Ma); (4) unnamed porphyritic dikes and stocks (~80–73 Ma); and (5) Lane...
Authors
Paul Stone, Howard J. Brown, M. Robinson Cecil, Robert J. Fleck, Jorge A. Vazquez, John A. Fitzpatrick, Jose J. Rosario
Petrographic, geochemical, and geochronologic data for cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
The purpose of this report is to summarize geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada (fig. 1). Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during...
Authors
Edward A. du Bray, David A. John, Peter G. Vikre, Joseph P. Colgan, Michael A. Cosca, Leah E. Morgan, Robert J. Fleck, Wayne R. Premo, Christopher S. Holm-Denoma
Exploring ends of eras in the eastern Mojave Desert: The road log
No abstract available.
Authors
David M. Miller, G.A. Spaulding, R.E. Reynolds, James Calzia, M.E. Wells, Robert J. Fleck, S. Baltzer
Geologic map and database of the Chocolate Mountain Aerial Gunnery Range, Riverside and Imperial Counties, California
The northwest-trending Chocolate Mountains are situated along the northeastern margin of the southern Salton Trough. The Chocolate Mountain Aerial Gunnery Range occupies most of the 75-km-long part of the Chocolate Mountains that lies between Salt Creek to the north and California State Highway 78 to the south. Mapping studies in the Chocolate Mountains within the gunnery range are few...
Authors
Robert E. Powell, Robert J. Fleck, Pamela M. Cossette
Late Neogene–Quaternary tephrochronology, stratigraphy, and paleoclimate of Death Valley, California, USA
Sedimentary deposits in midlatitude continental basins often preserve a paleoclimate record complementary to marine-based records. However, deriving that paleoclimate record depends on having well-exposed deposits and establishing a sufficiently robust geochronology. After decades of research, we have been able to correlate 77 tephra beds exposed in multiple stratigraphic sections in the...
Authors
Jeffrey R. Knott, Michael N Machette, Elmira Wan, Ralph E. Klinger, Joseph C Liddicoat, Andrei M. Sarna-Wojcicki, Robert J. Fleck, Alan L. Deino, John W Geissman, Janet L. Slate, David Wahl, Brian P. Wernicke, Stephen G. Wells, John C. Tinsley, Jeffrey C Hathaway, Veva M. Weamer
Analysis of the age and paleomagnetic orientation of the Broadwell Mesa Basalt, Bristol Mountains, CA
To add to the regional paleomagnetic data documenting block rotation in eastern California, we determined the age and paleomagnetic rotation of the Broadwell Mesa basalt, a basalt in the Bristol Mountains, CA as part of an effort to constrain the timing and rotation of blocks adjacent to the fault. The east-striking sinistral Broadwell Mesa fault cuts and separates the basalt into two...
Authors
Geoffrey Phelps, John Hillhouse, Robert J. Fleck, David M. Miller, David C. Buesch, Andrew J. Cyr, Kevin M. Schmidt
Paleomagnetism and 40Ar/39Ar geochronology of the Plio-Pleistocene Boring Volcanic Field: Implications for the geomagnetic polarity time scale and paleosecular variation
Paleomagnetic directions and 40Ar/39Ar ages have been determined for samples of lava flows from the same outcrops, where possible, for 84 eruptive units ranging in age from 3200 ka to 60 ka within the Boring Volcanic Field (BVF) of the Pacific Northwest, USA. This study expands upon our previous results for the BVF, and compares the combined results with the current geomagnetic polarity...
Authors
Jonathan T. Hagstrum, Robert J. Fleck, Russell C. Evarts, Andrew T. Calvert
By
Energy and Mineral Resources Mission Area, Natural Hazards Mission Area, Energy Resources Program, Geomagnetism Program, Mineral Resources Program, National Cooperative Geologic Mapping Program, National Laboratories Program, Science and Decisions Center, Volcano Hazards Program, Geologic Hazards Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center, Volcano Science Center
Geologic and geophysical maps and volcanic history of the Kelton Pass SE and Monument Peak SW Quadrangles, Box Elder County, Utah
The Kelton Pass SE and Monument Peak SW 7.5' quadrangles are located in Box Elder County, northwestern Utah (figure 1; plate 1). The northern boundary of the map area is 8.5 miles (13.7 km) south of the Utah-Idaho border, and the southern boundary reaches the edge of mud flats at the north end of Great Salt Lake. Elevations range from 4218 feet (1286 m) along the mud flats to 5078 feet...
Authors
Tracey J. Felger, David M. Miller, Victoria E. Langenheim, Robert J. Fleck
Gold-silver mining districts, alteration zones, and paleolandforms in the Miocene Bodie Hills Volcanic Field, California and Nevada
The Bodie Hills is a ~40 by ~30 kilometer volcanic field that straddles the California-Nevada state boundary between Mono Lake and the East Walker River. Three precious metal mining districts and nine alteration zones are delineated in Tertiary-Quaternary volcanic and Mesozoic granitic and metamorphic rocks that comprise the volcanic field. Cumulative production from the mining districts...
Authors
Peter G. Vikre, David A. John, Edward A. du Bray, Robert J. Fleck
Geochronology of Cenozoic rocks in the Bodie Hills, California and Nevada
The purpose of this report is to present geochronologic data for unaltered volcanic rocks, hydrothermally altered volcanic rocks, and mineral deposits of the Miocene Bodie Hills and Pliocene to Pleistocene Aurora volcanic fields of east-central California and west-central Nevada. Most of the data presented here were derived from samples collected between 2000–13, but some of the...
Authors
Robert J. Fleck, Edward A. du Bray, David A. John, Peter G. Vikre, Michael A. Cosca, Lawrence W. Snee, Stephen E. Box
Pacific Northwest Geologic Mapping: Northern Pacific Border, Cascades and Columbia
The Pacific Northwest is an area created by active and complex geological processes. On its path to the Pacific Ocean, the Columbia River slices through a chain of active volcanoes located along the western margin of the U.S. in Washington, Oregon, and northern California. These volcanoes rest above the active Cascadia subduction zone, which is the boundary where the oceanic tectonic plate dives...
Science and Products
Tabular geochronologic, geochemical, and isotopic data from igneous rocks in the Lane Mountain area, San Bernardino County, California
This dataset provides geochronologic, geochemical, and isotopic data for selected igneous rock samples collected in the Lane Mountain area about 20 kilometers northeast of Barstow, California. Uranium-lead (U-Pb) zircon geochronologic and whole-rock geochemical data were obtained for 62 samples of which 28 are from Permian to Triassic plutonic rocks and dikes, 24 are from Late Jurassic...
Data to accompany U.S. Geological Survey Data Series 1099: Petrographic, geochemical and geochronologic data for Cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
This dataset is the assembled analytical results of geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada. Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during...
Geologic map of the Beacon Rock quadrangle, Skamania County, Washington
The Beacon Rock 7.5′ quadrangle is located approximately 50 km east of Portland, Oregon, on the north side of the Columbia River Gorge, a scenic canyon carved through the axis of the Cascade Range by the Columbia River. Although approximately 75,000 people live within the gorge, much of the region remains little developed and is encompassed by the 292,500-acre Columbia River Gorge...
Geologic map of the Bodie Hills, California and Nevada
The Bodie Hills covers about 1,200 km2 straddling the California-Nevada state boundary just north of Mono Lake in the western part of the Basin and Range Province, about 20 km east of the central Sierra Nevada. The area is mostly underlain by the partly overlapping, middle to late Miocene Bodie Hills volcanic field and Pliocene to late Pleistocene Aurora volcanic field (John and others...
A tunnel runs through it — An inside view of the Tualatin Mountains, Oregon
The Tualatin Mountains form a northwest-striking ridge about 350 m high that separates Portland, Oregon, from the cities of the Tualatin Valley to the west. Known informally as the Portland Hills, the ridge is a late Cenozoic anticline, bounded by reverse faults that dip toward the anticlinal axis. The anticline is a broad, open fold consisting chiefly of Miocene Columbia River Basalt...
Filter Total Items: 41
Geochronologic, isotopic, and geochemical data from pre-Cretaceous plutonic rocks in the Lane Mountain area, San Bernardino County, California
Pre-Cretaceous, predominantly dioritic plutonic rocks in the Lane Mountain area, California, intrude metasedimentary and metavolcanic rocks considered part of the El Paso terrane. New geochronologic (uranium-lead zircon), geochemical, and isotopic data provide a reliable basis for dividing these pre-Cretaceous plutonic rocks into two mappable suites of Permian–Triassic and Late Jurassic...
Authors
Paul Stone, Howard J. Brown, M. Robinson Cecil, Robert J. Fleck, Jorge A. Vazquez, John A. Fitzpatrick
Characterization of the rhyolite of Bodie Hills and 40Ar/39Ar intercalibration with Ar mineral standards
The rhyolite of Bodie Hills (California) is characterized compositionally and the geochronology of selected phases is studied. Sanidine (BHs) from the rhyolite is well suited as a 40Ar/39Ar reference material with high K/Ca and radiogenic yield. Intercalibration with GA1550 biotite from the Dromedary igneous complex (New South Wales, Australia) yields an age of 9.7946 ± 0.0031 Ma for BHs...
Authors
Robert J. Fleck, Andrew T. Calvert, Matthew Coble, Joseph L. Wooden, Kip V. Hodges, Leslie A. Hayden, Matthijs C. van Soest, Edward A. du Bray, David A. John
Geochronologic, isotopic, and geochemical data from igneous rocks in the Lane Mountain area, San Bernardino County, California
We present new geochronologic, isotopic, and geochemical data for selected igneous rocks in the Lane Mountain area, California. We determined SHRIMP-RG U-Pb zircon ages for the following units: (1) Larrea complex (~253 Ma and ~149–146 Ma); (2) Daisy granodiorite (~151 Ma); (3) Jack Spring quartz monzonite (~85–82 Ma); (4) unnamed porphyritic dikes and stocks (~80–73 Ma); and (5) Lane...
Authors
Paul Stone, Howard J. Brown, M. Robinson Cecil, Robert J. Fleck, Jorge A. Vazquez, John A. Fitzpatrick, Jose J. Rosario
Petrographic, geochemical, and geochronologic data for cenozoic volcanic rocks of the Tonopah, Divide, and Goldfield Mining Districts, Nevada
The purpose of this report is to summarize geochemical, petrographic, and geochronologic data for samples, principally those of unmineralized Tertiary volcanic rocks, from the Tonopah, Divide, and Goldfield mining districts of west-central Nevada (fig. 1). Much of the data presented here for the Tonopah and Divide districts are for samples collected by Bonham and Garside (1979) during...
Authors
Edward A. du Bray, David A. John, Peter G. Vikre, Joseph P. Colgan, Michael A. Cosca, Leah E. Morgan, Robert J. Fleck, Wayne R. Premo, Christopher S. Holm-Denoma
Exploring ends of eras in the eastern Mojave Desert: The road log
No abstract available.
Authors
David M. Miller, G.A. Spaulding, R.E. Reynolds, James Calzia, M.E. Wells, Robert J. Fleck, S. Baltzer
Geologic map and database of the Chocolate Mountain Aerial Gunnery Range, Riverside and Imperial Counties, California
The northwest-trending Chocolate Mountains are situated along the northeastern margin of the southern Salton Trough. The Chocolate Mountain Aerial Gunnery Range occupies most of the 75-km-long part of the Chocolate Mountains that lies between Salt Creek to the north and California State Highway 78 to the south. Mapping studies in the Chocolate Mountains within the gunnery range are few...
Authors
Robert E. Powell, Robert J. Fleck, Pamela M. Cossette
Late Neogene–Quaternary tephrochronology, stratigraphy, and paleoclimate of Death Valley, California, USA
Sedimentary deposits in midlatitude continental basins often preserve a paleoclimate record complementary to marine-based records. However, deriving that paleoclimate record depends on having well-exposed deposits and establishing a sufficiently robust geochronology. After decades of research, we have been able to correlate 77 tephra beds exposed in multiple stratigraphic sections in the...
Authors
Jeffrey R. Knott, Michael N Machette, Elmira Wan, Ralph E. Klinger, Joseph C Liddicoat, Andrei M. Sarna-Wojcicki, Robert J. Fleck, Alan L. Deino, John W Geissman, Janet L. Slate, David Wahl, Brian P. Wernicke, Stephen G. Wells, John C. Tinsley, Jeffrey C Hathaway, Veva M. Weamer
Analysis of the age and paleomagnetic orientation of the Broadwell Mesa Basalt, Bristol Mountains, CA
To add to the regional paleomagnetic data documenting block rotation in eastern California, we determined the age and paleomagnetic rotation of the Broadwell Mesa basalt, a basalt in the Bristol Mountains, CA as part of an effort to constrain the timing and rotation of blocks adjacent to the fault. The east-striking sinistral Broadwell Mesa fault cuts and separates the basalt into two...
Authors
Geoffrey Phelps, John Hillhouse, Robert J. Fleck, David M. Miller, David C. Buesch, Andrew J. Cyr, Kevin M. Schmidt
Paleomagnetism and 40Ar/39Ar geochronology of the Plio-Pleistocene Boring Volcanic Field: Implications for the geomagnetic polarity time scale and paleosecular variation
Paleomagnetic directions and 40Ar/39Ar ages have been determined for samples of lava flows from the same outcrops, where possible, for 84 eruptive units ranging in age from 3200 ka to 60 ka within the Boring Volcanic Field (BVF) of the Pacific Northwest, USA. This study expands upon our previous results for the BVF, and compares the combined results with the current geomagnetic polarity...
Authors
Jonathan T. Hagstrum, Robert J. Fleck, Russell C. Evarts, Andrew T. Calvert
By
Energy and Mineral Resources Mission Area, Natural Hazards Mission Area, Energy Resources Program, Geomagnetism Program, Mineral Resources Program, National Cooperative Geologic Mapping Program, National Laboratories Program, Science and Decisions Center, Volcano Hazards Program, Geologic Hazards Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center, Volcano Science Center
Geologic and geophysical maps and volcanic history of the Kelton Pass SE and Monument Peak SW Quadrangles, Box Elder County, Utah
The Kelton Pass SE and Monument Peak SW 7.5' quadrangles are located in Box Elder County, northwestern Utah (figure 1; plate 1). The northern boundary of the map area is 8.5 miles (13.7 km) south of the Utah-Idaho border, and the southern boundary reaches the edge of mud flats at the north end of Great Salt Lake. Elevations range from 4218 feet (1286 m) along the mud flats to 5078 feet...
Authors
Tracey J. Felger, David M. Miller, Victoria E. Langenheim, Robert J. Fleck
Gold-silver mining districts, alteration zones, and paleolandforms in the Miocene Bodie Hills Volcanic Field, California and Nevada
The Bodie Hills is a ~40 by ~30 kilometer volcanic field that straddles the California-Nevada state boundary between Mono Lake and the East Walker River. Three precious metal mining districts and nine alteration zones are delineated in Tertiary-Quaternary volcanic and Mesozoic granitic and metamorphic rocks that comprise the volcanic field. Cumulative production from the mining districts...
Authors
Peter G. Vikre, David A. John, Edward A. du Bray, Robert J. Fleck
Geochronology of Cenozoic rocks in the Bodie Hills, California and Nevada
The purpose of this report is to present geochronologic data for unaltered volcanic rocks, hydrothermally altered volcanic rocks, and mineral deposits of the Miocene Bodie Hills and Pliocene to Pleistocene Aurora volcanic fields of east-central California and west-central Nevada. Most of the data presented here were derived from samples collected between 2000–13, but some of the...
Authors
Robert J. Fleck, Edward A. du Bray, David A. John, Peter G. Vikre, Michael A. Cosca, Lawrence W. Snee, Stephen E. Box
Pacific Northwest Geologic Mapping: Northern Pacific Border, Cascades and Columbia
The Pacific Northwest is an area created by active and complex geological processes. On its path to the Pacific Ocean, the Columbia River slices through a chain of active volcanoes located along the western margin of the U.S. in Washington, Oregon, and northern California. These volcanoes rest above the active Cascadia subduction zone, which is the boundary where the oceanic tectonic plate dives...
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government