Robert J Fleck (Former Employee)
Science and Products
Filter Total Items: 43
Miocene magmatism in the Bodie Hills volcanic field, California and Nevada: A long-lived eruptive center in the southern segment of the ancestral Cascades arc Miocene magmatism in the Bodie Hills volcanic field, California and Nevada: A long-lived eruptive center in the southern segment of the ancestral Cascades arc
The Middle to Late Miocene Bodie Hills volcanic field is a >700 km2, long-lived (∼9 Ma) but episodic eruptive center in the southern segment of the ancestral Cascades arc north of Mono Lake (California, U.S.). It consists of ∼20 major eruptive units, including 4 trachyandesite stratovolcanoes emplaced along the margins of the field, and numerous, more centrally located silicic...
Authors
David A. John, Edward A. du Bray, Richard J. Blakely, Robert J. Fleck, Peter G. Vikre, Stephen E. Box, Barry C. Moring
A half-million-year record of paleoclimate from the Lake Manix Core, Mojave Desert, California A half-million-year record of paleoclimate from the Lake Manix Core, Mojave Desert, California
Pluvial lakes in the southwestern U.S. responded sensitively to past climate through effects on rainfall, runoff, and evaporation. Although most studies agree that pluvial lakes in the southwestern U.S. reached their highest levels coeval with glacial stages, the specific timing of increased effective moisture and lake-level rise is debated, particularly for the southwesternmost lakes...
Authors
Marith C. Reheis, Jordon Bright, Steve P. Lund, David M. Miller, Gary Skipp, Robert J. Fleck
Geology and geochemistry of volcanic centers within the eastern half of the Sonoma volcanic field, northern San Francisco Bay region, California Geology and geochemistry of volcanic centers within the eastern half of the Sonoma volcanic field, northern San Francisco Bay region, California
Volcanic rocks in the Sonoma volcanic field in the northern California Coast Ranges contain heterogeneous assemblages of a variety of compositionally diverse volcanic rocks. We have used field mapping, new and existing age determinations, and 343 new major and trace element analyses of whole-rock samples from lavas and tuff to define for the first time volcanic source areas for many...
Authors
Donald S. Sweetkind, James J. Rytuba, Victoria E. Langenheim, Robert J. Fleck
Age, composition, and areal distribution of the Pliocene Lawlor Tuff, and three younger Pliocene tuffs, California and Nevada Age, composition, and areal distribution of the Pliocene Lawlor Tuff, and three younger Pliocene tuffs, California and Nevada
The Lawlor Tuff is a widespread dacitic tephra layer produced by Plinian eruptions and ash flows derived from the Sonoma Volcanics, a volcanic area north of San Francisco Bay in the central Coast Ranges of California, USA. The younger, chemically similar Huichica tuff, the tuff of Napa, and the tuff of Monticello Road sequentially overlie the Lawlor Tuff, and were erupted from the same...
Authors
Andrei M. Sarna-Wojcicki, Alan L. Deino, Robert J. Fleck, Robert J. McLaughlin, David Wagner, Elmira Wan, David B. Wahl, John W. Hillhouse, Michael Perkins
Ages and sources of components of Zn-Pb, Cu, precious metal, and platinum group element deposits in the goodsprings district, Clark County, Nevada Ages and sources of components of Zn-Pb, Cu, precious metal, and platinum group element deposits in the goodsprings district, Clark County, Nevada
The Goodsprings district, Clark County, Nevada, includes zinc-dominant carbonate replacement deposits of probable late Paleozoic age, and lead-dominant carbonate replacement deposits, copper ± precious metal-platinum group element (PGE) deposits, and gold ± silver deposits that are spatially associated with Late Triassic porphyritic intrusions. The district encompasses ~500 km2 although...
Authors
Peter G. Vikre, Quentin J. Browne, Robert J. Fleck, Albert H. Hofstra, Joseph L. Wooden
Geology, geochronology, and paleogeography of the southern Sonoma volcanic field and adjacent areas, northern San Francisco Bay region, California Geology, geochronology, and paleogeography of the southern Sonoma volcanic field and adjacent areas, northern San Francisco Bay region, California
Recent geologic mapping in the northern San Francisco Bay region (California, USA) supported by radiometric dating and tephrochronologic correlations, provides insights into the framework geology, stratigraphy, tectonic evolution, and geologic history of this part of the San Andreas transform plate boundary. There are 25 new and existing radiometric dates that define three temporally...
Authors
David L. Wagner, George J. Saucedo, Kevin B. Clahan, Robert J. Fleck, Victoria E. Langenheim, Robert J. McLaughlin, Andrei M. Sarna-Wojcicki, James R. Allen, Alan L. Deino
Science and Products
Filter Total Items: 43
Miocene magmatism in the Bodie Hills volcanic field, California and Nevada: A long-lived eruptive center in the southern segment of the ancestral Cascades arc Miocene magmatism in the Bodie Hills volcanic field, California and Nevada: A long-lived eruptive center in the southern segment of the ancestral Cascades arc
The Middle to Late Miocene Bodie Hills volcanic field is a >700 km2, long-lived (∼9 Ma) but episodic eruptive center in the southern segment of the ancestral Cascades arc north of Mono Lake (California, U.S.). It consists of ∼20 major eruptive units, including 4 trachyandesite stratovolcanoes emplaced along the margins of the field, and numerous, more centrally located silicic...
Authors
David A. John, Edward A. du Bray, Richard J. Blakely, Robert J. Fleck, Peter G. Vikre, Stephen E. Box, Barry C. Moring
A half-million-year record of paleoclimate from the Lake Manix Core, Mojave Desert, California A half-million-year record of paleoclimate from the Lake Manix Core, Mojave Desert, California
Pluvial lakes in the southwestern U.S. responded sensitively to past climate through effects on rainfall, runoff, and evaporation. Although most studies agree that pluvial lakes in the southwestern U.S. reached their highest levels coeval with glacial stages, the specific timing of increased effective moisture and lake-level rise is debated, particularly for the southwesternmost lakes...
Authors
Marith C. Reheis, Jordon Bright, Steve P. Lund, David M. Miller, Gary Skipp, Robert J. Fleck
Geology and geochemistry of volcanic centers within the eastern half of the Sonoma volcanic field, northern San Francisco Bay region, California Geology and geochemistry of volcanic centers within the eastern half of the Sonoma volcanic field, northern San Francisco Bay region, California
Volcanic rocks in the Sonoma volcanic field in the northern California Coast Ranges contain heterogeneous assemblages of a variety of compositionally diverse volcanic rocks. We have used field mapping, new and existing age determinations, and 343 new major and trace element analyses of whole-rock samples from lavas and tuff to define for the first time volcanic source areas for many...
Authors
Donald S. Sweetkind, James J. Rytuba, Victoria E. Langenheim, Robert J. Fleck
Age, composition, and areal distribution of the Pliocene Lawlor Tuff, and three younger Pliocene tuffs, California and Nevada Age, composition, and areal distribution of the Pliocene Lawlor Tuff, and three younger Pliocene tuffs, California and Nevada
The Lawlor Tuff is a widespread dacitic tephra layer produced by Plinian eruptions and ash flows derived from the Sonoma Volcanics, a volcanic area north of San Francisco Bay in the central Coast Ranges of California, USA. The younger, chemically similar Huichica tuff, the tuff of Napa, and the tuff of Monticello Road sequentially overlie the Lawlor Tuff, and were erupted from the same...
Authors
Andrei M. Sarna-Wojcicki, Alan L. Deino, Robert J. Fleck, Robert J. McLaughlin, David Wagner, Elmira Wan, David B. Wahl, John W. Hillhouse, Michael Perkins
Ages and sources of components of Zn-Pb, Cu, precious metal, and platinum group element deposits in the goodsprings district, Clark County, Nevada Ages and sources of components of Zn-Pb, Cu, precious metal, and platinum group element deposits in the goodsprings district, Clark County, Nevada
The Goodsprings district, Clark County, Nevada, includes zinc-dominant carbonate replacement deposits of probable late Paleozoic age, and lead-dominant carbonate replacement deposits, copper ± precious metal-platinum group element (PGE) deposits, and gold ± silver deposits that are spatially associated with Late Triassic porphyritic intrusions. The district encompasses ~500 km2 although...
Authors
Peter G. Vikre, Quentin J. Browne, Robert J. Fleck, Albert H. Hofstra, Joseph L. Wooden
Geology, geochronology, and paleogeography of the southern Sonoma volcanic field and adjacent areas, northern San Francisco Bay region, California Geology, geochronology, and paleogeography of the southern Sonoma volcanic field and adjacent areas, northern San Francisco Bay region, California
Recent geologic mapping in the northern San Francisco Bay region (California, USA) supported by radiometric dating and tephrochronologic correlations, provides insights into the framework geology, stratigraphy, tectonic evolution, and geologic history of this part of the San Andreas transform plate boundary. There are 25 new and existing radiometric dates that define three temporally...
Authors
David L. Wagner, George J. Saucedo, Kevin B. Clahan, Robert J. Fleck, Victoria E. Langenheim, Robert J. McLaughlin, Andrei M. Sarna-Wojcicki, James R. Allen, Alan L. Deino
*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