Albert H Hofstra (Former Employee)
Science and Products
Filter Total Items: 82
Deep permeable fault–controlled helium transport and limited mantle flux in two extensional geothermal systems in the Great Basin, United States Deep permeable fault–controlled helium transport and limited mantle flux in two extensional geothermal systems in the Great Basin, United States
This study assesses the relative importance of deeply circulating meteoric water and direct mantle fluid inputs on near-surface 3He/4He anomalies reported at the Coso and Beowawe geothermal fields of the western United States. The depth of meteoric fluid circulation is a critical factor that controls the temperature, extent of fluid-rock isotope exchange, and mixing with deeply sourced...
Authors
Amlan Banerjee, Mark Person, Albert Hofstra, Donald S. Sweetkind, Denis Cohen, Andrew Sabin, Jeff Unruh, George Zyvoloski, Carl W. Gable, Laura Crossey, Karl Karlstrom
Geochemical and stable isotopic data on barren and mineralized drill core in the Devonian Popovich Formation, Screamer sector of the Betze-Post gold deposit, northern Carlin trend, Nevada Geochemical and stable isotopic data on barren and mineralized drill core in the Devonian Popovich Formation, Screamer sector of the Betze-Post gold deposit, northern Carlin trend, Nevada
The Devonian Popovich Formation is the major host for Carlin-type gold deposits in the northern Carlin trend of Nevada. The Popovich is composed of gray to black, thin-bedded, calcareous to dolomitic mudstone and limestone deposited near the carbonate platform margin. Carlin-type gold deposits are Eocene, disseminated, auriferous pyrite deposits characterized by acid leaching...
Authors
William D. Christiansen, Albert H. Hofstra, Pamela B. Zohar, Gilles Tousignant
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
Evaluation of the role of magmatic volatiles from Eocene mafic to felsic igneous rocks in the formation of Carlin-type gold deposits of the Carlin trend and Jerritt Canyon District as constrained by preliminary He, Pb, Sr, and Nd isotopic data Evaluation of the role of magmatic volatiles from Eocene mafic to felsic igneous rocks in the formation of Carlin-type gold deposits of the Carlin trend and Jerritt Canyon District as constrained by preliminary He, Pb, Sr, and Nd isotopic data
No abstract available.
Authors
Albert H. Hofstra, Gary P. Landis, Wayne R. Premo, M.W. Ressel, Christopher D. Henry
'Forensic' geochemical approaches to constrain the source of Au-Ag in low-sulfidation epithermal ores 'Forensic' geochemical approaches to constrain the source of Au-Ag in low-sulfidation epithermal ores
In order to better constrain genetic processes involved in forming mineral deposits (and ultimately exploration models), it helps to know from where the metals of interest are derived. How the metals arrived at their point of deposition, and why they were deposited there, are separate issues. We are using three different techniques in an attempt to better understand these processes for...
Authors
James A. Saunders, G. D. Kamenov, Albert H. Hofstra, D. L. Unger, R. A. Creaser, F. Barra
Paleozoic stratigraphy and kinematics of the Roberts Mountains allochthon in the Independence Mountains, northern Nevada Paleozoic stratigraphy and kinematics of the Roberts Mountains allochthon in the Independence Mountains, northern Nevada
New biostratigraphic, stratigraphic, and structural data from deformed lower Paleozoic sedimentary units of the Roberts Mountains allochthon (RMA), Independence Mountains, Nevada, have enabled the identification of stratigraphic units within the allochthon that range in age from Late Cambrian through Late Devonian. The McAfee thrust fault emplaced a relatively thick (>200 m) sheet of...
Authors
Christopher S. Holm-Denoma, Albert H. Hofstra, Stephen A. Leslie, Paula J. Noble
Evolution of Ore Deposits and Technology Transfer Project: Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008 Evolution of Ore Deposits and Technology Transfer Project: Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008
Principal functions of the U.S. Geological Survey (USGS) Mineral Resources Program are providing assessments of the location, quantity, and quality of undiscovered mineral deposits, and predicting the environmental impacts of exploration and mine development. The mineral and environmental assessments of domestic deposits are used by planners and decisionmakers to improve the stewardship...
Authors
Robert O. Rye, Craig A. Johnson, Gary P. Landis, Albert H. Hofstra, Poul Emsbo, Craig A. Stricker, Andrew G. Hunt, Brian G. Rusk
Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits
In other parts of the world, previous workers have shown that sparry dolomite in carbonate rocks may be produced by the generation and movement of hot basinal brines in response to arid paleoclimates and tectonism, and that some of these brines served as the transport medium for metals fixed in Mississippi Valley-type (MVT) and sedimentary exhalative (Sedex) deposits of Zn, Pb, Ag, Au...
Authors
S. F. Diehl, A. H. Hofstra, A.E. Koenig, P. Emsbo, W. Christiansen, Chad Johnson
Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008 Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008
Principal functions of the Mineral Resources Program are providing information to decision-makers related to mineral deposits on federal lands and predicting the environmental consequences of the mining or natural weathering of those deposits. Performing these functions requires that predictions be made of the likelihood of undiscovered deposits. The predictions are based on geologic and
Authors
R. O. Rye, C. A. Johnson, G. P. Landis, A. H. Hofstra, P. Emsbo, C. A. Stricker, A.G. Hunt, B.G. Rusk
Hydrologic models of modern and fossil geothermal systems in the Great Basin: Genetic implications for epithermal Au-Ag and Carlin-type gold deposits Hydrologic models of modern and fossil geothermal systems in the Great Basin: Genetic implications for epithermal Au-Ag and Carlin-type gold deposits
The Great Basin region in the western United States contains active geothermal systems, large epithermal Au-Ag deposits, and world-class Carlin-type gold deposits. Temperature profiles, fluid inclusion studies, and isotopic evidence suggest that modern and fossil hydrothermal systems associated with gold mineralization share many common features, including the absence of a clear magmatic...
Authors
M. Person, A. Banerjee, A. Hofstra, D. Sweetkind, Y. Gao
Great Basin paleontological database Great Basin paleontological database
The U.S. Geological Survey has constructed a paleontological database for the Great Basin physiographic province that can be served over the World Wide Web for data entry, queries, displays, and retrievals. It is similar to the web-database solution that we constructed for Alaskan paleontological data (www.alaskafossil.org). The first phase of this effort was to compile a paleontological
Authors
N. Zhang, R. B. Blodgett, A. H. Hofstra
Great Basin Paleontological Bibliography Great Basin Paleontological Bibliography
Introduction This work was conceived as a derivative product for 'The Metallogeny of the Great Basin' project of the Mineral Resources Program of the U.S. Geological Survey. In the course of preparing a fossil database for the Great Basin that could be accessed from the Internet, it was determined that a comprehensive paleontological bibliography must first be compiled, something that...
Authors
Robert B. Blodgett, Ning Zhang, Albert H. Hofstra, Jared R. Morrow
Science and Products
Filter Total Items: 82
Deep permeable fault–controlled helium transport and limited mantle flux in two extensional geothermal systems in the Great Basin, United States Deep permeable fault–controlled helium transport and limited mantle flux in two extensional geothermal systems in the Great Basin, United States
This study assesses the relative importance of deeply circulating meteoric water and direct mantle fluid inputs on near-surface 3He/4He anomalies reported at the Coso and Beowawe geothermal fields of the western United States. The depth of meteoric fluid circulation is a critical factor that controls the temperature, extent of fluid-rock isotope exchange, and mixing with deeply sourced...
Authors
Amlan Banerjee, Mark Person, Albert Hofstra, Donald S. Sweetkind, Denis Cohen, Andrew Sabin, Jeff Unruh, George Zyvoloski, Carl W. Gable, Laura Crossey, Karl Karlstrom
Geochemical and stable isotopic data on barren and mineralized drill core in the Devonian Popovich Formation, Screamer sector of the Betze-Post gold deposit, northern Carlin trend, Nevada Geochemical and stable isotopic data on barren and mineralized drill core in the Devonian Popovich Formation, Screamer sector of the Betze-Post gold deposit, northern Carlin trend, Nevada
The Devonian Popovich Formation is the major host for Carlin-type gold deposits in the northern Carlin trend of Nevada. The Popovich is composed of gray to black, thin-bedded, calcareous to dolomitic mudstone and limestone deposited near the carbonate platform margin. Carlin-type gold deposits are Eocene, disseminated, auriferous pyrite deposits characterized by acid leaching...
Authors
William D. Christiansen, Albert H. Hofstra, Pamela B. Zohar, Gilles Tousignant
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
Evaluation of the role of magmatic volatiles from Eocene mafic to felsic igneous rocks in the formation of Carlin-type gold deposits of the Carlin trend and Jerritt Canyon District as constrained by preliminary He, Pb, Sr, and Nd isotopic data Evaluation of the role of magmatic volatiles from Eocene mafic to felsic igneous rocks in the formation of Carlin-type gold deposits of the Carlin trend and Jerritt Canyon District as constrained by preliminary He, Pb, Sr, and Nd isotopic data
No abstract available.
Authors
Albert H. Hofstra, Gary P. Landis, Wayne R. Premo, M.W. Ressel, Christopher D. Henry
'Forensic' geochemical approaches to constrain the source of Au-Ag in low-sulfidation epithermal ores 'Forensic' geochemical approaches to constrain the source of Au-Ag in low-sulfidation epithermal ores
In order to better constrain genetic processes involved in forming mineral deposits (and ultimately exploration models), it helps to know from where the metals of interest are derived. How the metals arrived at their point of deposition, and why they were deposited there, are separate issues. We are using three different techniques in an attempt to better understand these processes for...
Authors
James A. Saunders, G. D. Kamenov, Albert H. Hofstra, D. L. Unger, R. A. Creaser, F. Barra
Paleozoic stratigraphy and kinematics of the Roberts Mountains allochthon in the Independence Mountains, northern Nevada Paleozoic stratigraphy and kinematics of the Roberts Mountains allochthon in the Independence Mountains, northern Nevada
New biostratigraphic, stratigraphic, and structural data from deformed lower Paleozoic sedimentary units of the Roberts Mountains allochthon (RMA), Independence Mountains, Nevada, have enabled the identification of stratigraphic units within the allochthon that range in age from Late Cambrian through Late Devonian. The McAfee thrust fault emplaced a relatively thick (>200 m) sheet of...
Authors
Christopher S. Holm-Denoma, Albert H. Hofstra, Stephen A. Leslie, Paula J. Noble
Evolution of Ore Deposits and Technology Transfer Project: Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008 Evolution of Ore Deposits and Technology Transfer Project: Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008
Principal functions of the U.S. Geological Survey (USGS) Mineral Resources Program are providing assessments of the location, quantity, and quality of undiscovered mineral deposits, and predicting the environmental impacts of exploration and mine development. The mineral and environmental assessments of domestic deposits are used by planners and decisionmakers to improve the stewardship...
Authors
Robert O. Rye, Craig A. Johnson, Gary P. Landis, Albert H. Hofstra, Poul Emsbo, Craig A. Stricker, Andrew G. Hunt, Brian G. Rusk
Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits
In other parts of the world, previous workers have shown that sparry dolomite in carbonate rocks may be produced by the generation and movement of hot basinal brines in response to arid paleoclimates and tectonism, and that some of these brines served as the transport medium for metals fixed in Mississippi Valley-type (MVT) and sedimentary exhalative (Sedex) deposits of Zn, Pb, Ag, Au...
Authors
S. F. Diehl, A. H. Hofstra, A.E. Koenig, P. Emsbo, W. Christiansen, Chad Johnson
Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008 Isotope and Chemical Methods in Support of the U.S. Geological Survey Science Strategy, 2003-2008
Principal functions of the Mineral Resources Program are providing information to decision-makers related to mineral deposits on federal lands and predicting the environmental consequences of the mining or natural weathering of those deposits. Performing these functions requires that predictions be made of the likelihood of undiscovered deposits. The predictions are based on geologic and
Authors
R. O. Rye, C. A. Johnson, G. P. Landis, A. H. Hofstra, P. Emsbo, C. A. Stricker, A.G. Hunt, B.G. Rusk
Hydrologic models of modern and fossil geothermal systems in the Great Basin: Genetic implications for epithermal Au-Ag and Carlin-type gold deposits Hydrologic models of modern and fossil geothermal systems in the Great Basin: Genetic implications for epithermal Au-Ag and Carlin-type gold deposits
The Great Basin region in the western United States contains active geothermal systems, large epithermal Au-Ag deposits, and world-class Carlin-type gold deposits. Temperature profiles, fluid inclusion studies, and isotopic evidence suggest that modern and fossil hydrothermal systems associated with gold mineralization share many common features, including the absence of a clear magmatic...
Authors
M. Person, A. Banerjee, A. Hofstra, D. Sweetkind, Y. Gao
Great Basin paleontological database Great Basin paleontological database
The U.S. Geological Survey has constructed a paleontological database for the Great Basin physiographic province that can be served over the World Wide Web for data entry, queries, displays, and retrievals. It is similar to the web-database solution that we constructed for Alaskan paleontological data (www.alaskafossil.org). The first phase of this effort was to compile a paleontological
Authors
N. Zhang, R. B. Blodgett, A. H. Hofstra
Great Basin Paleontological Bibliography Great Basin Paleontological Bibliography
Introduction This work was conceived as a derivative product for 'The Metallogeny of the Great Basin' project of the Mineral Resources Program of the U.S. Geological Survey. In the course of preparing a fossil database for the Great Basin that could be accessed from the Internet, it was determined that a comprehensive paleontological bibliography must first be compiled, something that...
Authors
Robert B. Blodgett, Ning Zhang, Albert H. Hofstra, Jared R. Morrow