Albert H Hofstra
Al Hofstra is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Filter Total Items: 76
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 of public
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
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, or barite.N
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
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 geoenviro
Authors
R. O. Rye, C.A. Johnson, G. P. Landis, A. H. Hofstra, P. Emsbo, C. A. Stricker, A.G. Hunt, B.G. Rusk
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 bibliogra
Authors
N. Zhang, R. B. Blodgett, A. H. Hofstra
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 fluid sou
Authors
M. Person, A. Banerjee, A. Hofstra, D. Sweetkind, Y. Gao
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 had not p
Authors
Robert B. Blodgett, Ning Zhang, Albert H. Hofstra, Jared R. Morrow
Bald Mountain gold mining district, Nevada: A Jurassic reduced intrusion-related gold system
The Bald Mountain mining district has produced about 2 million ounces (Moz) of An. Geologic mapping, field relationships, geochemical data, petrographic observations, fluid inclusion characteristics, and Pb, S, O, and H isotope data indicate that An mineralization was associated with a reduced Jurassic intrusion. Gold deposits are localized within and surrounding a Jurassic (159 Ma) quartz monzoni
Authors
C. J. Nutt, A. H. Hofstra
Metallogeny of the Great Basin: Crustal evolution, fluid flow, and ore deposits
The Great Basin physiographic province in the Western United States contains a diverse assortment of world-class ore deposits. It currently (2006) is the world’s second leading producer of gold, contains large silver and base metal (Cu, Zn, Pb, Mo, W) deposits, a variety of other important metallic (Fe, Ni, Be, REE’s, Hg, PGE) and industrial mineral (diatomite, barite, perlite, kaolinite, gallium)
Authors
Albert H. Hofstra, Alan R. Wallace
Geology and geochemistry of jasperoids from the Gold Bar district, Nevada
Gold Bar is one of several Carlin-type gold mining districts located in the Battle Mountain-Eureka trend, Nevada. It is composed of one main deposit, Gold Bar; five satellite deposits; and four resources that contain 1.6 Moz (50 t) of gold. All of the deposits and resources occur at the intersection of north-northwest- and northeast-trending high-angle faults in slope facies limestones of the Devo
Authors
O. Yigit, A. H. Hofstra, M.W. Hitzman, E.P. Nelson
The giant Carlin gold province: A protracted interplay of orogenic, basinal, and hydrothermal processes above a lithospheric boundary
Northern Nevada hosts the only province that contains multiple world-class Carlin-type gold deposits. The first-order control on the uniqueness of this province is its anomalous far back-arc tectonic setting over the rifted North American paleocontinental margin that separates Precambrian from Phanerozoic subcontinental lithospheric mantle. Globally, most other significant gold provinces form in v
Authors
P. Emsbo, D.I. Groves, A. H. Hofstra, F.P. Bierlein
A special issue devoted to gold deposits in northern Nevada: Part 2. Carlin-type Deposits
This is the second of two special issues of Economic Geology devoted to gold deposits in northern Nevada. Readers interested in a general overview of these deposits, their economic significance, their context within the tectonic evolution of the region, and synoptic references on each gold deposit type are directed to the preface of the first special issue (John et al., 2003). Volume 98, issue 2,
Authors
Albert H. Hofstra, David John, Ted G. Theodore
Origin of high-grade gold ore, source of ore fluid components, and genesis of the Meikle and neighboring Carlin-type deposits, Northern Carlin Trend, Nevada
The Meikle mine exploits one of the world's highest grade Carlin-type gold deposits with reserves of ca. 220 t gold at an average grade of 24.7 g/t. Locally, gold grades exceed 400 g/t. Several geologic events converged at Meikle to create these spectacular gold grades. Prior to mineralization, a Devonian hydrothermal system altered the Bootstrap limestone to Fe-rich dolomite. Subsequently the roc
Authors
P. Emsbo, A. H. Hofstra, E.A. Lauha, G.L. Griffin, R.W. Hutchinson
Science and Products
- Publications
Filter Total Items: 76
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 of publicAuthorsRobert O. Rye, Craig A. Johnson, Gary P. Landis, Albert H. Hofstra, Poul Emsbo, Craig A. Stricker, Andrew G. Hunt, Brian G. RuskHydrothermal 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, or barite.NAuthorsS. F. Diehl, A. H. Hofstra, A.E. Koenig, P. Emsbo, W. Christiansen, Chad JohnsonIsotope 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 geoenviroAuthorsR. O. Rye, C.A. Johnson, G. P. Landis, A. H. Hofstra, P. Emsbo, C. A. Stricker, A.G. Hunt, B.G. RuskGreat 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 bibliograAuthorsN. Zhang, R. B. Blodgett, A. H. HofstraHydrologic 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 fluid souAuthorsM. Person, A. Banerjee, A. Hofstra, D. Sweetkind, Y. GaoGreat 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 had not pAuthorsRobert B. Blodgett, Ning Zhang, Albert H. Hofstra, Jared R. MorrowBald Mountain gold mining district, Nevada: A Jurassic reduced intrusion-related gold system
The Bald Mountain mining district has produced about 2 million ounces (Moz) of An. Geologic mapping, field relationships, geochemical data, petrographic observations, fluid inclusion characteristics, and Pb, S, O, and H isotope data indicate that An mineralization was associated with a reduced Jurassic intrusion. Gold deposits are localized within and surrounding a Jurassic (159 Ma) quartz monzoniAuthorsC. J. Nutt, A. H. HofstraMetallogeny of the Great Basin: Crustal evolution, fluid flow, and ore deposits
The Great Basin physiographic province in the Western United States contains a diverse assortment of world-class ore deposits. It currently (2006) is the world’s second leading producer of gold, contains large silver and base metal (Cu, Zn, Pb, Mo, W) deposits, a variety of other important metallic (Fe, Ni, Be, REE’s, Hg, PGE) and industrial mineral (diatomite, barite, perlite, kaolinite, gallium)AuthorsAlbert H. Hofstra, Alan R. WallaceGeology and geochemistry of jasperoids from the Gold Bar district, Nevada
Gold Bar is one of several Carlin-type gold mining districts located in the Battle Mountain-Eureka trend, Nevada. It is composed of one main deposit, Gold Bar; five satellite deposits; and four resources that contain 1.6 Moz (50 t) of gold. All of the deposits and resources occur at the intersection of north-northwest- and northeast-trending high-angle faults in slope facies limestones of the DevoAuthorsO. Yigit, A. H. Hofstra, M.W. Hitzman, E.P. NelsonThe giant Carlin gold province: A protracted interplay of orogenic, basinal, and hydrothermal processes above a lithospheric boundary
Northern Nevada hosts the only province that contains multiple world-class Carlin-type gold deposits. The first-order control on the uniqueness of this province is its anomalous far back-arc tectonic setting over the rifted North American paleocontinental margin that separates Precambrian from Phanerozoic subcontinental lithospheric mantle. Globally, most other significant gold provinces form in vAuthorsP. Emsbo, D.I. Groves, A. H. Hofstra, F.P. BierleinA special issue devoted to gold deposits in northern Nevada: Part 2. Carlin-type Deposits
This is the second of two special issues of Economic Geology devoted to gold deposits in northern Nevada. Readers interested in a general overview of these deposits, their economic significance, their context within the tectonic evolution of the region, and synoptic references on each gold deposit type are directed to the preface of the first special issue (John et al., 2003). Volume 98, issue 2,AuthorsAlbert H. Hofstra, David John, Ted G. TheodoreOrigin of high-grade gold ore, source of ore fluid components, and genesis of the Meikle and neighboring Carlin-type deposits, Northern Carlin Trend, Nevada
The Meikle mine exploits one of the world's highest grade Carlin-type gold deposits with reserves of ca. 220 t gold at an average grade of 24.7 g/t. Locally, gold grades exceed 400 g/t. Several geologic events converged at Meikle to create these spectacular gold grades. Prior to mineralization, a Devonian hydrothermal system altered the Bootstrap limestone to Fe-rich dolomite. Subsequently the rocAuthorsP. Emsbo, A. H. Hofstra, E.A. Lauha, G.L. Griffin, R.W. Hutchinson - Science
- Data
- Maps