Albert H Hofstra (Former Employee)
Science and Products
Filter Total Items: 89
Age constraints on Jerritt Canyon and other Carlin-type gold deposits in the western United States-relationship to mid-Tertiary extension and magmatism Age constraints on Jerritt Canyon and other Carlin-type gold deposits in the western United States-relationship to mid-Tertiary extension and magmatism
Carlin-type gold deposits are difficult to date and a wide range of ages has been reported for individual deposits. Therefore, several methods were employed to constrain the age of the gold deposits in the Jerritt Canyon district. Dated igneous rocks with well-documented crosscutting relationships to ore provided the most reliable constraints. K/Ar and 40 Ar/ 39 Ar dates on igneous rocks...
Authors
A. H. Hofstra, L.W. Snee, R. O. Rye, H. W. Folger, J.D. Phinisey, R.J. Loranger, A.R. Dahl, C. W. Naeser, H. J. Stein, M. Lewchuk
Evidence for Proterozoic and late Cretaceous-early Tertiary ore-forming events in the Coeur d'Alene district, Idaho and Montana Evidence for Proterozoic and late Cretaceous-early Tertiary ore-forming events in the Coeur d'Alene district, Idaho and Montana
New 40 Ar/ 39 Ar age spectra on sericite and lead isotope data on tetrahedrite, siderite, galena, bournonite, and stibnite, together with previously published isotopic, geochemical, and geologic studies provide evidence for two major vein-forming events in the Coeur d'Alene district and surrounding areas of the Belt basin. The data suggest that the zinc- and lead-rich veins (e.g., Bunker...
Authors
D. L. Leach, A. H. Hofstra, S. E. Church, L.W. Snee, R. B. Vaughn, R. E. Zartman
Fluid-inclusion gases in sphalerite, galena, and dolomite from the Silesian-Cracow Zn-Pb district, Poland Fluid-inclusion gases in sphalerite, galena, and dolomite from the Silesian-Cracow Zn-Pb district, Poland
The gases in fluid inclusions from samples of sphalerite, galena, and sparry dolomite from ore deposits in the Silesian-Cracow zinc-lead district were determined by mass spectrometry. The results show that CO2 is the major gas in the fluid inclusions with lesser amounts of CH4. Samples of galena and sphalerite also commonly contain H2S and short-chain hydrocarbon gases. Gases in...
Authors
D. L. Leach, L.E. Apodaca, A. Kozlowski, G. P. Landis, A. H. Hofstra
The composition of fluid inclusions in ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type Zn-Pb deposits Poland: Genetic and environmental implications The composition of fluid inclusions in ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type Zn-Pb deposits Poland: Genetic and environmental implications
The composition of fluids extracted from ore and gangue sulfide minerals that span most of the paragenesis of the Silesian-Cracow district was determined using a newly developed ion chromatographic (IC) technique. Ionic species determined were Na+, NH+4, Ca2+, Mg2+, K+, Rb+, Sr2+, Ba2+, Cl-, Br-, F-, I-, PO3-4, CO2-3, HS-, S2O2-3, SO2-4, NO-3, and acetate. Mineral samples included six...
Authors
J.G. Viets, A. H. Hofstra, P. Emsbo, A. Kozlowski
Chemical reaction path modeling of ore deposition in Mississippi Valley-type Pb-Zn deposits of the Ozark region, U.S. Midcontinent: A reply Chemical reaction path modeling of ore deposition in Mississippi Valley-type Pb-Zn deposits of the Ozark region, U.S. Midcontinent: A reply
No abstract available.
Authors
Geoffrey S. Plumlee, David L. Leach, Albert H. Hofstra, Gary P. Landis, Elisabeth L. Rowan, John G. Viets
Reconnaissance stream-sediment geochemistry of Twentynine Palms Marine Corps Base, California Reconnaissance stream-sediment geochemistry of Twentynine Palms Marine Corps Base, California
No abstract available.
Authors
Albert H. Hofstra, D.L. Fey, J. M. Motooka, D.A. Hopkins
Chemical reaction path modeling of ore deposition in Mississippi Valley-type Pb-Zn deposits of the Ozark region, US midcontinent Chemical reaction path modeling of ore deposition in Mississippi Valley-type Pb-Zn deposits of the Ozark region, US midcontinent
The Ozark region of the U.S. midcontinent is host to a number of Mississippi Valley-type districts, including the world-class Viburnum Trend, Old Lead Belt, and Tri-State districts and the smaller Southeast Missouri barite, Northern Arkansas, and Central Missouri districts. There is increasing evidence that the Ozark Mississippi Valley-type districts formed locally within a large...
Authors
G.S. Plumlee, D. L. Leach, A. H. Hofstra, G. P. Landis, E. L. Rowan, J.G. Viets
Geology and mineral resource potential of the Chattanooga 1° x 2° quadrangle, Tennessee and North Carolina — A preliminary assessment Geology and mineral resource potential of the Chattanooga 1° x 2° quadrangle, Tennessee and North Carolina — A preliminary assessment
No abstract available.
Authors
Sandra H. Clark, Gregory T Spanski, D.G. Hadley, A. H. Hofstra
Reconnaissance stream-sediment geochemistry of Death Valley National Monument, California Reconnaissance stream-sediment geochemistry of Death Valley National Monument, California
No abstract available.
Authors
Albert H. Hofstra, D.L. Fey, J. M. Motooka, B. H. Roushey, Lee-Ann Bradley
Handbook of geochemical data for the Trona 1 degree x 2 degrees Quadrangle; Southern California Mineral Resource Framework and Assessment Project Handbook of geochemical data for the Trona 1 degree x 2 degrees Quadrangle; Southern California Mineral Resource Framework and Assessment Project
No abstract available.
Authors
Albert H. Hofstra
Origin of late dolomite cement by CO2-saturated deep basin brines: evidence from the Ozark region, central United States Origin of late dolomite cement by CO2-saturated deep basin brines: evidence from the Ozark region, central United States
Studies of fluid inclusions in regionally extensive late dolomite cement (LDC) throughout the Ozark region show that CO2 effervescence was widespread during dolomite precipitation. On the basis of quantitative analyses of inclusion fluids, reaction-path modeling shows that LDC with trace amounts of sulfides can be deposited by effervescence of a CO2-saturated basin brine as it migrates...
Authors
D. L. Leach, G.S. Plumlee, A. H. Hofstra, G. P. Landis, E. L. Rowan, J.G. Viets
Genesis of sediment-hosted disseminated-gold deposits by fluid mixing and sulfidization: chemical-reaction-path modeling of ore- depositional processes documented in the Jerritt Canyon district, Nevada Genesis of sediment-hosted disseminated-gold deposits by fluid mixing and sulfidization: chemical-reaction-path modeling of ore- depositional processes documented in the Jerritt Canyon district, Nevada
Integrated geologic, geochemical, fluid-inclusion, and stableisotope studies of the gold deposits in the Jerritt Canyon district, Nevada, provide evidence that gold deposition was a consequence of both fluid mixing and sulfidization of host-rock iron. Chemical-reaction-path models of these ore-depositional processes confirm that the combination of fluid mixing, including simultaneous...
Authors
A. H. Hofstra
Science and Products
Filter Total Items: 89
Age constraints on Jerritt Canyon and other Carlin-type gold deposits in the western United States-relationship to mid-Tertiary extension and magmatism Age constraints on Jerritt Canyon and other Carlin-type gold deposits in the western United States-relationship to mid-Tertiary extension and magmatism
Carlin-type gold deposits are difficult to date and a wide range of ages has been reported for individual deposits. Therefore, several methods were employed to constrain the age of the gold deposits in the Jerritt Canyon district. Dated igneous rocks with well-documented crosscutting relationships to ore provided the most reliable constraints. K/Ar and 40 Ar/ 39 Ar dates on igneous rocks...
Authors
A. H. Hofstra, L.W. Snee, R. O. Rye, H. W. Folger, J.D. Phinisey, R.J. Loranger, A.R. Dahl, C. W. Naeser, H. J. Stein, M. Lewchuk
Evidence for Proterozoic and late Cretaceous-early Tertiary ore-forming events in the Coeur d'Alene district, Idaho and Montana Evidence for Proterozoic and late Cretaceous-early Tertiary ore-forming events in the Coeur d'Alene district, Idaho and Montana
New 40 Ar/ 39 Ar age spectra on sericite and lead isotope data on tetrahedrite, siderite, galena, bournonite, and stibnite, together with previously published isotopic, geochemical, and geologic studies provide evidence for two major vein-forming events in the Coeur d'Alene district and surrounding areas of the Belt basin. The data suggest that the zinc- and lead-rich veins (e.g., Bunker...
Authors
D. L. Leach, A. H. Hofstra, S. E. Church, L.W. Snee, R. B. Vaughn, R. E. Zartman
Fluid-inclusion gases in sphalerite, galena, and dolomite from the Silesian-Cracow Zn-Pb district, Poland Fluid-inclusion gases in sphalerite, galena, and dolomite from the Silesian-Cracow Zn-Pb district, Poland
The gases in fluid inclusions from samples of sphalerite, galena, and sparry dolomite from ore deposits in the Silesian-Cracow zinc-lead district were determined by mass spectrometry. The results show that CO2 is the major gas in the fluid inclusions with lesser amounts of CH4. Samples of galena and sphalerite also commonly contain H2S and short-chain hydrocarbon gases. Gases in...
Authors
D. L. Leach, L.E. Apodaca, A. Kozlowski, G. P. Landis, A. H. Hofstra
The composition of fluid inclusions in ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type Zn-Pb deposits Poland: Genetic and environmental implications The composition of fluid inclusions in ore and gangue minerals from the Silesian-Cracow Mississippi Valley-type Zn-Pb deposits Poland: Genetic and environmental implications
The composition of fluids extracted from ore and gangue sulfide minerals that span most of the paragenesis of the Silesian-Cracow district was determined using a newly developed ion chromatographic (IC) technique. Ionic species determined were Na+, NH+4, Ca2+, Mg2+, K+, Rb+, Sr2+, Ba2+, Cl-, Br-, F-, I-, PO3-4, CO2-3, HS-, S2O2-3, SO2-4, NO-3, and acetate. Mineral samples included six...
Authors
J.G. Viets, A. H. Hofstra, P. Emsbo, A. Kozlowski
Chemical reaction path modeling of ore deposition in Mississippi Valley-type Pb-Zn deposits of the Ozark region, U.S. Midcontinent: A reply Chemical reaction path modeling of ore deposition in Mississippi Valley-type Pb-Zn deposits of the Ozark region, U.S. Midcontinent: A reply
No abstract available.
Authors
Geoffrey S. Plumlee, David L. Leach, Albert H. Hofstra, Gary P. Landis, Elisabeth L. Rowan, John G. Viets
Reconnaissance stream-sediment geochemistry of Twentynine Palms Marine Corps Base, California Reconnaissance stream-sediment geochemistry of Twentynine Palms Marine Corps Base, California
No abstract available.
Authors
Albert H. Hofstra, D.L. Fey, J. M. Motooka, D.A. Hopkins
Chemical reaction path modeling of ore deposition in Mississippi Valley-type Pb-Zn deposits of the Ozark region, US midcontinent Chemical reaction path modeling of ore deposition in Mississippi Valley-type Pb-Zn deposits of the Ozark region, US midcontinent
The Ozark region of the U.S. midcontinent is host to a number of Mississippi Valley-type districts, including the world-class Viburnum Trend, Old Lead Belt, and Tri-State districts and the smaller Southeast Missouri barite, Northern Arkansas, and Central Missouri districts. There is increasing evidence that the Ozark Mississippi Valley-type districts formed locally within a large...
Authors
G.S. Plumlee, D. L. Leach, A. H. Hofstra, G. P. Landis, E. L. Rowan, J.G. Viets
Geology and mineral resource potential of the Chattanooga 1° x 2° quadrangle, Tennessee and North Carolina — A preliminary assessment Geology and mineral resource potential of the Chattanooga 1° x 2° quadrangle, Tennessee and North Carolina — A preliminary assessment
No abstract available.
Authors
Sandra H. Clark, Gregory T Spanski, D.G. Hadley, A. H. Hofstra
Reconnaissance stream-sediment geochemistry of Death Valley National Monument, California Reconnaissance stream-sediment geochemistry of Death Valley National Monument, California
No abstract available.
Authors
Albert H. Hofstra, D.L. Fey, J. M. Motooka, B. H. Roushey, Lee-Ann Bradley
Handbook of geochemical data for the Trona 1 degree x 2 degrees Quadrangle; Southern California Mineral Resource Framework and Assessment Project Handbook of geochemical data for the Trona 1 degree x 2 degrees Quadrangle; Southern California Mineral Resource Framework and Assessment Project
No abstract available.
Authors
Albert H. Hofstra
Origin of late dolomite cement by CO2-saturated deep basin brines: evidence from the Ozark region, central United States Origin of late dolomite cement by CO2-saturated deep basin brines: evidence from the Ozark region, central United States
Studies of fluid inclusions in regionally extensive late dolomite cement (LDC) throughout the Ozark region show that CO2 effervescence was widespread during dolomite precipitation. On the basis of quantitative analyses of inclusion fluids, reaction-path modeling shows that LDC with trace amounts of sulfides can be deposited by effervescence of a CO2-saturated basin brine as it migrates...
Authors
D. L. Leach, G.S. Plumlee, A. H. Hofstra, G. P. Landis, E. L. Rowan, J.G. Viets
Genesis of sediment-hosted disseminated-gold deposits by fluid mixing and sulfidization: chemical-reaction-path modeling of ore- depositional processes documented in the Jerritt Canyon district, Nevada Genesis of sediment-hosted disseminated-gold deposits by fluid mixing and sulfidization: chemical-reaction-path modeling of ore- depositional processes documented in the Jerritt Canyon district, Nevada
Integrated geologic, geochemical, fluid-inclusion, and stableisotope studies of the gold deposits in the Jerritt Canyon district, Nevada, provide evidence that gold deposition was a consequence of both fluid mixing and sulfidization of host-rock iron. Chemical-reaction-path models of these ore-depositional processes confirm that the combination of fluid mixing, including simultaneous...
Authors
A. H. Hofstra