John F. Slack
John Slack is a Scientist Emeritus with the USGS Geology, Energy & Minerals (GEM) Science Center in Reston, VA.
Science and Products
Filter Total Items: 69
Sulfur isotopes of host strata for Howards Pass (Yukon–Northwest Territories) Zn-Pb deposits implicate anaerobic oxidation of methane, not basin stagnation Sulfur isotopes of host strata for Howards Pass (Yukon–Northwest Territories) Zn-Pb deposits implicate anaerobic oxidation of methane, not basin stagnation
A new sulfur isotope stratigraphic profile has been developed for Ordovician-Silurian mudstones that host the Howards Pass Zn-Pb deposits (Canada) in an attempt to reconcile the traditional model of a stagnant euxinic basin setting with new contradictory findings. Our analyses of pyrite confirm the up-section 34S enrichment reported previously, but additional observations show parallel...
Authors
Craig A. Johnson, John F. Slack, Julie A. Dumoulin, Karen Duttweiler Kelley, Hendrik Falck
Cobalt Cobalt
Cobalt is a silvery gray metal that has diverse uses based on certain key properties, including ferromagnetism, hardness and wear-resistance when alloyed with other metals, low thermal and electrical conductivity, high melting point, multiple valences, and production of intense blue colors when combined with silica. Cobalt is used mostly in cathodes in rechargeable batteries and in...
Authors
John F. Slack, Bryn E. Kimball, Kim B. Shedd
Cobalt—Styles of deposits and the search for primary deposits Cobalt—Styles of deposits and the search for primary deposits
Cobalt (Co) is a potentially critical mineral. The vast majority of cobalt is a byproduct of copper and (or) nickel production. Cobalt is increasingly used in magnets and rechargeable batteries. More than 50 percent of primary cobalt production is from the Central African Copperbelt. The Central African Copperbelt is the only sedimentary rock-hosted stratiform copper district that...
Authors
Murray W. Hitzman, Arthur A. Bookstrom, John F. Slack, Michael L. Zientek
The hyper-enrichment of V and Zn in black shales of the Late Devonian-Early Mississippian Bakken Formation (USA) The hyper-enrichment of V and Zn in black shales of the Late Devonian-Early Mississippian Bakken Formation (USA)
Black shales of the Late Devonian to Early Mississippian Bakken Formation are characterized by high concentrations of organic carbon and the hyper-enrichment (> 500 to 1000s of mg/kg) of V and Zn. Deposition of black shales resulted from shallow seafloor depths that promoted rapid development of euxinic conditions. Vanadium hyper-enrichments, which are unknown in modern environments, are...
Authors
Clint Scott, John F. Slack, Karen Duttweiler Kelley
Transgressive-regressive cycles in the metalliferous, oil-shale-bearing Heath Formation (Upper Mississippian), central Montana Transgressive-regressive cycles in the metalliferous, oil-shale-bearing Heath Formation (Upper Mississippian), central Montana
The Upper Mississippian Heath Formation, which accumulated in the Big Snowy Trough of central Montana, has been known for three decades to contain mudrocks highly enriched in Zn, V, Mo, Ni and other metals, and source rocks for oil. The unit has more recently been recognized as a prospective tight oil play. Here we present petrographic, paleontologic, geochemical, and carbon and sulfur...
Authors
Julie A. Dumoulin, Craig A. Johnson, Karen D. Kelley, Palma J. Botterell, Paul C. Hackley, Clint Scott, John F. Slack
Source of salinity in the Broken Hill (Australia) Pb-Zn-Ag deposit: Insights from halogen ratios in fluid inclusions Source of salinity in the Broken Hill (Australia) Pb-Zn-Ag deposit: Insights from halogen ratios in fluid inclusions
Ratios of Na/Br, Br/Cl, and I/Cl were determined on leachates of fluid inclusions from the Broken Hill Pb-ZnAg deposit in Australia. Paragenetic relations suggest that whereas all analyzed inclusions formed during or after regional metamorphism, ion ratios are not greatly changed from those of the pre-metamorphic ore-forming fluids. Based on relatively high Br/Cl and I/Cl ratios, and low...
Authors
John F. Slack, D.A. Banks, R.T. Wilkin
Science and Products
Filter Total Items: 69
Sulfur isotopes of host strata for Howards Pass (Yukon–Northwest Territories) Zn-Pb deposits implicate anaerobic oxidation of methane, not basin stagnation Sulfur isotopes of host strata for Howards Pass (Yukon–Northwest Territories) Zn-Pb deposits implicate anaerobic oxidation of methane, not basin stagnation
A new sulfur isotope stratigraphic profile has been developed for Ordovician-Silurian mudstones that host the Howards Pass Zn-Pb deposits (Canada) in an attempt to reconcile the traditional model of a stagnant euxinic basin setting with new contradictory findings. Our analyses of pyrite confirm the up-section 34S enrichment reported previously, but additional observations show parallel...
Authors
Craig A. Johnson, John F. Slack, Julie A. Dumoulin, Karen Duttweiler Kelley, Hendrik Falck
Cobalt Cobalt
Cobalt is a silvery gray metal that has diverse uses based on certain key properties, including ferromagnetism, hardness and wear-resistance when alloyed with other metals, low thermal and electrical conductivity, high melting point, multiple valences, and production of intense blue colors when combined with silica. Cobalt is used mostly in cathodes in rechargeable batteries and in...
Authors
John F. Slack, Bryn E. Kimball, Kim B. Shedd
Cobalt—Styles of deposits and the search for primary deposits Cobalt—Styles of deposits and the search for primary deposits
Cobalt (Co) is a potentially critical mineral. The vast majority of cobalt is a byproduct of copper and (or) nickel production. Cobalt is increasingly used in magnets and rechargeable batteries. More than 50 percent of primary cobalt production is from the Central African Copperbelt. The Central African Copperbelt is the only sedimentary rock-hosted stratiform copper district that...
Authors
Murray W. Hitzman, Arthur A. Bookstrom, John F. Slack, Michael L. Zientek
The hyper-enrichment of V and Zn in black shales of the Late Devonian-Early Mississippian Bakken Formation (USA) The hyper-enrichment of V and Zn in black shales of the Late Devonian-Early Mississippian Bakken Formation (USA)
Black shales of the Late Devonian to Early Mississippian Bakken Formation are characterized by high concentrations of organic carbon and the hyper-enrichment (> 500 to 1000s of mg/kg) of V and Zn. Deposition of black shales resulted from shallow seafloor depths that promoted rapid development of euxinic conditions. Vanadium hyper-enrichments, which are unknown in modern environments, are...
Authors
Clint Scott, John F. Slack, Karen Duttweiler Kelley
Transgressive-regressive cycles in the metalliferous, oil-shale-bearing Heath Formation (Upper Mississippian), central Montana Transgressive-regressive cycles in the metalliferous, oil-shale-bearing Heath Formation (Upper Mississippian), central Montana
The Upper Mississippian Heath Formation, which accumulated in the Big Snowy Trough of central Montana, has been known for three decades to contain mudrocks highly enriched in Zn, V, Mo, Ni and other metals, and source rocks for oil. The unit has more recently been recognized as a prospective tight oil play. Here we present petrographic, paleontologic, geochemical, and carbon and sulfur...
Authors
Julie A. Dumoulin, Craig A. Johnson, Karen D. Kelley, Palma J. Botterell, Paul C. Hackley, Clint Scott, John F. Slack
Source of salinity in the Broken Hill (Australia) Pb-Zn-Ag deposit: Insights from halogen ratios in fluid inclusions Source of salinity in the Broken Hill (Australia) Pb-Zn-Ag deposit: Insights from halogen ratios in fluid inclusions
Ratios of Na/Br, Br/Cl, and I/Cl were determined on leachates of fluid inclusions from the Broken Hill Pb-ZnAg deposit in Australia. Paragenetic relations suggest that whereas all analyzed inclusions formed during or after regional metamorphism, ion ratios are not greatly changed from those of the pre-metamorphic ore-forming fluids. Based on relatively high Br/Cl and I/Cl ratios, and low...
Authors
John F. Slack, D.A. Banks, R.T. Wilkin