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: 64
Re-Os systematics and age of pyrite associated with stratiform Zn-Pb mineralization in the Howards Pass district, Yukon and Northwest Territories, Canada
Stratiform Zn-Pb deposits hosted in unmetamorphosed carbonaceous and siliceous mudstones of the Ordovician to Silurian Duo Lake Formation define the Howards Pass district in Yukon Territory and Northwest Territories, western Canada. Collectively, the deposits are amongst the largest in the world, containing drill-indicated and inferred resources of 423 Mt at 4.84 % Zn and 1.59 % Pb. Sulphide textu
Authors
Karen D. Kelley, David Selby, Hendrik Falck, John F. Slack
Evidence for early life in Earth’s oldest hydrothermal vent precipitates
Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Que
Authors
Matthew S. Dodd, Dominic Papineau, Tor Grenne, John F. Slack, Martin Rittner, Franco Pirajno, Jonathan O’Neil, Crispin T.S. Little
Regional geologic and petrologic framework for iron oxide ± apatite ± rare earth element and iron oxide copper-gold deposits of the Mesoproterozoic St. Francois Mountains terrane, southeast Missouri, USA
This paper provides an overview on the genesis of Mesoproterozoic igneous rocks and associated iron oxide ± apatite (IOA) ± rare earth element, iron oxide-copper-gold (IOCG), and iron-rich sedimentary deposits in the St. Francois Mountains terrane of southeast Missouri, USA. The St. Francois Mountains terrane lies along the southeastern margin of Laurentia as part of the eastern granite-rhyolite p
Authors
Warren C. Day, John F. Slack, Robert A. Ayuso, Cheryl M. Seeger
A special issue devoted to proterozoic iron oxide-apatite (±REE) and iron oxide copper-gold and affiliated deposits of Southeast Missouri, USA, and the Great Bear Magmatic Zone, Northwest Territories, Canada: Preface
No abstract available.
Authors
John F. Slack, L. Corriveau, M.W. Hitzman
Geochemistry, Nd-Pb Isotopes, and Pb-Pb Ages of the Mesoproterozoic Pea Ridge Iron Oxide-Apatite–Rare Earth Element Deposit, Southeast Missouri
Iron oxide-apatite and iron oxide-copper-gold deposits occur within ~1.48 to 1.47 Ga volcanic rocks of the St. Francois Mountains terrane near a regional boundary separating crustal blocks having contrasting depleted-mantle Sm-Nd model ages (TDM). Major and trace element analyses and Nd and Pb isotope data were obtained to characterize the Pea Ridge deposit, improve identification of exploration t
Authors
Robert A. Ayuso, John F. Slack, Warren C. Day, Anne E. McCafferty
The F'derik-Zouerate iron district: Mesoarchean and Paleoproterozoic iron formation of the Tiris Complex, Islamic Republic of Mauritania
High-grade hematitic iron ores (of HIF, containing 60-65 wt%Fe) have been mined in Mauritania since 1952 from Superior-type iron deposits of the F'derik-Zouerate district. Depletion of the high-grade ores in recent years has resulted in new exploration projects focused on lower-grade magnetite ores occurring in Algoma-type banded iron formation (of BIF, containing ca. 35 wt% Fe). Mauritania is t
Authors
Cliff D. Taylor, Carol A. Finn, Eric D. Anderson, Dwight Bradley, Mohamed Joud, Ahmed Taleb Mohamed, John D. Horton, Craig A. Johnson
U-Pb, Re-Os, and Ar/Ar geochronology of rare earth element (REE)-rich breccia pipes and associated host rocks from the Mesoproterozoic Pea Ridge Fe-REE-Au deposit, St. Francois Mountains, Missouri
Rare earth element (REE)-rich breccia pipes (600,000 t @ 12% rare earth oxides) are preserved along the margins of the 136-million metric ton (Mt) Pea Ridge magnetite-apatite deposit, within Mesoproterozoic (~1.47 Ga) volcanic-plutonic rocks of the St. Francois Mountains terrane in southeastern Missouri, United States. The breccia pipes cut the rhyolite-hosted magnetite deposit and contain clasts
Authors
John N. Aleinikoff, David Selby, John F. Slack, Warren C. Day, Renee M. Pillers, Michael A. Cosca, Cheryl Seeger, C. Mark Fanning, Iain Samson
Measurement of in situ sulfur isotopes by laser ablation multi-collector ICPMS: opening Pandora’s Box
Laser ablation multi-collector ICPMS is a modern tool for in situ measurement of S isotopes. Advantages of the technique are speed of analysis and relatively minor matrix effects combined with spatial resolution sufficient for many applications. The main disadvantage is a more destructive sampling mechanism relative to the ion microprobe technique. Recent advances in instrumentation allow precise
Authors
William I. Ridley, Michael Pribil, Alan E. Koenig, John F. Slack
Depositional conditions for the Kuna Formation, Red Dog Zn-PB-Ag-Barite District, Alaska, inferred from isotopic and chemical proxies
Water column redox conditions, degree of restriction of the depositional basin, and other paleoenvironmental parameters have been determined for the Mississippian Kuna Formation of northwestern Alaska from stratigraphic profiles of Mo, Fe/Al, and S isotopes in pyrite, C isotopes in organic matter, and N isotopes in bulk rock. This unit is important because it hosts the Red Dog and Anarraaq Zn-Pb-A
Authors
Craig A. Johnson, Julie A. Dumoulin, Robert A. Burruss, John F. Slack
Oxic to anoxic transition in bottom waters during formation of the Citronen Fjord sediment-hosted Zn-Pb deposit, North Greenland
Bulk geochemical data acquired for host sedimentary rocks to the Late Ordovician Citronen Fjord sediment-hosted Zn-Pb deposit in North Greenland constrain the redox state of bottom waters prior to and during sulphide mineralization. Downhole profiles for one drill core show trends for redox proxies (MnO, Mo, Ce anomalies) that suggest the local basin bottom waters were initially oxic, changing to
Authors
John F. Slack, Diogo Rosa, Hendrik Falck
Hydrothermal, biogenic, and seawater components in metalliferous black shales of the Brooks Range, Alaska: Synsedimentary metal enrichment in a carbonate ramp setting
Trace element and Os isotope data for Lisburne Group metalliferous black shales of Middle Mississippian (early Chesterian) age in the Brooks Range of northern Alaska suggest that metals were sourced chiefly from local seawater (including biogenic detritus) but also from externally derived hydrothermal fluids. These black shales are interbedded with phosphorites and limestones in sequences 3 to 35
Authors
John F. Slack, David Selby, Julie A. Dumoulin
The Late Cretaceous Middle Fork caldera, its resurgent intrusion, and enduring landscape stability in east-central Alaska
Dissected caldera structures expose thick intracaldera tuff and, uncommonly, cogenetic shallow plutons, while remnants of correlative outflow tuffs deposited on the pre-eruption ground surface record elements of ancient landscapes. The Middle Fork caldera encompasses a 10 km × 20 km area of rhyolite welded tuff and granite porphyry in east-central Alaska, ∼100 km west of the Yukon border. Intracal
Authors
Charles R. Bacon, Cynthia Dusel-Bacon, John N. Aleinikoff, John F. Slack
Science and Products
Filter Total Items: 64
Re-Os systematics and age of pyrite associated with stratiform Zn-Pb mineralization in the Howards Pass district, Yukon and Northwest Territories, Canada
Stratiform Zn-Pb deposits hosted in unmetamorphosed carbonaceous and siliceous mudstones of the Ordovician to Silurian Duo Lake Formation define the Howards Pass district in Yukon Territory and Northwest Territories, western Canada. Collectively, the deposits are amongst the largest in the world, containing drill-indicated and inferred resources of 423 Mt at 4.84 % Zn and 1.59 % Pb. Sulphide textu
Authors
Karen D. Kelley, David Selby, Hendrik Falck, John F. Slack
Evidence for early life in Earth’s oldest hydrothermal vent precipitates
Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Que
Authors
Matthew S. Dodd, Dominic Papineau, Tor Grenne, John F. Slack, Martin Rittner, Franco Pirajno, Jonathan O’Neil, Crispin T.S. Little
Regional geologic and petrologic framework for iron oxide ± apatite ± rare earth element and iron oxide copper-gold deposits of the Mesoproterozoic St. Francois Mountains terrane, southeast Missouri, USA
This paper provides an overview on the genesis of Mesoproterozoic igneous rocks and associated iron oxide ± apatite (IOA) ± rare earth element, iron oxide-copper-gold (IOCG), and iron-rich sedimentary deposits in the St. Francois Mountains terrane of southeast Missouri, USA. The St. Francois Mountains terrane lies along the southeastern margin of Laurentia as part of the eastern granite-rhyolite p
Authors
Warren C. Day, John F. Slack, Robert A. Ayuso, Cheryl M. Seeger
A special issue devoted to proterozoic iron oxide-apatite (±REE) and iron oxide copper-gold and affiliated deposits of Southeast Missouri, USA, and the Great Bear Magmatic Zone, Northwest Territories, Canada: Preface
No abstract available.
Authors
John F. Slack, L. Corriveau, M.W. Hitzman
Geochemistry, Nd-Pb Isotopes, and Pb-Pb Ages of the Mesoproterozoic Pea Ridge Iron Oxide-Apatite–Rare Earth Element Deposit, Southeast Missouri
Iron oxide-apatite and iron oxide-copper-gold deposits occur within ~1.48 to 1.47 Ga volcanic rocks of the St. Francois Mountains terrane near a regional boundary separating crustal blocks having contrasting depleted-mantle Sm-Nd model ages (TDM). Major and trace element analyses and Nd and Pb isotope data were obtained to characterize the Pea Ridge deposit, improve identification of exploration t
Authors
Robert A. Ayuso, John F. Slack, Warren C. Day, Anne E. McCafferty
The F'derik-Zouerate iron district: Mesoarchean and Paleoproterozoic iron formation of the Tiris Complex, Islamic Republic of Mauritania
High-grade hematitic iron ores (of HIF, containing 60-65 wt%Fe) have been mined in Mauritania since 1952 from Superior-type iron deposits of the F'derik-Zouerate district. Depletion of the high-grade ores in recent years has resulted in new exploration projects focused on lower-grade magnetite ores occurring in Algoma-type banded iron formation (of BIF, containing ca. 35 wt% Fe). Mauritania is t
Authors
Cliff D. Taylor, Carol A. Finn, Eric D. Anderson, Dwight Bradley, Mohamed Joud, Ahmed Taleb Mohamed, John D. Horton, Craig A. Johnson
U-Pb, Re-Os, and Ar/Ar geochronology of rare earth element (REE)-rich breccia pipes and associated host rocks from the Mesoproterozoic Pea Ridge Fe-REE-Au deposit, St. Francois Mountains, Missouri
Rare earth element (REE)-rich breccia pipes (600,000 t @ 12% rare earth oxides) are preserved along the margins of the 136-million metric ton (Mt) Pea Ridge magnetite-apatite deposit, within Mesoproterozoic (~1.47 Ga) volcanic-plutonic rocks of the St. Francois Mountains terrane in southeastern Missouri, United States. The breccia pipes cut the rhyolite-hosted magnetite deposit and contain clasts
Authors
John N. Aleinikoff, David Selby, John F. Slack, Warren C. Day, Renee M. Pillers, Michael A. Cosca, Cheryl Seeger, C. Mark Fanning, Iain Samson
Measurement of in situ sulfur isotopes by laser ablation multi-collector ICPMS: opening Pandora’s Box
Laser ablation multi-collector ICPMS is a modern tool for in situ measurement of S isotopes. Advantages of the technique are speed of analysis and relatively minor matrix effects combined with spatial resolution sufficient for many applications. The main disadvantage is a more destructive sampling mechanism relative to the ion microprobe technique. Recent advances in instrumentation allow precise
Authors
William I. Ridley, Michael Pribil, Alan E. Koenig, John F. Slack
Depositional conditions for the Kuna Formation, Red Dog Zn-PB-Ag-Barite District, Alaska, inferred from isotopic and chemical proxies
Water column redox conditions, degree of restriction of the depositional basin, and other paleoenvironmental parameters have been determined for the Mississippian Kuna Formation of northwestern Alaska from stratigraphic profiles of Mo, Fe/Al, and S isotopes in pyrite, C isotopes in organic matter, and N isotopes in bulk rock. This unit is important because it hosts the Red Dog and Anarraaq Zn-Pb-A
Authors
Craig A. Johnson, Julie A. Dumoulin, Robert A. Burruss, John F. Slack
Oxic to anoxic transition in bottom waters during formation of the Citronen Fjord sediment-hosted Zn-Pb deposit, North Greenland
Bulk geochemical data acquired for host sedimentary rocks to the Late Ordovician Citronen Fjord sediment-hosted Zn-Pb deposit in North Greenland constrain the redox state of bottom waters prior to and during sulphide mineralization. Downhole profiles for one drill core show trends for redox proxies (MnO, Mo, Ce anomalies) that suggest the local basin bottom waters were initially oxic, changing to
Authors
John F. Slack, Diogo Rosa, Hendrik Falck
Hydrothermal, biogenic, and seawater components in metalliferous black shales of the Brooks Range, Alaska: Synsedimentary metal enrichment in a carbonate ramp setting
Trace element and Os isotope data for Lisburne Group metalliferous black shales of Middle Mississippian (early Chesterian) age in the Brooks Range of northern Alaska suggest that metals were sourced chiefly from local seawater (including biogenic detritus) but also from externally derived hydrothermal fluids. These black shales are interbedded with phosphorites and limestones in sequences 3 to 35
Authors
John F. Slack, David Selby, Julie A. Dumoulin
The Late Cretaceous Middle Fork caldera, its resurgent intrusion, and enduring landscape stability in east-central Alaska
Dissected caldera structures expose thick intracaldera tuff and, uncommonly, cogenetic shallow plutons, while remnants of correlative outflow tuffs deposited on the pre-eruption ground surface record elements of ancient landscapes. The Middle Fork caldera encompasses a 10 km × 20 km area of rhyolite welded tuff and granite porphyry in east-central Alaska, ∼100 km west of the Yukon border. Intracal
Authors
Charles R. Bacon, Cynthia Dusel-Bacon, John N. Aleinikoff, John F. Slack