Ryan J McAleer, Ph.D.
Ryan J McAleer is a Research Geologist at the Florence Bascom Geoscience Center.
I am a Research Geologist at the Florence Bascom Geoscience Center in Reston, VA. I received a PhD in Geology from Indiana University in 2016. I currently run the 40Ar/39Ar geochronology, electron microprobe, and mineral separation laboratories in Reston, VA. I contribute to National Cooperative Geologic Mapping, Energy, and Mineral program projects as well as collaborative work with universities. I use detailed optical and electron petrography, metamorphic petrology, 40Ar/39Ar and U/Pb geochronology, and a variety of other analytical tools in my research. Some current research projects that I am a part of include work on:
- Determining the age of bedrock beneath the coastal plain of the southeastern U.S.
- Assessing the age and deformation mechanisms along the Blue Ridge Thrust
- The age(s) of the Petersburg Granite
- Causes and uses of photoluminesence in zircon
- Coupled substitution in sphalerite with a focus on germanium
- The age and origin of manganese oxide deposits in Virginia.
Professional Experience
2016-present, Research Geologist, USGS, Reston, VA
2011-2015, Graduate Student, Indiana University, Bloomington, IN
2011-2015, SCEP/Pathways student appointment, USGS, Reston, VA
2007-2010, Geologist, USGS, Reston, VA
Education and Certifications
Ph.D. Metamorphic Petrology, Indiana University, 2016 (Advisor: Bob Wintsch)
M.S. Geology, 2006 (Advisor: Jim Spotila)
B.S. Geology, 2004 (Senior Thesis Advisor: Terry Engelder)
Affiliations and Memberships*
2016-present, Mineralogical Society of America
2011-present, Geological Society of America
2019-present, Microscopy Society of America/Microanalysis Society
Science and Products
Filter Total Items: 27
Molecular-scale speciation of germanium and copper within sphalerite from Central Tennessee mining district (TN), Red Dog mining district (AK), and Metaline mining district (WA) Molecular-scale speciation of germanium and copper within sphalerite from Central Tennessee mining district (TN), Red Dog mining district (AK), and Metaline mining district (WA)
Oxidation state and bonding environment of Ge and Cu in ZnS and Zn mineral concentrates from a variety of sources [Central Tennessee mining district (TN), Metaline mining district, (WA), and Red Dog mine (AK)] were determined by linear combination fits from x-ray absorption spectroscopy (XAS) analysis. Sphalerites from the East Tennessee mining district contained Ge in concentrations...
Trace element composition and molecular-scale speciation characterization of sphalerite from Central and East Tennessee mining districts, Red Dog mining district (AK), and Metaline mining district (WA) Trace element composition and molecular-scale speciation characterization of sphalerite from Central and East Tennessee mining districts, Red Dog mining district (AK), and Metaline mining district (WA)
Germanium (Ge) is an element deemed critical globally, and used in electronics, communication, and defense applications. The supply of Ge is limited and as demand for it increases, its criticality increases. Germanium is exclusively recovered as a byproduct of either coal mining or zinc (Zn) mining, and the main mineral hosting Ge in Zn deposits is sphalerite (ZnS). However, the...
40Ar/39Ar data from the Janub Metamorphic Complex, Southern Jordan 40Ar/39Ar data from the Janub Metamorphic Complex, Southern Jordan
This data release includes 40Ar/39Ar collected at the U.S. Geological Survey for samples from the Janub Metamorphic Complex in Southern Jordan. Rock samples were collected by Hind Ghanem of the University of Jordan. Muscovite-rich microcores were drilled from a polished thick section of a deformed granitoid and analyzed by argon geochronology at the U.S. Geological Survey Bascom ARgon...
40Ar/39Ar isotopic data and electron microprobe data from muscovite in the Sukari gold deposit, Egypt 40Ar/39Ar isotopic data and electron microprobe data from muscovite in the Sukari gold deposit, Egypt
This data release includes electron microprobe and 40Ar/39Ar collected at the U.S. Geological Survey for samples from the Sukari gold deposit in the Eastern Desert of Egypt. Rock samples were collected by Basem Zoheir--Benha University/University of Kiel. Muscovite from a polished thick section of sericitized wall rock was analyzed by electron probe microanalysis at the U.S. Geological...
Mineral abundances within bulk and size-fractionated mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A. Mineral abundances within bulk and size-fractionated mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A.
Mineral abundances within bulk and size-fractionated mine waste from sampled historical waste piles from the Tar Creek Superfund Site, Oklahoma, U.S.A., were determined by Mineral Liberation Analysis (MLA) and X-Ray Diffraction (XRD). Data and methods reported are part of a research study published below in the 'Related External Resources' section.
Molecular speciation of Ge within sphalerite, hemimorphite, and quartz from mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A. Molecular speciation of Ge within sphalerite, hemimorphite, and quartz from mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A.
Oxidation state and bonding environment of Ge in minerals within mine waste from sampled historical waste piles from the Tar Creek Superfund Site, Oklahoma, U.S. were determined by linear combination fits from x-ray absorption near edge spectroscopy (XANES) analysis. Ge content in quartz within these wastes was determined using XANES edge steps, and Ge content in sphalerite was compared...
Elemental concentrations for bulk and size-fractionated mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A. Elemental concentrations for bulk and size-fractionated mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A.
Elemental concentrations for bulk and size-fractionated mine waste from sampled historical waste piles from the Tar Creek Superfund Site, Oklahoma, U.S. were determined after dissolution via acid digests or a sodium peroxide fusion. Elemental concentrations were determined for the leachate from a simulated rainwater leach of mine wastes. Data and methods reported are part of a research...
Electron microprobe analyses of sphalerite and hemimorphite from mine wastes from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A. Electron microprobe analyses of sphalerite and hemimorphite from mine wastes from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A.
Electron microprobe analyses of sphalerite (ZnS) and hemimorphite (Zn4Si2O7(OH)2·H2O) from sampled historical waste piles were conducted with a specific focus on germanium (Ge). In mine wastes at the Tar Creek Superfund Site, Oklahoma, USA, Ge is associated with ZnS (sphalerite) as expected, but weathering in the waste piles has led to a significant amount of Ge being incorporated into a...
40Ar/39Ar data from the Old Mine Park area, Trumbull, Connecticut 40Ar/39Ar data from the Old Mine Park area, Trumbull, Connecticut
This data release includes 40Ar/39Ar data from the U.S. Geological Survey for samples from Old Mine Park Area, Trumbull, Connecticut. Mineral samples were collected by Robert Wintsch and Harold Moritz. Potassium-bearing mineral grains were separated from the bulk sample and analyzed by argon geochronology at the U.S. Geological Survey Bascom ARgon Dating (BARD) Laboratory in Reston...
Electron microprobe and 40Ar/39Ar isotopic data from west-central New Hampshire Electron microprobe and 40Ar/39Ar isotopic data from west-central New Hampshire
This dataset accompanies planned publication 'Unmixing multiple metamorphic muscovite age populations with powder X-ray diffraction and 40Ar/39Ar analysis'. The 40Ar/39Ar and electron microprobe data are from samples adjacent to a lower greenschist facies shear zone in western New Hampshire. The geochronology coupled with the electron microprobe data provide a petrochronologic framework...
TOC, Reflectance and Raman Data from Eocene Green River Mahogany Zone TOC, Reflectance and Raman Data from Eocene Green River Mahogany Zone
Geological models for petroleum generation suggest thermal conversion of oil-prone sedimentary organic matter in the presence of water promotes increased liquid saturate yield, whereas absence of water causes formation of an aromatic, cross-linked solid bitumen residue. To test the influence of exchangeable hydrogen from water, organic-rich (22 wt. percent total organic carbon, TOC)...
Photoluminescence Imaging of Whole Zircon Grains on a Petrographic Microscope - An Underused Aide for Geochronologic Studies Photoluminescence Imaging of Whole Zircon Grains on a Petrographic Microscope - An Underused Aide for Geochronologic Studies
The refractory nature of zircon to temperature and pressure allows even a single zircon grain to preserve a rich history of magmatic, metamorphic, and hydrothermal processes. Isotopic dating of micro-domains exposed in cross-sections of zircon grains allows us to interrogate this history. Unfortunately, our ability to select the zircon grains in a heavy mineral concentrate that records...
Filter Total Items: 54
Insights into glendonite formation from the upper Oligocene Sagavanirktok Formation, North Slope, Alaska Insights into glendonite formation from the upper Oligocene Sagavanirktok Formation, North Slope, Alaska
The type locality for the upper Oligocene Nuwok Member of the Sagavanirktok Formation (Carter Creek, North Slope, Alaska, USA) contains abundant occurrence of glendonite, a pseudomorph after the calcium carbonate mineral ikaite, which typically forms in the shallow subsurface of cold marine sediments. The region during the time of Nuwok Member deposition was located at a high latitude...
Authors
John Counts, Madeleine Vickers, Martha Stokes, Whittney Spivey, Kristina Gardner, Jean Self-Trail, Jared Gooley, Ryan McAleer, Aaron M. Jubb, David Houseknecht, Richard Lease, Neil Griffis, Martin Vickers, Kasia Sliwinska, Hannah Tompkins, Adam Hudson
Geology of the Mount Rogers area, revisited: Evidence of Neoproterozoic continental rifting, glaciation, and the opening and closing of the Iapetus Ocean, Blue Ridge, VA–NC–TN Geology of the Mount Rogers area, revisited: Evidence of Neoproterozoic continental rifting, glaciation, and the opening and closing of the Iapetus Ocean, Blue Ridge, VA–NC–TN
Recent field and geochronological studies in eight 7.5-minute quadrangles near Mount Rogers in Virginia, North Carolina and Tennessee recognize (1) important stratigraphic and structural relationships for the Neoproterozoic Mount Rogers and Konnarock Formations, and the northeast end of the Mountain City window; (2) the separation of Mesoproterozoic rocks of the Blue Ridge into three age...
Authors
Arthur Merschat, Ryan McAleer, Christopher S. Holm-Denoma, C. Southworth
Extrusion tectonism of Indochina reassessed: constraints from 40Ar/39Ar geochronology from the Day Nui Con Voi metamorphic massif, Vietnam Extrusion tectonism of Indochina reassessed: constraints from 40Ar/39Ar geochronology from the Day Nui Con Voi metamorphic massif, Vietnam
The extrusion tectonic model for the southeastern margin of the Himalayan orogeny links the crustal shear activity along the Red River Shear Zone (RRSZ) to the opening of the South China Sea (SCS). The Day Nui Con Voi (DNCV) metamorphic massif in northern Vietnam strikes NW-SE, is bounded by the RRSZ to the south and continues along the strike where it meets the SCS. The DNCV is thus a...
Authors
Thi-Hue Dinh, Meng-Wan Yeh, Tung-Yi Lee, Michael J. Kunk, Robert P. Wintsch, Ryan McAleer
Redefinition of the Petersburg batholith and implications for crustal inheritance in the Dinwiddie terrane, Virginia, USA Redefinition of the Petersburg batholith and implications for crustal inheritance in the Dinwiddie terrane, Virginia, USA
Field relations as well as geochemical and petrologic studies of metaigneous rocks assigned to the Pennsylvanian–Permian Petersburg batholith identify at least two distinct rock types: foliated metagranitoid gneiss and massive to porphyritic granite. Foliated metagranitoid gneiss of mostly granodioritic composition is geochemically distinct from associated massive and porphyritic...
Authors
Mark Carter, Ryan McAleer, Christopher S. Holm-Denoma, Marcie Occhi, Brent Owens, Jorge Vazquez
Mapping ancient sedimentary organic matter molecular structure at nanoscales using optical photothermal infrared spectroscopy Mapping ancient sedimentary organic matter molecular structure at nanoscales using optical photothermal infrared spectroscopy
Elucidating the molecular structure of sedimentary organic matter (SOM) is key to understanding petroleum generation processes, as well as ancient sedimentary environments. SOM structure is primarily controlled by biogenic source material (e.g., marine vs. terrigenous), depositional conditions, and subsurface thermal history. Additional factors, e.g., strain, may also impact the...
Authors
Aaron M. Jubb, Martha Stokes, Ryan McAleer, Paul Hackley, Eoghan Dillion, Jing Qu
A novel non-destructive workflow for examining germanium and co-substituents in ZnS A novel non-destructive workflow for examining germanium and co-substituents in ZnS
A suite of complementary techniques was used to examine germanium (Ge), a byproduct critical element, and co-substituent trace elements in ZnS and mine wastes from four mineral districts where germanium is, or has been, produced within the United States. This contribution establishes a comprehensive workflow for characterizing Ge and other trace elements, which captures the full...
Authors
Sarah Hayes, Ryan McAleer, Nadine Piatak, Sarah White, Robert R. Seal,
The Sukari gold deposit, Egypt: Geochemical and geochronological constraints on the ore genesis and implications for regional exploration The Sukari gold deposit, Egypt: Geochemical and geochronological constraints on the ore genesis and implications for regional exploration
The Sukari gold deposit (>15 Moz Au) in the Eastern Desert of Egypt is hosted by a deformed granitoid stock (Sukari tonalite-trondhjemite intrusion) and mainly occurs as a network of crosscutting sulfide-bearing quartz (± carbonate) veins and intensely sulfidized-silicified-sericitized wall rock. Emplacement of the Sukari intrusion into a tectonized Neoproterozoic accretionary complex...
Authors
Basem Zoheir, Astrid Holzheid, Armin Zeh, Ryan McAleer, Mohamed El-Behairy, Ulrich Schwarz-Schampera, Torsten Graupner, David Lentz, Fahui Xiong
Vein-type gold formation during late extensional collapse of the Eastern Desert, Egypt: the Gidami deposit Vein-type gold formation during late extensional collapse of the Eastern Desert, Egypt: the Gidami deposit
Orogenic gold deposits, though construed to focused fluid flow during orogenesis, commonly post-date the main accretionary events. Several lines of evidence indicate that orogenic gold formation in the Arabian–Nubian Shield continued through the orogen collapse stage and associated rapid exhumation and thermal re-equilibration. The Gidami gold deposit in the Eastern Desert of Egypt is...
Authors
Basem Zoheir, Ryan McAleer, Matthew Steele-MacInnis, Armin Zeh, Wyatt Bain, Spencer Poulette
Germanium redistribution during weathering of Zn mine wastes: Implications for environmental mobility and recovery of a critical mineral Germanium redistribution during weathering of Zn mine wastes: Implications for environmental mobility and recovery of a critical mineral
Germanium (Ge) is a metal used in emerging energy technologies, communications, and defense, and has been deemed critical by the United States due to its essential applications and scarce supply. Germanium is recovered as a byproduct of zinc (Zn) sulfides, and mining and processing of these materials lead to waste that could act both as a source of extractable Ge and a source for...
Authors
Sarah White, Nadine Piatak, Ryan McAleer, Sarah Hayes, Robert R. Seal,, Laurel Schaider, James Shine
U-Pb and fission-track data from zircon and apatite resolve latest- and post-Alleghanian thermal histories along the Fall Line of the Atlantic margin of the southeastern United States U-Pb and fission-track data from zircon and apatite resolve latest- and post-Alleghanian thermal histories along the Fall Line of the Atlantic margin of the southeastern United States
Although the Atlantic continental margin of the eastern United States is an archetypal passive margin, episodes of rejuvenation following continental breakup are increasingly well documented. To better constrain this history of rejuvenation along the southern portion of this continental margin, we present zircon U-Pb (ZUPb) age, zircon fission-track (ZFT) age, apatite U-Pb (AUPb) age...
Authors
William Craddock, Paul O'Sullivan, Ryan McAleer
Evaluating aromatization of solid bitumen generated in the presence and absence of water: Implications for solid bitumen reflectance as a thermal proxy Evaluating aromatization of solid bitumen generated in the presence and absence of water: Implications for solid bitumen reflectance as a thermal proxy
Geological models for petroleum generation suggest thermal conversion of oil-prone sedimentary organic matter in the presence of water promotes increased liquid saturate yield, whereas absence of water causes formation of an aromatic, cross-linked solid bitumen residue. To test the influence of hydrogen from water, organic-rich (22 wt% total organic carbon, TOC) mudrock samples from the...
Authors
Paul Hackley, Aaron M. Jubb, Patrick Smith, Ryan McAleer, Brett Valentine, Javin Hatcherian, Palma Botterell, Justin Birdwell
Geology & mineralogy of the Old Mine Park area Trumbull Connecticut Geology & mineralogy of the Old Mine Park area Trumbull Connecticut
Old Mine Park, in the northern Trumbull area (also known as Long Hill) of southwestern Connecticut, is a recreation area encompassing the mineral-rich hill of “Saganawamps” and owned by the Town of Trumbull. Most of its 72 acres are wooded, rocky and undeveloped but it is surrounded by dense infrastructure and transportation, residential, retail, and commercial development (Figure 1). It...
Authors
Harold Moritz, Robert Wintsch, Bill Devlin, Ryan McAleer, Shinae Lee, SookJu Kim, Keewook Yi
Non-USGS Publications**
Berger, A.L., Gulick, S.P., Spotila, J.A., Upton, P., Jaeger, J.M., Chapman, J.B., Worthington, L.A., Pavlis, T.L., Ridgway, K.D., Willems, B.A. and McAleer, R.J., 2008. Quaternary tectonic response to intensified glacial erosion in an orogenic wedge. Nature Geoscience, 1(11), p.793.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Filter Total Items: 27
Molecular-scale speciation of germanium and copper within sphalerite from Central Tennessee mining district (TN), Red Dog mining district (AK), and Metaline mining district (WA) Molecular-scale speciation of germanium and copper within sphalerite from Central Tennessee mining district (TN), Red Dog mining district (AK), and Metaline mining district (WA)
Oxidation state and bonding environment of Ge and Cu in ZnS and Zn mineral concentrates from a variety of sources [Central Tennessee mining district (TN), Metaline mining district, (WA), and Red Dog mine (AK)] were determined by linear combination fits from x-ray absorption spectroscopy (XAS) analysis. Sphalerites from the East Tennessee mining district contained Ge in concentrations...
Trace element composition and molecular-scale speciation characterization of sphalerite from Central and East Tennessee mining districts, Red Dog mining district (AK), and Metaline mining district (WA) Trace element composition and molecular-scale speciation characterization of sphalerite from Central and East Tennessee mining districts, Red Dog mining district (AK), and Metaline mining district (WA)
Germanium (Ge) is an element deemed critical globally, and used in electronics, communication, and defense applications. The supply of Ge is limited and as demand for it increases, its criticality increases. Germanium is exclusively recovered as a byproduct of either coal mining or zinc (Zn) mining, and the main mineral hosting Ge in Zn deposits is sphalerite (ZnS). However, the...
40Ar/39Ar data from the Janub Metamorphic Complex, Southern Jordan 40Ar/39Ar data from the Janub Metamorphic Complex, Southern Jordan
This data release includes 40Ar/39Ar collected at the U.S. Geological Survey for samples from the Janub Metamorphic Complex in Southern Jordan. Rock samples were collected by Hind Ghanem of the University of Jordan. Muscovite-rich microcores were drilled from a polished thick section of a deformed granitoid and analyzed by argon geochronology at the U.S. Geological Survey Bascom ARgon...
40Ar/39Ar isotopic data and electron microprobe data from muscovite in the Sukari gold deposit, Egypt 40Ar/39Ar isotopic data and electron microprobe data from muscovite in the Sukari gold deposit, Egypt
This data release includes electron microprobe and 40Ar/39Ar collected at the U.S. Geological Survey for samples from the Sukari gold deposit in the Eastern Desert of Egypt. Rock samples were collected by Basem Zoheir--Benha University/University of Kiel. Muscovite from a polished thick section of sericitized wall rock was analyzed by electron probe microanalysis at the U.S. Geological...
Mineral abundances within bulk and size-fractionated mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A. Mineral abundances within bulk and size-fractionated mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A.
Mineral abundances within bulk and size-fractionated mine waste from sampled historical waste piles from the Tar Creek Superfund Site, Oklahoma, U.S.A., were determined by Mineral Liberation Analysis (MLA) and X-Ray Diffraction (XRD). Data and methods reported are part of a research study published below in the 'Related External Resources' section.
Molecular speciation of Ge within sphalerite, hemimorphite, and quartz from mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A. Molecular speciation of Ge within sphalerite, hemimorphite, and quartz from mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A.
Oxidation state and bonding environment of Ge in minerals within mine waste from sampled historical waste piles from the Tar Creek Superfund Site, Oklahoma, U.S. were determined by linear combination fits from x-ray absorption near edge spectroscopy (XANES) analysis. Ge content in quartz within these wastes was determined using XANES edge steps, and Ge content in sphalerite was compared...
Elemental concentrations for bulk and size-fractionated mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A. Elemental concentrations for bulk and size-fractionated mine waste from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A.
Elemental concentrations for bulk and size-fractionated mine waste from sampled historical waste piles from the Tar Creek Superfund Site, Oklahoma, U.S. were determined after dissolution via acid digests or a sodium peroxide fusion. Elemental concentrations were determined for the leachate from a simulated rainwater leach of mine wastes. Data and methods reported are part of a research...
Electron microprobe analyses of sphalerite and hemimorphite from mine wastes from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A. Electron microprobe analyses of sphalerite and hemimorphite from mine wastes from the Tar Creek Superfund Site, Tri-State Mining District, Oklahoma, U.S.A.
Electron microprobe analyses of sphalerite (ZnS) and hemimorphite (Zn4Si2O7(OH)2·H2O) from sampled historical waste piles were conducted with a specific focus on germanium (Ge). In mine wastes at the Tar Creek Superfund Site, Oklahoma, USA, Ge is associated with ZnS (sphalerite) as expected, but weathering in the waste piles has led to a significant amount of Ge being incorporated into a...
40Ar/39Ar data from the Old Mine Park area, Trumbull, Connecticut 40Ar/39Ar data from the Old Mine Park area, Trumbull, Connecticut
This data release includes 40Ar/39Ar data from the U.S. Geological Survey for samples from Old Mine Park Area, Trumbull, Connecticut. Mineral samples were collected by Robert Wintsch and Harold Moritz. Potassium-bearing mineral grains were separated from the bulk sample and analyzed by argon geochronology at the U.S. Geological Survey Bascom ARgon Dating (BARD) Laboratory in Reston...
Electron microprobe and 40Ar/39Ar isotopic data from west-central New Hampshire Electron microprobe and 40Ar/39Ar isotopic data from west-central New Hampshire
This dataset accompanies planned publication 'Unmixing multiple metamorphic muscovite age populations with powder X-ray diffraction and 40Ar/39Ar analysis'. The 40Ar/39Ar and electron microprobe data are from samples adjacent to a lower greenschist facies shear zone in western New Hampshire. The geochronology coupled with the electron microprobe data provide a petrochronologic framework...
TOC, Reflectance and Raman Data from Eocene Green River Mahogany Zone TOC, Reflectance and Raman Data from Eocene Green River Mahogany Zone
Geological models for petroleum generation suggest thermal conversion of oil-prone sedimentary organic matter in the presence of water promotes increased liquid saturate yield, whereas absence of water causes formation of an aromatic, cross-linked solid bitumen residue. To test the influence of exchangeable hydrogen from water, organic-rich (22 wt. percent total organic carbon, TOC)...
Photoluminescence Imaging of Whole Zircon Grains on a Petrographic Microscope - An Underused Aide for Geochronologic Studies Photoluminescence Imaging of Whole Zircon Grains on a Petrographic Microscope - An Underused Aide for Geochronologic Studies
The refractory nature of zircon to temperature and pressure allows even a single zircon grain to preserve a rich history of magmatic, metamorphic, and hydrothermal processes. Isotopic dating of micro-domains exposed in cross-sections of zircon grains allows us to interrogate this history. Unfortunately, our ability to select the zircon grains in a heavy mineral concentrate that records...
Filter Total Items: 54
Insights into glendonite formation from the upper Oligocene Sagavanirktok Formation, North Slope, Alaska Insights into glendonite formation from the upper Oligocene Sagavanirktok Formation, North Slope, Alaska
The type locality for the upper Oligocene Nuwok Member of the Sagavanirktok Formation (Carter Creek, North Slope, Alaska, USA) contains abundant occurrence of glendonite, a pseudomorph after the calcium carbonate mineral ikaite, which typically forms in the shallow subsurface of cold marine sediments. The region during the time of Nuwok Member deposition was located at a high latitude...
Authors
John Counts, Madeleine Vickers, Martha Stokes, Whittney Spivey, Kristina Gardner, Jean Self-Trail, Jared Gooley, Ryan McAleer, Aaron M. Jubb, David Houseknecht, Richard Lease, Neil Griffis, Martin Vickers, Kasia Sliwinska, Hannah Tompkins, Adam Hudson
Geology of the Mount Rogers area, revisited: Evidence of Neoproterozoic continental rifting, glaciation, and the opening and closing of the Iapetus Ocean, Blue Ridge, VA–NC–TN Geology of the Mount Rogers area, revisited: Evidence of Neoproterozoic continental rifting, glaciation, and the opening and closing of the Iapetus Ocean, Blue Ridge, VA–NC–TN
Recent field and geochronological studies in eight 7.5-minute quadrangles near Mount Rogers in Virginia, North Carolina and Tennessee recognize (1) important stratigraphic and structural relationships for the Neoproterozoic Mount Rogers and Konnarock Formations, and the northeast end of the Mountain City window; (2) the separation of Mesoproterozoic rocks of the Blue Ridge into three age...
Authors
Arthur Merschat, Ryan McAleer, Christopher S. Holm-Denoma, C. Southworth
Extrusion tectonism of Indochina reassessed: constraints from 40Ar/39Ar geochronology from the Day Nui Con Voi metamorphic massif, Vietnam Extrusion tectonism of Indochina reassessed: constraints from 40Ar/39Ar geochronology from the Day Nui Con Voi metamorphic massif, Vietnam
The extrusion tectonic model for the southeastern margin of the Himalayan orogeny links the crustal shear activity along the Red River Shear Zone (RRSZ) to the opening of the South China Sea (SCS). The Day Nui Con Voi (DNCV) metamorphic massif in northern Vietnam strikes NW-SE, is bounded by the RRSZ to the south and continues along the strike where it meets the SCS. The DNCV is thus a...
Authors
Thi-Hue Dinh, Meng-Wan Yeh, Tung-Yi Lee, Michael J. Kunk, Robert P. Wintsch, Ryan McAleer
Redefinition of the Petersburg batholith and implications for crustal inheritance in the Dinwiddie terrane, Virginia, USA Redefinition of the Petersburg batholith and implications for crustal inheritance in the Dinwiddie terrane, Virginia, USA
Field relations as well as geochemical and petrologic studies of metaigneous rocks assigned to the Pennsylvanian–Permian Petersburg batholith identify at least two distinct rock types: foliated metagranitoid gneiss and massive to porphyritic granite. Foliated metagranitoid gneiss of mostly granodioritic composition is geochemically distinct from associated massive and porphyritic...
Authors
Mark Carter, Ryan McAleer, Christopher S. Holm-Denoma, Marcie Occhi, Brent Owens, Jorge Vazquez
Mapping ancient sedimentary organic matter molecular structure at nanoscales using optical photothermal infrared spectroscopy Mapping ancient sedimentary organic matter molecular structure at nanoscales using optical photothermal infrared spectroscopy
Elucidating the molecular structure of sedimentary organic matter (SOM) is key to understanding petroleum generation processes, as well as ancient sedimentary environments. SOM structure is primarily controlled by biogenic source material (e.g., marine vs. terrigenous), depositional conditions, and subsurface thermal history. Additional factors, e.g., strain, may also impact the...
Authors
Aaron M. Jubb, Martha Stokes, Ryan McAleer, Paul Hackley, Eoghan Dillion, Jing Qu
A novel non-destructive workflow for examining germanium and co-substituents in ZnS A novel non-destructive workflow for examining germanium and co-substituents in ZnS
A suite of complementary techniques was used to examine germanium (Ge), a byproduct critical element, and co-substituent trace elements in ZnS and mine wastes from four mineral districts where germanium is, or has been, produced within the United States. This contribution establishes a comprehensive workflow for characterizing Ge and other trace elements, which captures the full...
Authors
Sarah Hayes, Ryan McAleer, Nadine Piatak, Sarah White, Robert R. Seal,
The Sukari gold deposit, Egypt: Geochemical and geochronological constraints on the ore genesis and implications for regional exploration The Sukari gold deposit, Egypt: Geochemical and geochronological constraints on the ore genesis and implications for regional exploration
The Sukari gold deposit (>15 Moz Au) in the Eastern Desert of Egypt is hosted by a deformed granitoid stock (Sukari tonalite-trondhjemite intrusion) and mainly occurs as a network of crosscutting sulfide-bearing quartz (± carbonate) veins and intensely sulfidized-silicified-sericitized wall rock. Emplacement of the Sukari intrusion into a tectonized Neoproterozoic accretionary complex...
Authors
Basem Zoheir, Astrid Holzheid, Armin Zeh, Ryan McAleer, Mohamed El-Behairy, Ulrich Schwarz-Schampera, Torsten Graupner, David Lentz, Fahui Xiong
Vein-type gold formation during late extensional collapse of the Eastern Desert, Egypt: the Gidami deposit Vein-type gold formation during late extensional collapse of the Eastern Desert, Egypt: the Gidami deposit
Orogenic gold deposits, though construed to focused fluid flow during orogenesis, commonly post-date the main accretionary events. Several lines of evidence indicate that orogenic gold formation in the Arabian–Nubian Shield continued through the orogen collapse stage and associated rapid exhumation and thermal re-equilibration. The Gidami gold deposit in the Eastern Desert of Egypt is...
Authors
Basem Zoheir, Ryan McAleer, Matthew Steele-MacInnis, Armin Zeh, Wyatt Bain, Spencer Poulette
Germanium redistribution during weathering of Zn mine wastes: Implications for environmental mobility and recovery of a critical mineral Germanium redistribution during weathering of Zn mine wastes: Implications for environmental mobility and recovery of a critical mineral
Germanium (Ge) is a metal used in emerging energy technologies, communications, and defense, and has been deemed critical by the United States due to its essential applications and scarce supply. Germanium is recovered as a byproduct of zinc (Zn) sulfides, and mining and processing of these materials lead to waste that could act both as a source of extractable Ge and a source for...
Authors
Sarah White, Nadine Piatak, Ryan McAleer, Sarah Hayes, Robert R. Seal,, Laurel Schaider, James Shine
U-Pb and fission-track data from zircon and apatite resolve latest- and post-Alleghanian thermal histories along the Fall Line of the Atlantic margin of the southeastern United States U-Pb and fission-track data from zircon and apatite resolve latest- and post-Alleghanian thermal histories along the Fall Line of the Atlantic margin of the southeastern United States
Although the Atlantic continental margin of the eastern United States is an archetypal passive margin, episodes of rejuvenation following continental breakup are increasingly well documented. To better constrain this history of rejuvenation along the southern portion of this continental margin, we present zircon U-Pb (ZUPb) age, zircon fission-track (ZFT) age, apatite U-Pb (AUPb) age...
Authors
William Craddock, Paul O'Sullivan, Ryan McAleer
Evaluating aromatization of solid bitumen generated in the presence and absence of water: Implications for solid bitumen reflectance as a thermal proxy Evaluating aromatization of solid bitumen generated in the presence and absence of water: Implications for solid bitumen reflectance as a thermal proxy
Geological models for petroleum generation suggest thermal conversion of oil-prone sedimentary organic matter in the presence of water promotes increased liquid saturate yield, whereas absence of water causes formation of an aromatic, cross-linked solid bitumen residue. To test the influence of hydrogen from water, organic-rich (22 wt% total organic carbon, TOC) mudrock samples from the...
Authors
Paul Hackley, Aaron M. Jubb, Patrick Smith, Ryan McAleer, Brett Valentine, Javin Hatcherian, Palma Botterell, Justin Birdwell
Geology & mineralogy of the Old Mine Park area Trumbull Connecticut Geology & mineralogy of the Old Mine Park area Trumbull Connecticut
Old Mine Park, in the northern Trumbull area (also known as Long Hill) of southwestern Connecticut, is a recreation area encompassing the mineral-rich hill of “Saganawamps” and owned by the Town of Trumbull. Most of its 72 acres are wooded, rocky and undeveloped but it is surrounded by dense infrastructure and transportation, residential, retail, and commercial development (Figure 1). It...
Authors
Harold Moritz, Robert Wintsch, Bill Devlin, Ryan McAleer, Shinae Lee, SookJu Kim, Keewook Yi
Non-USGS Publications**
Berger, A.L., Gulick, S.P., Spotila, J.A., Upton, P., Jaeger, J.M., Chapman, J.B., Worthington, L.A., Pavlis, T.L., Ridgway, K.D., Willems, B.A. and McAleer, R.J., 2008. Quaternary tectonic response to intensified glacial erosion in an orogenic wedge. Nature Geoscience, 1(11), p.793.
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government