Robert Ayuso
Robert Ayuso is a Research Geologist with the USGS Geology, Energy & Minerals (GEM) Science Center in Reston, VA.
Science and Products
Filter Total Items: 82
The Ellsworth terrane, coastal Maine: Geochronology, geochemistry, and Nd-Pb isotopic composition - Implications for the rifting of Ganderia The Ellsworth terrane, coastal Maine: Geochronology, geochemistry, and Nd-Pb isotopic composition - Implications for the rifting of Ganderia
The Ellsworth terrane is one of a number of fault-bounded blocks that occur along the eastern margin of Ganderia, the western-most of the peri-Gondwanan domains in the northern Appalachians that were accreted to Laurentia in the Paleozoic. Geologic relations, detrital zircon ages, and basalt geochemistry suggest that the Ellsworth terrane is part of Ganderia and not an exotic terrane. In...
Authors
K. J. Schulz, D. B. Stewart, R. D. Tucker, J.C. Pollock, R. A. Ayuso
Geological assessment of cores from the Great Bay National Wildlife Refuge, New Hampshire Geological assessment of cores from the Great Bay National Wildlife Refuge, New Hampshire
Geological sources of metals (especially arsenic and zinc) in aquifer bedrock were evaluated for their potential to contribute elevated values of metals to ground and surface waters in and around Rockingham County, New Hampshire. Ayotte and others (1999, 2003) had proposed that arsenic concentrations in ground water flowing through bedrock aquifers in eastern New England were elevated as...
Authors
Nora K. Foley, Robert A. Ayuso, Joseph D. Ayotte, Denise L. Montgomery, Gilpin R. Robinson
High arsenic concentrations and enriched sulfur and oxygen isotopes in a fractured-bedrock ground-water system High arsenic concentrations and enriched sulfur and oxygen isotopes in a fractured-bedrock ground-water system
Ground water with high arsenic concentrations (up to 26.6????mol L- 1) has sulfate enriched in 34S and 18O in the fractured-bedrock, ground-water system of the Kelly's Cove watershed, Northport, Maine, USA. The ranges of sulfur and oxygen isotope values in aqueous sulfate, ??34S[SO4] and ??18O[SO4], at the Kelly's Cove watershed are + 3.4 to + 4.9??? and - 2.0 to + 6.7???, respectively...
Authors
G. Lipfert, W.C. Sidle, A.S. Reeve, R. A. Ayuso, A.J. Boyce
Regional Fluid Flow and Basin Modeling in Northern Alaska Regional Fluid Flow and Basin Modeling in Northern Alaska
The foothills of the Brooks Range contain an enormous accumulation of zinc (Zn) in the form of zinc sulfide and barium (Ba) in the form of barite in Carboniferous shale, chert, and mudstone. Most of the resources and reserves of Zn occur in the Red Dog deposit and others in the Red Dog district; these resources and reserves surpass those of most deposits worldwide in terms of size and...
Authors
Robert A. Ayuso, Robert Burruss, Julie A. Dumoulin, Garth E. Graham, Anita G. Harris, Craig A. Johnson, Karen D. Kelley, David L. Leach, Paul G. Lillis, Erin E. Marsh, Thomas E. Moore, Christopher J. Potter, John F. Slack
By
Ecosystems Mission Area, Geology, Energy, and Minerals Mission Area, Energy Resources Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Alaska Science Center, Central Energy Resources Science Center, Geology, Energy & Minerals Science Center, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center
Studies by the U.S. Geological Survey in Alaska, 2005 Studies by the U.S. Geological Survey in Alaska, 2005
Summary The collection of papers that follows continues the series of U.S. Geological Survey (USGS) investigative reports in Alaska under the broad umbrella of the geologic sciences. This series represents new and sometimes-preliminary findings that are of interest to Earth scientists in academia, government, and industry; to land and resource managers; and to the general public. The...
Authors
David W. Houseknecht, Kenneth J. Bird, Michelle L. Coombs, Christina A. Neal, Rick L. Wessels, Robert G. McGimsey, John F. Slack, W.C. Pat Shanks, Susan M. Karl, Pamela A. Gemery, Peter E. Bittenbender, W. Ian Ridley, W. Matthew Burns, Daniel O. Hayba, Elisabeth L. Rowan, Robert A. Ayuso, Peter J. Haeussler, Gregory A. Wandless, Anna Colvin
Crustal contamination and crystal entrapment during polybaric magma evolution at Mt. Somma-Vesuvius volcano, Italy: Geochemical and Sr isotope evidence Crustal contamination and crystal entrapment during polybaric magma evolution at Mt. Somma-Vesuvius volcano, Italy: Geochemical and Sr isotope evidence
New major and trace element analyses and Sr-isotope determinations of rocks from Mt. Somma-Vesuvius volcano produced from 25 ky BP to 1944 AD are part of an extensive database documenting the geochemical evolution of this classic region. Volcanic rocks include silica undersaturated, potassic and ultrapotassic lavas and tephras characterized by variable mineralogy and different crystal...
Authors
M. Piochi, R. A. Ayuso, B. de Vivo, R. Somma
Science and Products
Filter Total Items: 82
The Ellsworth terrane, coastal Maine: Geochronology, geochemistry, and Nd-Pb isotopic composition - Implications for the rifting of Ganderia The Ellsworth terrane, coastal Maine: Geochronology, geochemistry, and Nd-Pb isotopic composition - Implications for the rifting of Ganderia
The Ellsworth terrane is one of a number of fault-bounded blocks that occur along the eastern margin of Ganderia, the western-most of the peri-Gondwanan domains in the northern Appalachians that were accreted to Laurentia in the Paleozoic. Geologic relations, detrital zircon ages, and basalt geochemistry suggest that the Ellsworth terrane is part of Ganderia and not an exotic terrane. In...
Authors
K. J. Schulz, D. B. Stewart, R. D. Tucker, J.C. Pollock, R. A. Ayuso
Geological assessment of cores from the Great Bay National Wildlife Refuge, New Hampshire Geological assessment of cores from the Great Bay National Wildlife Refuge, New Hampshire
Geological sources of metals (especially arsenic and zinc) in aquifer bedrock were evaluated for their potential to contribute elevated values of metals to ground and surface waters in and around Rockingham County, New Hampshire. Ayotte and others (1999, 2003) had proposed that arsenic concentrations in ground water flowing through bedrock aquifers in eastern New England were elevated as...
Authors
Nora K. Foley, Robert A. Ayuso, Joseph D. Ayotte, Denise L. Montgomery, Gilpin R. Robinson
High arsenic concentrations and enriched sulfur and oxygen isotopes in a fractured-bedrock ground-water system High arsenic concentrations and enriched sulfur and oxygen isotopes in a fractured-bedrock ground-water system
Ground water with high arsenic concentrations (up to 26.6????mol L- 1) has sulfate enriched in 34S and 18O in the fractured-bedrock, ground-water system of the Kelly's Cove watershed, Northport, Maine, USA. The ranges of sulfur and oxygen isotope values in aqueous sulfate, ??34S[SO4] and ??18O[SO4], at the Kelly's Cove watershed are + 3.4 to + 4.9??? and - 2.0 to + 6.7???, respectively...
Authors
G. Lipfert, W.C. Sidle, A.S. Reeve, R. A. Ayuso, A.J. Boyce
Regional Fluid Flow and Basin Modeling in Northern Alaska Regional Fluid Flow and Basin Modeling in Northern Alaska
The foothills of the Brooks Range contain an enormous accumulation of zinc (Zn) in the form of zinc sulfide and barium (Ba) in the form of barite in Carboniferous shale, chert, and mudstone. Most of the resources and reserves of Zn occur in the Red Dog deposit and others in the Red Dog district; these resources and reserves surpass those of most deposits worldwide in terms of size and...
Authors
Robert A. Ayuso, Robert Burruss, Julie A. Dumoulin, Garth E. Graham, Anita G. Harris, Craig A. Johnson, Karen D. Kelley, David L. Leach, Paul G. Lillis, Erin E. Marsh, Thomas E. Moore, Christopher J. Potter, John F. Slack
By
Ecosystems Mission Area, Geology, Energy, and Minerals Mission Area, Energy Resources Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Alaska Science Center, Central Energy Resources Science Center, Geology, Energy & Minerals Science Center, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center
Studies by the U.S. Geological Survey in Alaska, 2005 Studies by the U.S. Geological Survey in Alaska, 2005
Summary The collection of papers that follows continues the series of U.S. Geological Survey (USGS) investigative reports in Alaska under the broad umbrella of the geologic sciences. This series represents new and sometimes-preliminary findings that are of interest to Earth scientists in academia, government, and industry; to land and resource managers; and to the general public. The...
Authors
David W. Houseknecht, Kenneth J. Bird, Michelle L. Coombs, Christina A. Neal, Rick L. Wessels, Robert G. McGimsey, John F. Slack, W.C. Pat Shanks, Susan M. Karl, Pamela A. Gemery, Peter E. Bittenbender, W. Ian Ridley, W. Matthew Burns, Daniel O. Hayba, Elisabeth L. Rowan, Robert A. Ayuso, Peter J. Haeussler, Gregory A. Wandless, Anna Colvin
Crustal contamination and crystal entrapment during polybaric magma evolution at Mt. Somma-Vesuvius volcano, Italy: Geochemical and Sr isotope evidence Crustal contamination and crystal entrapment during polybaric magma evolution at Mt. Somma-Vesuvius volcano, Italy: Geochemical and Sr isotope evidence
New major and trace element analyses and Sr-isotope determinations of rocks from Mt. Somma-Vesuvius volcano produced from 25 ky BP to 1944 AD are part of an extensive database documenting the geochemical evolution of this classic region. Volcanic rocks include silica undersaturated, potassic and ultrapotassic lavas and tephras characterized by variable mineralogy and different crystal...
Authors
M. Piochi, R. A. Ayuso, B. de Vivo, R. Somma