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
Geochemical and isotopic study of soils and waters from an Italian contaminated site: Agro Aversano (Campania) Geochemical and isotopic study of soils and waters from an Italian contaminated site: Agro Aversano (Campania)
Lead isotope applications have been widely used in recent years in environmental studies conducted on different kinds of sampled media. In the present paper, Pb isotope ratios have been used to determine the sources of metal pollution in soils and waters in the Agro Aversano area. During three different sampling phases, a total of 113 surface soils (5-20. cm), 20 samples from 2 soil...
Authors
M.A. Bove, R. A. Ayuso, B. de Vivo, A. Lima, S. Albanese
Porphyry copper deposit model Porphyry copper deposit model
This report contains a revised descriptive model of porphyry copper deposits (PCDs), the world's largest source (about 60 percent) and resource (about 65 percent) of copper and a major source of molybdenum, gold and silver. Despite relatively low grades (average 0.44 percent copper in 2008), PCDs have significant economic and societal impacts due to their large size (commonly hundreds of...
Authors
Robert A. Ayuso, Mark D. Barton, Richard J. Blakely, Robert J. Bodnar, John H. Dilles, Floyd Gray, Fred T. Graybeal, John L. Mars, Darcy McPhee, Robert R Seal, Ryan D. Taylor, Peter G. Vikre
The role of ridge subduction in determining the geochemistry and Nd–Sr–Pb isotopic evolution of the Kodiak batholith in southern Alaska The role of ridge subduction in determining the geochemistry and Nd–Sr–Pb isotopic evolution of the Kodiak batholith in southern Alaska
The Paleocene Kodiak batholith, part of the Sanak–Baranof belt of Tertiary near-trench intrusive rocks, forms an elongate body (~ 150 km long) that transects Kodiak Island from SW to NE. The batholith consists of three zones (Southern, Central, and Northern) of kyanite-, muscovite-, and garnet-bearing biotite tonalite and granodiorite and less abundant granite that intruded an...
Authors
Robert A. Ayuso, Peter J. Haeussler, Dwight Bradley, David W. Farris, Nora K. Foley, Gregory A. Wandless
Preliminary model of porphyry copper deposits Preliminary model of porphyry copper deposits
The U.S. Geological Survey (USGS) Mineral Resources Program develops mineral-deposit models for application in USGS mineral-resource assessments and other mineral resource-related activities within the USGS as well as for nongovernmental applications. Periodic updates of models are published in order to incorporate new concepts and findings on the occurrence, nature, and origin of...
Authors
Byron R. Berger, Robert A. Ayuso, Jeffrey C. Wynn, Robert R. Seal
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
Mineral sources and transport pathways for arsenic release in a coastal watershed, USA Mineral sources and transport pathways for arsenic release in a coastal watershed, USA
Metasedimentary bedrock of coastal Maine contains a diverse suite of As-bearing minerals that act as significant sources of elements found in ground and surface waters in the region. Arsenic sources in the Penobscot Formation include, in order of decreasing As content by weight: löllingite and realgar (c.70%), arsenopyrite, cobaltite, glaucodot, and gersdorffite (in the range of 34–45%)...
Authors
Nora K. Foley, Robert A. Ayuso
Science and Products
Filter Total Items: 82
Geochemical and isotopic study of soils and waters from an Italian contaminated site: Agro Aversano (Campania) Geochemical and isotopic study of soils and waters from an Italian contaminated site: Agro Aversano (Campania)
Lead isotope applications have been widely used in recent years in environmental studies conducted on different kinds of sampled media. In the present paper, Pb isotope ratios have been used to determine the sources of metal pollution in soils and waters in the Agro Aversano area. During three different sampling phases, a total of 113 surface soils (5-20. cm), 20 samples from 2 soil...
Authors
M.A. Bove, R. A. Ayuso, B. de Vivo, A. Lima, S. Albanese
Porphyry copper deposit model Porphyry copper deposit model
This report contains a revised descriptive model of porphyry copper deposits (PCDs), the world's largest source (about 60 percent) and resource (about 65 percent) of copper and a major source of molybdenum, gold and silver. Despite relatively low grades (average 0.44 percent copper in 2008), PCDs have significant economic and societal impacts due to their large size (commonly hundreds of...
Authors
Robert A. Ayuso, Mark D. Barton, Richard J. Blakely, Robert J. Bodnar, John H. Dilles, Floyd Gray, Fred T. Graybeal, John L. Mars, Darcy McPhee, Robert R Seal, Ryan D. Taylor, Peter G. Vikre
The role of ridge subduction in determining the geochemistry and Nd–Sr–Pb isotopic evolution of the Kodiak batholith in southern Alaska The role of ridge subduction in determining the geochemistry and Nd–Sr–Pb isotopic evolution of the Kodiak batholith in southern Alaska
The Paleocene Kodiak batholith, part of the Sanak–Baranof belt of Tertiary near-trench intrusive rocks, forms an elongate body (~ 150 km long) that transects Kodiak Island from SW to NE. The batholith consists of three zones (Southern, Central, and Northern) of kyanite-, muscovite-, and garnet-bearing biotite tonalite and granodiorite and less abundant granite that intruded an...
Authors
Robert A. Ayuso, Peter J. Haeussler, Dwight Bradley, David W. Farris, Nora K. Foley, Gregory A. Wandless
Preliminary model of porphyry copper deposits Preliminary model of porphyry copper deposits
The U.S. Geological Survey (USGS) Mineral Resources Program develops mineral-deposit models for application in USGS mineral-resource assessments and other mineral resource-related activities within the USGS as well as for nongovernmental applications. Periodic updates of models are published in order to incorporate new concepts and findings on the occurrence, nature, and origin of...
Authors
Byron R. Berger, Robert A. Ayuso, Jeffrey C. Wynn, Robert R. Seal
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
Mineral sources and transport pathways for arsenic release in a coastal watershed, USA Mineral sources and transport pathways for arsenic release in a coastal watershed, USA
Metasedimentary bedrock of coastal Maine contains a diverse suite of As-bearing minerals that act as significant sources of elements found in ground and surface waters in the region. Arsenic sources in the Penobscot Formation include, in order of decreasing As content by weight: löllingite and realgar (c.70%), arsenopyrite, cobaltite, glaucodot, and gersdorffite (in the range of 34–45%)...
Authors
Nora K. Foley, Robert A. Ayuso