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
Emplacement of the Kodiak batholith and slab-window migration Emplacement of the Kodiak batholith and slab-window migration
The Kodiak batholith is one of the largest, most elongate intrusive bodies in the forearc Sanak-Baranof plutonic belt located in southern Alaska. This belt is interpreted to have formed during the subduction of an oceanic spreading center and the associated migration of a slab window. Individual plutons of the Kodiak batholith track the location and evolution of the underlying slab...
Authors
David W. Farris, Peter J. Haeussler, Richard Friedman, Scott R. Paterson, R. W. Saltus, Robert A. Ayuso
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
Chapter 9 The magma feeding system of Somma-Vesuvius (Italy) strato-volcano: New inferences from a review of geochemical and Sr, Nd, Pb and O isotope data Chapter 9 The magma feeding system of Somma-Vesuvius (Italy) strato-volcano: New inferences from a review of geochemical and Sr, Nd, Pb and O isotope data
A large database of major, trace and isotope (Sr, Nd, Pb, O) data exists for rocks produced by the volcanic activity of Somma-Vesuvius volcano. Variation diagrams strongly suggest a major role for evolutionary processes such as fractional crystallization, contamination, crystal trapping and magma maxing, occurring after magma genesis in the mantle. Most mafic magmas are enriched in LILE...
Authors
M. Piochi, B. de Vivo, R. A. Ayuso
U-Pb zircon ages and Pb isotope geochemistry of gold deposits in the Carolina slate belt of South Carolina U-Pb zircon ages and Pb isotope geochemistry of gold deposits in the Carolina slate belt of South Carolina
Volcanic rocks of the Persimmon Fork Formation host the largest known gold mines of the Carolina slate belt. U-Pb (SHRIMP) zircon ages have been obtained from rocks closely associated with pyrite-enargite-gold deposits at Brewer (quartz-topaz rhyolite breccia from the argillic alteration zone in the Brewer pit and felsic ash-flow tuff from the quartz sericite alteration zone), from the
Authors
Robert A. Ayuso, Joseph L. Wooden, Nora K. Foley, Robert R. Seal, A. Krishna Sinha
Oceanic Pb-isotopic sources of Proterozoic and Paleozoic volcanogenic massive sulfide deposits on Prince of Wales Island and vicinity, southeastern Alaska Oceanic Pb-isotopic sources of Proterozoic and Paleozoic volcanogenic massive sulfide deposits on Prince of Wales Island and vicinity, southeastern Alaska
Volcanogenic massive sulfide (VMS) deposits on Prince of Wales Island and vicinity in southeastern Alaska are associated with Late Proterozoic through Cambrian volcanosedimentary rocks of the Wales Group and with Ordovician through Early Silurian felsic volcanic rocks of the Moira Sound unit (new informal name). The massive sulfide deposits in the Wales Group include the Big Harbor...
Authors
Robert A. Ayuso, Susan M. Karl, John F. Slack, Peter J. Haeussler, Peter E. Bittenbender, Gregory A. Wandless, Anna Colvin
Lead isotopic compositions of soil and near-surface till profiles from a watershed containing arsenic-enriched groundwater in coastal Maine Lead isotopic compositions of soil and near-surface till profiles from a watershed containing arsenic-enriched groundwater in coastal Maine
Lead isotope compositions of soils and near-surface tills from an area of coastal Maine known to have groundwater with anomalously high arsenic contents were measured in order to determine the source of the lead and, by inference, possible sources of arsenic. Five soil and till sites were selected for detailed chemical and isotopic analysis. To construct profiles of the soil and till...
Authors
Robert Ayuso, Nora Foley, Gregory Wandless, Jeremy Dillingham, Anna Colvin
Science and Products
Filter Total Items: 82
Emplacement of the Kodiak batholith and slab-window migration Emplacement of the Kodiak batholith and slab-window migration
The Kodiak batholith is one of the largest, most elongate intrusive bodies in the forearc Sanak-Baranof plutonic belt located in southern Alaska. This belt is interpreted to have formed during the subduction of an oceanic spreading center and the associated migration of a slab window. Individual plutons of the Kodiak batholith track the location and evolution of the underlying slab...
Authors
David W. Farris, Peter J. Haeussler, Richard Friedman, Scott R. Paterson, R. W. Saltus, Robert A. Ayuso
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
Chapter 9 The magma feeding system of Somma-Vesuvius (Italy) strato-volcano: New inferences from a review of geochemical and Sr, Nd, Pb and O isotope data Chapter 9 The magma feeding system of Somma-Vesuvius (Italy) strato-volcano: New inferences from a review of geochemical and Sr, Nd, Pb and O isotope data
A large database of major, trace and isotope (Sr, Nd, Pb, O) data exists for rocks produced by the volcanic activity of Somma-Vesuvius volcano. Variation diagrams strongly suggest a major role for evolutionary processes such as fractional crystallization, contamination, crystal trapping and magma maxing, occurring after magma genesis in the mantle. Most mafic magmas are enriched in LILE...
Authors
M. Piochi, B. de Vivo, R. A. Ayuso
U-Pb zircon ages and Pb isotope geochemistry of gold deposits in the Carolina slate belt of South Carolina U-Pb zircon ages and Pb isotope geochemistry of gold deposits in the Carolina slate belt of South Carolina
Volcanic rocks of the Persimmon Fork Formation host the largest known gold mines of the Carolina slate belt. U-Pb (SHRIMP) zircon ages have been obtained from rocks closely associated with pyrite-enargite-gold deposits at Brewer (quartz-topaz rhyolite breccia from the argillic alteration zone in the Brewer pit and felsic ash-flow tuff from the quartz sericite alteration zone), from the
Authors
Robert A. Ayuso, Joseph L. Wooden, Nora K. Foley, Robert R. Seal, A. Krishna Sinha
Oceanic Pb-isotopic sources of Proterozoic and Paleozoic volcanogenic massive sulfide deposits on Prince of Wales Island and vicinity, southeastern Alaska Oceanic Pb-isotopic sources of Proterozoic and Paleozoic volcanogenic massive sulfide deposits on Prince of Wales Island and vicinity, southeastern Alaska
Volcanogenic massive sulfide (VMS) deposits on Prince of Wales Island and vicinity in southeastern Alaska are associated with Late Proterozoic through Cambrian volcanosedimentary rocks of the Wales Group and with Ordovician through Early Silurian felsic volcanic rocks of the Moira Sound unit (new informal name). The massive sulfide deposits in the Wales Group include the Big Harbor...
Authors
Robert A. Ayuso, Susan M. Karl, John F. Slack, Peter J. Haeussler, Peter E. Bittenbender, Gregory A. Wandless, Anna Colvin
Lead isotopic compositions of soil and near-surface till profiles from a watershed containing arsenic-enriched groundwater in coastal Maine Lead isotopic compositions of soil and near-surface till profiles from a watershed containing arsenic-enriched groundwater in coastal Maine
Lead isotope compositions of soils and near-surface tills from an area of coastal Maine known to have groundwater with anomalously high arsenic contents were measured in order to determine the source of the lead and, by inference, possible sources of arsenic. Five soil and till sites were selected for detailed chemical and isotopic analysis. To construct profiles of the soil and till...
Authors
Robert Ayuso, Nora Foley, Gregory Wandless, Jeremy Dillingham, Anna Colvin