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
Pb-Sr isotopic and geochemical constraints on sources and processes of lead contamination in well waters and soil from former fruit orchards, Pennsylvania, USA: A legacy of anthropogenic activities Pb-Sr isotopic and geochemical constraints on sources and processes of lead contamination in well waters and soil from former fruit orchards, Pennsylvania, USA: A legacy of anthropogenic activities
Isotopic discrimination can be an effective tool in establishing a direct link between sources of Pb contamination and the presence of anomalously high concentrations of Pb in waters, soils, and organisms. Residential wells supplying water containing up to 1600 ppb Pb to houses built on the former Mohr orchards commercial site, near Allentown, PA, were evaluated to discern anthropogenic...
Authors
Robert A. Ayuso, Nora K. Foley
Soil geochemical survey of abandoned mining sites in the Eastern-Central Peloritani Mountains, Sicily, Italy Soil geochemical survey of abandoned mining sites in the Eastern-Central Peloritani Mountains, Sicily, Italy
This investigation focused on topsoils (n = 122) and vertical profiles (n = 6) distributed over an area of 250 km2 in the eastern-central Peloritani Mountains, northeastern Sicily. Georeferenced concentration of 53 elements (including potentially harmful ones), determined by ICP-MS after an aqua regia leach, were used to produce geochemical maps by means of a GIS-aided spatial...
Authors
A. Consenza, A. Lima, Robert A. Ayuso, Nora K. Foley, S. Albanese, A. Messina, B. De Vivo
Geochemical and mineralogical characteristics of REE in granite-derived regolith: a model for the Southeast United States Geochemical and mineralogical characteristics of REE in granite-derived regolith: a model for the Southeast United States
Rare earth element (REE) ion-adsorption clay deposits are of global economic importance because they currently supply a significant portion of the world’s annual production of both light (LREE) and heavy REE (HREE). There is considerable ambiguity regarding the origin of this deposit type: The main criteria include the presence of large, generally granitic, igneous suites; long periods...
Authors
Nora K. Foley, Carleton R. Bern, Robert A. Ayuso, Bernard E. Hubbard, Anjana K. Shah
REE enrichment in granite-derived regolith deposits of the southeast United States: Prospective source rocks and accumulation processes REE enrichment in granite-derived regolith deposits of the southeast United States: Prospective source rocks and accumulation processes
The Southeastern United States contains numerous anorogenic, or A-type, granites, which constitute promising source rocks for REE-enriched ion adsorption clay deposits due to their inherently high concentrations of REE. These granites have undergone a long history of chemical weathering, resulting in thick granite-derived regoliths, akin to those of South China, which supply virtually...
Authors
Nora K. Foley, Robert A. Ayuso
Reconstruction of an early Paleozoic continental margin based on the nature of protoliths in the Nome Complex, Seward Peninsula, Alaska Reconstruction of an early Paleozoic continental margin based on the nature of protoliths in the Nome Complex, Seward Peninsula, Alaska
The Nome Complex is a large metamorphic unit that sits along the southern boundary of the Arctic Alaska–Chukotka terrane, the largest of several micro continental fragments of uncertain origin located between the Siberian and Laurentian cratons. The Arctic Alaska–Chukotka terrane moved into its present position during the Mesozoic; its Mesozoic and older movements are central to...
Authors
Alison B. Till, Julie A. Dumoulin, Robert A. Ayuso, John N. Aleinikoff, Jeffrey M. Amato, John F. Slack, W.C. Pat Shanks
Geochemical and Nd-Sr-Pb isotopic evolution of metabasites from rifting of continental lithosphere, Seward Peninsula, Alaska, and implications for paleogeographic reconstruction Geochemical and Nd-Sr-Pb isotopic evolution of metabasites from rifting of continental lithosphere, Seward Peninsula, Alaska, and implications for paleogeographic reconstruction
The chemical character of mafic rocks from the Arctic Alaska–Chukotka terrane records rifting of continental crust during the early Paleozoic, possibly during the Ordovician. The mafic rocks are part of a metamorphosed Neoproterozoic to Devonian continental margin sequence preserved in a Mesozoic metamorphic terrane, the Nome Complex, of Seward Peninsula, Alaska. Protoliths of the mafic...
Authors
Robert A. Ayuso, Alison Till
Science and Products
Filter Total Items: 82
Pb-Sr isotopic and geochemical constraints on sources and processes of lead contamination in well waters and soil from former fruit orchards, Pennsylvania, USA: A legacy of anthropogenic activities Pb-Sr isotopic and geochemical constraints on sources and processes of lead contamination in well waters and soil from former fruit orchards, Pennsylvania, USA: A legacy of anthropogenic activities
Isotopic discrimination can be an effective tool in establishing a direct link between sources of Pb contamination and the presence of anomalously high concentrations of Pb in waters, soils, and organisms. Residential wells supplying water containing up to 1600 ppb Pb to houses built on the former Mohr orchards commercial site, near Allentown, PA, were evaluated to discern anthropogenic...
Authors
Robert A. Ayuso, Nora K. Foley
Soil geochemical survey of abandoned mining sites in the Eastern-Central Peloritani Mountains, Sicily, Italy Soil geochemical survey of abandoned mining sites in the Eastern-Central Peloritani Mountains, Sicily, Italy
This investigation focused on topsoils (n = 122) and vertical profiles (n = 6) distributed over an area of 250 km2 in the eastern-central Peloritani Mountains, northeastern Sicily. Georeferenced concentration of 53 elements (including potentially harmful ones), determined by ICP-MS after an aqua regia leach, were used to produce geochemical maps by means of a GIS-aided spatial...
Authors
A. Consenza, A. Lima, Robert A. Ayuso, Nora K. Foley, S. Albanese, A. Messina, B. De Vivo
Geochemical and mineralogical characteristics of REE in granite-derived regolith: a model for the Southeast United States Geochemical and mineralogical characteristics of REE in granite-derived regolith: a model for the Southeast United States
Rare earth element (REE) ion-adsorption clay deposits are of global economic importance because they currently supply a significant portion of the world’s annual production of both light (LREE) and heavy REE (HREE). There is considerable ambiguity regarding the origin of this deposit type: The main criteria include the presence of large, generally granitic, igneous suites; long periods...
Authors
Nora K. Foley, Carleton R. Bern, Robert A. Ayuso, Bernard E. Hubbard, Anjana K. Shah
REE enrichment in granite-derived regolith deposits of the southeast United States: Prospective source rocks and accumulation processes REE enrichment in granite-derived regolith deposits of the southeast United States: Prospective source rocks and accumulation processes
The Southeastern United States contains numerous anorogenic, or A-type, granites, which constitute promising source rocks for REE-enriched ion adsorption clay deposits due to their inherently high concentrations of REE. These granites have undergone a long history of chemical weathering, resulting in thick granite-derived regoliths, akin to those of South China, which supply virtually...
Authors
Nora K. Foley, Robert A. Ayuso
Reconstruction of an early Paleozoic continental margin based on the nature of protoliths in the Nome Complex, Seward Peninsula, Alaska Reconstruction of an early Paleozoic continental margin based on the nature of protoliths in the Nome Complex, Seward Peninsula, Alaska
The Nome Complex is a large metamorphic unit that sits along the southern boundary of the Arctic Alaska–Chukotka terrane, the largest of several micro continental fragments of uncertain origin located between the Siberian and Laurentian cratons. The Arctic Alaska–Chukotka terrane moved into its present position during the Mesozoic; its Mesozoic and older movements are central to...
Authors
Alison B. Till, Julie A. Dumoulin, Robert A. Ayuso, John N. Aleinikoff, Jeffrey M. Amato, John F. Slack, W.C. Pat Shanks
Geochemical and Nd-Sr-Pb isotopic evolution of metabasites from rifting of continental lithosphere, Seward Peninsula, Alaska, and implications for paleogeographic reconstruction Geochemical and Nd-Sr-Pb isotopic evolution of metabasites from rifting of continental lithosphere, Seward Peninsula, Alaska, and implications for paleogeographic reconstruction
The chemical character of mafic rocks from the Arctic Alaska–Chukotka terrane records rifting of continental crust during the early Paleozoic, possibly during the Ordovician. The mafic rocks are part of a metamorphosed Neoproterozoic to Devonian continental margin sequence preserved in a Mesozoic metamorphic terrane, the Nome Complex, of Seward Peninsula, Alaska. Protoliths of the mafic...
Authors
Robert A. Ayuso, Alison Till