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 late cretaceous Donlin Creek gold deposit, Southwestern Alaska: Controls on epizonal ore formation The late cretaceous Donlin Creek gold deposit, Southwestern Alaska: Controls on epizonal ore formation
The Donlin Creek gold deposit, southwestern Alaska, has an indicated and inferred resource of approximately 25 million ounces (Moz) Au at a cutoff grade of 1.5 g/t. The ca. 70 Ma deposit is hosted in the Late Cretaceous Kuskokwim flysch basin, which developed in the back part of the arc region of an active continental margin, on previously accreted oceanic terranes and continental...
Authors
Richard J. Goldfarb, Robert A. Ayuso, Marti L. Miller, Shane W. Ebert, Erin E. Marsh, Scott A. Petsel, Lance D. Miller, Dwight Bradley, Chad Johnson, William C. McClelland
Arsenic in New England: Mineralogical and geochemical studies of sources and enrichment pathways Arsenic in New England: Mineralogical and geochemical studies of sources and enrichment pathways
Detailed mineralogical, geochemical and radiogenic isotopic studies of iron-sulfide and secondary iron oxy-hydroxide minerals in natural bedrock in coastal Maine and New Hampshire test the link between arsenic-rich sulfide minerals in bedrock and secondary oxy-hydroxide minerals. Samples were selected from over 70 bedrock localities, including 22 within the regionally extensive and...
Authors
Robert A. Ayuso, Nora K. Foley
Anthropogenic vs. natural pollution: An environmental study of an industrial site under remediation (Naples, Italy) Anthropogenic vs. natural pollution: An environmental study of an industrial site under remediation (Naples, Italy)
Heavy metal concentrations and Pb isotopic composition were determined in the soils, slags, scums and landfill materials from a shut down industrial (brownfield) site. This was the second largest integrated steelworks in Italy, and is now under remediation by a Government project. It is located in the outskirts of Napoli on the Bagnoli-Fuorigrotta plain (BFP), which is part of the Campi...
Authors
M. Tarzia, B. de Vivo, R. Somma, R. A. Ayuso, R.A.R. McGill, R.R. Parrish
Sulfur and lead isotope geochemistry of hypogene mineralization at the Barite Hill Gold Deposit, Carolina Slate Belt, southeastern United States: A window into and through regional metamorphism Sulfur and lead isotope geochemistry of hypogene mineralization at the Barite Hill Gold Deposit, Carolina Slate Belt, southeastern United States: A window into and through regional metamorphism
The Barite Hill gold deposit, at the southwestern end of the Carolina slate belt in the southeastern United States, is one of four gold deposits in the region that have a combined yield of 110 metric tons of gold over the past 10 years. At Barite Hill, production has dominantly come from oxidized ores. Sulfur isotope data from hypogene portions of the Barite Hill gold deposit vary...
Authors
Robert R. Seal,, Robert A. Ayuso, Nora K. Foley, Sandra H. B. Clark
Minimum age of the Neoproterozoic Seven Hundred Acre Island Formation and the tectonic setting of the Islesboro Formation, Islesboro block, Maine Minimum age of the Neoproterozoic Seven Hundred Acre Island Formation and the tectonic setting of the Islesboro Formation, Islesboro block, Maine
Two plat formal stratigraphic sequences occur on Islesboro, Penobscot Bay, Maine. The older Seven Hundred Acre Island Formation is at least 200 m thick, its base is not exposed, and it makes up fault-bounded blocks of siliceous colour-banded dolomitic marble, muscovite-rich quartzite, coarse-grained splendent muscovite-garnet-staurolite-andalusite schist, and calcareous metapelite, with...
Authors
David B. Stewart, Robert D Tucker, Robert Ayuso, Daniel R. Lux
Isotope geochemistry and fluid inclusion study of skarns from Vesuvius Isotope geochemistry and fluid inclusion study of skarns from Vesuvius
We present new mineral chemistry, fluid inclusion, stable carbon and oxygen, as well as Pb, Sr, and Nd isotope data of Ca-Mg-silicate-rich ejecta (skarns) and associated cognate and xenolithic nodules from the Mt. Somma-Vesuvius volcanic complex, Italy. The typically zoned skarn ejecta consist mainly of diopsidic and hedenbergitic, sometimes "fassaitic" clinopyroxene, Mg-rich and Ti-poor
Authors
H.A. Gilg, A. Lima, R. Somma, H. E. Belkin, B. de Vivo, R. A. Ayuso
Science and Products
Filter Total Items: 82
The late cretaceous Donlin Creek gold deposit, Southwestern Alaska: Controls on epizonal ore formation The late cretaceous Donlin Creek gold deposit, Southwestern Alaska: Controls on epizonal ore formation
The Donlin Creek gold deposit, southwestern Alaska, has an indicated and inferred resource of approximately 25 million ounces (Moz) Au at a cutoff grade of 1.5 g/t. The ca. 70 Ma deposit is hosted in the Late Cretaceous Kuskokwim flysch basin, which developed in the back part of the arc region of an active continental margin, on previously accreted oceanic terranes and continental...
Authors
Richard J. Goldfarb, Robert A. Ayuso, Marti L. Miller, Shane W. Ebert, Erin E. Marsh, Scott A. Petsel, Lance D. Miller, Dwight Bradley, Chad Johnson, William C. McClelland
Arsenic in New England: Mineralogical and geochemical studies of sources and enrichment pathways Arsenic in New England: Mineralogical and geochemical studies of sources and enrichment pathways
Detailed mineralogical, geochemical and radiogenic isotopic studies of iron-sulfide and secondary iron oxy-hydroxide minerals in natural bedrock in coastal Maine and New Hampshire test the link between arsenic-rich sulfide minerals in bedrock and secondary oxy-hydroxide minerals. Samples were selected from over 70 bedrock localities, including 22 within the regionally extensive and...
Authors
Robert A. Ayuso, Nora K. Foley
Anthropogenic vs. natural pollution: An environmental study of an industrial site under remediation (Naples, Italy) Anthropogenic vs. natural pollution: An environmental study of an industrial site under remediation (Naples, Italy)
Heavy metal concentrations and Pb isotopic composition were determined in the soils, slags, scums and landfill materials from a shut down industrial (brownfield) site. This was the second largest integrated steelworks in Italy, and is now under remediation by a Government project. It is located in the outskirts of Napoli on the Bagnoli-Fuorigrotta plain (BFP), which is part of the Campi...
Authors
M. Tarzia, B. de Vivo, R. Somma, R. A. Ayuso, R.A.R. McGill, R.R. Parrish
Sulfur and lead isotope geochemistry of hypogene mineralization at the Barite Hill Gold Deposit, Carolina Slate Belt, southeastern United States: A window into and through regional metamorphism Sulfur and lead isotope geochemistry of hypogene mineralization at the Barite Hill Gold Deposit, Carolina Slate Belt, southeastern United States: A window into and through regional metamorphism
The Barite Hill gold deposit, at the southwestern end of the Carolina slate belt in the southeastern United States, is one of four gold deposits in the region that have a combined yield of 110 metric tons of gold over the past 10 years. At Barite Hill, production has dominantly come from oxidized ores. Sulfur isotope data from hypogene portions of the Barite Hill gold deposit vary...
Authors
Robert R. Seal,, Robert A. Ayuso, Nora K. Foley, Sandra H. B. Clark
Minimum age of the Neoproterozoic Seven Hundred Acre Island Formation and the tectonic setting of the Islesboro Formation, Islesboro block, Maine Minimum age of the Neoproterozoic Seven Hundred Acre Island Formation and the tectonic setting of the Islesboro Formation, Islesboro block, Maine
Two plat formal stratigraphic sequences occur on Islesboro, Penobscot Bay, Maine. The older Seven Hundred Acre Island Formation is at least 200 m thick, its base is not exposed, and it makes up fault-bounded blocks of siliceous colour-banded dolomitic marble, muscovite-rich quartzite, coarse-grained splendent muscovite-garnet-staurolite-andalusite schist, and calcareous metapelite, with...
Authors
David B. Stewart, Robert D Tucker, Robert Ayuso, Daniel R. Lux
Isotope geochemistry and fluid inclusion study of skarns from Vesuvius Isotope geochemistry and fluid inclusion study of skarns from Vesuvius
We present new mineral chemistry, fluid inclusion, stable carbon and oxygen, as well as Pb, Sr, and Nd isotope data of Ca-Mg-silicate-rich ejecta (skarns) and associated cognate and xenolithic nodules from the Mt. Somma-Vesuvius volcanic complex, Italy. The typically zoned skarn ejecta consist mainly of diopsidic and hedenbergitic, sometimes "fassaitic" clinopyroxene, Mg-rich and Ti-poor
Authors
H.A. Gilg, A. Lima, R. Somma, H. E. Belkin, B. de Vivo, R. A. Ayuso