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
Rock chemistry and fluid inclusion studies as exploration tools for ore deposits in the Sila batholith, southern Italy Rock chemistry and fluid inclusion studies as exploration tools for ore deposits in the Sila batholith, southern Italy
The Sila batholith is the focus of an extensive petrogenetic research program, which includes an assessment of its potential to host granite-related ore deposits. Univariate and multivariate statistical techniques were applied to major- and minor-element rock geochemical data. The analysis indicates that the highest potential for mineralization occurs in corundum-normative, peraluminous...
Authors
B. de Vivo, R. A. Ayuso, H. E. Belkin, A. Lima, A. Messina, A. Viscardi
A method of quantitative analysis of trace elements in silicate rocks by energy-dispersive X-ray fluorescence spectroscopy A method of quantitative analysis of trace elements in silicate rocks by energy-dispersive X-ray fluorescence spectroscopy
No abstract available.
Authors
J.C. Jackson, R. A. Ayuso
Source of lead and mineralizing brines for rossie-type Pb-Zn veins in the Frontenac axis area, New York ( USA). Source of lead and mineralizing brines for rossie-type Pb-Zn veins in the Frontenac axis area, New York ( USA).
Veins composed mainly of calcite and some galena, sphalerite, fluorite, and other minerals are widespread in the Frontenac axis area of New York and Ontario. In New York, the veins (Fig. 1) occur mainly west and northwest of Gouverneur (Brown, 1983). The veins, mined in the 1800s for lead, were first described by Emmons (1838). Smyth (1903) called these the "Rossie lead veins," a name...
Authors
Robert Ayuso, Nora Foley, C. Brown
White mica geochemistry of the Catheart Mountain porphyry copper deposit, Maine White mica geochemistry of the Catheart Mountain porphyry copper deposit, Maine
White micas from hydrothermally altered and mineralized zones in the Catheart Mountain Cu-Mo porphyry deposit have regular compositional variations that are generally related to the contents of copper, total iron, and sulfur in the whole rock. Micas in unmineralized rocks exhibit no such relationship. White mica compositions reflect primarily the control imposed by the celadonitic...
Authors
Robert Ayuso
Lead-isotopic evidence for distinct source of granite and for distinct basement in the northern Appalachians, Maine Lead-isotopic evidence for distinct source of granite and for distinct basement in the northern Appalachians, Maine
Lead-isotopic compositions of feldspars in plutons of the coastal lithotectonic block (Avalonian basement), central Maine (Merrimack) synclinorium, and Connecticut Valley-Gaspé synclinorium in northern Maine (Granville basement) indicate the presence of three fundamentally different sources of Devonian granitic rocks in Maine. Plutons in the coastal lithotectonic block have the most...
Authors
R. A. Ayuso
Significance of tourmaline-rich rocks in the Grenville Complex of St. Lawrence County, New York Significance of tourmaline-rich rocks in the Grenville Complex of St. Lawrence County, New York
Feldspathic quartzite and metapelite of Middle Proterozic age north of Gouverneur, N.Y., contain abundant dravite-uvite (magnesian tourmaline). These rocks, more than 1,000 feet thick, are regionally metamorphosed to the upper amphibolite facies, are pyritic, and locally contain porphyroblastic scapolite. The rocks are underlain by talctremolite schist and a thick sequence of calcitic...
Authors
C. Ervin Brown, Robert Ayuso
Comparative geochronology in the reversely zoned plutons of the Bottle Lake Complex, Maine: U-Pb on zircons and Rb-Sr on whole rocks Comparative geochronology in the reversely zoned plutons of the Bottle Lake Complex, Maine: U-Pb on zircons and Rb-Sr on whole rocks
The Bottle Lake Complex is a composite granitic batholith emplaced into Cambrian to Lower Devonian metasedimentary rocks. Both plutons (Whitney Cove and Passadumkeag River) are very coarse grained hornblende and biotite-bearing granites showing petrographic and geochemical reverse zonation. Two linear whole rock Rb/Sr isochrons on xenolith-free Whitney Cove and Passadumkeag River samples...
Authors
R. A. Ayuso, Joseph Arth, A.K. Sinha, J. Carlson, D. Wones
Manganese-rich red tourmaline from the Fowler talc belt, New York. Manganese-rich red tourmaline from the Fowler talc belt, New York.
Red uvite containing up to 4.34 wt.% MnO is found in the Arnold talc mine near Fowler, New York, USA. Microprobe analyses give a composition of 51% uvite in the uvite-dravite series. Associated minerals in this manganiferous metamorphic assemblage (possibly an evaporite) are manganese-rich tremolite (hexagonite) braunite and quartz.-R.A.G.
Authors
R. A. Ayuso, C. Brown
Quartz-molybdenite veins in the Priestly Lake granodiorite, north-central Maine Quartz-molybdenite veins in the Priestly Lake granodiorite, north-central Maine
Quartz-molybdenite veins up to 15 cm in width occur in fine to medium-grained porphyritic biotite-hornblende granodiorite at Priestly Lake north-central Maine. An area of about 150 m x 150 m contains quartz-molybdenite veins; a larger area is characterized by barren quartz veins. Quartz-molybdenite veins are concentrated within the most felsic variants of the intrusion as suggested by...
Authors
Robert Ayuso, Stephen Shank
Science and Products
Filter Total Items: 82
Rock chemistry and fluid inclusion studies as exploration tools for ore deposits in the Sila batholith, southern Italy Rock chemistry and fluid inclusion studies as exploration tools for ore deposits in the Sila batholith, southern Italy
The Sila batholith is the focus of an extensive petrogenetic research program, which includes an assessment of its potential to host granite-related ore deposits. Univariate and multivariate statistical techniques were applied to major- and minor-element rock geochemical data. The analysis indicates that the highest potential for mineralization occurs in corundum-normative, peraluminous...
Authors
B. de Vivo, R. A. Ayuso, H. E. Belkin, A. Lima, A. Messina, A. Viscardi
A method of quantitative analysis of trace elements in silicate rocks by energy-dispersive X-ray fluorescence spectroscopy A method of quantitative analysis of trace elements in silicate rocks by energy-dispersive X-ray fluorescence spectroscopy
No abstract available.
Authors
J.C. Jackson, R. A. Ayuso
Source of lead and mineralizing brines for rossie-type Pb-Zn veins in the Frontenac axis area, New York ( USA). Source of lead and mineralizing brines for rossie-type Pb-Zn veins in the Frontenac axis area, New York ( USA).
Veins composed mainly of calcite and some galena, sphalerite, fluorite, and other minerals are widespread in the Frontenac axis area of New York and Ontario. In New York, the veins (Fig. 1) occur mainly west and northwest of Gouverneur (Brown, 1983). The veins, mined in the 1800s for lead, were first described by Emmons (1838). Smyth (1903) called these the "Rossie lead veins," a name...
Authors
Robert Ayuso, Nora Foley, C. Brown
White mica geochemistry of the Catheart Mountain porphyry copper deposit, Maine White mica geochemistry of the Catheart Mountain porphyry copper deposit, Maine
White micas from hydrothermally altered and mineralized zones in the Catheart Mountain Cu-Mo porphyry deposit have regular compositional variations that are generally related to the contents of copper, total iron, and sulfur in the whole rock. Micas in unmineralized rocks exhibit no such relationship. White mica compositions reflect primarily the control imposed by the celadonitic...
Authors
Robert Ayuso
Lead-isotopic evidence for distinct source of granite and for distinct basement in the northern Appalachians, Maine Lead-isotopic evidence for distinct source of granite and for distinct basement in the northern Appalachians, Maine
Lead-isotopic compositions of feldspars in plutons of the coastal lithotectonic block (Avalonian basement), central Maine (Merrimack) synclinorium, and Connecticut Valley-Gaspé synclinorium in northern Maine (Granville basement) indicate the presence of three fundamentally different sources of Devonian granitic rocks in Maine. Plutons in the coastal lithotectonic block have the most...
Authors
R. A. Ayuso
Significance of tourmaline-rich rocks in the Grenville Complex of St. Lawrence County, New York Significance of tourmaline-rich rocks in the Grenville Complex of St. Lawrence County, New York
Feldspathic quartzite and metapelite of Middle Proterozic age north of Gouverneur, N.Y., contain abundant dravite-uvite (magnesian tourmaline). These rocks, more than 1,000 feet thick, are regionally metamorphosed to the upper amphibolite facies, are pyritic, and locally contain porphyroblastic scapolite. The rocks are underlain by talctremolite schist and a thick sequence of calcitic...
Authors
C. Ervin Brown, Robert Ayuso
Comparative geochronology in the reversely zoned plutons of the Bottle Lake Complex, Maine: U-Pb on zircons and Rb-Sr on whole rocks Comparative geochronology in the reversely zoned plutons of the Bottle Lake Complex, Maine: U-Pb on zircons and Rb-Sr on whole rocks
The Bottle Lake Complex is a composite granitic batholith emplaced into Cambrian to Lower Devonian metasedimentary rocks. Both plutons (Whitney Cove and Passadumkeag River) are very coarse grained hornblende and biotite-bearing granites showing petrographic and geochemical reverse zonation. Two linear whole rock Rb/Sr isochrons on xenolith-free Whitney Cove and Passadumkeag River samples...
Authors
R. A. Ayuso, Joseph Arth, A.K. Sinha, J. Carlson, D. Wones
Manganese-rich red tourmaline from the Fowler talc belt, New York. Manganese-rich red tourmaline from the Fowler talc belt, New York.
Red uvite containing up to 4.34 wt.% MnO is found in the Arnold talc mine near Fowler, New York, USA. Microprobe analyses give a composition of 51% uvite in the uvite-dravite series. Associated minerals in this manganiferous metamorphic assemblage (possibly an evaporite) are manganese-rich tremolite (hexagonite) braunite and quartz.-R.A.G.
Authors
R. A. Ayuso, C. Brown
Quartz-molybdenite veins in the Priestly Lake granodiorite, north-central Maine Quartz-molybdenite veins in the Priestly Lake granodiorite, north-central Maine
Quartz-molybdenite veins up to 15 cm in width occur in fine to medium-grained porphyritic biotite-hornblende granodiorite at Priestly Lake north-central Maine. An area of about 150 m x 150 m contains quartz-molybdenite veins; a larger area is characterized by barren quartz veins. Quartz-molybdenite veins are concentrated within the most felsic variants of the intrusion as suggested by...
Authors
Robert Ayuso, Stephen Shank