scholarly journals Detailed petrographic descriptions and microprobe data for tertiary silicic volcanic rocks in drill hole USW G-1, Yucca Mountain, Nevada

10.2172/59792 ◽  
1985 ◽  
Author(s):  
F.A. Caporuscio ◽  
R.G. Warren ◽  
D.E. Broxton
Keyword(s):  
Volcanic Rocks ◽  
Drill Hole ◽  
Yucca Mountain ◽  
Silicic Volcanic ◽  
Microprobe Data

scholarly journals Stratigraphy and structure of volcanic rocks in drill hole USW-G1, Yucca Mountain, Nye County, Nevada

1981 ◽  
Author(s):  
R.W. Spengler ◽  
F.M. Byers ◽  
J.B. Warner
Keyword(s):  
Volcanic Rocks ◽  
Drill Hole ◽  
Yucca Mountain ◽  
Nye County

Regionally continuous Miocene rhyolites beneath the eastern Snake River Plain reveal localized flexure at its western margin: Idaho National Laboratory and vicinity

2020 ◽  
Vol 57 (3) ◽  
pp. 241-270
Author(s):  
Kyle L. Schusler ◽  
David M. Pearson ◽  
Michael McCurry ◽  
Roy C. Bartholomay ◽  
Mark H. Anders
Keyword(s):  
Volcanic Rocks ◽  
Snake River Plain ◽  
North American Plate ◽  
Snake River ◽  
Trace Element Geochemistry ◽  
Deep Borehole ◽  
Age Progression ◽  
Western Margin ◽  
Silicic Volcanic ◽  
River Plain

The eastern Snake River Plain (ESRP) is a northeast-trending topographic basin interpreted to be the result of the time-transgressive track of the North American plate above the Yellowstone hotspot. The track is defined by the age progression of silicic volcanic rocks exposed along the margins of the ESRP. However, the bulk of these silicic rocks are buried under 1 to 3 kilometers of younger basalts. Here, silicic volcanic rocks recovered from boreholes that penetrate below the basalts, including INEL-1, WO-2 and new deep borehole USGS-142, are correlated with one another and to surface exposures to assess various models for ESRP subsidence. These correlations are established on U/Pb zircon and 40Ar/39Ar sanidine age determinations, phenocryst assemblages, major and trace element geochemistry, δ18O isotopic data from selected phenocrysts, and initial εHf values of zircon. These data suggest a correlation of: (1) the newly documented 8.1 ± 0.2 Ma rhyolite of Butte Quarry (sample 17KS03), exposed near Arco, Idaho to the upper-most Picabo volcanic field rhyolites found in borehole INEL-1; (2) the 6.73 ± 0.02 Ma East Arco Hills rhyolite (sample 16KS02) to the Blacktail Creek Tuff, which was also encountered at the bottom of borehole WO-2; and (3) the 6.42 ± 0.07 Ma rhyolite of borehole USGS-142 to the Walcott Tuff B encountered in deep borehole WO-2. These results show that rhyolites found along the western margin of the ESRP dip ~20º south-southeast toward the basin axis, and then gradually tilt less steeply in the subsurface as the axis is approached. This subsurface pattern of tilting is consistent with a previously proposed crustal flexural model of subsidence based only on surface exposures, but is inconsistent with subsidence models that require accommodation of ESRP subsidence on either a major normal fault or strike-slip fault.

Contrasting origins of Cenozoic silicic volcanic rocks from the western Cordillera of the United States

2007 ◽  
Vol 70 (3) ◽  
pp. 251-267 ◽  
Author(s):  
Eric H. Christiansen ◽  
Michael McCurry
Keyword(s):  
United States ◽  
Volcanic Rocks ◽  
The United States ◽  
Western Cordillera ◽  
Silicic Volcanic

The South Portuguese Zone 1/400 000 LNEG-IGME-Junta de Andalusia common mapping program. A contribution for the Iberian Pyrite Belt VHMS exploration in Portugal and Spain

2020 ◽  
Author(s):  
João Xavier Matos ◽  
Keyword(s):  
Volcanic Rocks ◽  
Mineral Resources ◽  
Drill Hole ◽  
Iberian Pyrite Belt ◽  
Border Region ◽  
Variscan Orogeny ◽  
Development Fund ◽  
Cross Border ◽  
Felsic Volcanic ◽  
Mapping Program

<p>A regional South Portuguese Zone (SPZ) mapping and stratigraphic program in SW Iberia is presented. It is being developed by LNEG and IGME and financed by the GEO_FPI Project (www.geo-fpi.eu).</p><p>The SPZ is the southwesternmost geotectonic unit of the Variscan Orogeny in Iberia. The following domains are considered: Pulo do Lobo (early Frasnian -late Famennian); Iberian Pyrite Belt (IPB, late Famennian-late Visean), Baixo Alentejo Flysch Group (late Visean-late Moscovian) and Southwest Portugal (late Strunian-mid Bashkirian). The mapping program also includes the Mesozoic sequences of the Lusitanian, Santiago do Cacém, and Algarve basins and the Cenozoic Lower Tagus, Alvalade and Guadalquivir/Algarve basins. Proper research was conducted in the IPB, considered one of the most important metallogenetic VHMS deposit provinces worldwide with significant Cu, Zn, Pb, Ag, Au, Sn, In, Se and Ge resources. Currently, mining is being undertaken both in Portugal (Aljustrel, Neves-Corvo) and Spain (Las Cruces, Aguas Teñidas, La Magdalena, Sotiel, Riotinto). Field surveys were done using common stratigraphic and GIS database methodologies, developed in cooperation involving the Portuguese and Spanish Geological Surveys. A joint fieldwork was carried out in the border region (Guadiana and Chança river sections), allowing a better integration and correlation of geological data. Palynological studies performed at LNEG allowed dating of 113 Palaeozoic sediment samples in outcrop and drill hole sections. The same approach was used for U/Pb zircon geochronology using 31 samples of plutonic and volcanic rocks. Rock dating results obtained are important to constrain the geological structures of the IPB Volcano-Sedimentary Complex (VSC) that host the massive sulphide and stockwork mineralization. Key ore horizons, important to identify, are dated late Famennian (late Strunian) age in felsic volcanic and in sedimentary sequences and Tournaisian age felsic volcanic sequences. For upper VSC, zircon ages ca. 340–330 Ma were reported for the first time, suggesting new geodynamic interpretations. The main project outputs are the first 1/200.000 scale cross border and the 1/400.000 scale SPZ Geological Maps. The latter covers SW Iberia from Lisbon to Seville along 330 km. This scale was also considered in the following thematic maps developed by LNEG, IGME and JA: mineral occurrences, mining, and geological heritage. Another project activity was the development of a drill hole database and equipment acquisition for the Aljustrel (LNEG) and Peñarroya (IGME) drill core sheds. LNEG and Aljustrel Municipality also promoted mining and geological studies in the Algares (Aljustrel) mine sector on gossan, underground gallery mapping and mineral characterization. GEO_FPI Project has improved the geological knowledge of the cross border region and promoted IPB as a key mining region in Europe. Therefore, since 2010, exploration campaigns led to the discovery of the Semblana, Monte Branco, La Magdalena, Sesmarias, Lagoa Salgada Central and Elvira deposits. Regional surveys carried out to promote a common approach to SW Iberia and improve new business initiatives focused on mineral resources and territory management. These activities could predict a larger mapping program to be developed in central and northern sectors of the Portuguese-Spanish border. Acknowledgement: EU/Interreg-VA/Poctep/0052_GEO_FPI_5_E Project/ funded by European Regional Development Fund/ERDF.</p>

Low ?18O silicic volcanic rocks at the Calabozos caldera complex, southern Andes

1987 ◽  
Vol 95 (1) ◽  
pp. 71-81 ◽  
Author(s):  
Anita L. Grunder
Keyword(s):  
Volcanic Rocks ◽  
Southern Andes ◽  
Silicic Volcanic
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