Crystallization kinetics of albite from melts in the system NaAlSi3Os-H2O are not dramatically changed by the addition of l-2 wt.qo F or Cl. Vapor-undersaturated liquidus temperatures in the hydrous system are lowered 25 to 50'C in... more
Crystallization kinetics of albite from melts in the system NaAlSi3Os-H2O are not dramatically changed by the addition of l-2 wt.qo F or Cl. Vapor-undersaturated liquidus temperatures in the hydrous system are lowered 25 to 50'C in the presence of F, whereas Cl does not appreciably change the temperature of the hydrous liquidus. A Cl-rich vapor phase is found in the
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Volcanic ash from eastern Aleutian volcanoes (typical of circurn-Pacific volcanoes) is composed of rhyolitic (sil- ica-rich) glass, minerals (feldspars, pyroxene, hornblende and Fe-Ti oxides), and rock fragments. Melting tempera- tures of... more
Volcanic ash from eastern Aleutian volcanoes (typical of circurn-Pacific volcanoes) is composed of rhyolitic (sil- ica-rich) glass, minerals (feldspars, pyroxene, hornblende and Fe-Ti oxides), and rock fragments. Melting tempera- tures of the glasses, estimated from liquidus phase relations in the system Si02-KA1Si308-NaA1Si308, ranged from l,OOO°C to 1,300°C, whereas minerals begin melting at about 1,10O0C. Volcanic ash that is ingested into
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Compositions of volcanic glass from ash ejected during the 1992 eruptions of the Crater Peak vent of Mount Spurr are dominantly andesitic (SiOz of 61-62 weight percent), but they include much smaller amounts of dacitic ( S i 0 2 of 63-69... more
Compositions of volcanic glass from ash ejected during the 1992 eruptions of the Crater Peak vent of Mount Spurr are dominantly andesitic (SiOz of 61-62 weight percent), but they include much smaller amounts of dacitic ( S i 0 2 of 63-69 weight percent) and rhyolitic ( S i 0 2 of 74-77 weight percent) glass. In each eruption (June,
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... 1983), In general, scheelite skarn plutons which lack granodio-rite also lack hornblende, and those which TABLE 4 Characteristics of granitoids associated with scheelite skarns Name, location Size Granitoid type Mineralogy Chemistry... more
... 1983), In general, scheelite skarn plutons which lack granodio-rite also lack hornblende, and those which TABLE 4 Characteristics of granitoids associated with scheelite skarns Name, location Size Granitoid type Mineralogy Chemistry Sri Text PHSM Mu Ga Al K/Na Co Mg Po ...
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The 19891990 eruption of Redoubt Volcano produced medium-K calc-alkaline andesite and dacite of limited compositional range (58.263.4% SiO 2 ) and entrained quenched andesitic inclusions (55% SiO 2 ) which bear chemical similarities to... more
The 19891990 eruption of Redoubt Volcano produced medium-K calc-alkaline andesite and dacite of limited compositional range (58.263.4% SiO 2 ) and entrained quenched andesitic inclusions (55% SiO 2 ) which bear chemical similarities to the rest of the ejecta. The ...
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A group of soapstone statues found near the village of Esie in southwestern Nigeria is one of the largest collections of prehistoric sculpture found in sub-Saharan Africa. The statues were found at Esie by people of the Igbomina... more
A group of soapstone statues found near the village of Esie in southwestern Nigeria is one of the largest collections of prehistoric sculpture found in sub-Saharan Africa. The statues were found at Esie by people of the Igbomina sub-grouping of the Yoruba ethnic group when ...
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... Cr-spinel compositions, metadunite petrology, and the petrotectonic history of Blue Ridge ophiolites, Southern Appalachian Orogen, USA LOREN A. RAYMOND 1, SAMUEL E. SWANSON 2, ANTHONY B. LOVE 1 & JAMES F. ALLAN 1... more
... Cr-spinel compositions, metadunite petrology, and the petrotectonic history of Blue Ridge ophiolites, Southern Appalachian Orogen, USA LOREN A. RAYMOND 1, SAMUEL E. SWANSON 2, ANTHONY B. LOVE 1 & JAMES F. ALLAN 1 1Department of Geology, Appalachian ...
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