干旱区生态环境知识资源中心(Arid): Petrology, geochronology, and chemical evolution of the Twin Peaks Rhyolite Domes, Utah

Arid

DOI	10.2172/5285924
报告编号	DOE/ID/12079-4
来源ID	OSTI_ID: 5285924
	Petrology, geochronology, and chemical evolution of the Twin Peaks Rhyolite Domes, Utah
	Crecraft, H.R.; Nash, W.P.; Evans, S.H. Jr.
英文摘要	Two distinct sequences of silicic volcanism at the Twin Peaks volcanic field, Millard County, Utah, spanned periods from 2.74 +- .10 to 2.54 +- .09 m.y. and 2.43 +- .08 to 2.35 +- .08 m.y., and produced a total exposed volume of 4 km/sup 3/ of rhyolites and volcanoclastics. Wet chemical, x-ray fluorescence, microprobe, atomic absorption, and neutron activation methods have been employed to obtain a wide range of chemical data on whole rock and mineral separate samples. Calculated distribution coefficients are comparable to previously published values for high silica rocks. Each sequence is characterized by a systematic trend from < 72% to > 76% SiO/sub 2/. Accompanying this increase in SiO/sub 2/ over time are increases in Rb, Y, Sb, Cs, U, Th, HREE and decreases in Mg, Co, Fe, Sr, Ba, and LREE. Decreases in temperature and fO/sub 2/ and an increase in fH/sub 2/O are also indicated. These trends are very similar to gradients observed in ash flow tuffs erupted instantaneously from compositionally zoned magma chambers. Chemical evolution at Twin Peaks was dominated by the same mechanism of liquid state differentiation which produce the compositional zonation in larger silicic magma chambers.
出版年	1980
报告类型	Technical Report
语种	英语
国家	美国
来源学科分类	15 GEOTHERMAL ENERGY ; RHYOLITES ; AGE ESTIMATION ; CHEMICAL ANALYSIS ; PETROGRAPHY ; UTAH ; GEOLOGY ; MINERALOGY ; ABSORPTION SPECTROSCOPY ; ACTIVATION ANALYSIS ; ANORTHOSITES ; BIOTITE ; D CODES ; DISTRIBUTION FUNCTIONS ; ELECTRON MICROPROBE ANALYSIS ; FRACTIONATION ; GEOCHEMISTRY ; IRON OXIDES ; MAGMA ; PARTITION ; PETROGENESIS ; PYROXENES ; QUARTZ ; SILICA ; TITANIUM OXIDES ; TRACE AMOUNTS ; VOLCANIC REGIONS ; VOLCANIC ROCKS ; X-RAY FLUORESCENCE ANALYSIS ; CHALCOGENIDES ; CHEMISTRY ; COMPUTER CODES ; GABBROS ; IGNEOUS ROCKS ; IRON COMPOUNDS ; MICA ; MICROANALYSIS ; MINERALS ; NONDESTRUCTIVE ANALYSIS ; NORTH AMERICA ; OXIDES ; OXYGEN COMPOUNDS ; PLUTONIC ROCKS ; ROCKS ; ROCKY MOUNTAIN REGION ; SEPARATION PROCESSES ; SILICATES ; SILICON COMPOUNDS ; SILICON OXIDES ; SPECTROSCOPY ; TITANIUM COMPOUNDS ; TRANSITION ELEMENT COMPOUNDS ; USA ; X-RAY EMISSION ANALYSIS Geothermal Legacy
URL	http://www.osti.gov/scitech/servlets/purl/5285924
资源类型	科技报告
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/262664
推荐引用方式 GB/T 7714	Crecraft, H.R.,Nash, W.P.,Evans, S.H. Jr.. Petrology, geochronology, and chemical evolution of the Twin Peaks Rhyolite Domes, Utah,1980.