نتایج جستجو برای: calc alkaline

تعداد نتایج: 43545  

Journal: :Chemical Geology 2021

Obsidians found in silicic domes and rhyolitic tuffs are an ideal system to understand the formation conditions of calc-alkaline felsic magmas. The Optical Absorption Electron Paramagnetic Resonance (EPR) spectroscopic data presented this study demonstrate that Fe-speciation obsidians is different from observed other geological glasses (e.g., basaltic glasses) or synthetic Fe-bearing silicate g...

2008
R. J. SQUIRE A. J. CRAWFORD

TheOrdovician volcanic and intrusive rocks of the Cadia–Neville region, in the southern Molong Volcanic Belt section of the Macquarie Arc in central-western New South Wales, display a temporal progression from shoshonitic basaltic volcanism (e.g. Mt Pleasant Basalt Member) in the late Darriwilian to Gisbornian (ca 460–453 Ma) to small-volume dacitic medium-K calc-alkaline magmatism (e.g. Copper...

Journal: :journal of tethys 0

salafchegan-khorhe volcanic rocks are exposed within urumieh-dokhtar magmatic belt. different kinds of volcanic and subvolcanic rocks of calc-alkaline to alkaline character have been reported throughout this magmatic belt. since, isotopic investigations are very useful for detection of magma petrogenesis and because no isotopic studies have been done in this area, so a geochemical and isotopic ...

Journal: :Science 1977
B Dalmayrac J R Lancelot A Leyreloup

Uranium-lead data indicate that the high-pressure granulitic and charnockitic nuclei within the medium-grade metamorphic complex of the Peruvian coastal area must be related to an orogenic event 2 x 10(9) years ago. As in western Africa and Brazil, this old granulitic basement is reworked by Late Precambrian orogeny. Its presence along the Peru-Chile Trench must be taken into account in interpr...

2013
arol D. Frost Ronald Frost

The Proterozoic eon is characterized by an unusual abundance of ferroan feldspathic rocks that range in composition from granite to quartz syenites to feldspathoid-bearing syenites. Three associations of ferroan rocks may be recognized on the basis of major element compositions: (1) metaluminous alkalic to alkali-calcic syenites and granites associated with anorthosites and iron-rich basaltic r...

Journal: :The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists 1969

Journal: :The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists 1975

Journal: :Japanese Magazine of Mineralogical and Petrological Sciences 2001

Journal: :The Journal of the Geological Society of Japan 1970

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