نتایج جستجو برای: andesitic composition
تعداد نتایج: 260052 فیلتر نتایج به سال:
The most frequent and voluminous eruptive Kurasawa, 1983], (4) partial melting of the lower crust products at Mount St. Helens are dacitic in composition, [e.g., Grant et al., 1984; Reid and Cole, 1983], and (5) although a wide variety of magma types (basalt to formation of compositional gradients in response to rhyodacite) is represented. To address the petrogenesis of convective and diffusive...
The study area is located in the western portion of Isfahan, in Shahrekord-Dehsard Terrene. This area is part of the Sanandaj- Sirjan structural Zone. In this area, metamorphosed igneous outcrops contain greenschist and metabasite rocks. These rocks have metamorphed into greenschist facies and belong to the Triassic-Jurassic age. The etabasite is mainly composed of plagioclase, amphibole, epido...
Northeast of Meshkinshahr, Eocene igneous rocks are exposed and are composed mainly of andesite, basalt, andesitic basalt, tephrite and is sometimes analcimite. The chemical composition of the rocks are in the range of alkaline rocks with high potassium and shoshsonitic affinity. Two main hypotheses are that they are either primary analcite or replacement pseudomorphous of leucite. Analcime cr...
In southwest of the Jandaq City (northeast of Isfahan Province) and northwest of the Central-East Iranian Microcontinent (CEIM), the Eocene dykes with trachy-andesitic composition cross cut the quartz monzodioritic intrusion. The texture of these dykes is granular, intergranular and porphyritic. The studied dykes are composed of plagioclase (andesine and labradorite), clinopyroxene (diopside an...
Amygdaloidal, cavity- and fracture-filling zeolites in Eocene volcanic rocks from the Kuh-e-Aradeh of southern Kahrizak, in the northernmost part of Central Iran have been studied in some detail by optical, chemical analysis, SEM, and XRD techniques. The zeolites identified, in order of their relative time of formation from early to late, are tetranatrolite, analcime, natrolite, mesolite, stilb...
The study area is located in the Kerman province, 10 Km north of Rabor. Geologically, the area is situated in the eastern section of Dehaj-Sarduiyeh belt which is a part of Urumieh-Dokhtar magmatic assemblage. The dykes were intruded in the Eocene pyroclastic rocks and Pliocene sedimentary units. Petrographic studies show that these rocks are andesitic in composition. Mineralogically they are c...
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