نتایج جستجو برای: volcanic rocks
تعداد نتایج: 34325 فیلتر نتایج به سال:
This study investigates petrology and major, minor, and rare earth elements geochemistry of East Iranian Eocene–Oligocene volcanic rocks in Sistan suture zone, to examine their petrogenesis and magma evolution. The volcanic rocks include andesite, trachy-andesite, dacite and rhyolite. These calc-alkaline rocks of high-K series are enriched in Large Ion Lithophile Elements of Rb and Ba a...
Trachyandesites, trachytes and latites associated with ignimbrite and pyrocalstic rocks, characterized by shoshonitic affinity are the main Plio-Quaternary volcanic rocks in the Sabalan region (Ardabil). Plagioclase, K-feldspar, biotite associated with clinopyroxene and glass are the main constituents of these lavas. Plagioclases are andesine to labradorite while clinopyroxenes have augitic com...
[1] In the Inner Basin of the Columbia Hills, Gusev Crater is Home Plate, an 80 m platform of layered clastic rocks of the Barnhill class with microscopic and macroscopic textures, including a bomb sag, suggestive of a phreatomagmatic origin. We present data acquired by the Spirit Mars Exploration Rover by Alpha Particle X-Ray Spectrometer (APXS), Mössbauer Spectrometer, Miniature Thermal Emiss...
The central Oregon section of the Cascade Range volcanic arc is characterized byrelatively high Quaternary volcanic extrusion rates and hot-spring discharge rates, and by high conductive h at flow. However, a large area of near-zero near-surface onductive h at flow occurs in the younger volcanic rocks, due to downward and lateral flow of cold groundwater. Alternate models for the high heat flow...
The El'gygytgyn impact structure in Chukutka, Arctic Russia, is the only impact crater currently known on Earth that was formed in mostly acid volcanic rocks (mainly of rhyolitic, with some andesitic and dacitic, compositions). In addition, because of its depth, it has provided an excellent sediment trap that records paleoclimatic information for the 3.6 Myr since its formation. For these two m...
The Ethiopian Rift System consists of basins that are in different stages of evolution. Some of the rift-related basins in southwestern Ethiopia are half-grabens that have not evolved to symmetrical rifts since the initiation of rifting here in the middle Miocene. These basins contain fossiliferous Pliocene–Pleistocene volcaniclastic sediments and volcanic rocks and have been occupied by early ...
The studied volcanic and pluton rocks are located in west of Nir city in the Ardebil Province and south of Sabalan volcano. Volcanic rocks in the studied area are display basaltic to trachy-andesite composition with microlitic porphyry texture. The main minerals of basalt to trachyandesite rocks are plagioclase, pyroxene and olivine. Bordering to volcanic units, pluton of microgabbroic to micro...
The Razei region in the northwest of Ardabil is considered a part of West Alborz-Azerbaijan. Rocks in this area were created by Eocene volcanic activities. These rocks range from andesite to olivine basalt. The common texture of these rocks is Porphyritic with microlithic matrix. The phenocrysts of these rocks are often clinopyroxene, plagioclase, and olivine. The texture is made of microlithic...
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