نتایج جستجو برای: volcanic rock
تعداد نتایج: 52326 فیلتر نتایج به سال:
The Surk ophiolitic mélange is located at the south west of central Iran and along the Naein-Dehshir-Baft ophiolitic belt. In petrological sequence, peridotites are nominated the undermost part of rock unit, and then gabbros and volcanic rocks are at the following ranks respectively. The predominant peridotitet of this ophiolitic mélange is harzburgite. Lherzolite that is the primitive mantle r...
introduction agates are presumed as a kind of precious stone that could be formed in magmatic, metamorphic and even sedimentary environment. mechanism for agate formation is not clear and is produced in laboratories. some hot springs and geothermal activity or white chimneys in the ocean floor, have some deposits like chalcedony but never produce agate. agate formation temperature varies betwee...
ABSTRACT Light, fluorescent, and field emission scanning electron microscopy, combined with microbial counts on culture media, revealed the presence of numerous microorganisms (bacteria, fungi, and actimomycetes) living as rhizoplane populations of roots of at least three species of cactus and a wild fig tree growing in rocks without soil. These plants are responsible for weathering of volcanic...
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Band-e-Ghichy copper deposit is located in the northern margin of the Central Iran structural zone, about 120 km south of Shahrood and 70 km south east of Torud. Copper mineralization occurred in the rock units including sandstone, conglomerate and siltstone with the Oligocene age. Mineralization has occurred in the form of stratiform (syngenetic), stratabound (epigenetic) and supergen (the sur...
Eocene volcanic rocks in SW of Choupanan are exposed along the Choupanan fault as lava with andesite, trachyandesite to dacite composition and pyroclastic rocks. This area is a part of Central Iran (Yazd block). Andesite is the most predominant rock unit of the area and is composed of feldspars (andesine, oligoclase, and sanidine), amphibole (magnesio hastingsite, magnesian hastingsite, magnesi...
Silicic volcanic rocks are associated with most, if not all, continental ×ood basalt provinces and volcanic rifted margins, where they can form substantial parts of the eruptive stratigraphy and have eruptive volumes >104 km3. Poor preservation of silicic volcanic rocks following kilometer-scale uplift and denudation of the volcanic rifted margins, however, can result in only deeper level struc...
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