نتایج جستجو برای: volcanic rocks
تعداد نتایج: 34325 فیلتر نتایج به سال:
The precise location and relative elevation of Spirit during its traverses from the Columbia Memorial station to Bonneville crater were determined with bundle-adjusted retrievals from rover wheel turns, suspension and tilt angles, and overlapping images. Physical properties experiments show a decrease of 0.2% per Mars solar day in solar cell output resulting from deposition of airborne dust, co...
the study area is located at northwest of sarbisheh in south khorasan province and eastern border of lut block. in this area, tertiary (eocene-oligocene to pliocene) volcanic rocks consisting of basaltic andesite, dacite, rhyodacite, vitreous rhyolite (perlitic in some parts), tuff and ignimbrite are exposed. in the daghar mountain, a, b and c perlite layers with thicknesses of 102, 7 and 58 me...
pillow lavas are locally conspicuous. A unit consisting of dark, thinly bedded sandstone and siltstone, lccally ranging to several hundred feet thick, is lowermost in the exposed section. The middle division consists of about 3,500 feet of mixed andesi.:e and basalt volcaniclastic rocks ~ lahar, tuff breccia, volcanic sandstone, and conglomeratic beds which rest on relatively thin, fossiliferou...
base and precious metals associated with porphyry, epithermal and acid sulphate or high-snlphidation hydrothermal systems (Panteleyev, 1992; Panteleyev and Koyanagi, 1993, 1994). The majority of these systems are associated with the Early to Middle Jurassic Island Plutonic Suite and Early Jurassic B O M ~ Group rocks. The regional mapping component of this study focused primarily on potential t...
Bentonite deposits of economic interest are widespread in Tashtab Mountains (Khur), east of Isfahan province, Iran. Several bentonite deposits have been developed in this area as a result of Eocene volcanic alteration. These deposits are classified as Khur bentonite horizon. XRD analyses reveal that alteration products consist of Na-montmorillonite, kaolinite, quartz, calcite, and crystobalite....
The vein-type mineralization of the base (Zn, Pb, and Cu) and precious metals (Au) in the Qarah Changel area (northwest of Qazvin) is located in the southern part of the Tarom-Hashtjin metallogenic belt. Volcanic (trachy-andesite, rhyolite and dacite) and pyroclastic (tuff, tuffite and tuffaceous shale) (Eocene) rocks are the hosts of this mineralization. Distinctive alterations around minerali...
Introduction: Water liquid has been considered to be main fluid in cold Mars, though major sources of liquid water are not clearly found on Martian surfaces. Recently author (Y.M.) found carbon-bearing grains on plagioclase composition in druses of terrestrial volcanic basalts in Shimonoseki, Yamaguchi, Japan [1], where many scientists have been reported as normal “plagioclases” formed at hydro...
Volcanic eruptions and lava flows comprise one of the most highly stressed terrestrial environments for the survival of biological organisms; the destruction of botanical and biological colonies by molten lava, pyroclastic flows, lahars, poisonous gas emissions and the deposition of highly toxic materials from fumaroles is the normal expectation from such events. However, the role of lichens an...
The study area is located in the central part of the Siahrood geological map, Kharvanagh of Ahar town, in the East Azerbaijan Province. The volcanic rocks of the Kharvanagh area include trachybasalt, trachy-andesi-basalt and trachy-andesite. The main minerals in the rocks are plagioclase, pyroxene, olivine and hornblende and the main textures are microlitic-porphyry. At the contact between the ...
sahand volcanic-sub-volcanic dome, along with several other magmatic domes in northwest iran and the southern part of tabriz fault show adakitic geochemical characteristics. sahand dome has mainly dacitic composition. the sio2 content and mg number of sahand dome range from 64 to 73 wt% and 27 to 57 respectively. sahand dome can be classified as high silica adakitic (hsa) type. the rocks studie...
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