نتایج جستجو برای: lava rocks
تعداد نتایج: 24704 فیلتر نتایج به سال:
Damavand is a fascinating dormant stratovolcano, 60 km to the ENE of Tehran located in the Alborz Mountains. Damavand volcanic products consist of lava flows and pyroclastic fall, flow and surge deposits from different eruption cycles. The volcanic rocks ranges from trachyandesite to trachyadacite and minor basalt. The mineral assemblage consists of potash feldspar (Or43/7), Plagioclase (An25 t...
The 1285 m thick MIS core offers an invaluable opportunity to obtain a detailed record of volcanism in McMurdo Sound. Volcanic stratigraphy and preliminary petrologic data on volcanic rocks in the AND-1B core are reported here. Remarkable volcanic deposits include: a) a phonolitic pumice layer found at ≈85 mbsf which is not correlated to any known vent onshore; b) a black well sorted volcanic s...
Pleistocene basanitic rocks of Vesteris Seamount in the Greenland Sea had been found to exhibit an endolithic habitat largely consisting marine fungi that dwell within abundant vesicles, therefore representing cryptoendoliths. For first time, we demonstrate 3D X-ray microscopy can unravel how microorganisms access and migrate through vesicular rock. The fossil assemblages occur a set vesicles c...
Roshtkhar Iron deposit is located in southeast of Khorasan Razavi Province about 48 Km east of Roshtkhar. This deposit is geologically located in the northeast of the Lut block in the Khaf-Bardaskan volcanic- plutonic belt. Intermediate igneous rocks such as stock, dyke, lava and pyroclastic deposits are host rock. Igneous rocks are dioritic porphyry, monzosyenitic porphyry, andesite, basalt an...
The Harachiyama Formation comprises Lower Cretaceous volcanic rocks, which are distributed in the eastern margin of Kitakami Mountains northeastern Japan. Whole-rock chemical analysis, U–Pb zircon dating and Hf isotope analysis were performed to constrain formation age magmatic origin was discussed. lava tuff samples from Omoto Tsukue areas supported island-arc rhyolitic rocks (SiO2 content > 7...
The chemical compositions of relatively young mare lava flows have implications for the late volcanism on the Moon. Here we report the composition of soil along the rim of a 450-m diameter fresh crater at the Chang'e-3 (CE-3) landing site, investigated by the Yutu rover with in situ APXS (Active Particle-induced X-ray Spectrometer) and VNIS (Visible and Near-infrared Imaging Spectrometer) measu...
Dense layers of bacteria and fungi in the rhizoplane of three species of cactus (Pachycereus pringlei, Stenocereus thurberi, Opuntia cholla) and a wild fig tree (Ficus palmeri) growing in rocks devoid of soil were revealed by bright-field and fluorescence microscopy and field emission scanning electron microscopy. These desert plants are responsible for rock weathering in an ancient lava flow a...
The failure mode of lava-dilatant or compactant-depends on the physical attributes of the lava, primarily the porosity and pore size, and the conditions under which it deforms. The failure mode for edifice host rock has attendant implications for the structural stability of the edifice and the efficiency of the sidewall outgassing of the volcanic conduit. In this contribution, we present a syst...
River channels and valleys have been observed on several planetary bodies in addition to the Earth. Long sinuous valleys on Venus, our Moon and Jupiter's moon Io are clearly formed by lava, and branching valleys on Saturn's moon Titan may be forming today by rivers of methane. But by far the most dissected body in our Solar System apart from the Earth is Mars. Branching valleys that in plan res...
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