نتایج جستجو برای: ultramafic composition
تعداد نتایج: 260684 فیلتر نتایج به سال:
Soil microorganisms play key roles in ecosystem functioning and are known to be influenced by biotic and abiotic factors, such as plant cover or edaphic parameters. New Caledonia, a biodiversity hotspot located in the southwest Pacific, is one-third covered by ultramafic substrates. These types of soils are notably characterised by low nutrient content and high heavy metal concentrations. Ultra...
Warm fluids emanating from hydrothermal vents can be used as windows into the rocky subseafloor habitat and its resident microbial community. Two new vent systems on the Mid-Cayman Rise each exhibits novel geologic settings and distinctively hydrogen-rich vent fluid compositions. We have determined and compared the chemistry, potential energy yielding reactions, abundance, community composition...
Hasht-Sar Kaleybar mafic, ultramafic and syenitic dykes are surrounded by Majid Abad Formation, Palaeocene age, volcanic deposits. The suite is restricted within the Horand, Mahmud Abad and Mokhtekan thrust and reverse faults. Clinopyroxenites, the oldest unit of the suite, have tholeiitic volcanic arc character and have some similarities with tectonite layer of oceanic crust, like Group A pyro...
Abstract Micrometer sized stromatolitic structures called Frutexites are features observed in samples from the deep subsurface, and hot-spring environments. These comprised of fine laminations, columnar morphology, commonly consist iron oxides, manganese and/or carbonates. Although a biological origin is invoked, few reports have shown direct evidence their association with microbial activity. ...
Chromitites associated with strongly altered peridotite from six distinct localities in the Santa Elena ultramafic nappe (Costa Rica) have been investigated for the first time. Santa Elena chromitites commonly display a compositional variation from extremely chromiferous (Cr/(Cr+Al)=0.81) to intermediate and aluminous (Cr/(Cr+Al)=0.54). This composition varies along a continuous trend, correspo...
Some 43 samples collected from surficial sediments of Semnan Province (Alborz zone) and NE Isfahan Province (Central Iran zone) were analyzed, for constrains on provenance. Sand fraction were analyzed by XRF analyzer Philips Model PW 2450 in the laboratory of the Geology Survey Iran (GSI). Precision was 0.01%. Furthermore, 8 selected sediment samples and 8 samples from rock units from surroundi...
Huntite mineral with formula CaMg3(C03}4 is a natural carbonatic material with rhombohedral system that its composition is between dolomite (CaMg(C03h) and magnesite. For the first time Huntite was found in American Nevada province, then in other places i,e. Poland, Hungary, France, Australia, Iran and Greece. According to thermOdynamic, Huntite forms in condition of low pressure and tcm...
The Darvazeh-Chenar mafic- ultramafic body is part of ophiolitic complex of Neyriz in Fars Province that formed in association with closing of Neo-Tethys Ocean and Arabian- Iranian plate collision in Cretaceous. The Faryab ophiolitic rocks are also remnant of block of Tethys oceanic crust that were obducted on continental margins in late Cretaceous period. MgO, Fe2O3, Al2O3, Cr2O3 and TiO2 cont...
The Big Jim complex is a concentrically zoned ultramafic to felsic plutonic complex which intruded the pelitic Chiwaukum schist. Most of the major plutonic rock types (from websterite through hornblendite, gabbronorite, hornblende gabbro and diorite, to granodiorite) enclose harzburgite and metaperidotite xenoliths similar to foliated metaperidotite lenses included in the Chiwaukum schist. The ...
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