نتایج جستجو برای: ultramafic

تعداد نتایج: 1144  

2017
Melitza Crespo-Medina Katrina I. Twing Ricardo Sánchez-Murillo William J. Brazelton Thomas M. McCollom Matthew O. Schrenk

Uplifted ultramafic rocks represent an important vector for the transfer of carbon and reducing power from the deep subsurface into the biosphere and potentially support microbial life through serpentinization. This process has a strong influence upon the production of hydrogen and methane, which can be subsequently consumed by microbial communities. The Santa Elena Ophiolite (SEO) on the north...

2010
T. E. JOHNSON M. BROWN R. W. WHITE

Xenoliths of quartz-absent Fe-rich aluminous metapelite are common within the platinum group element-rich mafic ⁄ultramafic magmatic rocks of the Platreef. Relative to well-characterized protoliths, the xenoliths are strongly depleted in K2O and H2O, and have lost a substantial amount of melt (>50 vol.%). Mineral equilibria calculations in the NCKFMASHTO system yield results that are consistent...

2015
Philippe Birnbaum Thomas Ibanez Robin Pouteau Hervé Vandrot Vanessa Hequet Elodie Blanchard Tanguy Jaffré

High-elevation tropical islands are ideally suited for examining the factors that determine species distribution, given the complex topographies and climatic gradients that create a wide variety of habitats within relatively small areas. New Caledonia, a megadiverse Pacific archipelago, has long focussed the attention of botanists working on the spatial and environmental ranges of specific grou...

H. Ahmadipour

The Kuhshah ultramafic complex is located in the south-east of Sanandaj-Sirjan metamorphic zone, near the probable remnants of Neotethys plate in Iran. It consists of highly depleted harzburgites, dunites, chromitite bands and altered gabbros. The ultramafic parts have been intruded by numerous clinopyroxenite dykes and veins. In the harzburgites, there are different generations of olivine, ort...

معاف پوریان, غلامعلی, پورمعافی, سید محمد, امامی, محمد هاشم, وثوقی عابدینی, منصور ,

On the basis of petrographic observations and electron microprobe analyses data set on major and minor minerals from ultramafic- mafic rock suite with komatiitic to picritic - tholeiitic affinity, East of Fariman, we have investigated some of the petrological features of their parental magmas and condition of minerals crystallization. Major minerals in ultramafic rocks show various disequilibri...

Journal: Geopersia 2019

The present work was conducted to investigate the geotechnical properties of two meta-peridotites and meta-pyroxenites of an ultramafic complex mainly consisting of ultramafic rocks. For this purpose, microscopic studies were performed to determine the percentage of serpentinization in these rocks. In addition, a number of mechanical and physical tests were performed on collected samples with d...

Journal: :The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists 1975

Journal: :Plant and Soil 2021

Abstract Background and aims Ultramafic soils have high metal concentrations, offering a key opportunity to understand if such metals are strong predictors of leaf stoichiometry. This is particularly relevant for tropical forests where large knowledge gaps exist. Methods On the island Sulawesi, Indonesia, we sampled on sand, limestone, mafic ultramafic that present range soil concentrations. We...

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