نتایج جستجو برای: ultramafic composition
تعداد نتایج: 260684 فیلتر نتایج به سال:
The composition of the silicate portion of Martian regolith fines indicates derivation of the fines from mafic to ultramafic igneous rocks, probably rich in pyroxene. Rock types similar in chemical and mineralogical composition include terrestrial Archean basalts and certain achondrite meteorites. If these igneous rocks weathered nearly isochemically, the nontronitic clays proposed earlier as a...
The age and origin of the quartz-amphibole-pyroxene (qap) gneiss from the island of Akilia, southern West Greenland, have been the subject of intense debate since the light C-isotope composition of graphite inclusions in apatite was interpreted to indicate the presence of Earth's earliest biological activity. Although this claim for biogenic relicts has been vigorously challenged, the possibili...
This paper reviews the concentration of heavy metals particularly Cr and Ni in the serpentinised and ultramafic soil/rock throughout the different geological regions in the world which are produced due to anthropogenic means or due to natural weathering. Poor nutrient content, low Ca: Mg ratio, higher concentration of heavy metals is major reason for the sparse vegetation on such soil. The vege...
Background The ubiquity of nickel in the environment and its common presence in food and water mean that humans are constantly exposed to nickel. Although nickel is not acutely toxic at low levels, it is a carcinogen and has been linked to cellular oxidative stress [1]. Soils that develop on serpentinite, a metamorphic rock type derived from ultramafic igneous rocks (and the state rock of Calif...
A comprehensive study of a 340 m thick lenticular-sheet body ultramafic composition penetrated by structural well M-1 at depth about 2.2 km was accomplished. Its main volume is composed plagioharzburgite; fine-grained rocks norite and orthopyroxenite chilling zones are preserved on endocontacts. The the similar in to near underlying ore-bearing layered intrusion – Monchepluton. age 2510 ± 9 Ma ...
The mam plant communities of ultramafic (serpentine) outcrops of a Mediterranean area in central Italy are described and their successional pathway discussed. Four vegetation stages are distinguished: a) an endemic garigue stage, with high percentage of exposed rocky soil belonging to Armerio-Alyssetum bertolonii; b) a garigue stage similar to the previous one but with several Mediterranean eve...
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...
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