Stratabound scheelite and stratiform tourmalinites in the Archaean Malene supracrustal rocks, southern West Greenland
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چکیده
منابع مشابه
Geology, Age and Origin of Supracrustal Rocks at Akilia, West Greenland
New mapping, geochronology, and geochemistry of the supracrustal enclave and associated orthogneisses at Akilia, West Greenland, support a >3825 6 Ma age for the sequence and a chemical sedimentary origin for the controversial Fe-rich quartz-pyroxene gneisses. Lithologies of the enclave comprise laterally continuous, mappable units of mafic amphibolite, ultramafic rocks, and two Fe-rich quartzp...
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In the Palaeoproterozoic Nagssugtoqidian orogen of West Greenland reworked Archaean and juvenile Proterozoic orthogneisses occur side by side and are difficult to differentiate in the field. Archaean gneisses have tonalitic to trondhjemitic compositions with relatively low Al2O3 and Sr, and may have been derived from magmas formed by melting of basaltic or amphibolitic rocks at moderate pressur...
متن کاملMass-independent fractionation of sulfur isotopes in sulfides from the pre-3770 Ma Isua Supracrustal Belt, West Greenland
Redox chemistry of the coupled atmosphere–hydrosphere system has coevolved with the biosphere, from global anoxia in the Archean to an oxygenated Proterozoic surface environment. However, to trace these changes to the very beginning of the rock record presents special challenges. All known Eoarchean ( c . 3850–3600 Ma) volcanosedimentary successions (i.e. supracrustal rocks) are restricted to h...
متن کاملExtreme Nd-isotope heterogeneity in the early Archaean - fact or fiction? Case histories from northern Canada and West Greenland
Sm-Nd data on rock suites from early Archaean provinces in northern Canada and West Greenland clearly demonstrate that tectonothermal (i.e. igneous, metamorphic, tectonic) processes which affected the rocks long after their formation produced open-system behaviour leading to effective resetting of the Sm-Nd system accompanied by complete, or near-complete, Nd-isotope homogenisation. This means ...
متن کاملSetting and origin for problematic rocks from the \3.7 Ga Isua Greenstone Belt, southern west Greenland: Earth’s oldest coarse clastic sediments
Whether or not coarse detrital sedimentary rocks occur within the \3.7 Ga Isua Greenstone Belt (IGB), southern west Greenland, has been debated for some time. Repeated, regional metamorphic, deformational, and metasomatic events have obscured most protolith lithologies leading to misunderstandings about the stratigraphy and environments of deposition. Rocks here interpreted as meta-conglomerate...
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ژورنال
عنوان ژورنال: Bulletin Grønlands Geologiske Undersøgelse
سال: 1987
ISSN: 2597-2936,0105-3507
DOI: 10.34194/bullggu.v156.6698