نتایج جستجو برای: metamorphism and igneous
تعداد نتایج: 16828157 فیلتر نتایج به سال:
Metamorphic rocks in SW Arak composed from two groups including regional and contact metamorphism. Regional metamorphic rocks are composed of slate, phyllite and micaschists and locted in green-schist facies and contact metamorphic rocks are composed of spotted schist and hornfels respectively. Mineralogically, these rocks are composed of quartz, chlorite, muscovite, biotite and cordierite. Pet...
U-Pb analyses of zircon from ten samples of augen gneisses, eight mafic and intermediate metaigneous rocks and six metasediments from some tectonic domains along the Calabria-Peloritani Terrane (Southern Italy) contribute to knowledge of peri-Gondwanan evolution from Late-Proterozoic to Paleozoic times. All samples were equilibrated under amphibolite to granulite facies metamorphism during the ...
بررسی مورفولوژی، تغییرات شیمیایی و ژنز بلورهای گارنت موجود در سنگ های دگرگونی و آذرین در منطقه همدان
چکیده ندارد.
This paper is a complement to the Tectonometamorphic Map of the Canadian Shield, and contains a brief description of the metamorphic history of Proterozoic orogenic belts and rock sequences in the Canadian Shield in Ontario, with a focus on rocks of the Southern and Grenville provinces. Metamorphism in the Southern Province has generally been attributed to the Penokean orogeny (~1879–1820 Ma), ...
The studied area, as Ykeh-Chah unit, is a part of Golpayegan magmatic and metamorphic complex in Sanandaj-Sirjan structural zone. The unit consists of mylonitized and high- grade metamorphic rocks, including biotite-gneiss, biotite-garnet-gneiss, amphibolite and orthogneiss. The biotite gneiss and the biotite garnet gneiss have partly been migmatitized. They show various structures such as stro...
The Ross orogen of Antarctica is one of Earth’s great Phanerozoic mountain belts. It is thought from igneous geochemistry, deformation patterns, and sedimentation history to be the result of late Neoproterozoic and early Paleozoic plate-margin convergence between paleo-Pacifi c oceanic lithosphere and continental lithosphere represented by the composite East Antarctic shield. Convergence along ...
The key to comprehending the tectonic evolution of the Himalaya is to understand the relationships between large-scale faulting, anatexis, and inverted metamorphism. The great number and variety of mechanisms that have been proposed to explain some or all of these features re ̄ects the fact that fundamental constraints on such models have been slow in coming. Recent developments, most notably in...
11 Most mass extinctions during the last 500 m.y. coincide with eruptions of large igneous 12 provinces (LIP): the Cretaceous-Tertiary extinction was synchronous with the Deccan 13 flood volcanism, Permian-Triassic extinction with the eruption of the enormous 14 Siberian Traps, and End-Guadalupian extinction with the Emeishan volcanic province. 15 The causal link remains disputed, however, and ...
, ABSTRACT Metabasaltic rocks in the Klamath Mountains of California with 'komatiitic' major element concentrations were investigated in order to elucidate the origin of the magnesian signature. Trace-element concentrations preserve relict igneous trends and suggest that the rocks are not komatiitic basalts, but im~at~re arc rocks and within-plate alkalic lavas. Correlation of 'excess' MgO with...
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