نتایج جستجو برای: island arc
تعداد نتایج: 91659 فیلتر نتایج به سال:
Ophiolitic belt of Northern Sabzevar is invaded by basic, intermediate and acidic post-ophiolitic magmtism as dome, dyke and cone. Microscopically, the texture of the studied samples is porphyric and trachytic. Phenocryst mostly consists of amphibole, feldspar and clinopyroxene. All researchers that have investigated basic to acidic post ophiolitic magmatism of northern Sabzevar have consensus ...
A set of diabasic and lamprophyre dykes, trending NW-SE, cut the Neogene volcanic rocks that exposed in the south of Kerman city and west of Glomac village. They are characterized by porphyritic and glomeroporphyry textures. Lamprophyres contain course- grained phenocryst of olivine- pyroxene- amphibole in a matrix containing feldspars. diabasic rocks are dominated by main minerals including di...
Fathabad area is located in northwest of the city of Zarand (Kerman province) in the Posht-e-Badam block of the central Iran structural zone. The Ordovician–Silurian gabbroic stocks have intruded into volcanic-sedimentary rocks of the Rizu series. The gabbros are mainly composed of clinopyroxene, kaersutite, plagioclase and biotite. Electron microprobe analyses demonstrate that the clinopyroxen...
The central part of the Fennoscandian Shield in Finland is composed of the Palaeoproterozoic Svecofennian domain and the Archaean Karelian craton with a Palaeoproterozoic allochthonous and autochthonous cover. A cryptic suture separating these areas and another tentative suture dividing the Svecofennian into central and southern parts have been proposed. The chemical composition of sedimentary ...
Plate subduction continuously transports crustal materials with high-δ(18)O values down to the mantle wedge, where mantle peridotites are expected to achieve the high-δ(18)O features. Elevated δ(18)O values relative to the upper mantle value have been reported for magmas from some subduction zones. However, peridotites with δ(18)O values significantly higher than the well-defined upper mantle v...
A structural and petrological study of the Late Proterozoic rocks in the Wadi Kid area, Sinai, Egypt indicates the presence of an extensional metamorphic core complex in the northern Arabian–Nubian Shield. Gneissic domes throughout the Arabian–Nubian Shield resemble the core complex of the Wadi Kid area and as a result, they are interpreted as extensional metamorphic core complexes. The presenc...
The Matangkaka manganese deposit is an unusual Quaternary epithermal stratabound oxide from Ambitle Island in the Feni Group, New Ireland Province, Papua Guinea. a small volcanic island that has undergone explosive and effusive activity. Oldest rocks on consist of mafic–intermediate lavas epiclastic Pleistocene Volcano (Waramung Volcanics). These rest unconformably Oligocene calcilutites Basin....
The paper considers the Pd/Pt ratio in ores of Norilsk-1 and Talnakh deposits associated with Permian-Triassic intrusions Norilsk type comparison that lavas same age region. mean is 1 2–4 times higher than barren horizons intrusions. Such an increase implies these elements were borrowed by magma from small medium-sized crust previous stage Permian island-arc volcanism.
The geochemical discriminate diagrams help to distinguish the volcanics recovered from different tectonic settings but these diagrams tend to group the ocean floor basalts (OFB) under one class i.e., as mid-oceanic ridge basalts (MORB). Hence, a method is specifically needed to identify the OFB as normal (N-MORB), enriched (E-MORB) and ocean island basalts (OIB). We have applied Artificial Neur...
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