نتایج جستجو برای: volcanic arc granitoid
تعداد نتایج: 50524 فیلتر نتایج به سال:
The Rangraz area is located about 20 km north of Saveh, which is situated in the central part of Uromieh–Dokhtar magmatic arc. The exposed rocks in the study area consist of a volcanic and volcanoclastic subvolcanic dikes and quartz monzodiorite intrusions. Mineralization in this area is mostly related to the silicic, argillic and chloritization alteration assemblages. The Rangraz area consists...
Back-arc extension has been well documented in subduction plate tectonic regimes. However, the reasons why back-arc extensions are associated with some systems but not others have remained elusive. Here, spatio-temporal variations composition of Cenozoic basalts northeast Asian continental margin used to constrain mechanism for episodic extensions. Using geochemical data sensitive affinity, we ...
Eocene volcanic rocks in NE of Ordib, have a very good exposures near and along the Turkmeni-Ordib fault. These rocks, that are situated in the inner part of the Central Iran and margin of the Yazd block, comprise trachyte, trachy-andesite and basaltic trachy-andesite. Trachy-andesite is the pervasive rock unit. Rock forming minerals of these rocks are chloritized olivine, plagioclase, pyroxene...
the deep internal structure of the crust can be determined using appropriate seismic and electromagnetic methods. the natural source magnetotelluric (mt) method is the most suitable electromagnetic technique for probing into the deep crust. a long period magnetotelluric data set obtained in the southern chilean andes is investigated in this paper. dimensionality analysis shows that the data may...
The Grenada back-arc basin is located between the Aves Ridge, which hosted remnant Early Paleogene “Great Caribbean Arc,” and Eocene to Present Lesser Antilles Arc. Several earlier studies have proposed different modes of opening for this basin, including N-S E-W directions. main aim study constrain circumstances leading basin. Three combined wide-angle reflection seismic profiles were acquired...
The study area is located in the central part of the Siahrood geological map, Kharvanagh of Ahar town, in the East Azerbaijan Province. The volcanic rocks of the Kharvanagh area include trachybasalt, trachy-andesi-basalt and trachy-andesite. The main minerals in the rocks are plagioclase, pyroxene, olivine and hornblende and the main textures are microlitic-porphyry. At the contact between the ...
The Oligocene-Miocene granitic rocks of Deh Siahan, part of central Iranian volcanic belt, are intruded into Eocene volcano-sedimentary complex where their contact is marked by albite-epidote hornblende hornfels facies and granitic apophyses. The granitic rocks show enhanced LIL element abundances and low HFS/LIL ratios. Geochemical data, various trace element discriminant diagrams, enhanced Y/...
The strong association of iodine with organic material and the presence of the cosmogenic radioisotope I make the iodine isotopic system useful in tracing and dating studies of organic materials and their derivatives. We present here results from two new applications of this system, investigations of gas hydrates from the Peru Margin (ODP 201, Site 1230) and of fluids collected from the fore ar...
Arc magmas and the continental crust share many chemical features, but a major question remains as to whether these features are created by subduction or are recycled from subducting sediment. This question is explored here using Th/La, which is low in oceanic basalts (<0 2), elevated in the continents (>0 25) and varies in arc basalts and marine sediments (0 09–0 34). Volcanic arcs form linear...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید