نتایج جستجو برای: crustal contamination
تعداد نتایج: 61183 فیلتر نتایج به سال:
Amphibolites crop out in the NW Salmas as two relatively small bodies around Abati and Ureban villages. Based on petrography and mineral paragenesis, the composition of Abati and Ureban amphibolites consists mainly of epidote amphibolite and amphibolite, respectively. Relict of clinopyroxenes from a parental rock are present in some samples. Mineral paragenesis (high hornblende and plagioclase ...
Palaeoproterozoic sedimentary basins of north-eastern and central-eastern Australia are host to large amounts of variably deformed and metamorphosed Fe-rich tholeiitic rocks. Emplacement and/or extrusion of the mafic rocks occurred during one or more episodes of crustal thinning relating to a period of regional extension and sedimentation across Palaeoproterozoic northeastern Australia (ca. 173...
In southwest of Birjand, the Tertiary igneous rocks have oxposed in Cretaceous flysch type deposits. These bodies are made of micro quartzmonzodiorite, trachyandesite, andesite and dacite. The main texture in these rocks is porphyry. Their phenocrysts are plagioclase, hornblende and biotite. Plagioclases contain zoning. Pyroxene, quartz and opaque minerals are in groundmass. Often, hornblendes ...
Both the Sistan Suture Zone of eastern Iran and the Nehbandan Fault contain Plio-Quaternary Nehbandan mafic lavas. Positive anomalies in the large ion lithophile elements (LILE) and negative anomalies in Nb (niobium) exist in these mafic lavas. This indicates the occurrence of subduction magmatism and post-collision volcanism. Petrologic and geochemical analyses distinguished two groups of lava...
Incheh granitoid intrusive body is located in east of Heris, East-Azarbaidjan. It intruded the older rock units including the Sonajil sub-volcanic stock (upper Eocene-lower Oligocene) of micro-diorite porphyry composition. The Incheh intrusive ranges in composition from diorite through syeno-diorite to quartz-diorite. The major constituent minerals include plagioclase, hornblende, and pyroxene ...
Removing the crustal signature from teleseismic travel times is an important procedure to reduce the trade-off between crustal and mantle velocity heterogeneities in seismic tomography. Because reverberations of longand short-period body-wave arrivals in the crust affect the waveforms of the direct arrivals differently, the crustal effects on travel times measured by waveform cross correlation ...
Linear, north–south trending Peddavura greenstone belt occurs in easternmost part of the Dharwar Craton. It consists of pillowed basalts, basaltic andesites, andesites (BBA) and rhyolites interlayered with ferruginous chert that were formed under submarine condition. Rhyolites were divided into typeI and II based on their REE abundances and HREE fractionation. Rb–Sr and Sm–Nd isotope studies we...
The Piedade Granite (approximately 600 Ma) was emplaced shortly after the main phase of granite magmatism in the Agudos Grandes batholith, Apiaí-Guaxupé Terrane, SE Brazil. Its main units are: mafic mineral-rich porphyritic granites forming the border (peraluminous muscovite-biotite granodiorite-monzogranite MBmg unit) and core (metaluminous titanite-bearing biotite monzogranite BmgT unit) and ...
concentrations of eight metals namely, cr, mn, fe, co, ni, cu, zn and pb were examined in the surface sediments of discharge channels of six industries in lagos using x-ray fluorescence spectrometry.these channels drain into the isolo canal which empties into the lagos lagoon and eventually into the atlantic ocean. this study was conducted to detect any contamination levels within the sediment...
[1] Two of the most popular mechanisms for thickening the crust beneath the Tibetan Plateau are (1) pure shear with faulting and folding in the upper crust and horizontal shortening below and (2) flow of lower or middle crust without significant shortening of the upper crust. To help discriminate between the relative contributions of these two mechanisms, well-constrained estimates of upper cru...
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