نتایج جستجو برای: protolith
تعداد نتایج: 242 فیلتر نتایج به سال:
[1] Low-angle subduction of oceanic lithosphere may be an important process in modifying continental lithosphere. A classic example is the underthrusting of the Farallon plate beneath North America during the Laramide orogeny. To assess the relevance of this process to the evolution and composition of continental lithosphere, the mantle stratigraphy beneath the Mojave Desert was constrained usi...
The zircon record of complex high-grade gneiss terrains is key to interpreting their tectonothermal evolution. Typically, such studies focus on zircon-rich, felsic rocks, which commonly have a complicated (partial melting, inheritance, partial dissolution, and reprecipitation) record. Here we show that metamorphosed mafic rocks retained melts (i.e. in situ leucosomes) provide the evolution crus...
Major, minor, and trace element geochemistry as well iron oxidation state isotopes were investigated in serpentinites olivine-talc fels present along a metamorphic gradient the Bergell contact aureole (Central European Alps) to evaluate mobility during serpentine. This is an ideal target study dehydration of mantle rocks due increase temperature from greenschist facies conditions (350°C) amphib...
The Central Asian Orogenic Belt, or Altaids, is an amalgamation of volcanic arcs and microcontinent blocks that records a complex late Precambrian–Mesozoic accretionary history. Although microcontinents cored by Precambrian basement are proposed to play an integral role in the accretion process, a lack of isotopic data hampers volume estimates of newly produced arc-derived versus old-cratonic c...
Mehredjan bentonite deposit is located ~33 km southeast of Khoor in Isfehan province. It includes 15 discrete outcrops and occurs as layered and massive forms within a volcano-clastic sequence. Bentonitization process was accompanied with development of minerals such as montmorillonite, quartz, cristobalite, calcite, kaolinite, halite, albite, orthoclase, and muscovite. The collected field and ...
The Majerad metamorphic complex is located in the northern margin of the Central Iran structural zone and southeast of Shahrood, includes a wide variety of metacarbonate, metabasite (greenschist, amphibolite and garnet amphibolite), metapelite, metapsammite and metarhyolite. The protolith of metabasites has been submarine basaltic lava flows which erupted in the Late Neoproterozoic intracontine...
The studied shear zone is located in E-Qorveh (Kurdistan). The rocks of this zone are granite and granodiorite in composition. In present paper, deformed rocks, protomylonites and mylonites, are investigated in Sangin-Abad, Koh-e-Gazgaz and Poloserkan areas. Petrographic studies show that evidence of tectonic activities are such as myrmekite, recrystallized and slide alkali feldspars, fractured...
Boboluyieh bauxi te-laterite deposit of south-cast Kemlan is presented at the base of the Naiband Formation (upper Triassic) and was directly formed on a Karstic surface of dolomitic parts of the Shotori Formation. This dcposit has a reserve of 15 mill ion lonnes. Diaspore, boehmite, chlorite, hematite, goethite, kaolinite, anatase and rutile arc the major minerals in this deposit. The co...
The Pandian deposit is a newly discovered contact metasomatic skarn magnetite found in the Cainozoic super-thick overburden on northwest margin of Luxi Uplift (LXU). Presently, horizontal scale delineated by potential field (gravity and magnetic method) has shown giant for ore deposits, mapping ore-controlling structures vertical becomes primary task metallogenic prediction. In our study, wide-...
Abstract Our understanding of the nature crustal formation in Eoarchean is limited by scarcity and poor preservation oldest rocks variable imperfect protolith magmatic signatures. These limitations hamper our ability to place quantitative constraints on thermomechanical models for early genesis hence operative geodynamic regimes at that time. The recently discovered ca. 3.75 Ga Ukaliq supracrus...
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