نتایج جستجو برای: ophiolite complexes

تعداد نتایج: 138074  

2014
Marco Maffione Antony Morris Douwe J. J. van Hinsbergen

Serpentinization of ultramafic rocks during hydrothermal alteration at mid-ocean ridges profoundly changes the physical, chemical, rheological, and magnetic properties of the oceanic lithosphere. There is renewed interest in this process following the discovery of widespread exposures of serpentinized mantle on the seafloor in slow spreading oceans. Unroofing of mantle rocks in these settings i...

2012
D. Garcia-Castellanos

The aim of this work is to propose a first-order estimate of the crustal and lithospheric mantle geometry of the Arabia–Eurasia collision zone and to separate the measured Bouguer anomaly into its regional and local components. The crustal and lithospheric mantle structure is calculated from the geoid height and elevation data combined with thermal analysis. Our results show that Moho depth var...

Journal: :Geological Magazine 2022

Abstract Ophiolitic mélanges in Anatolia represent Mesozoic subduction-accretion complexes, which are unusually poor land-derived coarse-clastic rocks. A segment of the ophiolitic mélange Beynam region south Ankara was studied. The consists three accretionary units (AUs), distinguished by lithology, structure, age and geochemistry. At base there is a serpentinite mélange, overlain semi-intact U...

2002
THEO ANDREW ALASTAIR H. F ROBERTSON

The Beyşehir–Hoyran–Hadim Nappes crop out over 700 km from NW to SE. Above a regionally autochthonous Tauride carbonate platform the Beyşehir–Hoyran Nappes begin with a thrust sheet (c. 400 m) of mainly redeposited carbonates, quartzose sandstones and mudstones of Mid–Late Triassic age, interpreted as a proximal slope–base-of-slope succession. Above is a thrust sheet (c. 1 km) of Middle–Upper T...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2011
Marie-Laure Pons Ghylaine Quitté Toshiyuki Fujii Minik T Rosing Bruno Reynard Frederic Moynier Chantal Douchet Francis Albarède

The Isua Supracrustal Belt, Greenland, of Early Archean age (3.81-3.70 Ga) represents the oldest crustal segment on Earth. Its complex lithology comprises an ophiolite-like unit and volcanic rocks reminiscent of boninites, which tie Isua supracrustals to an island arc environment. We here present zinc (Zn) isotope compositions measured on serpentinites and other rocks from the Isua supracrustal...

2013
Gerald Stern Michael Wagreich

Chemistry of detrital garnets, chrome spinels and tourmalines of 30 selected samples in combination with the general heavy mineral distribution from 523 sandstone samples of the Upper Cretaceous to Eocene Gosau Group of the eastern part of the Eastern Alps and the western West Carpathians result in an advanced picture of sedimentary provenance and palaeogeographic evolution of that area. Garnet...

آرایی, شوجی, ترابی, قدرت, امامی, محمد هاشم , حسن احمد, احمد , سبزه‌یی, مسیب , محجل, محمد ,

In north of Anarak area, in the upper Proterozoic ophiolite, exist Massive and Vein type Rodingites. Vein type rodingites have formed in two phases. Massive or Static rodingites have formed during oceanic crust spreading and ophiolite formation, and Vein type or Dynamic rodingites have formed during Anarak ophiolite emplacement and tectonic activities. Abundance order of minerals in massive rod...

2016
Ben-Xun Su Mei-Fu Zhou Paul T. Robinson

We report Li isotopic compositions of olivine from the mantle sequence of the Luobusa ophiolite, southern Tibet. The olivine in the Luobusa ophiolite has Li concentrations from ~0.1 to 0.9 ppm and a broad range of δ(7)Li (+14 to -20‰). An inverse correlation of Li concentration and δ(7)Li in olivine from harzburgite suggests recent diffusive ingress of Li into the rock. Olivine from dunite enve...

2003
P. R. Johnson

The Bi’r Umq-Nakasib suture zone, 5-65 km wide and over 600 km long, consists of highly deformed ophiolite nappes and metavolcanic, metasedimentary, and intrusive rocks contained in one of the longest ophiolite-decorated shear zones in the Arabian-Nubian Shield. The rocks originated in a variety of juvenile oceanic environments and include assemblages formed in mid-ocean-ridge, subduction-zone,...

2018
Ramadan Abdelaziz Yasser Abd El-Rahman Sophie Wilhelm

Chromite is widely distributed in the east and southeast of Afghanistan, especially in Logar Province. Chromite mineralization is podiform-type and is hosted in the stratigraphically lowest ultramafic rocks of the Logar Ophiolite Complex. This ophiolite complex represents a remnant of an early Cretaceous oceanic crust that was thrusted over a late Permian to Mid-Jurassic platform-type sequence ...

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