نتایج جستجو برای: arabian shield

تعداد نتایج: 13565  

2007

A significant tin deposit has been identified in the northeast part of the Late Proterozoic Arabian Shield. Cassiterite-topaz-quartz greisens are distributed over 16 km2 in flat-topped cupolas of a highly evolved, zinnwaldite-bearing alkali-feldspar granite which composes part of the silsilah ring complex (lat 26"06'N, long 4240'E). The 587 m.y. old alkali-feldspar granite is overlain by a cara...

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,...

2002
M. Ravi Kumar D. S. Ramesh Joachim Saul Dipankar Sarkar Rainer Kind

[1] Analysis of receiver functions from an eight-station network on the Saudi Arabian shield indicates that the Moho depths vary between 35–38 km. The crust appears to be rather felsic in nature as evidenced by Poisson’s ratios of 0.25–0.27. A prominent negative phase following the Moho conversion is suggestive of a zone of velocity inversion. Indication of mantle stratification is observed ben...

2010
Mohamed G. Abdelsalam

1464-343X/$ see front matter 2009 Elsevier Ltd. A doi:10.1016/j.jafrearsci.2009.07.003 * Tel.: +1 573 341 4100; fax: +1 573 341 6935. E-mail address: [email protected] Deformed conglomeratic clasts exposed along the Neoproterozoic Nakasib Suture and the Oko Shear Zone are used to calculate three-dimensional (3D) tectonic strain associated with the latter to quantify strain associated with post-a...

2009
M. Al Saud

The analysis of drainage morphometry is usually a prerequisite to the assessment of hydrological characteristics of surface water basin. In this study, the western region of the Arabian Peninsula was selected for detailed morphometric analysis. In this region, there are a large number of drainage systems that are originated from the mountain chains of the Arabian Shield to the east and outlet i...

2014
Peter R. Johnson

Geologic investigations of the Arabian-Nubian Shield (ANS) are supported by a valuable, expanding dataset of geochronologic ages and isotopic analyses. U-Pb zircon SIMS, TIMS, and evaporation data provide robust temporal control on depositional, volcanic, and intrusive events. Nd, Sr, O and, increasingly, Hf isotopic studies provide insights into magma sources and constraints on crustal recycli...

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