Title of Thesis
CRUSTAL EVOLUTION OF CHAGAI – RASKOH ARC TERRANE, BALOCHISTAN, PAKISTAN.
Author(s)
Muhammad Rehan Ul-Haq Siddiqui.
Institute/University/Department Details
University Of Peshawar/ National Centre Of Excellence In Geology
Session
2004
Subject
Geology.
Number of Pages
353
Keywords (Extracted from title, table of contents and abstract of thesis)
chagai-raskoh, petrochemical studies, karakoram block, arabian plate, volcanics, paleocene volcanics, eocene volcanics, oligocene volcanics, miocene volcanics, plio-pleistocene volcanics
Abstract
The Chagai-Raskoh arc terrane occurs in the western part of Pakistan. In the regional geotectonic scenario this arc terrance belongs to an ancient Tethan convergence zone. Which was initiated probably during Early Jurassic, due to an intra-oceanic convergence in the Ceno Tethys. The are terrane exhibits spectacular field exposures of interstraified volcanic and sedimentary rocks, intruded by large plutons. The sedimentary rock formations from the late Early Jurassic to Recent arc well preserved, which represent excellent manifestations of sedimentary evolution from late Early Jurassic pelagic sedimens, through diversified varieties of Cretaceous to Oligocene shallow marine limestone, shale and sandstone deposits and Miocene onwards terrestrial sediments. The sedimentation in the arc terrane is interrupted by several episodes of magmatism that occurred during Cretaceous to quaternary. The Cretaceous and Paleocene volcanism is dominated by vbasaltic-andesites with minor basalts and andesites with their volcaniclastic counterparts, whereas Eocene onwards volcanism is generally dominated by andesites with minor dacites and their volcaniclastic equivalents. The mafic mineralogy (augite-biotite), anorthite contents (An68-15) and phenocrysts to groundmass ratios (20:80-45:55) in the volcanics rocks generally show progressive evolution towards younger volcanics.
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