GEOCHEMISTRY AND TECTONIC SETTING OF THE VOLCANIC ROCKS OF THE ZIARAT AREA, PAKISTAN

摘要

The volcaniclastic rocks of the area are exposed throughout the Ziarat district within the western part of the Sulaiman Thrust-Fold Belt, Pakistan. Exposed rocks include basic volcanic rocks, volcanic conglomerate and breccias, sandstone, mudstone and ash bed, while gem stone, asbestos and huge amount of chromites are associated close to the study area. Recently on January 29, 2010, the volcanic activity took place after 74 .4 my in the study area Ziarat, Pakistan. They are deposited by various processes of sediment gravity flows on the western margin of the Indian Plate and they exhibit indication by deposition by turbidity currents in over bank (-levee) complex between channels. Paleo-current pattern indicate a south-southwest flow direction and a source area to the north-northeast of area. XRF data on both major and trace elements plotted on various discrimination diagrams of the volcanic and associated intrusive rocks indicate that the analyzed samples fall in the field of within-plate alkali basalt or close to it. This suggests that the volcaniclastic sediments of the area were derived from a volcanic terrain composed of alkali basalts. Trace elements presented in various diagrams suggest that the parent magma was enriched in mantle source and confirm that the fragments of the volcanic conglomerate of the Bibai Formation were derived from volcanic terrane.