Breakup of Gondwanaland and Emplacement of the Ophiolitic Complex in Muslim Bagh Area of Baluchistan

Abstract

Many Lower and Upper Triassic fossils were discovered in the "Alozai Group”, “Loralai Limestone" and "Parh Group" in the Axial Zone of the Muslim Bagh area. Accordingly, they were distinguished from those in the Calcareous Zone. The Triassic sequence in the Axial Zone is characterized by pillow lava, hyaloclastites, olistostromes and hemipelagic sediments. Based on lithological characteristics, a narrow sedimentary basin, bounded on the south by the Indian continent and on the north by a mid-oceanic ridge, is reconstructed. These are regarded to suggest the breakup of Gondwanaland along the northern margin of the Indian continent. The volcanic rocks of the Bibai Formation are regarded as the products of the temporal island arc magmatism on the northern margin of the Indian continent in the latest Cretaceous. The process of the obductional emplacement of the Axial Zone upon the Calcareous Zone is also studied. The direction of the emplacement is estimated to be from NNW to SSE. The time of the emplacement is confirmed to be Paleocene and Early Eocene. The emplacement distances of the major thrust sheets are also estimated. The thin metamorphic layer which is associated with the major thrust beneath the ultramafic bodies is described, and the metamorphism is considered to be due to the baking effect of the oceanic plate which obducted on the Triassic sequence.