Abstract

The most complete Paleozoic sequence described from Pakistan is exposed in bedrock inliers and in ranges fringing the eastern Peshawar basin. Interbedded quartzite and argillite of the Precambrian and Cambrian Tanawal Formation is overlain unconformably by the Cambrian(?) Ambar Formation. The Misri Banda Quartzite unconformably overlies the Ambar and contains Ordovician Cruziana ichnofossils. New conodont discoveries restrict the ages of overlying formations as follows: Panjpir Formation, Llandoverian to Pridolian; Nowshera Formation, Lochkovian to Frasnian; and Jafar Kandao Formation, Kinderhookian to Westphalian. The Karapa Greenschist, consisting of metamorphosed lava flows, separates the Jafar Kandao from Upper Triassic (Carnian) marbles of the Kashala Formation. The Upper Triassic and Jurassic(?) Nikanai Ghar Formation forms the top of the section.

Correlatives to the Peshawar basin stratigraphy are present locally in the Sherwan synclinorium of Hazara and in the Khyber Pass region. The sequence contrasts markedly with the Paleozoic and Mesozoic section exposed south of the Khairabad thrust in the Attock-Cherat Range. This thrust and its northeastern continuation in Hazara north of Abbottabad thus form the boundary in Pakistan between the Lesser Himalayan and Tethyan Himalayan sections, a function performed by the Main Central thrust (MCT) in the central Himalaya of India and Nepal.

The newly dated Carboniferous to Triassic horizons provide the first firm age constraints on the protoliths of the high-grade Swat metasediments. The dating of the metasediments has, in turn, provided age constraints on pre-Himalayan tectonism and associated intrusions. Two major tectonic episodes during the Late(?) Cambrian and Carboniferous produced positive areas north of the Peshawar basin that provided coarse detritus to the Misri Banda Quartzite and Jafar Kandao Formation.

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