Stratigraphic characterization of the early Cambrian Abbottabad formation in the Sherwan area,Hazara region,N. Pakistan: Implications for early Paleozoic stratigraphic correlation in NW Himalayas,Pakistan

This paper attempts stratigraphic characterization of the early cambrian abbottabad formation exposed in the sherwan area,west of abbottabad. a regional correlation is carried out with the rest of the early paleozoic sequences exposed in northern pakistan including abbottabad,peshawar basin and salt range. stratigraphic sections are measured at aluli,pind khan khel and bir villages in the mapped area and at soban gali and muslimabad (sirbon hill),abbottabad. a three-fold subdivision of the abbottabad formation has emerged through this study; a) lower arenaceous unit (dominantly quartzite with subordinate pebbly conglomerate,sandstone and siltstone),b) middle dolomitic unit (dominantly dolomite with subordinate quartzite,siltstone,and conglomerate) and c) upper quartzite unit. the three members defined in this study are exclusively preserved in the sherwan area. elsewhere,either the only lower two members are preserved such as at the soban gali and sirbon hill,abbottabad or only the upper two units are present such as at swabi in the peshawar basin. in the latter,the misri banda quartzite that has an ordovician paleontological age but ~525 ma age defined by the youngest detrital zircon is possibly an equivalent of the upper quartzite member of the abbottabad formation defined in this study. the two are lithologically similar and the detrital zircon age resemble closely with the age of the abbottabad formation.