LITHOSTRATIGRAPHY AND VERTEBRATE BIOSTRATIGRAPHY OF THE EARLY MIOCENEHIMALAYAN FORELAND, ZINDA-PIR-DOME, PAKISTAN

Deposits in the Sulaiman foothills and Zinda Pir Dome in west-central Pakistan provide new insight into the critical early Miocene record of Himalayan Foreland sedimentation and paleobiology. The Chitarwata For mation, which underlies the Vihowa Formation in the Sulaiman foothills predates the Siwalik deposits on the Potwar Plateau of north-central Pakistan and provides a record of mammals spanning the interval betwee n the early Miocene Bugti fauna and middle Miocene to Pleistocene Siwa lik faunas. Siwalik deposits on the Potwar Plateau are no older than m iddle Miocene; they represent fluvial environments. In contrast, the C hitarwata and Lower Vihowa Formations in the Zinda Pir Dome represent coastal-delta plain and fluvial environments, respectively. Biostratig raphic information from the Chitarwata Formation, coupled with paleoma gnetic data (reported by Friedman et al., 1992) from coincident strata , suggest that coastal environments persisted in the area of the Sulai man foothills until about 18.6 Ma when they were replaced by fluvial e nvironments, probably representing the ancestral Indus River system. A pparently, during the early Miocene when sediments of the Chitarwata F ormation were accumulating on the western portion of the Himalayan For eland Basin much of the area of the Potwar Plateau to the north was be ing eroded. The overlying Vihowa Formation, along with the relatively contemporaneous Kamlial Formation on the Potwar Plateau, represent the appearance of widespread terrestrial sedimentation in the Himalayan F oreland Basin.