Himalayan Forelands: palaeontological evidence for Oligocene detrital deposits in the Bugti Hills (Balochistan, Pakistan)

In the southwestern Sulaiman geological province (Balochistan, Pakistan), t errestrial detrital facies from the Bugti Hills region have yielded the ric hest Tertiary vertebrate faunas to be found in Asia thus far. New fossils f rom five successive and distinct 'bone beds' bridge the supposed Oligocene sedimentary hiatus within the Sulaiman geological province; the lowermost c ontinental levels of the previously described Miocene Chitarwata Formation, known as the Bugti Member, are Oligocene in age in the Bugti area. Neither a mixture of heterochronic faunal elements nor endemism of any fauna is ev ident in this area. Additional microfaunal material from the Bugti Member c onstrains an Oligocene age for the lower Chitarwata Formation in Zinda Pir (northeast of the Bugti Hills). This Oligocene transition between the marin e Kirthar (Eocene) and continental Siwalik (Miocene) deposits consists of a regressive fluvio-deltaic system occupying a vast floodplain. It represent s an early-stage molasse in the palaeo-Indus Basin which drained western or ogenic highlands resulting from the collision between the Indian and Eurasi an plates.