Petrography and provenance of the Early Miocene Murree Formation, Himalayan Foreland Basin, Muzaffarabad, Pakistan

摘要

Murree Formation lies in the core of Hazara Kashmir Syntaxis, Sub-Himalayas, Pakistan. In the Muzaffarabad area, the Murree Formation extends from Ghori to Nauseri. The Early Miocene Murree Formation is underlain unconformably by the Ypresian to Early Lutetian Kuldana Formation and is in a fault contact with the Permian Panjal Formation. The Murree Formation contains litharenite and feldspathic litharenite. All of the plots in the QtFL diagram fall in recycled orogen provenance field, whereas ternary diagram (QmFLt) also suggests transitional recycled to quartzose recycled orogenic provenance for the sandstone of Murree Formation. Orogenic recycling occurs in the Lesser and Higher Himalayas where stratified rocks are deformed, uplifted and eroded. The detritus was then deposited in the Himalayan Foreland Basin by river meandering system. The detritus of rock fragments strongly suggests mixed sources of the Murree Formation sandstones. The modal analysis data were plotted in a diamond diagram for the recognition of the sediment source and tectonic setting of the provenance. The frequency of the non-undulatory monocrystalline quartz (Qnu) is larger in the sandstone as compared to the frequency of the undulatory monocrystalline quartz (Qu) and polycrystalline quartz (Qp). The greater abundance of Qnu suggests plutonic provenance for these sandstones. The plot of Q/(F + L) against Qp/(F + L) reveals that during the deposition of Murree Formation, the climatic conditions were semi-arid to semi humid. The XRD analyses of shale samples indicate quartz, carbonate and clays vary from 66-89%, 1-25% and 1-21%, respectively.