Research wil continue on the fluvial, Miocene Siwalik deposits of the Potwar Plateau in northern Pakistan. This involves construction of detailed sedimentological logs through the Chinji, Magri and Shok Pathan formations formations in several different parts of the basin where there is paleomagnetic age dating. Several important 50 to 100 m thick stratigraphic intervals in each measured sequence will be detailed sedimentologically and paleontologically over several km laterally, using photo mosaics and closely-spaced (100 m) logs. Paleosol carbonates will be sampled for Carbon isotope analysis. This will allow us to reconstruct the temporally and spatially varying paleoenvironments in terms of paleochannel geometry and hydraulics, nature of paleosols, animal and plant activity and deposition rates. Particular attention will be paid to: (1) the upper Shok Pathan Formation (6mpBP) where there is evidence for a major climatic, vegetational and faunal change and (2) the Chinji-Nagri transition (10 m.y.B.P.) where there is evidence of a major faunal turnover, increasing depositional rates, increasing proportion and grain size of channel deposits, and increasing channel size, but no evidence of a climatic change. It will then be possible to understand an important period of evolution of land organisms in relation to changes in the physical and chemical environment. This study will also have more general implications for the relationship between fluvial deposits (and the fossils they contain), tectonism and climate.
