ABSTRACT
Four stratigraphic sequences were measured and sampled from the Shinghar and Surghar ranges, Pakistan, for detailed magnetostratigraphic studies of the fluviatile Neogene and Quaternary Siwalik Group. The samples were subjected to blanket thermal demagnetization at 500 °C. Some of the samples, particularly those from the pale brown siltstone/claystone units, were further demagnetized to 600 °C to isolate the stable characteristic component of magnetization which was used to identify the magnetic polarity. The observed magnetic polarity reversal sequence is correlated with the standard Magnetic Polarity Time Scale (Berggren et al., 1985a), based on the magnetic pattern and the vertebrate fossils collected from the nearby Daud Khel area (Hussain et al., 1977) and from the Shinghar range during palaeomagnetic sampling. This correlation suggests that deposition of the Silwalik Group in this area started during the basal chron C5A time (11.8 myr) and continued till the later Matuyama chron (0.85 myr). A very thick sandstone is present in the section up to 3.5 km in thickness. This sandstone was probably deposited along the axis of the ancient Indus from 8 myr to 2.7 myr. At that time the axis of the Indus apparently shifted to the east.
