The Siwalik Molasse: A Sedimentary Record of Orogeny
Abstract
The Siwalik molasse basin lies on the southern margin of the Himalayan orogenic belt. Continuously exposed from the Sulaiman Range in western Pakistan to Assam in the eastern India, the Siwalilk sediments consist of over 7000 meters of fluvial sediments ranging in age from late Miocene to Pleistocene. The continuation of the mountain building activity which first uplifted the source area to the north, is now responsible for the deformation and hence exposure of these sediments. This deformation characteristically diminishes in intensity southwards from a boundary thrust fault to the undisturbed Indo-Pakistan shield. The Siwalik sediments have been extensively studied initially because of their excellent record of late Tertiary mammalian evolution, and more recently, because of their record of source area unroofing and changing sedimentary environments.
References
Johnson, G.D., Johnson, N M., Opdyke, N.D., and TahirkheIi, R.A.K., 1979. Magnetic Reversal Stratigraphy and Sedimentary Tectonic History of the Upper Siwalik Group, Eastern Salt Range and Southern Kashmir, in Farah and de Jong eds. Geodynamics of Pakistan, Geol. Survey of Pakistan, Memoir 11, pp. 149-165.
Mankinen, E.A., and Dalrymple, G.B., 1979. Revised Geomagnetic Polarity Time Scale for the Interval 0-5 my. B.P. Jour. Geophys. Res., v. 84, p. 615-626.
Opdyke, N.D., Lindsay, E., Johnson, G.D., Johnson, N.M., Tahirkheli, R.A K., and Mirza, M.A., 1979. Magnetic Polarity Stratigraphy and Vertebrate Paleontology of the Upper Siwalik Subgroup of Northern Pakistan. Paleogeography, Paleoclimatology, Paleoecology, v. 27, p. 1-34.
Visser, C.F. and Johnson, G.D., 1978. Structural Control of Late Pliocene Molasse Sedimentation, Jhelum Reentrant, Pakistan. Geol. Rundsch., v. 67, p. 15-37.
