RINE, J. M., and D. ACHELLING, Earth Sciences and Resources Institute, University of South Carolina, Columbia, SC; and A. M. BHUTTA, Geological Survey of Pakistan, Lahore, Pakistan

ABSTRACT: Evolution of a Shallow to Marginal Marine, Mixed Carbonate/Clastic Sequence making up the Paleogene Strata of the Southern Kirthar Mountains (Western Sindh, Pakistan)

Excellent exposures within the folded and thrust Southern Kirthar Range provide abundant data for reconstructing the depositional environments of Paleogene strata along the northwestern margin of the Indian Plate. The makeup of this rock sequence reflects the influence of the drifting Indian Plate and its eventual collision with the Eurasian Plate. The basal Rankikot Formation (Paleocene) unconformably overlies the Pab Sandstone (Cretaceous) and consists of poorly indurated shales and sandstones with minor limestone beds near the unit's top. The Rankikot was deposited in a fluvial/deltaic to coastal marine setting and is unconformably overlain by shallow marine carbonates of the Laki Formation (Eocene). The Laid consists predominantly of skeletal wackestones and packstones containing ollusc fragments, solitary corals, and large foraminiferal tests. The tests of Alveolina sp. are most abundant. Terrigenous-clastic input is almost nonexistent within the +200 meter thick Laki, reflecting a platform or stable continental margin setting. Distal terrigenous input is recorded in the Tiyon and Kirthar formations (Eocene), which overlie the Laid and consist of intercalated shales and skeletal limestones. The limestones contain abundant tests of the large foraminifera Lepidocyclina sp., Discocyclina sp., and Nummulites sp. More proximal terrigenous input is recorded in the Nari Formation (Oligocene), which consists of intercalated shales, fine-grained sandstones, and thin beds of foraminiferal limestones with Lepidocyclina sp. and Discocyclina sp. This mixed carbonate-clastic equence of Tiyon, Kirthar, and Nari records the approaching collision of the Indian and Eurasian plates. The Paleogene strata were uplifted following the collision

and are unconformably overlain by alluvial sediments of the Manchhar Formation (Miocene-Pleistocene?).

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.