Paleoecological and Biostratigraphic studies of Laki limestone member of Laki formation (ypresian) and tiyon formation (Late Ypresian-Lutetian), on the basis of smaller foraminifera, Thano Bula Khan, Sindh.

Abstract

Eocene succession of Lower Indus Basin; in terms of Laki Formation and Tiyon formation has remained an unsolved problem untill now; many of the geologists and Stratigraphic Committee of Pakistan believe Tiyon as a unit of Laki Formation. In this study an effort is made to prove the difference between both rock units on the basis of smaller foraminifera. Laki Formation and Tiyon formations are best exposed at RehmanDhoro and TiyonNai sections respectively which are their type sections. For this study the area of Thano Bula Khan, District Jamshoro, Sindh was selected shown in top sheet no. 35 0/15. The smaller foraminifera of Laki limestone member of the Laki Formation and Tiyon formation were identified and differentiated. By the study of smaller foraminifera it is observed that the difference among both the formations is an enough biostratigraphic evidence for the recognition of Tiyon (late Ypresian-Early Lutetian) as a distinct formation. Paleo-ecology on smaller foraminiferal basis was interpreted and the area of study is assigned shallow-deep marine depositional environment. The aim of this paper is to assess and present the lithological and smaller foraminiferal difference between two rock units of Eocene age in the Southern Indus Basin. An attempt has been made to provide sufficient Biostratigraphic evidence to recognize the Tiyon (late Ypresian- Early Lutetian) as a formation, by studying the Paleo-ecology of the studied area.