Microfacies analysis and diagenesis of the Lower Eocene Sakesar Limestone, Nilawahan Gorge, central Salt Range, Pakistan

Abstract

Foraminiferal biostratigraphy and sedimentological studies have been undertaken from the Lower Eocene (Ypresian) Sakesar Limestone from the Nilawahan Gorge in the central Salt Range, Northern Pakistan. A number of stratigraphically important benthonic larger foraminiferal species have been identified, which belong to the genera Lockhartia, Assilina, Nummulites, and Alveolina. Bioclastic wackestone and packstone are prominent microfacies where the bioclasts are benthonic larger foraminifera. The foraminiferal and the microfacies analysis point out inner neritic environments of the Sakesar Limestone. There are three lithological variations: limestone interbedded with shale, nodular limestone with subordinate marl, and very thick-bedded nodular limestone with chert nodules. Microfacies have been described in vertical thickness of 31 m of the Sakesar Limestone where the bioclastic wackestone and packstone are repeatedly encountered. Diagenetic characteristics include stylolisation, calcitisation, silicification and nodularity.

Journal of Nepal Geological Society, 2006, Vol. 33 pp.23-32