Himalayan Geology, Vol. 43 (1A), 2022, pp. 111-121, Printed in India
Paleoenvironments and sequence stratigraphy of the Early Jurassic Datta Formation, Chichali Nala, Surghar Range, Pakistan
SHUJA ULLAH1, NOWRAD ALI2, KHALID LATIF1*, SHAHID IQBAL3, MUHAMMAD TAHIR1, HAFIZ SHAHID HUSSAIN1, SYED ALI TURAB1, ADNAN MUMTAZ2, MOHIBULLAH MOHIBULLAH4
1National Centre of Excellence in Geology, University of Peshawar, Peshawar, Pakistan
2Department of Geology, University of Peshawar, Peshawar, Pakistan
3Department of Earth Sciences, Quaid-e-Azam University, Islamabad
4Department of Geology, University of Balochistan, Quetta
*Email (Corresponding author): khalidlatif@uop.edu.pk
Abstract: The Early Jurassic Datta Formation represents the oldest sediments exposed in the Chichali Nala, Surghar Range, Pakistan. This study includes facies analysis of the Datta Formation exposed in the Chichali Nala to propose the robust depositional model and sequence stratigraphy. The Formation is composed of medium to coarse grained sandstone with inter-bedded carbonaceous clays, limestone, shale and occasional dolomite. Based on outcrop data and petrographic analysis, five lithofacies are identified. The lithofacies include: 1) Channelized sandstone and alternate black shales, representing delta plain depositional setting, 2) Thick bedded sandstone, representing deposition in a delta front setting, 3) Carbonaceous clays, representing deposition in swamp setting of the delta plain, 4) Laterite, indicating the subaerial exposure of the platform to oxidizing conditions, and 5), Limestone interbedded with dolomite and shale lithofacies representing deposition in the lagoon environment. The formation represents its deposition in a third-order cycle that comprise three transgressive and two regressive episodes of the sea level. The proposed depositional model based on lithofacies data shows eight platform subaerial exposure cycles, which are represented by the laterite facies. Such exposures may represent the stream rejuvenation in the deltaic and lagoonal facies in the study area.
Keywords: Datta Formation; Early Jurassic; Paleoenvironment; Sequence Stratigraphy; Chichali Nala
