Microfacies analysis and depositional environment of the Cambrian Ambar Formation, Peshawar Basin, Pakistan

Abstract

The Cambrian Ambar Formation is composed of massive 
dolomite, dolomitic limestone, limestone, quarzitic dolomite, and 
sandy limestone. It is exposed in the Swabi and Turlandi areas, 
the northeastern part of the Peshawar Basin.  The present study 
deals with the sedimentological and petrographical aspects of the 
Ambar Formation. Algal laminated beds, dissolution cavities, 
chop-board weathering, stylolites, quartz, and calcite filled 
fractures together with open fractures are prominent in the 
outcrops. Based on microscopic studies, three microfacies are 
identified: (1) Siliciclastic Mudstone Microfacies (MF-1), (2) 
Dolomitic Packstone Microfacies (MF-2) and (3) Dolomitic 
Packstone-Grainstone Microfacies (MF-3) without taking 
consideration of the lithofacies in a single outcrop exposed in the 
studied section. The integration of the outcrop and petrographic 
observations indicate transitional to inner carbonate shelf setting 
ranging from supratidal to lagoon during the deposition of the 
Ambar Formation.