Depositional environments and microfacies of the upper Turonian–Maastrichtian Kawagarh Formation, Kalachitta Range, Lesser Himalayas, Pakistan

Abstract

The upper Turonian–Maastrichtian Kawagarh Formation represents a thick sequence of carbonates in the Kalachitta Range, Pakistan and it is the only stratigraphic record of Late Cretaceous sedimentation in northwestern Lesser Himalayas. Global sea-level marks a gradual fall of ∼40 to 50 m during the deposition of the Kawagarh Formation. This study is based on detailed outcrop and petrographic investigations of six stratigraphic sections exposed in Kalachitta Range. Carbonate grains are dominantly composed of pelecypods, oysters, trigonia and plankton distributed in a micritic groundmass. Five microfacies, (1) Planktonic Mudstone, Wackestone and Packstone Microfacies, (2) Pelecypodic Planktonic Mudstone and Wackestone Microfacies, (3) Pelecypodic Wackestone and Packstone Microfacies, (4) Marl Microfacies and (5) Dolostone Microfacies, were identified using distribution of faunal types and matrix. Based on faunal paleoecology, microfacies analysis and sedimentary structures, a shallow open-marine, northward-dipping ramp model has been proposed for the deposition of the Kawagarh Formation beginning with a transgressive cycle, which also corresponds to global sea-level rise, and possibly terminated by uplift owing to initial collision of the Indian Plate with the Kohistan-Ladakh Arc at the end of the Cretaceous.

KEYPOINTS

1. Paleontological and paleoecological evidence is used to develop a shallow, open-marine ramp deposition model for the Kawagarh Formation.

2. The initiation of Kawagarh sedimentation with transgression in the late Turonian synchronise with global sea-level curve. Sedimentation was terminated by initial collision of the Indian Plate with the Kohistan-Ladakh Arc.

Keywords:

• Kalachitta Range
• Cretaceous
• microfacies
• Kohistan-Ladakh Arc
• carbonate ramp
• Kawagarh Formation

Acknowledgements

We would like to thank all of our colleagues with whom we have collaborated for this study. The conclusions drawn here are produced after many conversations. We especially acknowledge Nadeem Anjum from Geological Survey of Pakistan and Hamad Raheem from Pakistan Museum of Natural History.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The fieldwork and laboratory experiments have been financially supported by the Institute of Geology, University of the Punjab.