Abstract:
The Spera Ragha-Urghargai region, comprising part of the western Sulaiman Thrust-Fold Belt, is divisible into two lithostratigraphic domains: a) the Spera Ragha-Chinjun area and: b) the Urghargai-Mazu Ghar area, on the basis of sharply contrasting lithostratigraphic characters of their Middle Cretaceous-Eocene successions. The underlying succession of the Triassic Wulgai Formation, Jurassic Loralai Limestone and UpperJurassic-Middle Cretaceous Parh Group and the indiscriminately overlying succession of the Miocene-Pliocene Siwalik Group, however, have comparable lithostratigraphic characters. The division line between the two domains is a thrust zone, which we consider as continuation of the Bibai Thrust Zone. Within the Spera Ragha-Chinjun area the Middle Cretaceous Bibai formation comprises only the in-situ basic volcanic rocks which disconformably underlie the Upper Cretaceous Fort Munro Formation. The succession also include the Upper Cretaceous Moro Formation, Pab Sandstone, Paleocene Dungan Formation and Eocene Ghazij and Kirthar Formations. Stratigraphic succession of the Urghargai-Mazu Ghar area, among other formations, include the Jurassic Loralai Limestone, which has a thrusted lower contact with the Paleocene Dungan Formation of the Spera Ragha-Chinjun area, and Upper Cretaceous Mughal Kot Formation, which transitionally and conformably overlies the volcaniclastic wuccession of the Bibai formation. Also a new lithostratigraphy unit of Pleistocene-Sub-Recent age, the “Spezendai breccia”, has been described for the first time. It is suggested that the Middle Cretaceous-Paleocene succession of the Urghargai-Mazu Ghar area was formed in deep marine environment far away from the succession of the Spera Ragha-Chinjun area, which developed in marginal shallow marine environments, and was later on juxtaposed by tectonic transport along the Bibai Thrust.
Page(s):
61-82
DOI:
DOI not available
Published:
Journal: Acta mineralogica pakistanica, Volume: 11, Issue: 1, Year: 2000