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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 3. (March)

First Page: 512

Last Page: 512

Title: Cyclic Sedimentation of Cretaceous-Paleocene Reservoir Sandstones in West-Central Pakistan: ABSTRACT

Author(s): Wayne A. Pryor, M. N. Qazi, K. A. R. Ghori, S. M. Shuaib

Article Type: Meeting abstract


The Upper Cretaceous and Paleocene sequence in the eastern Sulaiman Range of west-central Pakistan records continuous cyclic sedimentation in shallow-marine, shelf environments. These rocks are 800 m thick and are representative of at least 50 cycles of shoreface and fluvial to fluviotidal origin. Lithogenetic studies using sedimentary structures, trace fossils, and vertical sequences indicate that the shoreline orientation was northwest-southeast with the open shelf on the northeast. Shallow-marine carbonate rocks of the Cretaceous Mughalkot Formation grade abruptly into 26 shoreface cycles and 10 fluvial to fluviotidal cycles of the Cretaceous Pab Sandstone. Gradationally above this are 14 shoreface cycles of the Paleocene Khadro Formation, distinguished from the underl ing Pab Sandstone by the increased amounts of argillaceous matrix and lower-shoreface shales.

The Mughalkot carbonate rocks and the lower-shore-face shale interbeds of the Pab and Khadro Formations may serve as hydrocarbon source beds for the Pab and Khadro sandstone reservoir beds.

This sequence suggests a rather uniform rate of subsidence with episodic transgressions and controlled-sediment-supply progradation. The abrupt increase in the amount of argillaceous detritus during the early Paleocene suggests a significant change in the source-area character.

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