Abstract: Reinterpretation of Maastrichtian and Early Paleocene Strata in Baluchistan Province, Pakistan: Synsedimentary Tectonic Influence on Sequence Stratigraphy along the Indo-Afghan Collisional Belt
ADAMS, ROY D., Energy & Geoscience Institute, University of Utah, USA; JOHN M. L. CATER, Petroleum Geologists Group, University of Reading, UK
Summary
The Parh Group, Moro Group, and Khadro Formation have been
studied in the northern Kithar Range on the western side of the
Sibi Embayment of Baluchistan Province, Pakistan. Biostratigraphic
data assign Maastrichtian ages to the Parh and Moro groups and an
early Paleocene
age
to the Khadro Formation. Five surfaces that
record subaerial exposure and erosion of marine deposits and/or
paleosol formation on marine deposits are recognized. These five
surfaces, interpreted as sequence boundaries created by falls in
relative sea level, have been correlated over approximately 3600
square kilometers.
Previous workers in the region (British Petroleum 1981, 1982;
Hunting Survey 1961; Shah 1977, 1991) either reported the erosive
surfaces as parallel unconformities with minor erosion or did not
recognize them. None of the previous researchers recognized all
five surfaces, nor did they recognize the extensive and variable
erosion along the surfaces. Incised valleys are interpreted to be
present along each of the four Maastrichtian-age
surfaces. The
early Paleocene surface is not believed to include incised valleys;
instead a well-developed paleosol is present.
The origin of these erosive surfaces is ascribed to both tectonic and eustatic processes. Beck et al. (1996) presented evidence for Late Cretaceous initiation of the collision between the Indian and Afghan plates. Data from Baluchistan pertaining to these erosive surfaces support and strengthen their conclusion. In comparison, Haq et al. (1988) interpret only two “eustatic” falls during the Maastrichtian and early Paleocene.
AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah