Schelling, Daniel D.1, John M. Hurst2, Amir Ayub3
(1) Structural Geology International, LLC, Salt Lake City, UT
(2) Novus West Asia, Dubai, United Arab Emirates
(3) Premier-Kufpec Pakistan, Islamabad, Pakistan
ABSTRACT: Structural Styles and Evolution of a Transpressional Plate Margin and Fold-Thrust Belt; the Kirthar Range of Western Pakistan
Located along the presently active, western transpressional plate margin to the Indian subcontinent, the north-south trending Kirthar Range of western Pakistan includes a complex set of structural systems that have generally developed as a result of structural interference and overprinting since the collision of the Indian subcontinent with Eurasia and the Afghan block. Within the southern Kirthar Range, structural systems have developed primarily as a result of thin-skinned detachment tectonics, with fault-propagation, hanging wall anticlines defining the primary hydrocarbon targets. Further north, however, within the central and northern Kirthar Ranges, transpressional tectonics have resulted in significant uplift, on the scale of 7 to 10 km, along deep-seated fault systems that originate below the massive, Jurassic Chiltan Limestone. Clear evidence for detachment tectonics within the central and northern Kirthar ranges is restricted to the Tertiary stratigraphic section and may or may not involve passive roof duplexing. Within the central Kirthar Range, in the vicinity of Kalat, structural overprinting has resulted in the deformation of previously developed compressional systems by late-stage strike slip systems. However, within the Quetta syntaxis, where the north-south trending Kirthar Range meets the east-west trending, southern sector of the Sulaiman Range, complex structural interference patterns have resulted in the formation of the Zarghun structure along which gas was discovered in 1998. The overall interaction of compressional and strike-slip structural styles along the Kirthar Range has therefore resulted in complex structural systems that must be understood for succesful hyrdrocarbon exploration in this recently recognized hydrocarbon province.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.