Wrench Movements in the Baluchistan Arc and Relation to Himalayan-Indian Ocean Tectonics

Satellite photographs provide evidence that the structural discontinuity between the east-west-trending Makran Ranges and the north-south-trending Kirthar and Sulaiman Ranges of the Baluchistan Arc is among the world's major left-lateral shear belts. The Kirthar Sulaiman shear occurs at the junction of the Himalayan and Baluchistan arcs and may have influenced the development of the western Himalayan syntaxis. A similar belt of right-lateral shear is suggested at the junction of the Himalayan and Burmese arcs (eastern Himalayan syntaxis). Between the two extremes the Himalayan arc appears to be affected by gigantic tear faults cutting across the east-west-trending fold and thrust axes. The tectonic pattern suggests that these cross structures are zones of differential lateral movement within the crust related to linear features of sea-floor spreading in the Indian Ocean, the northward drift and underthrust of India beneath the southern edge of the Asian craton.