Cambrian geology of the Salt Range of Pakistan: Linking the Himalayan margin to the Indian craton

摘要

Sedimentological, detrital zircon, and biotic analyses of Cambrian deposits from the Salt Range of Pakistan show that these southwesternmost Himalayan strata were depositionally contiguous with rocks further to the south on the Indian craton. This continuity refutes the recent suggestion that the Salt Range thrust represents the boundary between the Indian Shield and an ancient, exotic Himalayan terrane. During the Cambrian, a northward-thickening and northward-deepening succession draped the northern Indian craton and Himalayan region, extending as far north as the current suture with Tibet. In the Indian and Nepali Lesser Himalaya, much of this succession has subsequently been eroded, exposing rocks >1.6 Ga. Eroded Cambrian and Neoproterozoic strata help refute a model implying that the Lesser Himalaya is defined by rocks with only >1.6 Ga age signatures. Equivalence of the Panjal-Khairabad fault, which lies to the north of the Salt Range in Pakistan, with the merged Main Central thrust and South Tibet fault system of India is supported by similar contrasts in Neoproterozoic and Paleozoic stratigraphy across these faults.