LATE CRETACEOUS OPHIOLITE OBDUCTION AND PALEOCENE INDIA-ASIA COLLISION IN THE WESTERNMOST HIMALAYA

Collision of the Kohistan island are with Asia at similar to 100 Ma re sulted in N-S compression within the NeoTethys at a spreading center n orth of the Indo-Pakistani craton. Subsequent India-Asia convergence c onverted the Neo-Tethyan spreading center into a short-lived subductio n zone. The hanging wall of the subduction zone became the Waziristan, Khost and Jalalabad igneous complexes. During the Santonian-Campanian (late Cretaceous), thrusting of the NW Indo-Pakistani craton beneath Albian oceanic crust and Cenomanian volcano-sedimentary complex, gener ated an ophiulite-radiolarite belt. Ophiolite obduction resulted in te ctonic loading and flexural subsidence of the NW Indian margin and sub -CCD deposition of shelf-derived olistostromes and turbidites in the f oredeep. Campanian-Maastrichtian calciclastic and siliciclastic sedime nt gravity flows derived from both margins filled the foredeep as a hu ge allochthon of Triassic-Jurassic rise and slope strata was thrust ah ead of the ophiolites onto the Indo-Pakistani craton. Shallow to inter mediate marine strata covered the foredeep during the late Maastrichti an. As ophiolite obduction neared completion during the Maastrichtian, the majority of India-Asia convergence wasaccommodated along the sout hern margin of Asia. During the Paleocene, India was thrust beneath a second allochthon that included open marine middle Maastrichtian color ed melange which represents the Asian Makran-Indus-Tsangpo accretionar y prism. Laterites that formed on the eroded ophiolites and structural ly higher colored melange during the Paleocene were unconformably over lapped by upper Paleocene and Middle Eocene shallow marine limestone a nd shale that delineate distinct episodes of Paleocene collisional and Early Eocene post-collisional deformation.