Late Cretaceous ophiolite obduction and Paleocene India-Asia collision in the westernmost Himalaya

Late Cretaceous ({dollar}sim{dollar}100 Ma) collision of the Kohistan island arc with Asia caused a temporary jump of subduction southward to a spreading center just north of the Indian craton. Subsequently, during the Late Cretaceous (Santonian-Campanian), the NW Indian craton was thrust beneath Albian oceanic crust and a Cenomanian volcano-sedimentary complex. Underthrusting generated an ophiolite-radiolarite belt consisting of the obducted Waziristan, Khost and adjacent ophiolites as well as a complex allochthon of deep marine strata. Tectonic loading and flexural subsidence of the NW Indian margin resulted in sub-CCD deposition of shelf-derived olistostromes and turbidites in the foredeep. Santonian-Maastrichtian calciclastic and siliciclastic sediment gravity flows derived from both margins filled the foredeep as a huge allochthon of Triassic-Jurassic deep marine, rise, slope and shelf strata was thrust ahead of the ophiolites onto the Indian craton. Shallow to intermediate marine strata covered the foredeep during the upper Maastrichtian. During the early Paleocene, India was thrust beneath a second allochthon of open marine uppermost Maastrichtian colored melange that represents the Asian Makran-Indus-Tsangpo accretionary prism. This event represents the initial collision of India and Asia. Laterites formed on the eroded ophiolites and structurally higher colored melange were unconformably overlapped by upper Paleocene and Middle Eocene shallow marine limestones that delineate distinct episodes of collisional and post-collisional deformation. Late Paleocene-Early Eocene post-collisional deformation of the Indian and Asian continental margins may have been at least partly responsible for contemporaneous global warming as well as a remarkable shift in the carbon isotopic ratio of the world's oceans. That shift indicates a relative decrease in the rate of burial of {dollar}sp{lcub}12{rcub}{dollar}C-rich organic carbon. The carbon isotopic shift of the oceans as well as global (greenhouse) warming may have been driven, at least in part, by organic carbon exhumed from marine strata that was oxidized to CO{dollar}sb2{dollar} and incorporated into the biosphere during post-collisional deformation of India and Asia.