Isotopic and Geochemical Studies of the Ladakh Accretionary Prism North West Himalaya

Abstract

Proposed a new modified model of late stage newlinedevelopment in the collision zone that explains a plausible mechanism for newlinederivation of fluid at deeper level into the mantle and its transportation to the newlinesurface and attendant interaction with the marine components of LAP. According newlineto this model, following the breakoff of the down going Indian continental plate, newlinemantle upwelling took place resulting in decompressional fluid release and newlinemelting. Whereas the younger Kohistan part of magmatic arc may be part of this newlinemagmatic activity, the extensive veining sweeping through the accretionary prism newlineis caused by the fluid activity. However, the isotopic signatures of these fluids newlinewere modified through fractionation and interaction with the marine sediments newlinex newlinetowards southern margin. The fluid involved in the formation of veins migrated in newlinesmall pulses from the mantle simultaneously with the formation of Kohistan newlinemagmatic arc during the Miocene period. As against the general wisdom, that the newlineIndian plate swept beneath the Asian plate and seized the subduction process newlineduring late Oligocene-early Miocene, the results of the present study imply newlinereactivation of mantle magmatic activity at the collision zone during the Miocene newlineepoch. newline