ABSTRACT: The Nidar ophiolite in Ladakh Himalaya is a substantial fragment of oceanic lithosphere preserved along the western continuance of the Indus – Yarlung-Tsangpo suture zone. It was generated in a supra-subduction zone setting and is linked in development to the Dras intra-Tethyan volcanic arc. Earlier reported Hauterivian – Aptian radiolarians from the volcano-sedimentary succession atop the ophiolite were used to constrain the age of the ophiolite and duration of arc volcanism. Re-assessment of radiolarian taxonomy and biostratigraphy reveals an upper Barremian to upper Aptian range for the Nidar volcano-sedimentary section, the same as for the marine sedimentary cover atop the Dazhuqu ophiolite in the southern Tibet. The lower limit of its stratigraphic range places a minimum temporal constraint on the Nidar ophiolite generation in the late Barremian (ca 126 Ma). This compares well with radiometric age for the ophiolite (124Â± 1 Ma). The sedimentary successions of both ophiolites bear resemblance in the record of associated arc volcanism. Dras arc volcanism in the Nidar section began in the early Aptian. The Nidar and Dazhuqu ophiolites are interpreted as distal chronological equivalents developed in association with the same intra-Tethyan subduction system. Parallels between the evolution of this Cretaceous intra-Tethyan subduction system and other systems in the region remain uncertain.
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