Early Cretaceous radiolarians from the Indus suture zone, Ladakh, northern India

Abstract

The Nidar ophiolitic complex in estern Ladakh, northem India, consists of u1tramafic rocks, gabbro and sedimentary-volcanic member, in ascending order. The sedimentary-volcanic member in thee Nidar area is about 370 m in thickness, and is composed of altemating chert, japerite, volcanic rocks, red shale, volcanic conglomerate, sandstone and shale. Among these rocks, chert and shale yields well-preserved radiolarian fossils, which range in age, at least, from Hauterivian to Aptian (Early Cretaceous). These ages are consistent with the Sm-Nd mineral-whole rock isochron age of the underlying gabbro. The lithology, ages and geochemical characteristics of the Nidar ophiolitic complex indicate that the complex formed in an intra-oceanic volcanic arc setting. A chert block from the Shergol ophiolitic melange in westem Ladakh yields Albian radiolarians.