Continental collision tectonics: Evidence from the Himalaya and the neighbouring regions

Abstract The evolution of the Himalaya and the tectonics of neighbouring regions are generally believed to be due to continent-to-continent collision of the Eurasian and the Indian plates. During the last decade, many new data have been obtained and examined and a suite of models has been developed to explain the evolution of the Himalaya and the neighbouring regions. These models could broadly be classified into three categories. The subdivision of the Himalaya into five main structural units is now well accepted. A tectogenetic diagram of the Himalaya is briefly discussed. Ophiolites are reported to occur all along the Indus-Tsangpo Suture zone. Results of geochemical analysis of an ophiolite sequence from Dras in Kashmir Himalaya are presented. Surface wave dispersion and attenuation investigations have revealed the crustal and upper mantle structure below the Himalaya and Tibet plateau. The finding of low-velocity layers is consistent with the concept that horizontal compression has been responsible for creating these weak zones and the inferred elevated temperatures in the vicinity of the Moho discontinuity below Tibet. Earthquake focal-mechanism solutions and interpretation of Landsat imagery indicate that convergence of the Indian plate with Eurasia continues and is accommodated partly by crustal shortening and partly by lateral mass movement at the northwest and the northeast margins of the Indian plate. Palaeomagnetic data from the Himalaya belt and central Asia can be interpreted in support of Molnar and Tapponnier's model of continental collision.