Paleomagnetism and geochronology of the Precambrian mafic dyke swarms of Indian sub-continent and sedimentary formations of Mongolia and Kazakhstan in central Asia - understanding the Precambrian paleogeography and tectonic evolution of India and central Asian microcontinents.

摘要

The first paper presented in this dissertation attempts to examine the igneous history of the younger suite of Harohalli alkaline dykes intruding the Dharwar craton in southern India providing robust constraints on the age of the Harohalli alkaline dyke swarm paleomagnetic pole at ∼1192 Ma. A tentative reconstruction at ∼1.2 Ga using the Harohalli pole places India at intermediate to high latitudes with Laurentia and Australia in a configuration quite different from archetypal Rodinia.;The second paper documents new paleomagnetic and geochronological results from the Anatapur alkaline mafic dykes of the Dharwar, Paleoproterozoic Gwalior traps of the Bundelkhand and Malani Igneous Suite of the Marwar cratons of the Indian subcontinent. The paleomagnetic results from our previous studies on the Harohalli alkaline dykes, Upper Vindhyan sequence and Majhgawan kimberlite are also reviewed in an attempt to constrain the paleogeography of the Indian subcontinent from 1.8 Ga to 580 Ma.;Third paper in this dissertation documents new paleomagnetic and geochronological data from the Precambrian mafic dykes intruding granitoids and supracrustals of the Archean Bundelkhand craton (BC) in northern Peninsular India and is significant in constraining the position of India at 2.0 and 1.1 Ga. The paleomagnetic data from the ∼ 2.0 Ga Bundelkhand dykes and the paleomagnetic data from the Bastar/Cuddapah suggest that the North and South Indian blocks of the Peninsular India were in close proximity by at least 2.5 Ga. The paleomagnetic and geochronological results from Mahoba dyke swarm are significant in constraining the age of the Upper Vindhyan strata to >1000 Ma.;The fourth manuscript documents new paleomagnetic and geochronologic data from the Baydaric block (Mongolia) and Lesser Karatau block (Kazakhstan) in an attempt to enhance our understanding of the complex origin of the microcontinental blocks that form the Central Asian Orogenic Belt (CAOB). The combined analysis of the paleomagnetic and geochronological data from the carbonate rocks of the Tamdy Series of the Lesser Karatau block and the Bayan Gol and Tsagaan oloom Formations of the Baydaric microcontinents, island arc complexes and other cratonic blocks is consistent with a tropical archipelago of microcontinents in a peri-Siberian configuration.