Tectonic and Isotopic evolution of the Dharwar Craton, India

The crustal evolution of a craton could be studied from analysing its zircon U-Pb record and associated isotopic and elemental composition. The Dharwar Craton in southern India is one such craton on which several independent studies have been conducted on isolated domains within the craton. In this thesis, we have attempted to create a robust tectonic and isotopic evolution model of the Dharwar Craton which also includes previously published data. This thesis is divided into four chapters spanning from the Archean origins of the craton to the latest thermal events affecting various domains within the craton. Chapter 1 deals with zircon U-Pb dating, rare earth element (REE) composition and Lu-Hf isotopic analysis from granitoids sampled across the various domains within the Dharwar Craton to evaluate the crustal evolution episodes from individual domains and compare them to build a robust crustal architecture model for the Dharwar Craton including previously published data. Chapter 2 deals with the detrital record of the Dharwar Craton deposited within the various volcano-sedimentary greenstone belts that unconformably overly the basement granitoid gneisses and igneous batholiths through detrital zircon U-Pb dating, REE compositions. The detrital sequences sampled from the Western Dharwar Craton have been analysed for detrital zircon Lu-Hf isotopes to further constrain the crustal evolution processes within the Western Dharwar Craton. Chapter 3 deals with the detrital record of the Kaladgi-Badami basin, an east-west trending intracratonic Paleoproterozoic basin that unconformably overlies the northern part of Dharwar Craton, which formed as part of the widespread Proterozoic sedimentation across India termed as Purana basins. The detrital zircon U-Pb dating, REE compositional data from various stratigraphic units has been used to infer potential source regions and to compare with sedimentary records across other Paleoproterozoic basins across India and Madagascar to understand the post-assembly tectonic process within the Dharwar Craton which led to the formation of the Kaladgi-Badami basin. Chapter 4 deals with the thermal record of the Western Dharwar Craton by magmatic and meta-igneous zircon, apatite and monazite: U-Pb dating, REE composition sampled along the western margin along the Dharwar Craton including the adjacent Coorg block and Karwar block. The difference between ages obtained using high-temperature zircon (>800° C) U-Pb dating and medium temperature (450—550° C) apatite U-Pb dating was used to infer the timing and spatial extent of the last thermal event experienced across the Dharwar Craton and correlate with contemporaneous tectonic events.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 202