C12-enrichment along intraformational unconformities within Proterozoic Bhander Limestone, Son valley, India and its implication (original) (raw)

The Proterozoic era (2500 - 543 Ma) represents an important time in Earth history in terms of tectonic, atmospheric, oceanic and biologic evolutions. Major tectonic evolutions of this time include amalgamation of continental nuclei to form supercontinents and their break-up during (i) Palaeoproterozoic, (ii) transition from Palaeoproterozoic to Mesoproterozoic, (iii) transition from Mesoproterozoic to Neoproterozoic (e.g. Grenvillian event), and (iv) Neoproterozoic (e.g. Rodinia and Pan-African event). Dramatic change of climate in global scale, and the related biological evolution leading to the advent of multicellular life also took place during the Proterozoic. Abundant presence of redox-sensitive elements viz. Fe and U in Proterozoic rocks implies a unique ocean chemistry, which would have been neither completely anoxic and iron rich as hypothesized for the Archaean seas, nor fully oxic as supposed for most of the Phanerozoic oceans. A refined understanding of these phenomena and how they are interrelated requires detailed multidisciplinary studies of the Proterozoic successions. A National Seminar on "Proterozoic System of India: Evolution and Economic Potential" was organised by the Department of Applied Geology, Indian School of Mines, Dhanbad, on November 11 - 12, 2005. The aim of the seminar was to collate multidisciplinary studies in the Proterozoic successions of Indian subcontinent, to analyze the present status of our understanding, and to identify areas for future research, including emerging trends in mineral exploration. About 43 research papers were submitted for the seminar by 82 authors from different National Institutes and abroad. These were distributed in 6 technical sessions covering Basement for the Proterozoic, Proterozoic Tectonics, Proterozoic Magmatism and Metamorphism, Proterozoic Mineralisation, Sedimentation, Climate and Life, and Socioeconomic aspects of Proterozoic terrains. The present volume is the outcome of contributions received for the National Seminar and some invited papers. The papers cover four different aspects of Proterozoic geology: (i) structure and tectonics, (ii) magmatism, metamorphism and mobile belt evolution, (iii) sedimentation, (iv) mineralisation, and ground water resources.