SHRIMP U–Pb c. 1860 Ma anorogenic magmatic signatures from the NW Himalaya: implications for Palaeoproterozoic assembly of the Columbia Supercontinent
Published:January 01, 2009
Sandeep Singh, A. K. Jain, Mark E. Barley, 2009. "SHRIMP U–Pb c. 1860 Ma anorogenic magmatic signatures from the NW Himalaya: implications for Palaeoproterozoic assembly of the Columbia Supercontinent", Palaeoproterozoic Supercontinents and Global Evolution, S. M. Reddy, R. Mazumder, D. A. D. Evans, A. S. Collins
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The basal parts of the Higher Himalayan Crystallines (HHC), Lesser Himalayan sedimentary sequences and mylonite zone at the base of Main Central Thrust (MCT) within the NW Himalaya clearly demonstrate anorogenic magmatic signatures at around 1860 Ma, as indicated by SHRIMP U–Pb zircon ages from Bandal granitoids, Kulu–Bajura mylonite and Wangtu granitoids along the Sutlej Valley, Himachal Pradesh. Some of the zircon crystals contain older cores mostly extending back to 2600 Ma. We report for the first time a 3000 Ma old zircon core from Wangtu granitoids, which indicates reworking of ensialic Archaean crust during the assembly of the Columbia Supercontinent between 2.1 and 1.8 Ga. During the Himalayan collisional tectonics, the reworked Archaean and Palaeoproterozoic crust was imbricated and placed adjacent to each other in the Higher Himalayan Crystallines, the Inner Lesser Himalayan window zone and the Kulu–Bajura Nappe.
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Palaeoproterozoic Supercontinents and Global Evolution
The Palaeoproterozoic era (2500–1600 Ma) was a critical period of Earth history, with dynamic evolution from the deep planetary interior to its surface environment. Several lines of geological evidence suggest the existence of at least one pre-Rodinia supercontinent, named Nuna or Columbia, which formed near the end of Palaeoproterozoic time. Prior to this assembly, there may have been an older supercontinent (Kenorland) or perhaps only independently drifting supercratons. The tectonic records of amalgamation and dispersal of these ancient landmasses provide a framework that links processes of the deep Earth with those of its fluid envelope. The sixteen papers in this volume present reviews and new analytical data that span the geological record of Palaeoproterozoic Earth and provide a current picture of Palaeoproterozoic research. The volume provides a useful reference book for students and professional geoscientists interested in this important period of global evolution.