Zircon provenances provide paleogeographic constraints on models reconstructing the Paleoproterozoic Columbia Supercontinent |
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| Institution: | 1. School of Earth and Planetary Sciences, Curtin University, Perth 6845, Australia;2. Center for Global Tectonics, State Key Laboratory for Geological Processes and Mineral Resources, China University of Geosciences,Wuhan, Hubei Province, 430074, China;3. Crystal World, Australian Mineral Mines Pty. Ltd., 13 Olive Road, Devon Meadows, Victoria 3977, Australia;1. School of Earth Sciences and Engineering, Sun Yat-sen University, Guangzhou 510275, China;2. Guangdong Provincal Key Lab of Geodynamics and Geohazards, Sun Yat-sen University, Guangzhou 510275, China;3. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;4. Bureau of Xinjiang Geology and Mineral Resources Development, Urumqi 830000, China |
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| Abstract: | Paleoproterozoic orogens of the North Australian Craton are related to the assembly of the Columbia Supercontinent. The roles of the distinct orogens in the Paleoproterozoic craton amalgamation are poorly understood due to the lack of surface exposure. The age and isotopic systematics of detrital zircon grains hosted in Paleoproterozoic sedimentary sequences are used to unravel the geological history of the craton, in terms of paleogeography and tectonic setting. The oldest (Early Paleoproterozoic) metasedimentary units are characterised by detrital zircon ages peaking at ca. 2500 Ma. The zircon εHf values show large variations in the different orogens and range from ?18 to +6. The overlaying youngest turbiditic units show minor accumulation of Archean detritus. Units from apparently different metasedimentary sequences have a major detrital zircon age population at ca. 1865 Ma, and a relatively restricted range of zircon εHf values between ?7.3 and +2.6. The isotopic distinctiveness of the oldest units is attributed to local variations in the depositional environment, probably due to horst-graben architecture of the early Paleoproterozoic basin. The youngest turbiditic units blanketed this early horst-graben architecture and in part have a local provenance. Potential detritus sources include South Australian Craton, Dharwar Craton and Aravalli-Lesser Himalayan terrains in India, South China, and Madagascar (Africa). This finding indicates that these regions might have been connected before the Columbia Supercontinent was formed. The ubiquitous ca. 2500 Ma magmatic event records the assembly of these cratonic fragments in a previous supercontinent called Kernorland. In addition, the data do not support a proximity of the North Australian Craton with the North China Block, Western Laurentia (North America), and Kaapvaal Craton (Africa) during Columbia amalgamation. |
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