Provenance of latest Mesoproterozoic to early Neoproterozoic (meta)-sedimentary rocks and implications for paleographic reconstruction of the Yili Block |
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| Institution: | 1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China;2. School of Earth, Atmosphere & Environment, Monash University, Melbourne, VIC 3800, Australia;3. College of Earth Science, Chengdu University of Technology, Chengdu 610059, China;1. Institute of the Earth''s Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk 664033, Russia;2. Earth Dynamics Research Group, ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS), Curtin University, GPO Box U1987, WA 6845, Australia;3. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China;4. Tianjin Institute of Geology and Mineral Resources, Tianjin 300170, China;5. The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, GPO Box U1987, WA 6845, Australia;1. Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong;2. Department of Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA 15260-3332, USA;3. Department of Geology, Northwest University, Xi''an 710069, China |
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| Abstract: | The Yili Block is one of the major Precambrian microcontinents of the Central Asian Orogenic Belt (CAOB). Detrital zircon U-Pb ages and Hf isotopic data of the Meso-Neoproterozoic (meta)-sedimentary units within the Yili Block constrain the tectonic affinity and early history of the block. Detrital zircon U-Pb ages, in combination with related magmatic age data, indicate that the Tekesi and Kusitai groups were deposited during the latest Mesoproterozoic-earliest Neoproterozoic (1040–960 Ma) and early Neoproterozoic (<926 Ma), respectively. Zircons from the Kusitai Group yield major age groups at 941–910 Ma and 1887–1122 Ma, whereas the Tekesi Group have a dominant age group at ca. 2.0–1.1 Ga with age peaks at ca. 1.9 Ga, 1.8 Ga, 1.75–1.70 Ga, 1.58 Ga, 1.5 Ga, 1.47–1.43 Ga and 1.27–1.20 Ga. A minor age peak of ca. 2.5 Ga is also recognized in the middle part of the Tekesi Group. Early Neoproterozoic detrital zircons with relatively uniform εHf(t) values (+0.7 to +3.2) were mainly derived from contemporaneous magmatic rocks in the Yili Block. The Central Tianshan Block provides a likely source for detritus with ages of ca. 1.7–1.4 and 2.5 Ga. The predominant late Paleoproterozoic to latest Mesoproterozoic detrital zircons with positive εHf(t) values (+0.5 to +12.0) in the Yili Block were probably derived primarily from regions exhumed during collisional assembly of Rodinia. These populations are consistent with those from the late Mesoproterozoic-early Neoproterozoic (meta)-sedimentary successions in the Central Tianshan, Kokchetav-North Tianshan and Erementau-Niyaz blocks, and Southeast Siberia and northeastern Laurentia cratons. The Yili Block, together with the Precambrian microcontinents in the southwestern Central Asian Orogenic Belt, was likely located at the margin of Rodinia supercontinent, between the southeast Siberia and northeast Laurentia during the early Neoproterozoic. |
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