Journal article
Transitional time of oceanic to continental subduction in the Dabie orogen: Constraints from U–Pb, Lu–Hf, Sm–Nd and Ar–Ar multichronometric dating
Lithos, Vol.110(1), pp.327-342
2009
Handle:
https://hdl.handle.net/2376/116703
Abstract
We investigated the oceanic-type Xiongdian high-pressure eclogites in the western part of the Dabie orogen with combined U–Pb, Lu–Hf, Sm–Nd and Ar–Ar geochronology. Three groups of weighted-mean
206Pb/
238U ages at 315
±
5, 373
±
4 and 422
±
7 Ma are largely consistent with previous dates. In contrast, Lu–Hf and Sm–Nd isochron dates yield identical ages of 268.9
±
6.9 and 271.3
±
5.3 Ma. Phengite and amphibole Ar–Ar total fusion analyses give Neoproterozoic apparent ages, which are geologically meaningless due to the presence of excess
40Ar. Plagioclase inclusions in zircon cores suggest that the Silurian ages likely represent protolith ages, whereas the Carboniferous ages correspond to prograde metamorphism, based on the compositions of garnet inclusions. Despite weakly-preserved prograde major- and trace element zoning in garnet, a combined textural and compositional study reveals that the consistent Lu–Hf and Sm–Nd ages of ca. 270 Ma record a later event of garnet growth and thus mark the termination of high-pressure eclogite–facies metamorphism. The new U–Pb, Lu–Hf and Sm–Nd ages suggest a model of continuous processes from oceanic to continental subduction, pointing to the onset of prograde metamorphism prior to ca. 315 Ma for the subduction of oceanic crust, while the peak eclogite–facies metamorphic episode is constrained to between ca. 315 and 270 Ma. Thus, the initiation of continental subduction is not earlier than ca. 270 Ma.
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Details
- Title
- Transitional time of oceanic to continental subduction in the Dabie orogen: Constraints from U–Pb, Lu–Hf, Sm–Nd and Ar–Ar multichronometric dating
- Creators
- Hao Cheng - State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, ChinaRobert L King - School of Earth and Environmental Sciences, Washington State University, Pullman, Washington 99164, USAEizo Nakamura - Institute for Study of the Earth's Interior, Okayama University at Misasa, Tottori 682-0193, JapanJeffrey D Vervoort - School of Earth and Environmental Sciences, Washington State University, Pullman, Washington 99164, USAYong-Fei Zheng - CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, ChinaTsutomu Ota - Institute for Study of the Earth's Interior, Okayama University at Misasa, Tottori 682-0193, JapanYuan-Bao Wu - State Key Laboratory of Geological Processes and Mineral Resources, Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, ChinaKatsura Kobayashi - Institute for Study of the Earth's Interior, Okayama University at Misasa, Tottori 682-0193, JapanZu-Yi Zhou - State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China
- Publication Details
- Lithos, Vol.110(1), pp.327-342
- Academic Unit
- Environment, School of the (CAS)
- Publisher
- Elsevier B.V
- Identifiers
- 99900547403101842
- Language
- English
- Resource Type
- Journal article