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Sui Y, Huang C, Zhang R, Wang Z, Ogg J, Kemp DB. Astronomical time scale for the lower Doushantuo Formation of early Ediacaran, South China. Sci Bull (Beijing) 2018; 63:1485-1494. [PMID: 36658830 DOI: 10.1016/j.scib.2018.10.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/21/2018] [Accepted: 10/23/2018] [Indexed: 01/21/2023]
Abstract
Nearly 90% of the Ediacaran Period (635-541 Ma) of the Neoproterozoic is represented by the Doushantuo Formation (DST Fm) in South China. Its lowest Member I is a 3.7 m-thick cap carbonate deposited at the termination of the Cryogenian Marinoan glaciation. The DST Fm consists of alternating organic-rich black shale and thinly bedded dolostone, and it contains some of the oldest records of multi-cellular life and three pronounced negative carbon isotope excursions. The Jiulongwan (JLW) section is a well-studied reference section for these Ediacaran events. Spectral analysis of geochemical data through the lower DST Fm (22.3 m) shows 27 predominant ∼90 cm sedimentary cycles that correspond to 405-ka long eccentricity cycles. The power spectra of the 405-ka tuned Ca and Fe/Ti series show significant peaks at ∼1.2-Ma, 405-ka, 133-ka, 128-ka, 100-ka, 82-ka, ∼31-ka and 29-ka periods, respectively. A 11.16 Ma-long astronomical time scale has been constructed for the lower DST Fm and provide a duration of 1.6 Ma for the cap carbonate (Member I) based on the 405-ka long eccentricity cycle tuning. Using the U-Pb age of 635.2 ± 0.6 Ma for the volcanic ash bed at the Member I/II boundary, we proposed a 636.8 Ma age for the base of the DST Fm. These ages and astronomical timescale provide important new constraints on the subdivision of Ediacaran strata, and have implications for understanding the character of the first negative δ13C excursion (EN1). Orbital forcing may have been played an important role for the climate changes and the evolution of Ediacaran multi-cellular life and the carbon cycle variations.
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Affiliation(s)
- Yu Sui
- State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
| | - Chunju Huang
- State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China.
| | - Rui Zhang
- State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
| | - Zhixiang Wang
- State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China
| | - James Ogg
- State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China; State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu 610059, China; Department of Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - David B Kemp
- State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences, China University of Geosciences, Wuhan 430074, China; School of Geosciences, University of Aberdeen, Aberdeen, Scotland AB24 3UE, UK
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