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Long-term evolution of terrestrial inputs from the Ediacaran to early Cambrian: Clues from Nd isotopes in shallow-marine carbonates, South China

Wei, G-Y; Ling, H-F; Shields, GA; Chen, T; Lechte, M; Chen, X; Qiu, C; ... Zhu, M; + view all (2019) Long-term evolution of terrestrial inputs from the Ediacaran to early Cambrian: Clues from Nd isotopes in shallow-marine carbonates, South China. Palaeogeography, Palaeoclimatology, Palaeoecology , 535 , Article 109367. 10.1016/j.palaeo.2019.109367. Green open access

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Abstract

The emergence and radiation of metazoans have been widely attributed to a progressively more oxidizing surface environment through the Ediacaran–Cambrian transition interval. However, the root causes for atmospheric and oceanic oxygenation are still disputed. Long-term tectonic changes could possibly have led to atmospheric oxygenation but geochemical evidence for this linkage remains elusive. In this study, we analyzed the radiogenic Nd isotopic compositions (εNd) of shallow-marine carbonates from South China in order to track secular variations in terrestrial inputs from Ediacaran to early Cambrian time. Compared with most other geochemical indices, the Nd isotope system in carbonates is less susceptible to early diagenetic exchange and can thus act as a robust proxy for continental materials undergoing weathering. We interpret an abrupt excursion to lower εNd values during the middle Ediacaran as due to rapid exchange of different water masses. However, the more gradual trend towards lower Nd isotope values from the Ediacaran to early Cambrian, accompanied by increasing 87Sr/86Sr ratios of the studied carbonates, likely indicates the enhanced weathering of old continental rock following the assembly of Gondwana. Increased net accumulation of atmospheric oxygen as a result of enhanced organic carbon burial may have benefited from intense continental denudation.

Type: Article
Title: Long-term evolution of terrestrial inputs from the Ediacaran to early Cambrian: Clues from Nd isotopes in shallow-marine carbonates, South China
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.palaeo.2019.109367
Publisher version: https://doi.org/10.1016/j.palaeo.2019.109367
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Science & Technology, Physical Sciences, Life Sciences & Biomedicine, Geography, Physical, Geosciences, Multidisciplinary, Paleontology, Physical Geography, Geology, Neodymium isotope record, Continental denudation, Tectonic activity, Neoproterozoic oxygenation event, Animal radiation, EARTH-ELEMENT GEOCHEMISTRY, DOUSHANTUO FORMATION, NEODYMIUM ISOTOPES, ATMOSPHERIC OXYGEN, OCEAN CIRCULATION, SEAWATER, RISE, DIAGENESIS, RODINIA, CONSTRAINTS
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10092454
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