Spatiotemporal evolution of late Neoproterozoic marine environments on the Yangtze Platform (South China): Linking continental weathering and marine C-P cycles

Autor(en)

Simon V. Hohl, Shao-Yong Jiang, Harry Becker, Hai-Zhen Wei, Wei Guang-Yi, Juan Xu, Qingjun Guo, Sebastian Viehmann, David van Acken

Abstrakt

The geodynamic reorganization of major cratonic blocks during the assembly of Gondwana in the late Neoproterozoic caused a (bio)geochemical evolution of marine habitats that witnessed fluctuating seawater oxygenation and nutrient fluxes. Previous studies of carbonates deposited on the Yangtze Platform (South China) have shown their use as reliable archives of paleo-redox and bio-productivity changes intrinsically linked to continental weathering fluxes and water mass cycling. Despite its complex submarine morphology, only a few carbonate-bearing sections comprising deeper depositional environments of the Yangtze Platform have been evaluated. Here we report temporal, lateral, and vertical variations of stable C and radiogenic Sr, Nd, and Os isotopic compositions together with trace element and rare earth and yttrium (REY) systematics in carbonates from the Doushantuo Formation representing different paleo-marine environments of the Yangtze Platform, including I) inner shelf, II) restricted intra-shelf basin, III) slope and IV) deep-water basin sections to trace the extent and evolution of paleo water masses. Variations in shale-normalized (subscript SN) Ce anomalies argue for variably oxidizing atmosphere/ocean conditions. The combination of REY

_SN systematics with carbonate associated P enrichments defines three distinct local water masses from which the carbonates precipitated: i) fully oxidized shallow-water, ii) nutrient-poor intra-shelf basin waters, and iii) organic carbon-rich slope and deep-waters with temporal evolution to higher dissolved pO

₂. Negative carbon isotope excursions in the carbonates such as during the putative Shuram equivalent Doushantuo Negative Carbon Excursion (DOUNCE) correlate with less negative Ce

_SN anomalies and ambient seawater shifts to more radiogenic initial

⁸⁷Sr/

⁸⁶Sr and

¹⁸⁷Os/

¹⁸⁸Os, but unradiogenic

¹⁴³Nd/

¹⁴⁴Nd compositions, arguing for coupling of redox and weathering trends. Our comprehensive geochemical study highlights the vertical and temporal variations of physicochemical water mass properties recorded in late Neoproterozoic Yangtze Platform carbonates until the emergence of the first metazoans.

Organisation(en)

Department für Lithosphärenforschung

Externe Organisation(en)

China University of Geosciences, Freie Universität Berlin (FU), University College Dublin, Tongji University, Nanjing University, Chinese Academy of Sciences (CAS)

Journal

Global and Planetary Change

Band

216

Anzahl der Seiten

13

ISSN

0921-8181

DOI

https://doi.org/10.1016/j.gloplacha.2022.103927

Publikationsdatum

09-2022

Peer-reviewed

Ja

ÖFOS 2012

105128 Geomikrobiologie, 105105 Geochemie, 105121 Sedimentologie

Schlagwörter

ASJC Scopus Sachgebiete

Oceanography, Global and Planetary Change

Sustainable Development Goals

SDG 14 – Leben unter Wasser

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/da6972aa-d16b-4054-97e6-31b179c5b0e7