Greigite as an indicator for salinity and sedimentation rate change : evidence from the Yangtze River delta, China

Chen, Y, Zhang, W ORCID: https://orcid.org/0000-0003-0722-5950, Nian, X ORCID: https://orcid.org/0000-0002-3164-9254, Sun, Q, Ge, C, Hutchinson, SM ORCID: https://orcid.org/0000-0003-0072-1062, Cheng, Q, Wang, F, Chen, J and Zhao, X 2021, 'Greigite as an indicator for salinity and sedimentation rate change : evidence from the Yangtze River delta, China' , Journal of Geophysical Research: Solid Earth .

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Abstract

Ferrimagnetic greigite (Fe3S4) is widespread in the sedimentary environment. Despite abundant reports of greigite occurrence in marine and lacustrine deposits, its formation mechanisms in deltaic deposits remain poorly studied. Here we investigate greigite in Holocene Yangtze River delta deposits using granulometric, magnetic and geochemical methods. The studied cores consist of tidal river, estuary, shallow marine and delta facies in ascending order. The greigite‐bearing layers are found predominantly in the accreting tidal flat facies during the transgression stage and secondarily in the shallow marine facies during the regression stage of the delta's Holocene development. These sedimentary intervals have a higher total sulfur (TS) content and total sulfur to total organic carbon ratios (TS/TOC) suggesting the accumulation of iron sulfides, including greigite, under reducing estuarine and shallow marine conditions. The greigite‐bearing layers in the tidal flat facies have lower Sr/Ba ratios, in comparison to the shallow marine facies, indicating a lower salinity environment. Supported by the dating results, it is suggested that the higher sedimentation rate of the tidal flat facies, caused by rapid sea‐level rise during the early Holocene, favors the formation and preservation of greigite. Our results indicate that the magnetic detection of greigite provides a simple and useful tool for inferring salinity and sedimentation rate changes, and hence better a understanding of the heterogeneity of depositional processes in Holocene delta environments.

Item Type: Article
Additional Information: ** Article version: VoR ** From Crossref journal articles via Jisc Publications Router **Journal IDs: pissn 2169-9313; eissn 2169-9356 **History: issued 04-02-2021; published_online 04-02-2021 **License for this article: starting on 04-02-2021, , http://onlinelibrary.wiley.com/termsAndConditions#vor
Schools: Schools > School of Environment and Life Sciences
Journal or Publication Title: Journal of Geophysical Research: Solid Earth
Publisher: Wiley/American Geophysical Union (AGU)
ISSN: 2169-9313
Related URLs:
Funders: National Natural Science Foundation of China
SWORD Depositor: Publications Router
Depositing User: Publications Router
Date Deposited: 17 Feb 2021 08:55
Last Modified: 17 Feb 2021 10:13
URI: http://usir.salford.ac.uk/id/eprint/59596

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