Greigite as an Indicator for Salinity and Sedimentation Rate Change: Evidence From the Yangtze River Delta, China

Chen, Yinglu; Zhang, Weiguo; Nian, Xiaomei; Sun, Qianli; Ge, Can; Hutchinson, Simon M.; Cheng, Qinzi; Wang, Feng; Chen, Jin; Zhao, Xuanqi

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.

Citation

Chen, Y., Zhang, W., Nian, X., Sun, Q., Ge, C., Hutchinson, S. M., …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, 126(3), e2020JB021085. https://doi.org/10.1029/2020jb021085

• Journal Article Type: Article
• Acceptance Date: Jan 29, 2021
• Online Publication Date: Sep 8, 2023
• Publication Date: Mar 1, 2021
• Deposit Date: Feb 17, 2021
• Publicly Available Date: Aug 4, 2021
• Journal: Journal of Geophysical Research: Solid Earth
• Print ISSN: 2169-9313
• Electronic ISSN: 2169-9356
• Publisher: American Geophysical Union
• Volume: 126
• Issue: 3
• Pages: e2020JB021085
• DOI: https://doi.org/10.1029/2020jb021085
• Keywords: Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Geochemistry and Petrology, Geophysics
• Publisher URL: https://doi.org/10.1029/2020JB021085
• Related Public URLs: https://agupubs.onlinelibrary.wiley.com/journal/21699356
• Additional Information: 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; Access Information : An edited version of this paper was published by AGU. Copyright 2021 American Geophysical Union.; Funders : National Natural Science Foundation of China; Projects : 41976158;41576094;41771009; Grant Number: 41976158, 41576094, 41771009