Xubin Wang, Lin Dong, Tong Li, Kun Ling, Changhu Zhang, Yijie Bin, Ziyi Wang, Zhijun Jin, Jinhua Fu
{"title":"利用氮硫同位素联用重建氧化还原景观鄂尔多斯盆地(华北)延长地层中-晚三叠世昌七层组案例研究","authors":"Xubin Wang, Lin Dong, Tong Li, Kun Ling, Changhu Zhang, Yijie Bin, Ziyi Wang, Zhijun Jin, Jinhua Fu","doi":"10.1029/2024GC011656","DOIUrl":null,"url":null,"abstract":"<p>Euxinia, a crucial geological condition, usually signifies more severe extinction events attributed to deoxygenation in Earth's history. Despite extensive exploration of various proxies in paleoredox studies, most are primarily utilized to reconstruct atmospheric <i>p</i>O<sub>2</sub>, the proportion of anoxic water relative to the entire basin, and broader trends in redox states. Few, however, hold the capacity to precisely delineate local euxinia within confined areas. To address this gap and gain insights into the temporal and spatial extent of benthic euxinia, we propose leveraging the synergistic analysis of total nitrogen isotopes (δ<sup>15</sup>N<sub>TN</sub>) and pyrite sulfur isotopes (δ<sup>34</sup>S<sub>py</sub>). Our study focuses on the Triassic Chang 7 Member from the Yanchang Formation, Ordos Basin, North China. Through coupling the δ<sup>15</sup>N<sub>TN</sub> and δ<sup>34</sup>S<sub>py</sub> systematics on 11 drill cores within the Ordos Basin, we reconstruct the temporal and spatial distribution of the benthic euxinia zone during the Chang-7 period. Our results suggest strong spatial heterogeneity of benthic redox conditions, with the euxinia boundary shifting from the central lake to the southwestern sections. Moreover, we identify redox-controlling factors, including organic carbon loading, water depth, and potential water circulation, and evaluate their interplay with benthic euxinia. Furthermore, the discernment of water circulation patterns may provide an innovative approach to restore the paleowind direction. These findings highlight the effectiveness of coupling δ<sup>15</sup>N<sub>TN</sub> and δ<sup>34</sup>S<sub>py</sub> in reconstructing the local benthic redox landscape of benthic environments, and enrich our understanding of biogeochemical processes.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"25 8","pages":""},"PeriodicalIF":2.9000,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC011656","citationCount":"0","resultStr":"{\"title\":\"Reconstructing Redox Landscape With Coupled Nitrogen-Sulfur Isotopes: A Case Study From Middle-Late Triassic Chang 7 Member of the Yanchang Formation in the Ordos Basin (North China)\",\"authors\":\"Xubin Wang, Lin Dong, Tong Li, Kun Ling, Changhu Zhang, Yijie Bin, Ziyi Wang, Zhijun Jin, Jinhua Fu\",\"doi\":\"10.1029/2024GC011656\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Euxinia, a crucial geological condition, usually signifies more severe extinction events attributed to deoxygenation in Earth's history. Despite extensive exploration of various proxies in paleoredox studies, most are primarily utilized to reconstruct atmospheric <i>p</i>O<sub>2</sub>, the proportion of anoxic water relative to the entire basin, and broader trends in redox states. Few, however, hold the capacity to precisely delineate local euxinia within confined areas. To address this gap and gain insights into the temporal and spatial extent of benthic euxinia, we propose leveraging the synergistic analysis of total nitrogen isotopes (δ<sup>15</sup>N<sub>TN</sub>) and pyrite sulfur isotopes (δ<sup>34</sup>S<sub>py</sub>). Our study focuses on the Triassic Chang 7 Member from the Yanchang Formation, Ordos Basin, North China. Through coupling the δ<sup>15</sup>N<sub>TN</sub> and δ<sup>34</sup>S<sub>py</sub> systematics on 11 drill cores within the Ordos Basin, we reconstruct the temporal and spatial distribution of the benthic euxinia zone during the Chang-7 period. 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Reconstructing Redox Landscape With Coupled Nitrogen-Sulfur Isotopes: A Case Study From Middle-Late Triassic Chang 7 Member of the Yanchang Formation in the Ordos Basin (North China)
Euxinia, a crucial geological condition, usually signifies more severe extinction events attributed to deoxygenation in Earth's history. Despite extensive exploration of various proxies in paleoredox studies, most are primarily utilized to reconstruct atmospheric pO2, the proportion of anoxic water relative to the entire basin, and broader trends in redox states. Few, however, hold the capacity to precisely delineate local euxinia within confined areas. To address this gap and gain insights into the temporal and spatial extent of benthic euxinia, we propose leveraging the synergistic analysis of total nitrogen isotopes (δ15NTN) and pyrite sulfur isotopes (δ34Spy). Our study focuses on the Triassic Chang 7 Member from the Yanchang Formation, Ordos Basin, North China. Through coupling the δ15NTN and δ34Spy systematics on 11 drill cores within the Ordos Basin, we reconstruct the temporal and spatial distribution of the benthic euxinia zone during the Chang-7 period. Our results suggest strong spatial heterogeneity of benthic redox conditions, with the euxinia boundary shifting from the central lake to the southwestern sections. Moreover, we identify redox-controlling factors, including organic carbon loading, water depth, and potential water circulation, and evaluate their interplay with benthic euxinia. Furthermore, the discernment of water circulation patterns may provide an innovative approach to restore the paleowind direction. These findings highlight the effectiveness of coupling δ15NTN and δ34Spy in reconstructing the local benthic redox landscape of benthic environments, and enrich our understanding of biogeochemical processes.
期刊介绍:
Geochemistry, Geophysics, Geosystems (G3) publishes research papers on Earth and planetary processes with a focus on understanding the Earth as a system. Observational, experimental, and theoretical investigations of the solid Earth, hydrosphere, atmosphere, biosphere, and solar system at all spatial and temporal scales are welcome. Articles should be of broad interest, and interdisciplinary approaches are encouraged.
Areas of interest for this peer-reviewed journal include, but are not limited to:
The physics and chemistry of the Earth, including its structure, composition, physical properties, dynamics, and evolution
Principles and applications of geochemical proxies to studies of Earth history
The physical properties, composition, and temporal evolution of the Earth''s major reservoirs and the coupling between them
The dynamics of geochemical and biogeochemical cycles at all spatial and temporal scales
Physical and cosmochemical constraints on the composition, origin, and evolution of the Earth and other terrestrial planets
The chemistry and physics of solar system materials that are relevant to the formation, evolution, and current state of the Earth and the planets
Advances in modeling, observation, and experimentation that are of widespread interest in the geosciences.