Organic carbon oxidation and the associated pyrite formation in deep sediments at the Nankai subduction zone

Nan，Jingbo1,2; Tsang，Man Yin3; Yao，Weiqi2

2024-11-01

10.1016/j.marpetgeo.2024.107081

Marine and Petroleum Geology   影响因子和分区

0264-8172

The preservation of organic carbon (OC) in marine sediments is crucial for Earth's climate by sequestering CO. While OC is mostly remineralized before it reaches the seafloor, a notable fraction is buried in deep-sea sediments, particularly at subduction zones known for their enhanced sedimentation rates that promote OC burial. The mechanisms behind OC recycling and decomposition within subduction zone sediments are governed by biologically mediated redox reactions involving a range of electron acceptors, which facilitate the sequential oxidation of OC. However, direct evidence regarding such effects on OC in deep sediments remains limited. In this study, we examine the contents of pyrite and trace metals of molybdenum (Mo), vanadium (V), and cesium (Cs) in organic-rich deep sediments from the Nankai subduction zone. We find that the pyrite, sulfate, diagenetic illite, and OC contents covary in Unit V, highlighting the important role of organoclastic sulfate reduction and biotic smectite-to-illite reaction at 60–70 °C in OC oxidation and pyrite formation. The profiles of Mo, V, and Cs also align with these processes in the same interval. Our findings contribute to an in-depth understanding of OC dynamics in subduction zones, emphasizing the complex interactions within deep sediments that may influence the global carbon cycle.

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GEOSCIENCES

2-s2.0-85202568391

Scopus

1.Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences,Nanjing,210008,China
2.Department of Ocean Science and Engineering,Southern University of Science and Technology,Shenzhen,518055,China
3.School of Oceanography,University of Washington,Seattle,98195,United States

Nan，Jingbo,Tsang，Man Yin,Yao，Weiqi. Organic carbon oxidation and the associated pyrite formation in deep sediments at the Nankai subduction zone[J]. Marine and Petroleum Geology,2024,169.

Nan，Jingbo,Tsang，Man Yin,&Yao，Weiqi.(2024).Organic carbon oxidation and the associated pyrite formation in deep sediments at the Nankai subduction zone.Marine and Petroleum Geology,169.

Nan，Jingbo,et al."Organic carbon oxidation and the associated pyrite formation in deep sediments at the Nankai subduction zone".Marine and Petroleum Geology 169(2024).