Advances in Earth Science
Xin Chang,Mingyu Zhang,Yu Gu,Houjie Wang,Xiting Liu. Formation Mechanism and Controlling Factors of Authigenic Pyrite in Mud Sediments on the Shelf of the Yellow Sea and the East China Sea[J]. Advances in Earth Science, 2020, 35(12): 1306-1320.
The formation process of marine authigenic pyrite （FeS2） is closely related to the organic mineralization process， representing an important part of the global C-S-Fe biogeochemical cycle. Since the Holocene highstand of sea level， the shelves of the Yellow Sea and the East China Sea have developed mud deposits extensively， in which a large number of authigenic pyrites are present， which provides an opportunity to study their genesis and controlling factors. In terms of spatial distribution， the distribution of pyrite is accompanied by fine-grained mud sediments， because fine-grained sediments are relatively rich in organic matter， and the relatively stable depositional environment is conducive to the progress of microbial sulfate reduction. The differences in sedimentary dynamics， organic matter sources and marine productivity in the Yellow Sea and the East China Sea lead to differences in the formation and burial of pyrite， which in turn cause differences in related indicators （such as the C/S ratio）. In the vertical direction， the content of pyrite generally increases with the increase of depth， indicating that as the depth of burial increases， the dissolved oxygen in the pore water is depleted， which is beneficial to the sulfate reduction； the sulfur isotope of pyrite becomes isotopically heavy with the depth （enrichment of 34S）， which may be related to the openness of the diagenetic system， or the sulfate reduction driven by anaerobic oxidation of methane. In addition， the sedimentation rate controls the content and isotopic composition of pyrite via affecting the burial of organic matter， the efficiency of communication between pore water and seawater， and the location of the sulfate- methane transition zone. The mud areas of the shelves of the Yellow Sea and the East China Sea have accumulated a large number of excellent research results in sedimentary dynamics and sedimentary processes. On this basis， combined with advanced analyzing methods such as multi-sulfur isotopes， in-situ elemental on single pyrite crystal， the potential value of pyrite could be excavated to deal with major scientific issues such as the modern ocean C-S-Fe cycle and deep-time ocean chemical evolution.