Mobility of rhenium and selenium during chemical weathering and their implication for petrogenic organic carbon oxidation  

作　　者：Yuhong ZHANG Jin WANG Yuanxin QU Chao ZHU Zhangdong JIN 

机构地区：[1]State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi'an 710061,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Xi'an Institute for Innovative Earth Environment Research,Xi'an 710061,China [4]Institute of Global Environmental Change,Xi'an Jiaotong University,Xi'an 710049,China

出　　处：《Science China Earth Sciences》2024年第3期740-750,共11页中国科学（地球科学英文版）

基　　金：financially supported by the National Key Research and Development Program of China(Grant No.2022YFF0800500);the National Natural Science Foundation of China(Grant No.41991322)。

摘　　要：The oxidative weathering of petrogenic organic carbon(OC_(petro)) is an important source of carbon dioxide(CO_(2)) into the atmosphere on geological timescales and significantly influences the carbon cycle and global climate change. However, at present, a robust proxy to assess OC_(petro)oxidation is lacking. Riverine rhenium(Re) has emerged as a potential proxy to trace OC_(petro)oxidation, but little is known about Re sources and its relationship with OC_(petro)oxidation. To better understand the robustness of this proxy, we analyzed a shale weathering profile from the early Cambrian Shuijingtuo Formation in Chengkou County, Chongqing City, to address the mobility of Re and selenium(Se) and their relationship with the oxidation of OC_(petro)by analyses of the elemental variation and sequential extraction. The results showed that the chemical index of alteration(CIA)increases from the fresh bedrock to the weathered sections, indicating enhanced weathering intensity. Based on the sequential extraction and mass transfer coefficients(τ), Re and Se mainly exist in the organic phase of shale and are paired lost with OC_(petro) during weathering, with no obvious correlation with sulfide minerals. Furthermore, the different proportions of Re and Se loss with OC_(petro) loss can be attributed to their different geochemical behaviors during weathering. Our study supports Re as a robust proxy to trace OC_(petro) oxidation, whereas Se is the potential one. In the future, combined studies on various sedimentary rock profiles with catchment basins are needed to determine the sources of riverine Re and Se and their relationships with OC_(petro) oxidation.

关 键 词：Rhenium and selenium SHALE MOBILITY OC_(petro) Chemical weathering 

分 类 号：P512.1[天文地球—地质学] P59