Origin and preservation mechanisms of organic matter in carbonate concretions from Lower Cambrian black shales in South China
文献类型：期刊论文
| 作者 | Fang, Xinyan1,2,3; Zhang, Qing4; Wu, Liangliang1,2; Geng, Ansong1,2; Liu, Shufen1,2,3; Wang, Pufan1,2,3; Liang, Xiao5 |
| 刊名 | ORGANIC GEOCHEMISTRY
 |
| 出版日期 | 2024-11-01 |
| 卷号 | 197页码:20 |
| 关键词 | High maturity Qiongzhusi Formation Limestone lens Bound biomarkers Trace elements |
| ISSN号 | 0146-6380 |
| DOI | 10.1016/j.orggeochem.2024.104876 |
| 英文摘要 | Carbonate concretions are widely used in paleoclimate, paleoenvironmental, and paleontological studies, and even in the study of potential life on Mars. These petrological, elemental, isotopic, and lipid biomarker signals in Meso-Cenozoic carbonate concretions (relatively low thermal maturity) can effectively preserve details of seawater conditions and benthic ecosystems during the deposition of their host sediments/rocks. However, such research on Precambrian-Cambrian carbonate concretions under highly mature conditions remains scarce, and the ability of these ancient carbonate concretions to retain their original biogenic information remains uncertain. To achieve that, this study examines two Cambrian carbonate concretions, using samples from the center, transition, and rim of each, and their adjacent host black shales from the Lower Cambrian Qiongzhusi Formation in the Yangtze Block, South China. Organic and inorganic geochemical analyses were combined to elucidate the origin and preservation process of organic matter (OM) in these ancient Cambrian carbonate concretions. The results show that the thermal maturity of OM within these concretions (1.8 % EqVRo) is relatively low compared to their adjacent host shales (2.9 % EqVRo). Hopanes and steranes are detectable in both free and calciteoccluded hydrocarbons within these concretions, with concentrations of individual compounds ranging from 0.001 to 0.800 mu g/g TOC, whereas kerogen-bound hydrocarbons lack detectable biomarkers. The results indicate that the two Cambrian carbonate concretions were formed mainly within the iron reduction and bacterial sulfate reduction zones, extending to depths of 10 to 38 m below the sediment-water interface. The OM within these concretions mainly inherited the initial unaltered signature of OM from the Qiongzhusi host shale. The carbonate concretions protected the internal OM from further thermal and secondary (e.g., biodegradation) alteration processes and might also prevent the formation of the conventional macromolecular skeletal kerogen manifested by the absence of bound biomarkers. The biomarkers, in both free and occluded forms, in the Cambrian carbonate concretions still retained their original source information, providing valuable insights into ancient biogeochemical processes during sediment burial and ancient seawater chemistry during the early Cambrian. |
| WOS研究方向 | Geochemistry & Geophysics |
| 语种 | 英语 |
| WOS记录号 | WOS:001334070400001 |
| 源URL | [http://ir.gig.ac.cn/handle/344008/81218]  |
| 专题 | 有机地球化学国家重点实验室 |
| 通讯作者 | Wu, Liangliang |
| 作者单位 | 1.CAS Ctr Excellence Deep Earth Sci, Guangzhou 510640, Peoples R China 2.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Organ Geochem, Guangzhou 510640, Peoples R China 3.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 4.Guangdong Acad Sci, Inst Ecoenvironm & Soil Sci, Guangzhou 510650, Peoples R China 5.CCDC Geol Explorat & Dev Res Inst CNPC, Chengdu 610051, Peoples R China |
| 推荐引用方式 GB/T 7714 | Fang, Xinyan,Zhang, Qing,Wu, Liangliang,et al. Origin and preservation mechanisms of organic matter in carbonate concretions from Lower Cambrian black shales in South China[J]. ORGANIC GEOCHEMISTRY,2024,197:20. |
| APA | Fang, Xinyan.,Zhang, Qing.,Wu, Liangliang.,Geng, Ansong.,Liu, Shufen.,...&Liang, Xiao.(2024).Origin and preservation mechanisms of organic matter in carbonate concretions from Lower Cambrian black shales in South China.ORGANIC GEOCHEMISTRY,197,20. |
| MLA | Fang, Xinyan,et al."Origin and preservation mechanisms of organic matter in carbonate concretions from Lower Cambrian black shales in South China".ORGANIC GEOCHEMISTRY 197(2024):20. |
入库方式： OAI收割
来源：广州地球化学研究所
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