A case study on how astronomical cycles affect the organic carbon accumulation  

作　　者：Yang Li Ren-Chao Yang Carlos Zavala Liang Dong Valentin Trobbiani 

机构地区：[1]Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals,Shandong University of Science and Technology,Qingdao 266590,Shandong Province,China [2]Laboratory for Marine Mineral Resources,Qingdao National Laboratory for Marine Science and Technology,Qingdao 266071,Shandong Province,China [3]Geology Department,Universidad Nacional del Sur,Bahía Blanca 8000,Argentina [4]Geología de Cuencas Sedimentarias(GCS)Argentina,Bahía Blanca 8000,Argentina

出　　处：《Journal of Palaeogeography》2023年第4期637-651,共15页古地理学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.41972146);the China Scholarship Council(Grant No.202008370261)。

摘　　要：The paleoclimate change impacts the sedimentary environment and process,which in turn control the accumulation of organic carbon.Numerous studies have shown that the paleoclimate is controlled by astronomical cycles.Hence,understanding how these cycles impact the accumulation of organic carbon is a critical question that requires in-depth discussion.Previous studies have shown that Milankovitch cycle can be revealed from the sediments of the 7^(th)Oil Member(Chang 7 Member for short)of the Triassic Yanchang Formation in the southern Ordos Basin,suggesting that the deposition was controlled by astronomically-forced climate changes.Building on previous research,this study collected natural gamma(GR)data of Chang 7 Member from the N36 Well to further analyze astronomical cycles,combined with X-ray fluorescence(XRF)analysis and total organic carbon(TOC)tests,to reconstruct the paleoenvironment and analyze the organic matter enrichment characteristics.The results of this contribution show that,paleoclimate,paleo-redox conditions,paleo-water level,paleo-productivity and sediment accumulation rate(SAR)collectively controlled the enrichment of organic matter.Notably,this study identified the presence of eccentricity,obliquity,precession,and the 1.2 Myr long obliquity cycle in the Chang 7 Member.These cycles controlled the paleoenvironmental changes at different timescales and influenced the enrichment of organic matter,which has implications for subsequent energy exploration.

关 键 词：CYCLOSTRATIGRAPHY Milankovitch cycle Organic matter enrichment Paleoenvironmental Ordos Basin Chang 7 Member 

分 类 号：P532[天文地球—古生物学与地层学] P512.2[天文地球—地质学]