Red algal evidence for a marine regression during closure of the Paleo-Asian Ocean in the Junggar Basin and its linkage to hydrocarbon generation  

作　　者：Ruijie ZHANG Jian CAO Lizeng BIAN Wenxuan HU Liuwen XIA Bin ZHANG Yong TANG Wenjun HE 

机构地区：[1]School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China [2]PetroChina Xinjiang Oilfield Company,Karamay 834000,China

出　　处：《Science China Earth Sciences》2024年第9期2845-2863,共19页中国科学（地球科学英文版）

基　　金：jointly supported by the National Natural Science Foundation of China(Grant Nos.42230808,42102148);the PetroChina Science and Technology Major Project(Grant No.2021DJ0108)。

摘　　要：The closure of the Paleo-Asian Ocean was a significant geological event in northern Pangea during the Carboniferous-Permian.It had a significant effect on climate,biota,and environmental conditions of the Late Paleozoic Ice Age,and resulted in the development of vast energy resources.This paper reports on the first discovery of marine red algal fossils in the Junggar Basin and its linkage to hydrocarbon generation.Red algae occur mainly in the Fengcheng Formation(ca.300 Ma)and provide direct fossil evidence for closure of the Paleo-Asian Ocean.The red algal fossils contain well-preserved reproductive organs,such as cystocarps and carpospores.High concentrations of C_(27) steranes(C_(27) regular steranes/sum of C_(27)-C_(29) regular steranes×100=14.30%-21.30%)and the marine biomarker 24-n-propylcholesterane(C_(30) diasterane[βα20S]/sum of C_(27)-C_(30) diasteranes[βα20S]×100=1.15%-1.85%)were detected in the red-algae-bearing hydrocarbon source rocks.Thermal experiments that simulate hydrocarbon generation show that the oil generation potential of the red-algae-bearing source rocks is 363.71 mg g^(-1) total organic C.This result,combined with oil-source rock correlations,indicates these rocks contributed to the formation of oil and gas resources,particularly in the marginal areas of the depression.The lake basin inherited the water and biological conditions of the Paleo-Asian Ocean during a marine regression,which was an important factor in the development of these high-quality hydrocarbon source rocks in an alkaline saline lake.The results advance our understanding of the evolution of the Paleo-Asian Ocean,interactions between the ocean and a lake during the deposition of terrestrial hydrocarbon source rocks,and whether red algae can effectively generate hydrocarbons.

关 键 词：Biotic precursor 24-n-propylcholesterane Regressive lake basin Fengcheng Formation Junggar Basin 

分 类 号：Q949.9[生物学—植物学] P618.13[天文地球—矿床学]