南京大学曹剑教授团队近日取得一项新突破。他们的最新研究揭示了准噶尔盆地古亚洲洋闭合期间海退的红藻证据及其与生烃的联系。2024年8月5日出版的《中国科学：地球科学》杂志发表了这项成果。

本文报道了准噶尔盆地海相红藻化石及其与生烃的联系。红藻主要产于风城组(ca.300Ma)，为古亚洲海洋的闭合提供了直接的化石证据。这些红藻化石包含保存完好的生殖器官，如囊果和果孢子。在含红藻烃源岩中检测到高浓度的C₂₇甾烷(C₂₇规则甾烷/C₂₇-C₂₉规则甾烷之和×100=14.30%- 21.30%)和海洋生物标志物24-n-正丙基胆甾烷(C₃₀二甾烷[βα20S]/C27- C30二甾烷[βα20S]之和×100=1.15%-1.85%)。

模拟生烃的热模拟实验表明，含红藻烃源岩的生油潜力为363.71mg g^-1总有机碳。这一结果结合油源岩对比表明，这些岩石对油气资源的形成有贡献，特别是在坳陷边缘地区。湖盆在海退过程中继承了古亚洲海洋的水环境和生物条件，这是在碱性盐湖中形成优质烃源岩的重要因素。研究结果推进了研究人员对古亚洲海洋演化、陆相烃源岩沉积过程中海洋与湖泊的相互作用以及红藻是否能有效生烃等问题的理解。

据介绍，古亚洲洋的闭合是石炭纪—二叠纪期间泛古陆北部的一个重大地质事件。它对晚古生代冰期的气候、生物群和环境条件产生了重大影响，并导致了大量能源资源的开发。

附：英文原文

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

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

Issue&Volume: 2024/08/05

Abstract: 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. 300Ma) 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 C₂₇ steranes (C₂₇ regular steranes/sum of C₂₇–C₂₉ regular steranes×100=14.30%–21.30%) and the marine biomarker 24-n-propylcholesterane (C₃₀ diasterane [βα20S]/sum of C₂₇–C₃₀ 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 363.71mg 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.

DOI: 10.1007/s11430-023-1343-9

Source: https://www.sciengine.com/10.1007/s11430-023-1343-9