中国石油天然气集团公司石油勘探研究院张水昌团队近日取得一项新成果。他们的最新研究提出了寒武纪海洋碳循环的新模式。2024年5月21日出版的《中国科学：地球科学》发表了这项成果。

据悉，碳循环的经典模式表明，富含¹²C的有机碳的广泛埋藏导致碳同位素δ¹³C正偏移(CIE)，而有机碳的大量氧化导致负CIE。然而，BAsal寒武纪碳同位素偏移(BACE)和Steptoean正碳同位素偏移(SPICE)等全球事件分别为全球负和正δ¹³C偏移，它们也表现出显著的有机碳埋藏异常，显示出碳同位素异常与有机碳埋藏的解耦。

研究基于对塔里木盆地塔东2井寒武纪海洋碳循环和古海洋演化记录分析的基础上，提出了一种包含海洋溶解有机碳(DOC)的寒武系海洋碳循环新模式。研究发现如下：(1)寒武纪海洋存在大量DOC储层，受洋流和古氧化还原条件的调节，对海洋碳循环具有重要影响。(2)早寒武世海洋DOC储层的氧化作用导致了BACE和寒武纪含油气系统的亚洲现象，而SPICE时期海洋DOC储层的扩张导致了全球正δ¹³C偏移，没有明显的有机碳埋藏。

(3)塔里木盆地东部坳陷深盆沉积环境可能促进了芙蓉世富有机质黑色页岩的发育，与SPICE时期的有机碳埋藏相对应，具有超深层油气勘探的潜在前景。今后的研究重点应集中在海洋DOC储层的形成机制、储量规模、影响因素、抵御力和环境效应等方面。预计在地球系统科学、油气勘探等领域将取得新的突破。

附：英文原文

Title: A novel model of the carbon cycle in the Cambrian ocean

Author: Huajian WANG, Shuichang ZHANG, Xiaomei WANG, Jin SU, Yuntao YE, Yuke LIU

Issue&Volume: 2024/05/21

Abstract: The classic model of the carbon cycle suggests that the extensive burial of ¹²C-enriched organic carbon leads to a positive carbon isotope (δ¹³C) excursion (CIE), while massive oxidation of organic carbon results in a negative CIE. However, global events such as the BAsal Cambrian Carbon isotope Excursion (BACE) and the Steptoean Positive Carbon Isotope Excursion (SPICE) are global negative and positive δ¹³C excursions, respectively, and they also exhibit significant organic carbon burial anomalies, displaying decoupling between carbon isotope anomalies and organic carbon burial. Based on the analyses of the Cambrian carbon cycle and paleoceanographic evolution records from well Tadong2 in the Tarim Basin, we propose a novel model of the carbon cycle in the Cambrian ocean that incorporates oceanic dissolved organic carbon (DOC). Our findings are as follows. (1) The Cambrian ocean maintained substantial DOC reservoirs, which were regulated by ocean currents and paleo-redox conditions and exerted significant influence on the oceanic carbon cycle. (2) The oxidation of the oceanic DOC reservoirs during the early Cambrian led to the BACE and the Asian Phenomenon of the Cambrian petroleum systems, while the expansion of the oceanic DOC reservoirs during the SPICE resulted in a global positive δ¹³C excursion and the absence of significant organic carbon burial. (3) The deep-basin sedimentary environment in the eastern depression of the Tarim Basin may have fostered the development of organic-rich black shales during the Furongian Series, corresponding to organic carbon burial during the SPICE and representing potential prospects for ultra-deep oil and gas exploration. Future research should focus on the formation mechanism, reserve scale, and influencing factors of the oceanic DOC reservoirs, as well as their resource and environmental effects. It is expected that new breakthroughs will be made in the fields of Earth system science and oil and gas exploration.

DOI: 10.1007/s11430-023-1313-2

Source: https://www.sciengine.com/10.1007/s11430-023-1313-2