臼齿碳酸盐岩：解密前寒武纪海洋化学性质的钥匙_旷红伟.pdf

书书书第 25 卷第 1 期2023 年2 月古地理学报JOUNAL OF PALAEOGEOGAPHY(Chinese Edition)Vol.25No.1Feb 2023文章编号:16711505(2023)01000122DOI:107605/gdlxb202301001臼齿碳酸盐岩:解密前寒武纪海洋化学性质的钥匙*旷红伟1彭楠1王玉冲2白华青3祁柯宁1柳永清11 中国地质科学院地质研究所，北京 1000372 中国矿业大学(北京)地球科学与测绘工程学院，北京 1000833 中国地质科学院，北京 100037摘要臼齿构造(Molar tooth structure，MTS)是指主要由微米级微亮晶方解石充填的、具有肠状褶皱等特殊形态和结构的前寒武纪沉积构造。具有臼齿构造的这类前寒武纪碳酸盐岩称为臼齿碳酸盐岩(Molar toothcarbonate，MTC)。MTS 具有全球分布、时代限定、形态多样、由微米级微亮晶方解石组成及早期成岩等基本特征，该认识早已得到学界广泛认同。在系统归纳 MTC 的地理分布、发育时限、宏观形态和微观组构的基础上，再次总结性地剖析了物理作用、生物作用和生物地球化学作用 3 类主要成因假说的基本论点及其局限性。长期以来，作为一种大量出现于中新元古代、具全球性分布的特殊碳酸盐岩类或沉积构造，研究关注的焦点和热点是 MTS 形成与消失的机制。尽管 MTS 成因还有争议，但其所具有的早期成岩特征，使越来越多的研究者将其作为前寒武纪海洋地球化学环境重建的重要研究对象。MTC 的兴衰与前寒武纪海洋化学性质演化和前寒武纪一系列全球性事件密不可分。在此基础上提出 MTC 进一步研究的方向:一是探索 MTC 事件与相关全球性事件(如叠层石、冰川事件等)相互响应、促进或消长的关系，MTS 的兴衰如何协同 Columbia 和 odinia 超大陆的聚散过程;二是从 MTS 微亮晶方解石微观组构出发，采用行之有效的地球化学方法，将 MTC 的形成、演化、更替与前寒武纪海洋性质以及大气圈、生物圈的演化相结合，进一步完善 MTC 成因理论，为前寒武纪诸多重大科学问题的研究提供参考。关键词臼齿碳酸盐岩臼齿构造微观组构古海洋前寒武纪第一作者简介旷红伟，女，1969 年生，博士，中国地质科学院地质研究所教授，主要从事沉积学、中新元古代地层学与事件沉积的研究工作。E-mail:。中图分类号:P588.24+5文献标志码:A*国家重点研发计划:地球系统与全球变化(编号:2022YFF0800302)，中国地质调查项目(编号:DD20221649)，国家自然科学基金项目(编号:42072135;41472082)，北京市科技计划课题国际创新资源合作项目(编号:Z201100008320007)联合资助。Co-funded byNational Key esearch and Development Program of China(No 2022YFF0800302)，China Geological Survey(No DD20221649)，the National Nat-ural Science Foundation of China(Nos 42072135;41472082)，Peking International Innovation and esource Cooperation Program(NoZ201100008320007)收稿日期:20220721改回日期:20220922Molar tooth carbonate:a key to understand geochemistrycharacteristics of the Precambrian oceanKUANG Hongwei1PENG Nan1WANG Yuchong2BAI Huaqing3QI Kening1LIU Yongqing11 Institute of Geology，Chinese Academy of Geological Sciences，Beijing 100037，China2 College of Geosciences and Surveying Engineering，China University of Mining and Technology(Beijing)，Beijing 100083，China3 Chinese Academy of Geological Sciences，Beijing 100037，China古地理学报2023 年 2 月AbstractMolar tooth structure(MTS)refers to a series of peculiar，ptygmatically folded and sparfilled cracks in finegrained carbonates of the Precambrian Particular Precambrian carbonate with MTSis called the Molar tooth carbonate(MTC)Consensuses have been achieved that the MTS is globally dis-tributed and composed of micro-sized sparry calcite，developed during a specific time limit，early diage-netic product，and has diversified morphologies Based on a systematical summary of the palaeogeographi-cal distribution，development time limit，macro morphology，and the micro fabric of MTS，this papersystematically analyzes the basic arguments and limitations of the three hypotheses of MTC origin，i.e，thephysical origin，biological origin，and the biogeochemical origin hypothesis As a globally distributed spe-cial carbonate that only appeared during the Meso-and Neoproterozoic，the focuses and hot spots of theMTC researches are the formation and disappear mechanisms Although there are still controversies aboutthe formation mechanism，the early diagenetic characteristics of the MTC made a growing number of geolo-gists regard the MTC as an important recorder to reestablish the geochemical properties of the Precambrianocean The flourishing and(or)dismissal of the MTC has a close relationship with the evolution of paleo-cean properties，the supercontinent cycles，and a series of global geological events Further researches a-bout the MTC can go in two aspects:one is to explore the reciprocal response，promotion or inhibition re-lationship between the MTC and global events such as stromatolites，glacial events，etc，and how to cou-ple the MTC events to the assembly and breakup processes of the Columbia and odinia supercontinents;the other is the microscopic fabric of the microspar in the MTS，select adopt effective geochemical meth-ods，in order to combine the researches of the occurrence，evolution，and cessation of the MTC with theevolution and changes of atmosphere，biosphere，and the Precambrian ocean properties，and finally im-prove the theory of the MTC formation mechanism All these researches will help and provide clues to solveseveral major Precambrian scientific problemsKey wordsmolar tooth carbonate，molar tooth structure，microfabric，paleo-ocean，PrecambrianAbout the first authorKUANG Hongwei，born in 1969，is a professor and doctoral supervisor atthe Institute of Geology，CAGS She is mainly engaged in sedimentology，Meso-Neoproterozoic stratigra-phy and event sedimentology E-mail:臼齿构造(Molar tooth structure，MTS)是一种具有肠状褶皱等特殊形态和结构的前寒武纪沉积构造。具有这类特殊沉积构造的碳酸盐岩，称为臼齿碳酸盐岩(Molar tooth carbonate，MTC)。Bauer-man(1885)最早用该词来描述加拿大美国北部边境附近 Belt 超群中一种类似于大象臼齿斑纹特征的碳酸盐岩。最古老的 MTC 零星出现在太古宙末期，其后广泛发育在中新元古代克拉通盆地内碳酸盐岩缓坡台地的潮间浅海潮下带。臼齿碳酸盐岩事件是自第一次大氧化事件(Great Oxygena-tion Event，GOE)(Lyons et al，2014)以来至新元古代“雪球事件”之前，在前寒武纪海洋中发生的全球性地球化学沉积事件，在新元古代拉伸纪达到发育顶峰，而在成冰纪雪球地球事件前几乎全部消失，参与了近一半的地球演变历史(2.6 0.72 Ga?)。MTC 的出现丰富了碳酸盐岩成因类型与结构构造(Kah and Bartley，2021)，也为追溯和揭示元古宙海洋性质及其演变提供了绝佳材料。对于缺乏古生物化石的元古宇来说，MTC 明确的形成时代与环境，不仅提供了很好的地层对比与沉积环境类比的标志物(旷红伟等，2011a，2019)，而且可为古海洋地球化学研究与全球古地理重建提供依据和材料(Kah and Bartley，2021