【摘要】 臼齿(Molar Tooth)碳酸盐岩问题已经研究了100多年,许多学者都对它的成因提出了不同的假设,但始终未能取得共识。通过对现有各种臼齿碳酸盐岩成因假说概括评述,指出了这些成因假说中存在的种种问题和矛盾,并提出了臼齿碳酸盐岩生物成因的可能性。从元古宙生物演化的规律说明臼齿碳酸盐岩形成、繁盛及衰退的时期与地球上真核生物的出现和繁盛及后生动物出现的界线相一致;从臼齿碳酸盐岩形成的构造背景、气候条件和沉积环境、结构构造特征、化学组成(特别是黄铁矿的形态和SnO2的富集)、碳、氧同位素的分布规律以及生物标志物的多样性等方面提出了臼齿碳酸盐岩生物成因可能性的证据;还特别指出元古宙叠层石的生长和繁盛与臼齿碳酸盐岩的发育呈负相关关系。同时也阐述了生物成因解释遇到的困难,并指出今后应大力开展臼齿碳酸盐岩形成的沉积环境与岩相,特别是早期成岩作用和相关地球化学特征研究。从元古宙古海洋化学性质的变化着手研究将成为揭示臼齿碳酸盐岩成因的根本手段。更多还原

【Abstract】 The origin for Molar Tooth carbonate rocks has been studied more than 100 years, and many scholars have put forward different hypotheses about it. Up to now, a consensus still has not been reached. This study cites all kinds of origin hypotheses for Molar Tooth carbonate rocks at present, points out all the problems and controdictions in these origin hypotheses and advances the possibility of biologic origin for Molar Tooth carbonate rocks. The biological evolution regularity of the Proterozoic illustrates the formation, blooming and withering periods of Molar Tooth carbonate rocks corresponded to the appearing and blooming time boundary of the Eucaryotes and appearing time boundary of the Metazoans. The evidences that prove the possibility of biologic origin for Molar Tooth carbonate rocks include: the structure features, chemical components (especially the shape of pyrite and abundance of SnO2) , the distribution regularity of carbon and oxygen isotopes and the diversity of biomarkers. It is emphasized that there is a negative correlation between the growth and blooming of the Proterozoic stromotolites and Molar Tooth carbonate rocks development. Difficulties in explaining the biologic origin are also set forth. Finally, this study points out that future research should be focused on the sedimentary environments and lithofacies for the formation of Molar Tooth carbonate rocks, especially their early diagenesis and relavent geochemistry.Studies on the change of chemical features of ancient oceans in the Proterozoic will be the fundamental means to probe the origin for Molar Tooth carbonate rocks.更多还原