臼齿构造碳酸盐岩是全球各大陆中、新元古代时期普遍发育的、具有特殊成因意义的碳酸盐岩类型,到目前为止,已在全球20多个地区近50多个中、新元古代地层剖面中被发现.百余年来,有关MT的研究越来越深入,进展显著.从前期和前人较少关注的有关MT与宿主岩石的关系,尤其是从MT与宿主岩石地球化学特征的关系及其所揭示的地质意义出发,通过薄片、电子探针、背散射、阴极发光等测试手段及C、O、Sr同位素的系统测试,对辽东地区新元古代南关岭组、营城子组及兴民村组MT及其宿主岩石的成分、结构、微观组构等特征进行了深入研究.研究证明,MT是原生或早期成岩的产物,由原生海水埋藏成岩和海水直接成岩形成；MT与宿主岩石具有相似的地球化学特征,具有同生或准同生的特点,形成于温暖的正常海水环境,并于Sturtian冰期前终止发育.锶、碳同位素同全球中、新元古代碳-锶同位素理论曲线类比表明,大连新元古代南关岭组和营城子组的形成时限为760～950 Ma,兴民村组形成时限为720～800 Ma,与胶辽徐淮地区新古代地层具有良好可对比性.%The Molar-tooth carbonate (briefly, MT) is one type of carbonates which is developed widely with special origin implication. Until now, MT structures have been found in over 50 stratigraphic sections of Me-so-and Neoproterozoic in more than twenty regions in the world. Since more than one hundred years, the research of MT has achieved significant progress, but it is still a question for geologists. Studying from the relationship between MT and host rocks, especially the relationship between MT and geochemical characteristic of host rocks and its geological implication, and using testing methods such as thin section, electron probe, back-scattering spectrometry, cathodoluminescence (CD, and the systematic testing of C, O, Sr isotopes, the paper focuses on the composition, structure, microscopic structure of MT and its host rocks from Neoproterozoic Nanguanling, Yingchengzi and Xingmincun formations in Dalian, eastern Liaoning Province. It is proved that MT is the production of original or early diagenesis, which was crystallized or diagenesised from the original sea water directly. MT and its host rocks have similar geochemistry with syngenetic or Penecontemporaneous characteristics, and formed in warm normal oceanic environment and disappeared before glaciagenic Sturtian Period. The analogy of the Sr and C isotopes of MT to the global theory curves of Meso-and Neoproterozoic Sr and C isotopes shows that the geological age of the Neoproterozoic Nanguanling and Yingchengzi Formations in Dalian is 760 - 950 Ma, and the Xingmincun Formation is 720 - 800 Ma. The Neoproterozoic strata in Jiao -Liao - Xu - Huai subprovince are well correlated.
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