| 吉辽地区新元古代臼齿碳酸盐岩岩相的若干岩石学特征研究 |
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| 关键词:Molar Tooth structure carbonates petrological feature sedimentary facies |
| 基金项目:国际地质对比计划项目IGCP447(批准号:SC/GEO/546/447);国家自然科学基金项目(批准号:40172043);科技部国家重点基础研究项目(001CB711002) |
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| Sedimentary Lithofacies and Petrological Features of Neoproterozoic MT Structures-Bearing Carbonates in Jilin-Liaoning Area |
| Molar Tooth Structure( called Mtfor short) is a special sedimentary structure developed in Jilin-Liaoning area. The macro- and micro- features and the environment for its formation are discussed in this paper. MT of this area mainly occurrs in Proterozoic strata and can be classified into two types: one remains in situ and the other has been transported. The in situ type, which can be subdivided into filament-shaped, ribbon-like and tumorous subtype and 13 microfacies mostly occurs in arenaceous limestones, calcareous siltstone and silty mudstone, while the micro-crystal allochthonous MT carbonates are distributed in arenaceous limestones, calcareous siltstones or silt mudstones. MT structures in Jilin-Liaoning area are closely related to storms. Hummocky cross bedding and graded bedding, for example,are developed commonly at the surface of rocks. MTS-bearing rocks contist of two parts: the matrix and the micro-sparry carbonates. Petrographic statistic show that terrigenous debris in the matrix is less than 30%, pyrite and hematite account for about 0～3%, and the matrix is dominated by Ca, Mg, Al, Si, K and Fe. MT micro-sparry carbonates clearly differ from their carbonate matrix in terms of composition, texture and mineralogy. The material comprises merely peaks of Si and Ca. MT microsparite in macro-structures are mostly homogenous and composed of uniform, isometric or polygonal calcite aggregates,which are about 0.01 mm on average and have clear boundary with the matrix. MT carbonates were formed and developed in the subtidal environment of the stable cratonic ramp, especially in the lower part of the upward-shallowing cycle within the middle-upper deep ramp. |
| KUANG Hong-wei,LIU Yan-xue,MENG Xiang-hua,GE Ming,CAI Guo-yin.2004.Sedimentary Lithofacies and Petrological Features of Neoproterozoic MT Structures-Bearing Carbonates in Jilin-Liaoning Area[J].Acta Geoscientica Sinica,25(6):647-652. |
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