摘要
吉林南部通化二道江剖面新元古界万隆组广泛发育缓坡碳酸盐岩沉积,其中发育的一种特殊的碳酸盐岩——臼齿碳酸盐岩,近年来引起了中国乃至世界各国地质学家的重视。通过对野外露头的详细观察和描述、室内薄片观察、扫描电镜、能谱分析等测试手段,揭示了二道江剖面万隆组的地层、岩石、臼齿构造(MT)及沉积岩相和沉积环境特征。臼齿构造是特指那些发育在前寒武纪细粒碳酸盐岩中有清晰边界、粒度在0·01mm左右的由等轴或多边形的微亮晶方解石组成的集合体,其形态可分为条带状构造、瘤状构造及棱角碎块状构造。臼齿构造的形成严格受沉积岩相和沉积环境的控制。万隆组由下而上可分为3段第1段下部为发育臼齿构造的纹层状泥晶灰岩、砂屑灰岩及风暴砾屑灰岩,为中—深缓坡沉积环境的产物;上部由浅缓坡相的泥灰岩、钙质页岩、砂屑灰岩与叠层石灰岩组成;第2段为厚层泥晶灰岩和粉屑泥晶灰岩、瘤状灰岩组成的深缓坡相沉积;第3段本剖面未出露。万隆组形成于缓坡沉积环境,其中浅缓坡相可分为4种岩相组合,中缓坡相可分为11种岩相组合,深缓坡相有6种岩相组合。
Ramp carbonate rocks are widely developed in the Wanlong Formation of Neoproterozoic in the Erdaojiang section, Tonghua County, southern Jilin Province, which consists of a special type of carbonate rocks, named the Molar-tooth carbonate rock. In the recent years, the discovery of Molar-tooth carbonate rock has been greatly emphasized by the Chinese and international geologists. Based on the observation and description of outcrops, thin-section observation, scanning elecstructure, lithofacies and sedimentary environments are respectively documented. Molar-tooth struc- tures refer to the aggregations of equal-axised or polygonal microspar calcite with a crystal size of 0.01mm and a clear boundary, which are mainly developed in the Precambrian fine-grained carbonate rocks.The morphology of Molar-tooth can be divided into ribboned, nodular and clastic forms. The formation of the Molar-tooth structure is strictly controlled by sedimentary lithofacies and environments. The Wanlong Formation can be divided into three members. For the first member, the lower part is composed of Molar-tooth-bearing laminated micrite, calcarenite and stormy calcirudite, deposited in the middle-outer ramp environment; the upper part is made up of mudstone, calcishale, calcisiltite and laminated limestone, laid down in the shallow ramp environment. The second member deposited in the deep ramp environment is made up of thickly-bedded micrite, calcimicrite and nodular limestone. The third member is not exposed in this section. The Wanlong Formation is developed in the ramp environment. The shallow, middle and deep ramp facies include 4, 11 and 6 lithofacies associations respectively.
出处
《古地理学报》
CAS
CSCD
2006年第4期457-466,共10页
Journal of Palaeogeography：Chinese Edition
基金
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)
长江大学自然科学发展基金资助
关键词
吉林省
通化市
二道江剖面
新元古界
万隆组
臼齿构造
碳酸盐岩
沉积岩相
Jilin Province, Tonghua County, Erdaojiang section, Neoproterozoic, Wanlong Formation, Molar-tooth structure, carbonate rocks, sedimentary lithofacies
