中国南方宝塔组灰岩的岩石学特征及其对“龟裂纹”成因的指示——以贵州桐梓县红花园乡宝塔组灰岩为例  

Petrology of Limestone of Baota Formation in South China and Its Indication to the Genesis of “Turtle Crack”: A Case Study of Baota Formation Limestone at Honghuayuan Township in Tongzi County, Guizhou Province

作　　者：禚喜准[1] 陈骁帅 张林炎[2] 崔建军[2] 熊辉 

机构地区：[1]辽宁工程技术大学地质系,辽宁阜新123000 [2]中国地质科学院地质力学研究所,北京100081

出　　处：《地球学报》2017年第6期872-882,共11页Acta Geoscientica Sinica

基　　金：国家自然科学基金项目(编号:41402101);中国地质调查局地质调查项目"钦-杭结合带及临区深部地质调查"(编号:121201104000160916)联合资助~~

摘　　要：宝塔组灰岩广泛分布于扬子区,以独特的"龟裂纹"构造,成为区域地层对比的良好标志,但"龟裂纹"形貌与岩石内部成分和结构的关系尚不明确。基于野外露头和定向切面观察,依据颜色和形貌,将该灰岩划分为"灰黑色网纹"和"灰白色基质"两种组分;垂直岩层的切面上,二者空间分布杂乱,"灰黑色网纹"并非"V"字形排列;平行岩层的风化表面与新鲜切面均呈网纹状,在形貌上基本一致。运用阴极发光、荧光、扫描电镜、TOC和硬度测试等手段,对"灰黑色网纹"和"灰白色基质"的岩石学特征进行了对比分析。研究表明,前者颜色较深,为硬度较低的生物碎屑灰岩,有机质含量较高,荧光下可见沥青脉;后者颜色较浅,为硬度较高的泥晶灰岩,有机质含量较低,荧光不明显。两种组分在颜色、空间排列特征和抗风化能力方面的差异,是宝塔组灰岩在地表产生"龟裂纹"形貌的内因。The Baota limestone is widely distributed in the Yangtze area, and is characterized by unique ＂turtle crack＂ structure, which is a good marker for regional stratigraphic correlation. However, the relationship between the morphology of the ＂turtle crack＂ and the internal composition and structure of the rock remains unclear. Field outcrops and directional section observations indicate that Baota Formation limestone could be divided into two components, namely ＂grayish black reticulate patterns＂ and ＂grayish white matrix＂; on the cut plane perpendicular to the strata, distal distribution of both components is in disorder, and the ＂V＂ shape arrangement is not obvious; cut plane which is parallel to the strata shares the same reticular morphology as weathering surface. Using cathodoluminescence, fluorescence, SEM, TOC and hardness testing, the authors carried out a series of comparative analyses on the petrological characteristics of ＂grayish black＂ reticulate patterns and ＂grayish white matrix＂. The results show that the former component is darker bioclastic limestone with lower hardness and higher content of organic matter, and asphalt veins can be seen under fluorescence; the latter component is lighter micrite with higher hardness and lower content of organic matter, and the fluorescence is not obvious. The difference in color and anti-weathering capability between two components is the internal cause for Baota Formation limestone forming ＂turtle crack＂ structure morphology on the ground.

关 键 词：宝塔组 “龟裂纹”构造 组构差异性 抗风化能力 

分 类 号：P534.42[天文地球—古生物学与地层学] P588.245[天文地球—地质学]