陕西镇安石炭系—二叠系界线剖面层序地层和相对海平面变化研究  

Sequence stratigraphy and relative sea-level change in the Carboniferous-Permian boundary section at Xikou, Zhen`an County, Shaanxi

作　　者：张海军[1] 王训练[1] 夏国英[2] 王雷[1] 张志祥[3] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质调查局天津地质矿产研究所,天津300170 [3]内蒙古自治区地质调查院,内蒙古呼和浩特010020

出　　处：《地质通报》2004年第4期336-344,共9页Geological Bulletin of China

基　　金：中国地质调查局基础地质综合研究项目<中国古大陆环境变化及其年代;生物;层序;事件;化学和构造地层响应>;国家自然科学基金项目(批准号:40172014);中国科学院南京地质古生物研究所现代古生物学和地层学开放研究实验室课题基金项目(编号:013101)联合资助

摘　　要：在陕西镇安西口上石炭统逍遥阶至下二叠统隆林阶的剖面上,区分出含生物碎屑灰泥灰岩、生物碎屑粒泥灰岩、生物碎屑泥粒灰岩、生物碎屑颗粒灰岩、团块颗粒灰岩和核形石颗粒灰岩6种主要的碳酸盐岩微相类型。通过详细的微相特征分析,确定了碳酸盐岩沉积过程中的水动力状况和相对水深变化趋势,识别出低能潮下型碳酸盐旋回A1、A2及高能浅滩型碳酸盐旋回B1、B2两类4种高频旋回。根据这些高频旋回在剖面上的有序叠置型式,将镇安西口地区的上石炭统逍遥阶至下二叠统隆林阶划分出12个四级层序和5个II型三级层序地层单元,反映了这一地区晚石炭世逍遥期至早二叠世隆林期曾发生过12次四级相对海平面波动和5次明显的三级相对海平面升降。In the section from the Upper Carboniferous Xiaoyao Stage to Lower Permian Longlin Stage at Xikou, Zhen`an, Shaanxi Province, from below upward, 6 main types of carbonate microfacies are identified. They are bioclastic mudstone, bioclastic wackstone, bioclastic packstone, bioclastic grainstone, lump grainstone, and oncolite grainstone. Based on the detailed analysis of these microfacies, the hydrodynamic conditions and the trend of relative change in water depth during deposition of carbonate are determined, and four types of high-frequency cycles, types A1 and A2 in the low-energy subtidal zone and types B1 and B2 in high-energy shoals, are distinguished. According to the ordered stacking patterns of these high-frequency cycles in the vertical section, 12 4th-order sequences and 5 3rd-order sequences are recognized. This suggests that 12 4th-order relative sea-level fluctuations and 5 3rd-order pronounced relative sea-level changes took place from the Late Carboniferous Xiaoyao Age to Early Permian Longlin Age in this area.

关 键 词：碳酸盐岩 微相 层序地层 海平面变化 石炭系一二叠系界线 陕西镇安 

分 类 号：P534.45[天文地球—古生物学与地层学] P534.46[天文地球—地质学]