云南罗平中三叠世大凹子剖面牙形石生物地层及其沉积环境研究  

CONODONTS STRATIGRAPHY AND SEDIMENTARY ENVIRONMENT OF THE MIDDLE TRIASSIC AT DAAOZI SECTION OF LUOPING COUNTY,YUNNAN PROVINCE,SOUTH CHINA

作　　者：黄金元[1] 张克信[2] 张启跃[3] 吕涛[3] 周长勇[3] 白建科[3] 

机构地区：[1]中国地质大学研究生院地球科学学院,武汉430074 [2]中国地质大学教育部生物与环境地质重点实验室,武汉430074 [3]中国地质调查局成都地质调查中心,成都610081

出　　处：《微体古生物学报》2009年第3期211-224,共14页Acta Micropalaeontologica Sinica

基　　金：中国区域地质调查项目(编号:1212010610211);国家自然科学基金(编号:40621002;400830212)

摘　　要：罗平生物群产出于关岭组二段,该段大凹子精细剖面细致的沉积学描述记录显示,剖面岩性变化趋势为:从生物扰动灰岩到含硅质结核的条带泥晶灰岩(钙屑浊积岩)向白云岩演化。剖面详细的牙形石生物地层研究表明,牙形石带属于Nicoraella kockeli带,同时该带可分两个亚带,即Nicoraella kockeli type 1亚带和Nicoraella kocke-li type 2亚带。牙形石生物地层年代确定在Anisian期的Pelsonian亚期。通过大凹子剖面含牙形石段产出环境分析表明:深灰色具脉状层理含泥质灰岩的开阔台地相沉积环境牙形石产出较少且保存一般,而深黑色纹层状泥晶灰岩段台间盆地相沉积环境中牙形石产出丰富且保持完好。大凹子剖面沉积构造研究表明:罗平生物群产出于台间盆地相钙屑浊流沉积环境。Luoping biota come from the second member of the Guanling Formation, and the detailed description of the sedimentology from the Daaozi profile of this member shows the lithological changes： from bioturbation limestone to siliceous nodules and belts limestone （calcium turbidite） and further to the dolomite. Detailed conodont biostratigraphic studies in the profile have shown that eonodonts belong to Nicoraella kockeli Zone, which can be subdivided into two subzones as Nicoraella kockeli type 1 Subzone and Nicoraella kockeli type 2 Subzone. Therefore, the age of conodont biostratigraphy is the Pelsonian substage of Anisian. The conodonts distribution shows that the plateform environment yields few conodonts and mostly preserved in the clark gray argillaceous limestone with vein bedding, and interplateform environment has rich conodonts well-preserved in the dark laminated-bedded mudstone limestone. The sedimentary structure study of the Daaozi section indicates that the Luoping biota belongs to the calcium turbidlte depositional environment of interplateform basin facies.

关 键 词：牙形石Pelsonian亚期 中三叠世 沉积环境 关岭组 大凹子剖面 罗平 云南 

分 类 号：Q915[天文地球—古生物学与地层学]