中国科学院南京地质古生物研究所机构知识库

以川西北地区剑阁县上寺乡猫儿塘二叠系标准剖面为例,通过野外剖面观察、岩石薄片、铸体薄片和微体古生物化石薄片观察鉴定等方法,从宏观到微观将岩性特征与古生物特征相结合,并对比周边其他二叠系剖面特征,剖析了二叠系主要地层界线及区域差别,提出了川西北地区二叠系划分标准及地层划分标志。猫儿塘剖面自下而上划分为中统梁山组、栖霞组及茅口组,上统吴家坪组及大隆组,与下伏地层上石炭统黄龙组假整合接触,与上覆地层下三叠统飞仙关组整合接触。根据有孔虫化石的分布,自下而上划分出3个有孔虫带:StaffellaNankinella带、Neoschwagerina带和Neoschwagerina craticulifera带,分别对应于早二叠世空谷阶下部、空谷阶上部和中二叠世罗德阶、沃德阶。发现了华南二叠纪标准分子Hayasakaia和Ipciphyllum,分别对应于早二叠世空谷阶和中二叠世卡匹敦阶。在大隆组中识别出长兴期2个菊石生物带:Penglaites带及Pleuronodoceras带。认为依据猫儿塘二叠系标准剖面建立各层位划分标准及划分标志是可靠的,与前人及其他剖面具有可比性,仅二叠系底界线及栖霞组-茅口组界线仍需要深入研究分析。

Through field section measurement,observations of rock thin section,casting thin sections and micro body fossils,combined with the analysis of lithological and palaeontological features,the correlation of Permian section at Maoertang of Jiange County with other Permian sections in the surrounding areas is made,the main stratigraphic boundaries and regional differences of the Permian system are analyzed and the Permian division standard and stratigraphic division marker in the northwest Sichuan region are proposed.It shows that the Permian Maoertang section can be divided into Middle Permian Liangshan Formation,Qixia Formation and Maokou Formation,and Upper Permian Wujiaping Formation and Dalong Formation.At the bottom,the Permian strata are parallel unconformable in contact with the underlying Upper Carboniferous Huanglong Formation and on the top,it is conformably in contact with the Lower Triassic Feixianguan Formation.According to the distribution of foraminiferal fossils,three foraminiferal zones are recognized from bottom to top of the Permian strata:Staffella-Nanknella zone,Neoschwagerinazone and Neoschwagerina craticulifera zone,which correspond to the lower part of the early Permian Konggu Stage,the upper part of Konggu Stage and the Middle Permian Rhodian Stage and Ward Stage respectively.South China Permian standard molecules Hayasakaia and Icpciphyllum have been found in the section,which correspond to the early Permian Hollowness Stage and the Middle Permian Kapiturn Stage,respectively.In addition,in the Dalong formation,Penglaites zone and Pleuronodoceras zone of ammonoidal belts of Changxing period have been recognized.It is considered that the establishment of the stratigraphic division standard and division mark based on the standard section of Maoertang Permian is reliable,and the Maoertang Permian section can be correlated with the previous section and other sections.However,the bottom boundary of Permian and the boundary between Qixia Formation and Maokou Formation still need further study and analysis.