内蒙古林西地区晚二叠世-早三叠世孢粉组合及三叠系的发现  

Late Permian-Early Triassic Palynological Assemblages in Linxi,Inner Mongolia and Discovery of Triassic Strata

作　　者：杨兵[1] 张雄华[1] 葛梦春[1] 赵省民[2] 韦一[1] 黄兴[1] 栾腾飞 魏信祥 杨志勇 

机构地区：[1]中国地质大学地球科学学院,湖北武汉430074 [2]中国地质调查局油气资源调查中心,北京100029 [3]甘肃省地矿局第三地质矿产勘察院,甘肃兰州730050

出　　处：《地球科学（中国地质大学学报）》2014年第7期784-794,共11页Earth Science-Journal of China University of Geosciences

基　　金：中国地质调查局项目"内蒙古1:25万锡林浩特市;林西县幅区调修测"(No.1212010510507)

摘　　要：内蒙古林西县官地剖面二叠系林西组第五段灰色、深灰色板岩中发现了大量孢粉化石,经鉴定计有54属90种,以蕨类植物孢子和裸子植物花粉为主,见有较多晚二叠世的常见分子,根据其与邻区的孢粉生物地层对比,确定林西组第五段时代为晚二叠世晚期.该剖面林西组第六段中发现有孢粉化石9属9种,其孢粉组成成分呈现出早三叠世孢粉组合特征,其时代应为早三叠世.由于林西组第六段岩性特征也发生变化,出现了紫灰色的粉砂质板岩夹层,且见有少量火山角砾.与下伏典型的林西组在岩性上有较大的差别,而与区域上下三叠统老龙头组相似.综合岩性特征、古生物化石特征、古气候特征及与邻区对比,将原划为林西组第六段的地层改划为下三叠统老龙头组.三叠系/二叠系界线划在林西组第五段与老龙头组之间.Large amount of spores and pollen （mainly consist of pteridophyta spores and gymnospermous pollen）,including 54 genera and 90 species,were discovered in the fifth member of Late Permian Linxi Formation,Guandi section,Linxi,Inner Mongolia.The fifth member of Linxi Formation was assumed to belong to the Late Permian,for the preservations of special Late Permian spores and pollen,and biostratigraphic correlations to adjacent areas.9 genera and 9 species were also found from the sixth member of Linxi Formation.They should belong to the Early Triassic,for the existing characteristics of the Early Triassic palynological assemblages.In addition,the lithology of the sixth member of Linxi Formation varies from that of the underlain parts of Linxi Formation,but similar to that of adj acent Laolongtou Formation,for the yielding of purple-gray silty slate and volcanic breccias interbeds.The sixth member of Linxi Formation might belong to the Early Triassic Laolongtou For-mation,evidenced by the integration of lithology,fossils,paleo-climate records and correlations to adjacent areas.The Permian-Triassic boundary is placed in the interval between the fifth member of Linxi Formation and Laolongtou Formation.

关 键 词：孢粉组合 晚二叠世 早三叠世 林西组 老龙头组 地层学 

分 类 号：P534[天文地球—古生物学与地层学]