【作者】 刘振锋； 郝守刚； 王德明； 刘建波；

【Author】 Liu Zhenfeng Hao Shougang Wang Deming Liu Jianbo (Department of Geology,Peking University,Beijing 100871)

【机构】 北京大学地球与空间科学学院；

【摘要】 云南曲靖地区是我国非海相下泥盆统的标准剖面所在地。本次工作逐层实测了徐家冲组剖面,从剖面的沉积旋回入手,研究分析了沉积旋回的特征、岩石组合特征,根据植物化石和动物化石讨论了该剖面徐家冲组的沉积环境和地质年代。徐家冲组厚841．84 m,分为93个沉积旋回。其沉积模式是由砂岩、粉砂岩、泥岩和粉砂岩构成四元结构的沉积旋回,每个旋回都是从砂岩开始,以粉砂岩或泥岩结束。徐家冲组的沉积模式与典型辫状河、曲流河及三角洲沉积体系都有明显的区别。沉积环境应该是三角洲平原靠陆部分的河流环境。亚环境有河床、漫滩、天然堤、泛滥平原、废弃河道及岸后湖泊。根据植物化石及双壳类、鱼类化石,徐家冲组中下部地质时代为(晚)布拉格期,上部为早埃姆斯期。同时讨论建立了徐家冲植物群及组合带。更多还原

【Abstract】 Qujing area of Yunnan Province is the locality of the standard section of non-marine Lower Devo- nian in China.We measured Xujiachong Formation,studied its characteristics of sedimentary cycles,rock assem- blages and discussed its sedimentary environment and geological age based on the plant fossils and animal fossils. The thickness of Xujiachong foundation is 841.84 m,with 93 sedimentary cycles.Its sedimentary model is 4-unit structure cycles composed of sandstone,siltstone,mudstone and siltstone,each beginning with sandstone and end- ing with siltstone or mudstone.The sedimentary model of Xujiachong Formation differs obviously from typical braid- ed stream,meandering stream and delta sedimentary system.The sedimentary environment should be fluvial of delta plain near continent.The sub-environment are stream bed,beach,natural dam,overflooded plain,deserted stream and back lakes.According to the fossils of plants,bivalves and fishes,the lower and middle parts of Xujia- thong Formation may correlated to(late)Pragian,the upper part to early Emsian.At the same time,The Xujia- thong Flora and flora assemblages were established.更多还原