滇中易门地区早前寒武纪地层化石的发现及其意义

The discovery and significance of the fossils from the Early Precambrian strata in the Yimen region, central Yunnan

关键词:  滇中易门地区  易门群  昆阳群  宏体多细胞化石  早期生命演化

Key words:  Yimen region in central Yunnan  Yimen Group  Kunyang Group  macroscopic multicellular fossil  early lift evolution

摘要:

通过1：50 000区域地质调查，在滇中易门地区新厘定出一套古元古界地层易门群，可细分为6个组级单元。在易门群亮山组灰黑色碳泥质板岩中首次发现保存较好的宏体多细胞生物化石，在易门群永靖哨组深灰色泥质灰岩中发现数枚毫米级结构清晰的多细胞生物化石；在中元古界昆阳群美党组灰紫色泥质板岩中发现长约20cm的宏体多细胞化石。通过镜下分析、电子探针及电镜扫描的研究，化石成分主要为C、O、P元素。本次发现填补了云南境内早前寒纪地层无生物化石记录的空白，对地球早期环境演化与生命进化的研究具有重要意义。

Abstract:

The Palaeoproterozoic Yimen Group including six formations was established during the 1:50 000 regional geological survey in the last years in the Yimen region, central Yunnan. The abundant well-preserved macroscopic multicellular fossils were successively found in the greyish dark carbonaceous-muddy slates in the Liangshan Formation and the dark grey muddy limestones in the Yongjingshao Formation in the Yimen Group. The macroscopic multicellular fossils 20 cm in length were also found in the grayish purple muddy slates in the Meidang Formation in the Mesoproterozoic Kunyang Group. The microprobe and scanning electron microscopy analysis indicates that the compositions of the fossils collected from the above-mentioned Formations consist dominantly of the elements carbon, oxygen and phosphorus. The discovery will fill the fossil-free gaps in the Early Precambrian strata in Yunnan, and also will be important to the study of the early history of the Earth and lift evolution.