北京十三陵中元古界长城系沉积相标志及沉积环境演化模式

北京十三陵地区中元古界长城系包括5个组：常州沟组、串岭沟组、团山子组、大红峪组、高于庄组，前2个组主要由碎屑岩组成，后3个组主要由碳酸盐岩组成。众多的沉积相标志从不同侧面说明：常州沟组沉积属于滨浅海碎屑岩沉积环境；从串岭沟组开始，其沉积环境向碳酸盐岩沉积环境过渡；后3个组沉积时的环境为典型的陆表海碳酸盐岩沉积环境。在综合研究的基础上给出了沉积环境演化模式。另外，长城系还有许多特殊的沉积现象值得进一步研究和讨论：世界上最古老的宇宙球粒；高于庄组白云岩层面上双脊波痕的内碎屑颗粒成因和硅化白云岩内青鱼骨状层理及硅质团粒的成因；特别是在大红峪组首次发现太阳星云物质－碳质球粒陨石。

Sedimentary facies indicators and sedimentary environments models of the Changcheng System of Mesoproterozoic in Ming Tombs District, Beijing

There are 5 formations in the Changcheng System of Mesoproterozoic in the Ming Tombs District,Beijing.They are named as the Changzhougou,Chuanlinggou,Tuanshanzi,Dahongyu and Gaoyuzhuang formations.The former two formations consist of siliciclastics,and the others are composed of carbonate rocks.Numerous sedimentary facies indicators indicate that the Changzhougou Formation was de- posited in the shore zone and shallow marine environments.From the beginning of Chuanlinggou stage,the sedimentary environment changed from clastics to carbonate rocks.Thus,the sedimentary environment of the latter 3 stages were characterized by deposition of carbonate rocks in a typical epicontinental sea set- ting.The evolving sedimentary models of the Changcheng System were set up from the integrated study.In addition,related sedimentary problems need to be further investigated.They include problems such as the world oldest iron cosmic spherules,the origin of intraclastic grains with double crested wave rippling marks on dolomite bed surfaces,the origin of herringbone cross stratification in silicified dolomite and that of si- licified pellets,and in particular the origin of the solar nebula material,namely carbonaceous chondrite discovered for the first time from the Dahongyu Formation.