燕山中元古界大红峪组微生物席碎片的发现及初步研究

Discovery of Microbial Mat chips from Proterozoic Dahongyu Formation of North China

元古代碳酸盐岩沉积孕育了大量与微生物活动有关的沉积构造,但是对于相同时期的碎屑岩沉积环境中微生物引起的沉积构造的研究却很少。在元古代碎屑岩沉积环境中发现的最常见的与微生物活动有关的沉积构造是皱饰构造和变余波痕,前人研究结果已经证明它们为微生物引起的沉积构造。在华北地台中元古界长城系大红峪组砂岩层面上发育一些与变余波痕和皱饰构造共生的一种特殊的沉积现象,即纺锤状砂质碎片。通过研究证实这些砂质碎片是微生物与物理营力相互作用形成的,也就是微生物席碎片。其发现有益于以后对类似沉积构造的研究;也有助于认识和了解中元古代生物群演化、古生命环境。

Sedimentary structures produced by microbial activity are well known from Proterozoic carbonate sediments, but little is discovered in contemporaneous siliciclastic facies. Wrinkle structures and palimpsest ripples＂ are closely related sedimentary＂ structures that are commonly found in ancient siliciclasties, and previous research has confirmed that they may represent microbial activity. Wrinkle structures, palimpsest ripples and spindly sand chips are discovered on the surface of sandstone, of the Dahongyu Formation. Sedimentelogic and petrographic information of sand chips suggests that they are one kind of structures induced by microbial activity and physical process, called microbial mat chips. This discovery will be of great benefit to succeeding studies on these structures, and provide fresh insight into the evolution of Mesoprot- erozoie bacteria and other organisms ,as well as the associated paleoenvirenments.