中文摘要：

北京西北郊南口虎峪一带的中元古界长城系大红峪组发育完整，以一套混积岩系为特征。在南口虎峪剖面中，海侵体系域砂岩地层与高水位体系域砂泥质白云岩和叠层石白云岩组成了较有规律的层序地层相序，可以作为混积岩系层序地层划分的典型代表。在大红峪组的海侵体系域砂岩中，交余波痕、微生物形成的砂质碎片和皱饰构造表明了席底的发育，特别是其中所发育的微生物砂质碎片不但代表了碎屑岩中的一种特殊的“内碎屑”，而且其特殊的形态和产出特点成为窥视前寒武纪砂岩中席底发育的一种典型标志，从而有益于今后对类似沉积构造的阐释与研究；高水位体系域砂泥质白云岩中的纹理化构造似乎也是一种席底构造，它与其中的叠层石生物丘一起代表了前寒武纪海底微生物孤军作战的特殊生境。对该剖面大红峪组的初步研究表明，在前寒武纪地层中，除了要关注叠层石之类的微生物沉积构造以外，碎屑岩中也存在微生物活动的若干证据印席底构造（第五类原生沉积构造），由此说明正是由于微生物新陈代谢的多样性才使其成为地球上无所不在及其无与伦比的巨大生物量。

英文摘要：

The Mesoproterozoic Dahongyu Formation well-developed at Huyu section in Nankou Town, Beijing is characterized by a mixed rock system. In this section, the regular sedimentary succession composed of both the sandstone strata of the transgressive system tract and the sandy to muddy dolomite strata of the high-stand system tract enables the Dahongyu Formation to become an emblem on the sequence division of mixed rock system. In the transgressive sandstones, lots of special primary sedimentary structures, indicating the development of matground in the Precambrian, include the wrinkle structure, the palimpsest ripple and the microbial-mat chip, etc. Especially for microbial-mat chips, the typical marks of both the particular configuration and the special outputting represent the development of matground in the Precambrian and demonstrate a kind of special intraclasts in clastic rocks. Thus, the brief introduction on the microbialmat chips of the transgressive sandstones of the Mesoproterozoic Dahongyu Formation at Huyu section is useful to the study of the similar Precambrain sedimentary structures. On the other hand, the laminae structures developed in the sandy to muddy dolomites of the high-stand system tract are also a kind of mat-ground structures. Both the stromatolite bioherms and the laminae structures can represent the particular habitat characterized by the microbial doing battle in isolated force in the Precambrian. The preliminary studies on sequence stratigraphy and on sedimentary facies show the importance of the studies on evidences of microbial activities （i. e. the matground structures that are still nominated as the primary sedimentary structures of a fifth category）. All of this also indicates the diversity of microbial metabolism allows the microbial to become the huge incomparable biomass on Earth.