微生物成因沉积构造(Microbially Induced Sedimentary Structures, MISS) 是底栖微生物群及其生命活动与沉积物相互作用形成的沉积构造,是微生物群生命活动的重要产物,多出现在陆源碎屑岩中,也是微生物群落在碎屑沉积中最重要的地质记录。该类构造在前寒武纪的广布性和显生宙的局限分布性,对于研究地球表层环境的演变具有重要意义。通过对鲁山地区野外露头发育的MISS的详细观察和描述,依据其成因和形态观察,将其分为微生物席生长构造(Mat growth feature)、微生物席破坏构造(Mat destruction feature) 和微生物席腐烂构造(Mat decay feature) 三种类型,包括瘤状突起、不规则侧向生长脊、多边形网状生长脊、多边形脱水裂痕、纺锤状脱水裂痕、不规则网状脱水裂痕、次圆状网状脱水裂痕、砂火山构造等8个主要形态构造。根据宏观形态、镜下特征等,分析讨论了MISS的形态构造、成分、成因、沉积环境等。对含有MISS石英砂岩的镜下石英颗粒及其矿物组分特征的研究发现,宏观上形态各异的MISS的镜下特征差别不大,并且在MISS形成过程中生物物理沉积和生物化学沉积共同起着作用,同时也发现微生物群落可能多生长在中等水动力、沉积物为细粒的环境中。
Microbially Induced Sedimentary Structures (MISS) rise from the interaction of benthic microbiota with physical sedimentdynamics. It was the important product and geological record in clastic sediments of microbial community activity. Research on MISS isof great significance for understanding evolution of earth-surface environment, because MISS was widely found in terrigenousfragmentary rock of Precambrian and was occasionally distributed in Phanerozoic. Based on observation, description and genesis ofoutcrops, the MISS in Lushan area can be divided into three types: Mat growth feature, Mat destruction feature, and Mat decay feature.With the aid of micromorphological observation, we analyzed and discussed morphological feature, geologic structure, components,genesis and sedimentary environment of MISS. Based on microscopic analysis for quartz grain and composition characteristic of MISS, we found that microbial community develop in the relatively high-energy and fine-grained sediments environment. Therefore, weconclude that MISS mainly developed near intertidal zone to supralittoral zone. This research will contribute to the discrimination of thepaleocurrent direction, intensity and ionic content, and can also help reconstruct paleoenvironment to a certain extent.