The Study For Some Typical Matground Structures Of Changcheng System In Yanshan Area Of North China

In addition to the stromatolite, microbial related primary sedimentary structures developed in matground are highly facies-indicative and can aid in paleoenvironmental reconstruction, which is the chief reason for the terminology as"the primary sedimentary structure of a fifth category". The wide spread distribution in the Precambrian and the sporadically distribution in the Phanerozoic, especially for their mischance flowage in sea floor after the mass extinction event, make this category of sedimentary structures become meaningful and useful to study the evolutionary change of earth surface.Some representative types of the microbial-induced primary sedimentary structures are developed in clastic rocks and carbonates of the Mesoproterozoic in the Yanshan area of North China. The palimpsest ripple, the wrinkle structure and the spindle crack in silty mudstones of the Chuanlinggou Fm. at the Jixian section, the mud-crack-like crack in sandy and muddy dolomites of the upper part of the Tushanzi Fm. at the Jixian section, and the microbial sand chip in transgressive sandstones of the Dahongyu Fm. at the Huyu section, are the representative of the microbial-induced structures developed in clastic rocks. Large-scale wrinkle structures and palimpsest ripples in limestones of the Gaoyuzhuang Fm. at the Qiangou section in Yanqing, are the representative of the microbial-induced primary sedimentary structures in carbonate rocks.Therefore, both the observation and the preliminary study about the microbial-induced primary sedimentary structure in the Mesoproterozoic of the Yanshan area can provide some useful information for the reconstruction of sedimentary environment of the Precambrian, and are conducive to recognize the metabolic diversity and the great biomass of microbes as well as the great affection of them to the surface environment of the earth.