ABSTRACT Silicified Mesoproterozoic stratifom stromatolites of the ca. 1400 Ma Gaoyuzhuang Formation in northern China contain microbial fossils preserved in a synsedimentary context rich in carbonate precipitates. Benthic microbial fossils were preserved by early silicification in growth position. Carbonate precipitation took place concurrently with accumulation of fine-grained sediment, and within the time frame of microbial growth and movements. The kinetics of the sedimentary process is thus calibrated by the rates commensurate with the behavioral responses of ancient microorganisms. Since both mineral and organic components of these ancient stromatolites remained preserved, their mutual relationship could be assessed. Extensive microbial growth, mat formation, and accumulation of organic matter required time and indicated the extent of sedimentary pauses. Carbonate precipitation took place in the absence of microorganisms, inhibiting their successful colonization and growth. The interplay between biological and abiotic forces in the formation of Gaoyuzhuang stromatolite permits an approximation of actual rate of carbonate precipitation, which often exceeds that of microbial settlement and growth. The relationship between microbial growth and precipitates in stromatolites under study is generally antagonistic, indicating limited involvement of microbial activities in the precipitation process.