Chuaria circularis from the early Mesoproterozoic Suket Shale, Vindhyan Supergroup, India: Insights from light and electron microscopy and pyrolysis-gas chromatography

摘要

Chuaria circularis (Walcott 1899) from the Suket Shale of the Vindhyan Supergroup (central India) has been reinvestigated for its morphology and chemical composition using biostatistics, electron microscopy and pyrolysis-gas chromatography. Morphology and microscopic investigations provide little clues on the specific biological affinity of Chuaria as numerous preservational artifacts seem to be incorporated. On the contrary, the predominance of n-aliphatic pyrolysates of presently studied Chuaria from India rather supports an algal affinity. Moreover, the reflectance of C. circularis can be used to obtain a comparative maturity parameter of the Precambrian sediments. The review of the age and geographical distribution of C. circularis constrains that this species cannot be considered as an index fossil for the Proterozoic time.