Biological Mineralization At The Bottom Of Cambrian Niutitang Formation Of Tianmen Mountain In Hunan

By studying the fossil contained in rock and bedrock of early Cambrian NiutitangFormation located at Tianmen mountain of Zhang Jiajie in Hunan, and combinedwith previous studies to discuss the feature of biota combination in the bottom ofNiutitang Formation, then discuss the sedimentary environment andbiological mineralization at the ore rock in these area.This paper mainly studies the black shale at the bottom of Cambtian NiutitangFormation in the area of Hunan Tianmen Mountain. We chose5exposed profile inthis area to measured. Which are at Yunpan, Houping, Daping and Sancha. Based onthe profile’s study, compared with the existing date, we found that the underlyingstrata of Cambrian Niutitang Formation is Sinnian Dengyin Formation, and those twoformation are unconformity contact relation. Sinaian Dengying Formation mainlydeveloped gray white thick bedded and massive dolomite, clipped phosphate rockand siliceous rocks. At the bottom of Niutitang Formation is black and thick-massivphosphorite, clipped dolomitic lenses and barite lens, occasionally have siliceousrocks, and contains the phosphatic nodule; upward is ore bearing strata, mainly haveblack carbonaceous shale, containing a large number of posphatic nodule; above thisis thick layer shaped carbon black shale and calcareous shale.After the observation of the sample sheet and fossil specimens in the bed rock,The study found that the reisa biota combination contain edsponge spicule, tubularfossils and fossilized algae in the bottom of Niutitang Formation, which is differentwith the “Songlin biota”, the refore the new biota do not belong to “Songlin biota”.While the biogenic assembly only contained in bedrock, is different with the biogenicassembly in upper and lower strata, shows that the environment is differentbetween the upper and lower strata.It is an abrup to scillation, and it shows theenvironment is lack of oxygen and has shallow water. In the profile of Daping, itcontains barite ore in the seam part, and there is also a small amount of baritedeposits in other sections. And in the thin display, it shows that barite andpyritizated algae are in layered distribution. It is speculated that the biological eventshappened in early Cambrian at Hunan Tianmen Mountain may be related to hydrothermal deposition.The study also found that large number of dispersed Sponge Spicule structure,some tiny bacteria structure and dispersion of panktonic algae mineralizationstructures in the ore bearing strata and lower strata in the area of Hunan TianmenMountain. It shows that the direct participation of microorganisms in theore-forming process. Through the study of fossils in the sample sheet and theanalysis of fossil minerals structure, combined with previous research results, theNickel and Molybdenum ore deposit in the bottom of Niutitang Formation in Hunanbelongs to biological absorption type.