| Two global glaciers events developed in the Neoproterozoic, respectively Marinoan Sturtian glacial and glacial corresponding domestic chang an glaciation and Nantuo glaciation in southern China,Data shows that the two have reached ice age near the equator. The Kirschivink think there may be some puddles Ice equatorial region, the associated sedimentary evidence has been recognized by many scholars.The author collected carbonate rock samples in a drilling core of Nantuo Formation from Songtao County in eastern Guizhou Province. 1.5m thick glacial deposits of carbonate rock, carbonate rock hand specimens showed that the upper and lower strata completely without borders, showing the transition relationship, microscopic identification results also showed normal deposition Characteristics. On outcrops contrast by other Nantuo Ice Age Found Jianhe, etc., were not found in carbonate sediments corresponding.The 1.5m thick lithologic by the upper, middle and lower segments. Under paragraph(ZK102-1 ~ ZK102-4) debris from the inside of the particle size increases fines dolomite, dolomite sand debris, gravel crumbs dolomite composition, the middle(ZK102-5 ~ ZK102-10) to(including micro) dolomite(including) silty clay and rocks(including micro) dolomite(including) clayey siltstone; upper section(ZK102-11 ~ ZK102-18) lithology of uniform size shavings dolomite. Lithologic debris in different size, different mineral components are each segregated laminar pattern- stripes-stripes- lamellar interval output. Microscopic characteristics change rock show 1.5m thick carbonate sedimentary environment experienced at least once seawater from deep ? shallow ? deep process.Analytical methods for the use of micro-drilling technique(trace elements were analyzed using plasma mass spectrometry) carbonate rock drill powder sample was dissolved in 0.5M acetic acid solution, to ensure that the sample is dissolved carbonate rock minerals, from Portland debris pollution.Based on of petrography, geochemical characteristics combined with a comprehensive analysis of the above carbonate rocks environment. Geochemical analysis including trace elements, carbon and oxygen isotopes and biological characteristics of the compound mark.Carbon analysis of carbonate rocks, carbon and oxygen isotope data standard seawater oxygen isotope data far, all show negative drift characteristics, which ?18O is 0.7 ~-16.3 ‰, ?13C in between-1.5 ‰ ~-9.9 ‰. Only ZK102-11 and oxygen isotope values ZK102-12 shows similar characteristics with modern seawater. Negative oxygen isotope shift may be related to the oxidation of methane hydrate. Trace element analysis show Sc, Cr, As enrichment, and the elements i V?Co?Zn?Ga ?Ba?Tl?Bi extremely depleted. REE curves show positive Eu anomalies and rare earth enriched features with modern seawater standard distribution patterns are inconsistent. After analysis, presumably detrital material was dissolved in seawater seawater REE composition, so that the seawater REE positive Eu anomalies characteristic; and rare earth enriched with modern iron(hydrogen) oxide colloid(river, estuary and acid mine drainage) REE distribution curves consistent, suggesting that the sedimentary environment is an iron-rich environment.Biomarker data(Pr / Ph) <1, described sample sedimentary environment anoxic reductive environment, according to the analysis of maternal pristane and phytane, which period may lower organisms(cyanobacteria?) Events.In summary, eastern Guizhou Nantuo Ice Age carbonate rocks environment is an iron-rich anoxic reductive environment. |
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