贵州省松桃县道坨超大型锰矿床地质地球化学特征

Geological and Geochemical Characteristics of the Daotuo Super-Large Manganese Ore Deposit at Songtao Country in Guizhou Province

本文报导了贵州省松桃县新发现的一个全隐伏的超大型锰矿床——道坨锰矿床的地质地球化学基本特征,为进一步开展科学研究奠定基础。矿床赋存在新元古代成冰系(南华系)大塘坡组底部的含锰碳质页岩中,主要由条带状、块状、气泡状菱锰矿矿石组成。主量元素特征为Al_2O_3、TiO_2、Fe_2O_3含量较低,中等程度的P_2O_5富集,MnO、MgO含量相对较高,Fe/Mn比值低。微量元素特征为Rb、Nb和Pb亏损,Co、Zn、Sr、Mo相对富集。稀土元素总稀土含量高、中稀土轻微富集、Ce的正异常明显为特征。道坨锰矿含锰层位中黄铁矿的δ^(34)S_(-VCDT)值异常高,并且变化范围小,所测试黄铁矿的δ^(34)S_(-VCDT)值介于56.2‰~63.3‰,平均60.8‰。新发现的道坨超大型锰矿床属于典型的大塘坡式锰矿床,其发现不仅为研究新元古代大规模成锰作用提供了新机遇,同时也为研究成冰系环境演化及其资源、生物效应提供了新契机。

Daotuo manganese ore deposits at Songtao County in Guizhou province is a newly explored super-large and concealed Mn-carbonate ore deposit. In this paper, we pioneered to report basic geological and geochemical characteristics of the deposit. The ores are hosted in the basal of the Cryogenican Datangpo Formation, comprising primarily of banded, massive and bubble Mn-carbonate ores. The major elements show low A12Oa, TiO2, and Fe203 contents, moderate P^Os contents, relative high MnO and MgO contents, and low Fe/Mn ratios. The trace elements show depletion in Rb, Nb and Pb, relative enrichment in Co, Zn, Sr, and Mo. The REEs are characterized by high total REE contents, relative middle REE enrichment compared to light REE and heavy REE, and obvious positive Ce anomalies. The pyrites in the Mn bearing series of Daotuo manganese ore deposits have extremely high 834 S VCDT values, with 834 S_VCDT values range from 56. 2%0 to 63. 3%0 with a mean of 60. 8%0. in summary, the Daotuo manganese ore deposit is a typical Datnagpo-type manganese ore deposit, which provide us a unique opportunity to study Neoproterozoic manganese mineralization and its well-characterized Cryogenian-to- Middle Precambrian stratigraphic framework also provides a unique opportunity to rack the co-evolution of coupled tectonics, the Snowball Earth event, sedimentary manganese metallogenesis, marine chemistry and rise of earth＇s early animals.