ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    黔东松桃地区李家湾锰矿床地质、地球化学特征及成因信息

    Geological, Geochemical Characteristics and Genetic Information of the Lijiawan Manganese Deposit in Songtao Area, East Guizhou

    • 摘要: 李家湾锰矿床是黔东松桃地区较为典型的"大塘坡式"锰矿床之一,也是近年来在该地区新发现的一个大型隐伏锰矿床,是杨立掌锰矿体在外围的深部延伸。笔者在野外地质调查的基础上,重点对该矿床的锰矿石及其围岩开展系统的地质和地球化学特征研究,探讨锰矿床的成矿物质来源、成因和成矿环境。该矿床主要的矿石形态有块状、条带状、花斑状3种,主要锰矿物为菱锰矿和钙菱锰矿。锰矿层中MnO、CaO、MgO含量较高,TiO2、Al2O3、K2O、Na2O含量较低,含锰岩系富集Rb、Ba、Th、Cs、Zr、Ga等元素;SiO2/Al2O3值显示其物质来源并非正常的陆源,通过Al/(Al+Fe+Mn)、(Fe+Mn)/Ti、Fe/Ti、Y/Ho、Nb/Ta、U/Th值,Fe-Mn-(Cu+Co+Ni)×10图解表明,锰矿具有热水沉积特征;Mn/Fe、Sr/Ba、V/(V+Ni)值揭示锰矿沉积环境为浅海、还原环境。稀土元素总量较高,轻稀土富集,含锰岩系Eu、Ce的异常、La/Ce值、∑REE和∑HREE总量反映锰矿沉积过程受热水活动影响,大地构造环境处于被动大陆边缘。由此表明,李家湾锰矿形成于较强的还原环境,锰矿形成是由热水沉积和正常沉积的混合作用形成,属于热水沉积成因。

       

      Abstract: The Lijiawan manganese deposit is one of the typical "Datangpo type" deposits in Songtao area of Guizhou province, which is a large concealed type manganese deposit disicovered in recent years and is also the deep peripheral extension of the Yanglizhang manganese ore bodies. Based on the field geological investigation, this paper focuses on the study of the geological, geochemical characteristics and its surrounding rocks of this manganese deposit, and then the ore-forming sources, genetic and mineralized environment of this deposit have been discussed. The results show that the ores occurred as massive, banded and mottled types, with mainly manganese minerals of rhodochrosite and greinerite. The content manganese layer has high MnO, CaO and MgO contents, but it has low TiO2, Al2O3, K2O and Na2O contents, and the manganese-bearing rock series are enriched in Ba, Th, Rb, Cs, Zr, Cs and Ga elements. The SiO2/Al2O3 ratio shows the materials were not sourced from normal terrigenous;The Al/(Al+Fe+Mn), (Fe+Mn)/Ti, Fe/Ti, Y/Ho, Nb/Ta and U/Th ratios, Fe-Mn-(Cu+Co+Ni) * 10 diagram show that the manganese ore has hydrothermal sedimentary characteristics;The Mn/Fe, Sr/Ba, V/(V+Ni) ratios reveal that the manganese ore was formed in shallow water and reductive sedimentary environment. The total REE is higher, with LREE enrichment;The manganese-bearing rock series have Eu and Ce anomalies;The La/Ce ratio, the REE and HREE values reflecct that the manganese deposition process was effected by hydrothermal activity, with a tectonic environment of passive continental margin. According to the characteristics mentioned above, it's included that the Lijiawan manganese deposit was formed in strong reducing environment, which was sourced from the mixing of hydrothermal and normal deposition.

       

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