塔什库尔干地区老并铁矿床地质特征及成因分析

Study on Characteristics and Genesis of the Laobin Iron Deposit in Tashikuergan, Inner Xinjiang

老并铁矿床位于新疆西昆仑-喀喇昆仑造山带西段．塔什库尔干陆块内的塔阿阿-塔吐鲁沟铁制钒成矿带中。矿体主要呈层状、似层状、透镜状赋存于古元古界布伦阔勒群中的黑支石英片岩和斜长角闪片岩内，并与顶底板围岩呈渐变过渡、互层产出、同步褶曲。老并铁矿稀土元素含量总体较低，具早前寒武纪海洋化学沉积特征，在PAAS标准化的稀土元素分布曲线显示LREE亏损、HREE富集．强Eu，和La的正异常及不明显的Cr异常，表明老并铁矿床的形成与海底火山活动关系密切．其矿床特征与Algoma型铁矿相似；磁铁矿轼同位素δ^18O值为3．3‰～4．6‰，显示研究区磁铁矿为原生沉积成因。结合成矿地质背景及矿床地质特征认为，老并铁矿床属海底火山沉积变质成因。

The Laobing iron deposit is located in the TaAXi to TaTuLuGou iron copper vanadium metallogenic belt of Tashikuergan in the west Kunlun to Kala Kunlun orogenic belt. The ore bodies occurred in plagioclase-hornblende schist and biotite-quartz schist of Palaeoproterozoic Bulunkuole group with lamellar and near-bedded or lenticular shapes, and showed Gradual transition, synchronous fold and interbedded output with roof and floor of surrounding rock. The REE contents of Laobing deposit are low, showing characteristics of early Precambrian ocean chemical deposition. In the PAAS-nornqalized REE pattern,LREE are depleted and HREE are enriched relatively, with strong Eu and La positive anomaly and no visible Ce anomaly, indicates that iron ore formation is closely related with submarine volcanic activity, and the deposit characteristics are similar with Algoma iron ore. Magnetite oxygen isotopes delta ^18O value distribute in 3.3 - 4.6%irange, shows mainly magnetites are original sedimentary magnetite magnetite. Combine the ore-forming geo- logical background and ore deposit geology characteristics, considers the genesis of Laobing iron deposit belongs to the submarine volcano sedimentary-metamorphism.