投稿时间：2016-07-27
修订日期：2017-06-19
网络发布日期：2017-09-06
中文摘要:罗河铁矿床是20世纪80年代在长江中下游成矿带庐枞盆地中发现的规模最大的铁矿床。经深部找矿勘探工作，2013年在罗河铁矿床主矿体800~1000 m之下又发现了小包庄铁矿床，这是近年来在长江中下游成矿带深部找矿工作中的重大进展之一，对该矿床地质特征的总结和形成时代的精确厘定，是正确分析矿床成因机制，完善玢岩型铁矿床成矿理论的关键。文章在已有研究的基础上，通过详细的钻孔岩芯观察、系统的岩相学和矿相学及电子探针分析测试工作，查明了罗河铁矿和小包庄铁矿的矿化蚀变特征，厘定了矿化阶段，初步探讨了成矿作用过程；对小包庄铁矿床进行了高精度金云母40Ar-39Ar同位素年代学研究，获得坪年龄为（130.32±0.78） Ma，相应的等时线年龄为（130.5±1.5） Ma，反等时线年龄为（130.4±1.3） Ma。结合庐枞盆地及区域成岩成矿时代，认为盆地内玢岩型铁矿床集中形成于130 Ma左右，是长江中下游成矿带第二阶段（135~126 Ma）成矿作用的产物。
Abstract:The Luohe iron deposit is the largest iron deposit in Luzong volcanic basin in the Middle-Lower Yangtze River Valley metallogenic belt. Through the deep ore exploration work, the Xiaobaozhuang iron deposit was discovered at 800~1000 m below the main orebody of the Luohe iron deposit in 2013, which is one of the most significant prospecting progresses in the Middle-Lower Yangtze River Valley metallogenic belt. Summarizing the characteristics of Luohe and Xiaobaozhang iron deposits and constraining the mineralization age of Xiaobaozhuang iron deposit are crucial to understanding the genesis and geodynamic processes of the ore deposit and are important for perfecting porphyrite iron deposit metallogenic theory. Based on the primary research achievements, the authors carried out a detailed study of the geological characteristics of the deposit through careful field work and petrographic, mineralogical and EPMA analysis. The authors identified the mineralization and alteration characteristics, divided the ore-forming process into metallogenic stages, and primarily discussed the mineralization process of Luohe and Xiaobaozhuang iron deposits. High-precision 40Ar-39Ar dating on phlogopite from Xiaobaozhuang iron deposit was carried out, which yielded a well-defined 40Ar-39Ar plateau age of (130.32±0.78) Ma, with an isochron age of (130.5±1.5) Ma and an inverse isochron age of (130.4±1.3) Ma. The Xiaobaozhuang iron deposit and the other porphyrite iron deposits were all formed at the early stage of Early Cretaceous at about 130 Ma in Luzong volcanic basin, and were the products of the second period (135~126 Ma) mineralization in the Middle-Lower Yangtze River Valley metallogenic belt.
keywords:geochemistry 40Ar-39Ar isotope chronology Luohe iron deposit Xiaobaozhuang iron deposit Luzong volcanic basin Middle-Lower Yangtze River Valley metallogenic belt
文章编号：
中图分类号：P618.31;P597+.3
文献标志码：
基金项目:本文受到中国地质调查局地质调查工作项目（工作项目编码：1212011120862、12120114038001）的资助
引用文本：
张赞赞,张舒,吴明安,吕博,王克友,张千明.2017.庐枞盆地小包庄铁矿床地质特征及40Ar-39Ar同位素年代学研究[J].矿床地质,36(4):795~815ZHANG ZanZan,ZHANG Shu,WU MingAn,LÜ Bo,WANG KeYou,ZAHNG QianMing.2017.Geological characteristics and 40Ar-39Ar geochronology of Xiaobaozhuang iron deposit in Luzong volcanic basin[J].Mineral Deposits36(4):795~815
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