投稿时间：2012-02-15
修订日期：2012-06-19
中文摘要:荷花坪锡多金属矿床是南岭中段湘南地区新发现的一个大型矿床,发育有印支期和燕山期2期成岩、成矿作用。文章对不同期矿石中的黄铁矿分别进行了稀有气体同位素研究。测试结果表明,印支期矽卡岩型矿石中的黄铁矿:3He/4He=0.15～2.49 Ra,38Ar/36Ar=0.18733～0.18902,40Ar/36Ar=310.45～523.98,20Ne/22Ne=9.727～9.830,21Ne/22Ne=0.0286～0.0310;燕山期蚀变碎裂岩型矿石中的黄铁矿:3He/4He=0.15～4.33 Ra,38Ar/36Ar=0.18750～0.18843,40Ar/36Ar=331.78～602.62,20Ne/22Ne=9.736～9.858,21Ne/22Ne=0.0286～0.0305,显示区内两期成矿流体均为大气饱和水、地壳流体和地幔流体的混合流体。印支期矽卡岩型矿石中地幔He所占比例为2.34%～41.40%,平均18.16%;燕山期蚀变碎裂岩型矿石中地幔He所占比例为2.34%～72.12%,平均27.41%,燕山期幔源流体的作用强度略高于印支期。湘南地区印支期基性岩浆活动及荷花坪矿床印支期成矿过程中有幔源物质的参与,二者共同指示南岭地区中生代构造体制的转换或岩石圈伸展减薄可能始于印支主期(244～230 Ma)之后的224 Ma左右,即晚三叠世。
Abstract:The Hehuaping tin-polymetallic deposit is a large deposit newly discovered in southern Hunan Province. It consists of four main ore bodies located in the southeast portion of Wangxianling Indosinian granite pluton, and the ore-forming process underwent early Indosinian period and late Yanshanian period, forming skarn-type ores and altered cataclasitic-type ores, respectively. Noble gas isotopic analyses of fluid inclusions in pyrite from different periods of ores indicate that, in the early skarn-type ores, 3He/4He ratios vary from 0.15 to 2.49 Ra (Ra=1.4×10-6, modern atmospheric ratio), 38Ar/36Ar ratios from 0.18733 to 0.18902, 40Ar/36Ar ratios from 310.45 to 523.98, 20Ne/22Ne ratios from 9.727 to 9.830, and 21Ne/22Ne ratios from 0.0286 to 0.0310; and that, in the late altered cataclasitic-type ores, 3He/4He ratios vary from 0.15 to 4.33 Ra, 38Ar/36Ar ratios from 0.18750 to 0.18843, 40Ar/36Ar ratios from 331.78 to 602.62, 20Ne/22Ne ratios from 9.736 to 9.858, and 21Ne/22Ne ratios from 0.0286 to 0.0305. The data obtained suggest that the ore-forming fluid was a mixed solution of meteoric water, mantle fluid and crustal fluid. Basic igneous materials (between 224 Ma to 205 Ma) in southern Hunan and mantle fluids were involved in the early metallogenic process (224 Ma), suggesting that the Mesozoic tectonic regime transformation in Nanling region possibly took place in late Triassic (224 Ma±).
keywords:geology noble gases isotope ore-forming fluid tectonic regime transform Hehuaping Sn-polymetallic deposit
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中图分类号：618.44
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基金项目:本文得到国家自然科学基金(40972073)项目资助
引用文本：
蔡明海,王显彬,长尾敬介,彭振安,郭腾飞,刘虎,谭泽模.2012.湘南荷花坪锡多金属矿床稀有气体同位素特征及其地质意义[J].矿床地质,31(6):1163~1170CAI MingHai,WANG XianBin,Keisuke NAGAO,PENG ZhenAn,GUO TengFei,LIU Hu,TAN ZeMo.2012.Noble gas isotopic characteristics of Hehuaping tin-polymetallic deposit, southern Hunan Province[J].Mineral Deposits31(6):1163~1170
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