南岭西段苗儿山-越城岭复式岩体内外接触带矿集区岩浆形成演化与不同元素组合矿床形成关系研究

Many ores with different element assemblage such as W，W(Sn), W-Mo, Sn, Pb-Zn and Cu have been found in the contact zone around the Miaoershan-Yuechengling complex pluton in the western Nanling ore belt, forming an ore rich domain around the complex pltuon. This ore rich domain provides an excellent window to reveal the relationship between magma evolution and genesis of ores with different element associations. Based on field observation and microscopic identification of W(Sn), W-Mo, Cu and Pb-Zn ores, this project will focus on isotope age of ores and associated clossely felsic intrusions, the sources of rocks and ores with different element associations, compositions of different silicate melt exsolved volatile, rare gas isotope ratios of ore-forming fluids and silicate melt exsolved volatile, the differences of ore-bearing felsic rocks and barren felsic rocks in F and Cl concentration in mica, zircon Ce4+/Ce3+ ratios, and apatite trace element composition. Based on the above work, the spatial and temporal distribution of mineralization and associated magmatic rocks in the Miaoershan-Yuechenling complex pluton and the relationship between the formation of ores and magmatic activities will be revealed; the key factors controlling the formation of ores with different element associations and the reasons why many ores were formed around the Miaoershan-Yuechenling complex pluton and the differences of ore-bearing intrusives and and barren intrusives in geochemical features will be discussed; the forming processes and forming models for deposits with different element assemblage will be proposed. This project plays an important role in understanding completely the relationshop between the evolution of felsic magmas and formation of deposits with different element associations, in analyzing characteristics and dynamic background of mineralization in the western Nanling ore belt and in supervising ore prospecting in the Nanling ore belt.

南岭成矿带西段苗儿山-越城岭复式岩体内外接触带发育一系列W、W(Sn)、W-Mo、Sn、Pb-Zn及Cu等矿床，形成矿集区，为研究岩浆形成演化与不同元素组合矿床形成提供了良好条件。本项目以区内W（Sn）、W-Mo、 Pb-Zn及Cu矿床为主要研究对象，通过矿床及共生岩体同位素定年、不同元素组合矿床及共生岩体源区异同分析、岩浆出溶挥发相成分及其稀有气体同位素组成与成矿流体稀有气体同位素组成异同、成矿与非成矿岩体云母矿物矿化剂元素含量、锆石Ce4+/Ce3+、磷灰石微量元素组成等，探讨复式岩体内外接触带矿集矿床时空结构及成矿演化；分析成矿与不同期次岩浆活动的关系；阐明复式岩体内外接触带矿床发育及形成不同元素组合矿床的主要控制因素；论证成矿岩体地球化学指标及建立成矿模式。该项目对深入了解岩浆形成演化与不同元素组合矿床形成的关系，分析南岭西段成矿特征以及指导南岭西段的找矿工作等都有着较重要的意义。

苗儿山—越城岭复式岩体是南岭成矿带西段出露面积最大的复式岩体，围绕岩体内外接触带发育一系列不同元素组合的矿床，形成多元素组合矿床发育区。项目主要分析矿集区界牌矽卡岩型钨铜矿床、牛塘界矽卡岩型钨矿床、瞬王山石英脉型钨矿床、云头界石英脉钨钼矿床和长岗岭岩体接触带型锡多金属矿床有关岩体锆石U-Pb年龄、辉钼矿Re-Os及锡石U-Pb年龄，岩体主微量元素及Sr-Nd-Hf同位素、成矿流体温度、盐度及H-O同位素组成；阐明矿集区矿床时空分布、探讨发育多种元素组合矿床的主要控制因素及成矿元素析出机制。牛塘界钨矿床成矿岩体锆石U-Pb年龄约为421.8±1.6Ma,岩脉中浸染状锡石U-Pb年龄约426±6Ma;界牌W-Cu矿成矿岩体锆石U-Pb年龄约为422±11Ma，长岗岭Sn多属矿床成矿岩体锆石年龄约420.5±4.1Ma; 瞬王山W矿床岩体锆石220.4±2.4Ma；云头界钨钼床成矿岩体锆石U-Pb和辉钼矿Re-Os等时线年龄都约为216Ma。主要矿床区发育多期次岩浆活动，时间跨度大于10Ma；苗儿山—越城岭矿集区成岩成矿发生于加里东期和印支期，而不是过去推测的燕山期，南岭成矿带在加里东期和印支期也发生较大规模的成矿作用。主要矿床岩体Nd(t)值在-7.6~-13.9之间，T2DM在1400~2400Ma之间，在Nd(t)—t图上位于华南元古宙演化区。界牌含铜矿化岩体在SiO2—P2O5相关性、Th（Y）—Rb图及CaO/(Mg+FeO)—Al2O3/(Mg+FeO)图上显示混合I型和S型花岗岩特征，而其它钨和钨钼矿化岩体显示S型花岗岩特征。这表明含铜矿化岩体为元古宙基底变沉积岩夹变火成岩部分熔融形成的，而钨及钨钼成矿岩体为元古宙变沉积岩部分熔融形成的。源区差异是控制形成不同元素组合矿床主要控制因素。.主要矿成矿流体为中低温（350-180C）低盐度流体，多均一至液相，成矿过程中未发生沸腾。成矿流体H-O同位素组成特征表明主体为岩浆水，有大气降水混入；成矿流体温度-盐度显示两种变化趋势，一为盐度和温度变化关系不明显，另一为盐度和温度呈正相关关系。这说明成矿元素析出主要为流体混合或降温所致。.岩浆期石英及磷灰石中发育流体包裹体和岩体的稀土元素配分模式具有四分组效应可作为成矿岩体重要标志。