Timing and Source of the Hermyingyi W-Sn Deposit in Southern Myanmar, SE Asia: Evidence from Molybdenite Re-Os Age and Sulfur Isotopic Composition
Timing and Source of the Hermyingyi W-Sn Deposit in Southern Myanmar, SE Asia: Evidence from Molybdenite Re-Os Age and Sulfur Isotopic Composition
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DOI：
10.1007/s12583-018-0860-y
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发表时间：
2019-02
影响因子：
3.3
通讯作者：
Hai Jiang;Shaoyong Jiang;Wenqian Li;K. Zhao
中科院分区：
文献类型：
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作者：
Hai Jiang;Shaoyong Jiang;Wenqian Li;K. Zhao
位于东南亚缅甸南部的赫敏吉钨锡存款矿床是一个典型的石英脉型钨锡存款矿床。含矿石英脉主要产于侵入于石炭纪麦吉统变质沉积岩中的赫明依二长花岗岩中。根据矿物组合和横切面关系，可划分为四个成矿阶段：（1）硅-氧化物阶段;（2）石英-硫化物阶段;（3）贫石英脉阶段;（4）表生阶段。存款中5个辉橄榄岩样品的Re-Os模式年龄为67.8±1.6 ~ 69.2± 1.6Ma（加权平均年龄为68.7± 1.2Ma），等时线年龄为68.4± 2.5Ma（MSWD=0.18，2σ）。该Re-Os年龄与已发表的Hermingyi二长花岗岩锆石U-Pb年龄（70.0± 0.4Ma）（MSWD=0.9，2σ）在误差范围内一致，表明二长花岗岩岩浆活动与钨锡成矿作用之间存在成因联系。新的高精度年代学资料表明，缅甸南部的花岗质岩浆活动及其伴生的钨锡成矿作用发生在晚白垩世（70-68 Ma）。辉长岩中Re含量极低（22.9 ~ 299 ppb），硫化物δ 34 S值在+1.9‰ ~+5.6‰之间，表明成矿金属主要来源于壳源花岗质岩浆。
The Hermyingyi W-Sn deposit, situated in southern Myanmar, SE Asia, is a typical quartz-vein type W-Sn deposit. The ore-bearing quartz veins are mainly hosted by the Hermyingyi monzogranite which intruded into the Carboniferous metasedimentary rocks of Mergui Series. According to mineral assemblages and crosscutting relationships, four ore-forming stages are recognized: (1) silicate-oxide stage; (2) quartz-sulfide stage; (3) barren quartz vein stage; (4) supergene stage. Five molybdenite samples from the deposit yield Re-Os model ages ranging from 67.8±1.6 to 69.2±1.6 Ma (weighted mean age of 68.7±1.2 Ma), and a well-defined isochron age of 68.4±2.5 Ma (MSWD=0.18, 2σ). This Re-Os age is consistent with the previously published zircon U-Pb age of the Hermyingyi monzogranite (70.0±0.4 Ma) (MSWD=0.9, 2σ) within errors, which indicates a genetic link between the monzogranitic magmatism and W-Sn mineralization. The new high-precision geochronological data reveal that the granitic magmatism and associated W-Sn mineralization in southern Myanmar took place during the Late Cretaceous (70-68 Ma). The extremely low Re contents (22.9 ppb to 299 ppb) in molybdenite, coupled with sulfide δ34S values in the range of +1.9‰ to +5.6‰ suggest that ore-forming metals were predominately sourced from the crustal-derived granitic magma.