赣西北九岭中北部晚侏罗世S型花岗岩成矿专属性分析

Metallogenic specialization of late Jurassic S-type granites in middle-northern Jiuling Mountain in northwestern Jiangxi

对赣西北石门楼地区黑云母二长花岗(斑)岩进行了锆石U-Pb年代学、岩石地球化学、锆石和黑云母矿物地球化学研究。黑云母二长花岗(斑)岩LA-ICP-MS锆石U-Pb加权平均年龄145.6~148.4Ma,属晚侏罗世晚期。岩石属普通低分异S型花岗岩,为中等还原(Fe2O3/FeO=0.18~0.19,Ce4+/Ce3+=14~158,lg(fO2)D=-22.4^-6.9,平均-13.8(>IW-3.6))、强演化(K/Rb=153~206)、低分异(Rb/Sr=1.6~4.2)、较低温(T锆石Ti=619~881℃,平均750℃)岩浆。岩浆来源为上地壳富砂屑源区,由起源于古中元古代地壳物质(双桥山群)的新元古代花岗岩类源岩重熔再造作用形成。该类岩体具形成钨矿床的成矿物质、时代及空间专属性和成矿可能性。

The zircon U-Pb geochronology, petrogeochemistry,zircon and biotite mineral geochemistry of biotite monzogranite (- porphyry) in Shimenlou area of northwestern Jiangxi province have been studied.The LA- ICP-MS zircon U-Pb206 Pb/238 U weighted average ages of zircons from the biotite monzogranite (-porphyry) are in the range of145.6~148.4 Ma,suggesting late Late Jurassic.The rock is common low fractionation S-type granite.The magma properties are moderately reductive (the ratio of Fe2O3/FeO = 0.18~ 0.19,the ratio of Ce 4+/Ce3+=14~158, log10 ( f O2) D=-22.4^-6.9,averaging -13.8 (> IW-3.6)),strong evolution (the ratio of K/Rb =153~206),low fractionation (the ratio of Rb/Sr =1.6~4.2) and low temperature ( T (zircon) Ti = 619~881℃,averaging 750℃).The magma was derived from the magma source enriched area of the upper crust,which was formed by remelting and regenerating of the Neoproterozoic granitoids derived from the early Mesoproterozoic crustal material (Shuangqiao Mountain Group).The rock has the metallogenic material,time and spatial specialization and metallogenic possibility of forming tungsten deposit.