胶东地区破碎带蚀变岩型金矿时代的测定及其地质意义

通过对胶东半岛西北部超大型破碎带蚀变岩型金矿 -新城金矿的强烈热液交代成因黄铁绢英岩 Rb- Sr等时线法测年 ,获得 116 .6± 5 .3Ma成矿年龄。结合本区焦家、仓上等大型 -超大型金矿蚀变矿物、石英流体包裹体的 Rb- Sr等时线年龄、K- Ar年龄 (10 5± 7Ma;10 6± 2 Ma;113.5± 0 .6 Ma)等前人成果 ,确定胶东半岛西北部破碎带蚀变岩型金矿成矿时代主要集中在 10 0～ 117Ma。与围岩花岗岩、花岗闪长岩的成岩年龄 (16 0～ 15 0 Ma;130～ 12 6 Ma)存在着近 10 Ma的时差 ,并根据(87Sr/ 86 Sr) i比值以及已有的 C、H、O稳定同位素资料表明 ,即使成矿物质部分来源于围岩花岗岩类 ,但成矿作用与岩浆活动无明显的成因关系 ,而是深部循环的大气降水或幔源 C- H - O流体参与成矿作用的结果

Datingof gold mineralization for super-large altered tectonite-type gold deposits inNorthwestern Jiaodong Peninsula and its implications for gold metallogeny

In order to understand the genesis of ore deposits, it is fundamental to know the timing of gold deposition. Alteredtectonitetype gold deposits, occurred in northwestern Jiaodong Peninsula, containing several superlarge gold ore deposits, is dated by RbSr isochron and KAr method for goldbearing altered tectonites and minerals at 117~100Ma. This age is significantly younger than that of emplacement of its host intrusions(160~150Ma for Linglong granites and 130~126Ma for Guojialing granodiorites), precluding the direct genetic link between gold mineralization and acidic magmatism. The 87Sr/86Sr initial ratio suggests that, although oreforming materials of gold deposits were derived partly from Guojialing granodiorites, there exist other sources. It is, therefore, concluded that this type of gold deposit is not traditionally magmatic hydrothermal genesis, but the product of mixing fluids by meteoric water or manltederived CHO fluids after the emplacement of granitic and granodioritic intrusions.