河南板厂银多金属矿床钾长石氩-氩年龄及其地质意义

^(40)Ar-^(39)Ar Age of Potash Feldspar from the Banchang Ag-Cu-Pb-Zn-(Mo) Deposit in Henan and Its Geological Significance

河南内乡板厂矿床通过近年来的勘查工作,为一大型斑岩—热液型银铜铅锌(钼)矿床。本文对该矿床斑岩型铜矿石中钾长石进行了Ar-Ar定年,获得两个年龄坪:900~1150℃年龄坪包括了43.4%的39Ar,坪年龄为(148.1±1.6)Ma,反等时线年龄为(145.7±2.3)Ma;1200~1450℃年龄坪包括了48.8%的39Ar,坪年龄为(161.0±1.6)Ma,反等时线年龄(159.0±14.0)Ma。前者代表了该矿床的成矿年龄,后者代表了含矿斑岩的成岩年龄。该二阶段年龄谱特征反映了板厂矿床成岩成矿的阶段性。在我国不少矿区的Ar-Ar法年龄谱上均有多坪显示,这与我国许多矿区成矿作用和构造事件的多期多阶段特征一致。

The Benchang large-size porphyry-hydrothemal type Ag-Cu-Pb-Zn-（Mo） deposit in Neixiang County, Heron Provinoe, was discovered recently. Based on Ar-Ar gecochology of potash feldspar from this deposit, there are two chronological plateaus： ① 900-1150℃ ehronological plateau includes 43.4 % of 39Ar and has plateau age of （148.1 ± 1.6 ） Ma and revised isochronal of （145.7 ± 2.3） Ma; ② 1200-1450℃ chronological plateau includes 48.8 % of 39Ar and has plateau age of （161.0 ± 1.6） Ma and revised isochr^al age of （159.0 ± 14.0）Ma. The fcwmer is the age of the mineralization and thelatter is the age of porphyry. This two-stage age pattern shows the multi-stage features of both magmatism and mineralization in the Banehang deposit. In fact, the Ar-Ar age patterns of many deposits in China have more than one chronic plateaus, to the multiple-stage features of mineralization and tectonic events in these deposits.