河北邯郸洪山铜矿Ar-Ar和U-Pb年龄及其对成矿时代的限定

【研究目的】近年来在邯郸洪山岩体及其周边发现多处铜金矿（化）体。成矿时代确定是厘定矿床成因和分析成矿作用过程的关键。【研究方法】在详细野外地质工作的基础上，对赋矿岩石中锆石及铜矿化热液蚀变矿物黑云母分别采用了U-Pb和⁴⁰Ar-³⁹Ar阶段加热法进行了同位素测年。【研究结果】测得洪山铜矿床矿化蚀变产物黑云母⁴⁰Ar-³⁹Ar坪年龄为（127.62±0.5）Ma。2件赋矿岩石锆石U-Pb年龄分别为（130.45±0.94）Ma和（131.4±1.8）Ma。【结论】年龄测试结果显示，区内铜矿化的发生与正长斑岩侵位关系密切，属区内早白垩世酸性岩浆热液活动的产物。根据太行山南段夷平面和洪山岩体盖层厚度，推测太行山南段因地壳隆升，洪山岩体剥蚀了约2000 m。赋存于岩体上方或顶部的铜矿体已遭受不同程度剥蚀，岩体中心区域深部找矿前景不容乐观。

Ar-Ar and U-Pb ages of Hongshan copper deposit, Handan City, Hebei Province and their limitation on mineralization age

This paper is the result of mineral exploration engineering.Objective] Some copper and gold bodies have been found around Hongshan pluton in recent years. The determination of metallogenic age is the key to determine the genesis of ore deposits and analyze the metallogenic process.Methods] On the basis of detailed field geological work, the isotopic dating of zircon and copper-mineralized hydrothermal alteration mineral biotite in orehosting rocks were carried out by using U-Pb and ⁴⁰Ar-³⁹Ar stage heating methods, respectively.Results] Hydrothermal biotite alteration occurred at(127.62±0.5) Ma, the U-Pb ages of the zircons from ore-bearing rock are (130.45±0.94) Ma and (131.4±1.8) Ma, respectively.Conclusions] The results of age test show that copper mineralization is closely related to the acidic hydrothermal activity after the emplacement of fine-grained syenite porphyry. According to the planation surface of the southern Taihang mountain and the thickness of the cover layer of the rock mass, it is speculated that the Hongshan pluton has been denuded about 2000 meters due to crustal uplift, prospecting potential of the copper deposit is not promising.Highlights: Combining the deposit formation age with the later regional tectonic uplift evolution, analyze the denudation and retention of the ore body, conclude the prospecting prospect is not optimistic in the central area of rock mass.