玲珑金矿田黑云母二长岩的发现及其Ar-Ar热年代学意义

DISCOVERY OF BIOTITE MONZOLITE AND Ar-Ar THERMOCHRONOLOGY SIGNIFICANCE IN LINGLONG GOLD FIELD

胶东玲珑金矿田地表以下2070 m处发现黑云母二长岩,不仅可以探索该区金矿成矿物质的来源,而且对研究矿床成因提供了新的证据。黑云母二长岩在胶东金矿集中区地表及其他钻孔岩芯中尚未见报道,通过显微镜下观察、鉴定,具有典型的二长结构。非金属矿物主要有斜长石、正长石、石英、黑云母和角闪石;含有较多的金属矿物,主要为原生的黄铁矿和磁铁矿等。黑云母的40Ar-39Ar热年代学研究表明,黑云母二长岩的成岩年龄为123.7±1.5 Ma,晚于玲珑花岗岩、滦家河花岗岩和郭家岭花岗岩,与玲珑金矿的形成年龄非常接近。尽管玲珑金矿矿体中的金属矿物并不一定直接来源于黑云母二长岩,但从形成时间分析,二者具有成因联系。黑云母二长岩在侵入过程中可能为金矿的形成提供成矿物质、成矿流体,而且为成矿物质和成矿流体的运移提供能量及驱动力。因而可以推断,黑云母二长岩的侵入与玲珑金矿成矿作用关系密切。

The biotite monzolite that was discovered at 2170 meters below the surface in Linglong Gold Field in Jiaodong is not only used to find out the source of ore-forming material,but also is used to furnish new evidence for study the cause of mineralization of gold deposit. As the new rock types that was discovered in this area,Biotite monzonitichas the typical monzonitic texture under microscope. The non-metallic minerals composed the rock mainly are plagioclase,sodium feldspar,quartz,biotite and hornblende. It contains more metal minerals that mainly are pyrite and magnetitethan the other magmatic rocks in Northwest of Jiaodong. The biotite40Ar-39 Ar thermochronology indicate that the age of the formation of biotite monzonite is 123. 7 ± 1. 5 Ma which was later than the time of formation of Linglong granite,Luanjiahe granite and Guojialing granites,and is very close with the age of the formation of Linglong Gold Deposit. Although it is not sure that the metal minerals in the gold ore bodies in Linglong gold field directly come from biotite monzonite,the result of analysis of the characteristics of their generation time demonstrate that the metal minerals and biotite monzonite form in the same period and come from the same originate. In the process of invasion of the Biotite monzonite magma,it supply ore-forming materials for the formation of gold mine,and provides energy and driving force for ore-forming elements and ore-forming fluid migration. It can be deduced that the gold mineralization is closely related with the intrusion of biotite monzonite