摘要
东坪式金矿床产于华北克拉通北缘深大断裂─—尚义－赤城断裂的南侧，海西期水泉沟正长岩杂岩体内外接触带。矿体具有明显的分层性，自上而下矿石类型由石英脉型向钾、硅化蚀变岩型过渡。矿床形成于燕山早期，成矿物质主要来源于正长岩杂岩体。矿石铅同位素组成与正长岩杂岩体相似，在^（２０７）Ｐｂ／^（２０６）Ｐｂ－^（２０８）Ｐｂ／^（２０６）Ｐｂ图解上，矿石、正长岩、矿石中的钾长石脉石及太古宇桑干群变质岩里线性分布，矿石与正长岩在铅同位素组成上更接近，而与太古宙变质岩有明显的区别。在穿脉剖面上，随着钾、硅化蚀变程度的增加，Ｕ、Ｔｈ含量降低，铅同位素矢量特征值Ｖ_１、Ｖ_２值随蚀变程度增加有降低的趋势，但近矿脉样品由于受矿化影响而不同于蚀变围岩。矿石和蚀变围岩的Ｖ_１、Ｖ_２值与其所处的海拔高度ｈ呈正相关关系，ｈｖ_１＝１３５１＋９．３Ｖ_１，相关系数ｒ＝０．７７；ｈｖ_２＝１２２２＋１７．２ Ｖ_２，相关系数ｒ＝０．９２。根据对华北克拉通金矿床铅同位素组成范围的研究资料，取Ｖ_１＝－７０，Ｖ_２＝－３０作为东坪式金矿矿石铅同位素组成的下限，则矿床可以延伸至７００ｍ左右的海拔高程，即东坪金矿床的垂向延伸可超过１０００ ｍ。表明有必要进一步加?
The Dongping-type gold deposits occur at the inner and outer contact zones of the Shuiquangou syenite complex, which locates to the south of the northern margin fault of the North China Craton. There are three types of ores in this type of deposits, pyrite-quartz vein type, pyrite - quartz - K-feldspar type, and pyrite- K -feldsparthized syenite type. The ore types vary from auriferous quartz vein at the upper part to silicified and K-feldsparthized syenite at the bottom of the ore bodies. The hydrothermal gold mineralization occurred in early Yanshanian Period, although the Shuiquangou syenite complex emplaced in Hercynian Period. The Pb, S, Si isotope and trace element investigations suggest that the principal ore forming material came from the syenite complex. The Pb isotopic compositions of the ores are similar to those of the syenite, as shown in the ^(207) Pb / ^(206)Pb -^(208)Pb / ^(206) Pb diagram, the ores, syenite, and Archean metamorphic rocks are linearly correlated and the ores are more closely related to the syenite than Archean metamorphic rocks do. Within a lateral transection profile that traversing a auriferous quartz vein, the contents of U and Th decrease as the K-feldsparthization and silicification increase, while the V_1 and V_2 have a similar variation trend with the exception of the samples near the auriferous vein. The V_1 and V_2 are pos- itively correlated to the elevation of the samples, where, hv_1 = 1 351 + 9. 3 V_1 with a correlation coefficient r = 0. 77; hv_2 = 1 222 + 17. 2 V_2, with r = 0. 92. Regarding the lead isotope data of gold deposits within the North China Craton,V_1 = -70 and V_2 = - 30 are taken as the lower limits of the Dongping-type deposits, and the maximum vertical extension of gold mineralization will be exceed 1 000 m. Thus, the gold exploration to the lower part of the gold mineralization should be reinforced in future exploration campaign.
出处
《地球化学》
CAS
CSCD
北大核心
2000年第3期223-230,共8页
Geochimica
基金
国家攀登预选资助!(95-预-25)
中国科学院重点基金!(KZ-952-91-414)
关键词
铅同位素
正长岩
热液金矿
金矿床
化探评价
lead isotope
syenite
hydrothermal gold deposit
Dongping
Hebei Province
