晋东北地区义兴寨金矿综合找矿模型

SYNTHETIC MODEL FOR SEARCHING GOLD DEPOSITS-AN EXAMPLE FROM YIXINGZHAI GOLD DEPOSIT, NORTHEASTERN SHANXI PROVINCE

本文根据地质、地球物理、地球化学和遥感资料提出了义兴寨金矿成矿的"Φ"形构造模式,指出分布于山西省东北部太古宙变质杂岩中的义兴寨金矿田处于环形重力低异常被两条北西向相背倾向航磁解译线性构造束切割所构成的地球物理"Φ"形构造区内,并与水系沉积物Mo、Br、Ag、Cu的环状异常晕被北两向Pb、Zn线状异常叠加所形成的地球化学"Φ"形构造相吻合.矿田内已知义兴寨和辛庄两个中型金矿床分别位于北西向断裂切割燕山期孙庄闪长杂岩岩体所形成的地质"Φ"形构造的两端.陡倾、走向近南北的金-多金属硫化物石英脉穿切孙庄闪长岩及其伴生浅成相隐爆角砾岩,与两条航磁解译线性构造相接,总体上被限制在二者之间并展现出北西向排列的趋势.不同类别的"Φ"形构造、燕山期多朗侵位的复成份中酸性岩浆岩侵入体、时代不一、成份复杂的脉岩系、古老东西向基底构造的活化和组合复杂的重砂矿物、水系沉积物Mo、Bi、Ag、Cu、Pb、Zn异常是该类型金矿床的重要找矿标志.

'Ф' Shaped structure has been proposed as a new tectonic model for veined gold mineralization based on the data of geology, geophysics, geochemistry and remote sensing from Yixingzhai gold deposits, north-eastern Shanxi province, China. Two middle-large-sized gold deposits formed during the Mesozoic and some gold-cooper mineral occurences in the Archean metamorphic complexes are found within a geophysical '?' shaped structure consisting of the circular gravity low anomaly and the cutting linear structure from interpretation of geophysical data. The '?' shaped structure shows well coincidence with the '?' shaped geochemical anomaly which makes up of the circular halos of Mo. Bi Ag and Cu stream sedimentary anomalies superposed by north-western linear stream seddimentary anomalies of the elements Pb and Zn. Yixingzhai and Xinzhuang gold deposits in the orefield are on the either end of the '?' shaped structure which is composed of the Mesozoic intrusion crossed by a fault with northeastern trend. Gold-polymetallic sulfide quartz-veins with steep and near south-northern or north-western trend in both gold deposits pass through Shunzhuang dioritic intrusion and the exploded breccia pipe related closely with the intrusion, and join with the linear structures interpretated from magnetic data. These veins are limited between the linear structures and show a north-easternly distribution. It is very important guides to searching for this type of gold deposits that the 'Ф' shaped structures occur in various type and the Mesozoic intrusions with intermediate to acidic composition, that the dyke series intruded in different period are well developed, that the oldest faults with east-western trend in the basement are reactive and that the complicated assemblages of both heavy minerals and stream sedimentary anomalies of the elements Bi. Ag. Cu. Pb. Zn occure.