| Dongyang region of Fujian is in the middle of Fujian Province,loated in the the south of middle section of Zhouning-Hua'an fault uplift belt,the interaction of Yangmei-Donghua(NE)fault and Ancun chuikou(NW)fault.The volcanic rocks are widely distributed,and the magmatic activity are intense and frequent in the Dongyang region.Gold is the main mineral,and the Youxi-Dehua-Yongtai gold prospect area is known as the "Golden Triangle" of Fujian Province.Dongyang gold mine belongs to the Circum Pacific metallogenic belt.It is the product of the volcanic movement in the middle Yanshan period and the subduction of the oceanic plate to the Eurasian plate.There are more than 20 deposits,such as Shuangqishan gold deposit,Qiucun Gold Deposit,Xiaoban gold deposit,and so on.In recent years,the different levels of exploration and research are carried out to the deposites.Due to the low level of regional deep geophysical exploration,there has been no breakthrough in deep prospecting.The purpose of this paper is to study the regional structure and the distribution of regional mineral characteristics based on the characteristics of regional physical properties and geophysical field of the Dongyang metallogenic belt by carrying out comprehensive geophysical exploration in Dongyang region.Based on the characteristics of typical gold deposits(points)that have been explored and studied,combined with the characteristics of geophysical field of the Dongyang metallogenic belt,comprehensive geophysical research and regional geological,metallogenic background and regional gold metallogenic model,we research and discussion the metallogenic law of gold deposits of Dongyang metallogenic belt.The resistivity of rocks is generally high in Dongyang metallogenic belt,and the characteristics of high resistivity and high intensification can be used as one of the prospecting indicators in the region.Dongyang metallogenic belt is located in the transition area between Jianou-Nanping and Liancheng-Longyan gravity anomaly areas,and is in the gravity gradient zone.Bouguer gravity anomaly isoline is general NW trend.It's a reaction of deep and large faults.There are two abnormal high residual gravity in NW direction,which is basically consistent with the measured gravity profile detection results.The magnetic field of the region is complex and great change,and it is distributed alternately with high and low in north-east strip.According to the characteristics of regional magnetic anomalies,Dongyang region is divided into two second-order structural units: Jiemian-Shangyong fault uplift zone and Zhongxian-Shuikou volcano fault depression zone.They are correspond to Shouning-Hua'an fault uplift zone and Fuding-Pinghe fault depression zone respectively.Dongyang metallogenic belt has experienced many tectonic changes since Jinning movement,formed a tectonic framework with deep or large faults as the main body,and supplemented by secondary faults.In space,the faults are relatively concentrated and distributed in belts,and the fault direction is mainly NE-NNE and NW-NNW.According to the characteristics of comprehensive geophysical field of Dongyang metallogenic belt and ground geology,we analysis and research the regional fault structure,the volcano structure and the intrusive rocks,and infer 80 faults,47 intrusive rock and 16 volcanic structures.The main types of gold deposits in Dongyang metallogenic belt are epithermal gold deposits and metamorphic gold deposits.The epithermal gold deposits are distributed in ore belt,and the direction is consistent with the main north-west structural direction.The epithermal gold deposits are located in the east side of the Northeast uplift belt,from the Qiucun-Leitan area to the Lingtouping-qiweishan area in the South East,the deposites are generally distributed in Northwest belt,and are controlled by the structure obviously.The metamorphic hydrothermal type gold deposits are mainly formed in the special lithology horizon about the shear deformation and the fold structure position.There are Shuangqishan deposite,Xiaoban deposite,Shankeng deposit and so on,they are mainly distributed at the intersection of the NE trending uplift belt and the NW trending metallogenic structural belt,and formed under the influence of metamorphic hydrothermal fluid,magmatic hydrothermal fluid and later structure.The mineralization of Dongyang gold deposit is mainly related to the late jurassic and early cretaceous volcanic activity in time,controlled by the tectonic margin of the Large volcanos in space,mainly distributed at the edge of deep and large faults,the small rock masses and the basins,and distributed in northwest direction generally.In all,the research results of this paper lay a theoretical foundation for the breakthrough of deep prospecting in Dongyang metallogenic belt. |
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