广东富湾银矿区地震地质环境研究
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摘要
广东富湾银矿床是国内银矿储量最大的矿床。为保障矿区的安全生产,降低金属矿开采诱发地震的风险,对矿区地震地质环境进行了系统调查研究。矿区位于丘陵地貌区,四周为三角洲冲积平原地貌所围绕。矿区处于由上三叠统小坪组地层构成的向斜之中,灰黑色薄层状含炭质泥岩、炭质页岩及煤层等软弱层发育。矿区内走向NNE-NE向和NWW向的断裂构造发育,钻孔揭示到的断裂物质组成以硅化岩、硅化角砾岩、胶结紧密的构造角砾岩等为主要特征,遥感卫星影像与地形地貌并没显示出断裂自晚第四纪以来有活动的迹象。在现今构造挤压应力场作用下,矿区范围走向NWW的断裂F6、F7容易发生走滑,而NE-NNE向的断裂F3、F4、F5则相对处于受挤压的状态。研究结果表明:矿区25 km范围地震活动性相对较弱。在日后矿山开采过程中,应注意断裂构造复活、矿体应力变化、软弱围岩或地质弱面等矿震诱发因素的影响。
The Fuwan silver deposit has the largest ore reserves in China. For mining safety and reducing the risk of mining induced earthquakes, seismic and geological environment were studied in detail. The mine area located in hilly surrounding with the alluvial plain. Owing to the syncline composed of Upper Triassic(Xiaoping Formation), dark gray thin carbonaceous mudstone, carbonaceous shale and coal seam developed. There were fractures in the direction of NNE-NE and NWW with the substance characteristics of silicified rock, silicifiedbreccia and tectonic breccia. The satellite-remote-sensing image and geomorphology showed that the fractures had no activity sign since the Late Quaternary. With the regional tectonic stress, the fractures in the direction of NWW would produce strike-slip(f6and f7), and the fractures in the direction of NE-NNE would be in the status of extrusion. The results showed that the seismic activity was weak in the Fuwan silver mine area within the radius of25 km. In the future of the mining process, the factors of mining induced earthquakes, such as the activity of the fractures, the changes of orebody stress, and geological weak layers should be paid more attention to.
引文
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