长江中下游成矿带磁异常揭示的深部构造与成矿关系  

Relationship between metallogenic setting and the deep crustal structures revealed by magnetic data of the Middle-Lower Yangtze River Valley Metallogenic Belt

作　　者：陈安国[1,2] 周涛发 刘东甲[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]合肥工业大学矿床成因与勘查技术研究中心,合肥230009

出　　处：《岩石学报》2017年第11期3599-3609,共11页Acta Petrologica Sinica

基　　金：国家重点研发计划(2016YFC0600206);国家自然科学基金项目(41320104003;41672081)联合资助

摘　　要：长江中下游成矿带是我国最主要的铁铜金多金属成矿带之一。本文通过高精度航磁异常数据分析成矿带内磁异常的分布特征,研究表明,火山岩盆地和郯庐断裂带沿线的正磁异常呈团块状分布,而大别造山带和九华山的正磁异常呈宽缓分布,前者与成矿带内以铁矿化为主的多金属矿床密切相关。航磁异常边界识别结果清晰揭示了郯庐断裂带、晓天-磨子潭断裂和襄樊-广济断裂等区内重要的深大断裂,九江附近的边界可能是郯庐断裂带的南延。长江中下游及邻域的居里等温面深度变化范围约为23.5~31.5km,沉积盆地下方居里等温面总体呈现拗陷,火山岩盆地下方居里等温面总体呈现隆起,郯庐断裂带沿线的居里等温面呈带状分布的隆起。大别造山带和九华山下方居里等温面呈现拗陷,有别于火山岩盆地和郯庐断裂带沿线的居里等温面隆起。长江中下游成矿带内主要的铁铜多金属矿床点集中分布在居里等温面隆起或隆起边缘部位,指示了长江中下游早白垩世剧烈的岩浆活动使区域大地热流值相对较高,地壳深部的构造格局和岩浆活动制约了浅部的成矿。The Middle-Lower Yangtze River Valley Metallogenic Belt （MLYB） is one of the most significant polymetallic belts in China. Based on high precision aeromagnetic data of the MLYB, we analyzed the distribution characteristics of magnetic anomalies. The positive magnetic anomalies along volcanic basins and Tan-Lu fault is characterized by massive distribution, which is closely related to iron-polymetallic deposits of the MLYB, but the positive magnetic anomalies in the Dabie orogenic belt and Mount Jiuhua have a wide range distribution. Analysis results of edge detection on aeromagnetic data clearly reveal the location of the Tan-Lu Fault Zone, the Xiaotian-Mozitan fault and the Xiangfan-Guangji fault. The edge near Jiujiang City may be the southern extension of the Tan-Lu Fault Zone. The Curie point isotherm with the depth of 23.5~31.5km of MLYB and its adjacent areas, which is concave in the sedimentary basins （e.g., Poyanghu, northern Jiangsu）, and convex in the volcanic basins （e.g., Ningwu, Luzong）, and along the Tan-Lu Fault Zone. The Curie point isotherm was concave in the Dabie orogenic belt and Mount Jiuhua, which is obviously different from volcanic basins. The main Fe-Cu polymetallic deposits of the MLYB is close to the convex Curie point isothermal, indicating Early Cretaceous magmatic activity area had higher heat flow value. The tectonic pattern of the deep crust and magmatic activity restrict the shallow mineralization.

关 键 词：磁异常 边界识别 居里等温面 长江中下游成矿带 郯庐断裂带 

分 类 号：P612[天文地球—矿床学] P631[天文地球—地质学]