摘要
长江中下游成矿带是我国最主要的铜铁金多金属成矿带之一。本文利用卫星重力数据计算布格重力异常,采用波数域迭代的Parker-Oldenburg位场迭代反演方法,通过重力数据反演获得长江中下游成矿带及邻区的三维Moho面结构,结合研究区已有的研究成果,探讨了研究区的深部构造格局。研究结果表明:研究区范围内Moho面总体从南西往北东有逐渐变浅趋势,最浅处位于长江口海域和杭州湾海域约28~29km,最深处位于大别山区约38~39km;长江中下游及邻区下方Moho面的隆起形态呈"V"字型,与地表的"V"字型构造特征相呼应,Moho面隆起的最深处位于"V"字型转折端附近,向两侧Moho面呈抬升状,北东走向的"V"字型东支隆起幅度和规模都要明显大于北西走向的"V"字型西支;卫星化极磁异常显示长江中下游成矿带的正磁异常高值集中分布在"V"字型东支的宁芜、庐枞、繁昌、怀宁等火山岩盆地;钦杭成矿带东段Moho面也明显上隆,隆起的中心沿钦杭成矿带的南侧边界断裂的东南侧线性分布。长江中下游成矿带和钦杭成矿带东段的Moho面条带状隆起带可能指示了地幔上隆、岩浆上涌并在壳幔边界处与下地壳发生底侵作用的深部边界,来自于壳、幔的深部含矿岩浆通过深大断裂等地壳薄弱点向上运移,并在适当的位置形成金属矿集区。
The Middle-Lower Yangtze River Valley Mineralization Belt （MLYB） is one of the most significant polymetallic belts in China. Based on available satellite-derived free-air gravity anomalies and elevation database sets, this study obtained the 3D Moho pattern of the MLYB and Its adjacent areas using Parker-Oldenburg wave number domain iteration method. Combined with existing research results, the deep tectonic framework in the study area was also addressed. The results show that the Moho depth generally presents a decreasing trend from southwest to northeast in the study area, with the shallowest location （28～29km） between the Yangtze Estuary and the Hangzhou Bay sea, and the deepest （38～39km） within the Dabie Mountain. The deepest location of the Moho uplifting is near the turning point of V shape, with two sides of the Moho lifted. The uplift amplitude and scale of the NE trending eastern branch of the V shape is apparently greater than that of the NW trending west branch. Satellite magnetic anomalies indicate that high positive magnetic anomaly values in the MLYB concentrate on volcanic rocks basins （such as Ningwu, Luzong, Fanchang and Huaining） in the eastern branch of V shape. The Moho in the eastern section of Qin Hang metallogenic belt also uplifted notably, with the center of “mantle uplift” distributed along the southeast of the fault in the south boundary of the metallogenic belt. The striped uplift zone of the Moho within the MLYB and also the eastern section of the Qin Hang metallogenic belt possibly indicates mantle uplifting and magma upwelling, as well as the deep boundary of underplating between crust mantle and lower crust. Meanwhile, ore bearing magma from the lower crust or mantle migrated upwards along deep faults of the brittle crust, and precipitated in favorable positions to form metallic ore cluster areas.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2017年第6期1299-1311,共13页
Acta Geologica Sinica
基金
国家自然科学基金重大国际(地区)合作与交流项目(编号41320104003)
国家重点研发计划项目(2016YFC0600206)联合资助的成果
关键词
卫星重力异常
卫星磁异常
莫霍面
长江中下游成矿带
钦杭成矿带
Gravity anomaly derived from satellite altimetry
Magnetic anomaly compiled from satellite, marine, aeromagnetic and ground magnetic surveys
Moho
Middle-Lower Yangtze River Valley Metallogenic Belt
Qin-Hang metallogenic belt
