| 南岭成矿带多尺度重力场及深部构造特征 |
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| 引用本文： | 陈国雄,刘天佑,孙劲松,欧 洋,刘 双.南岭成矿带多尺度重力场及深部构造特征[J].地球科学,2014,39(2):240-250. |
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| 作者姓名： | 陈国雄 刘天佑 孙劲松 欧 洋 刘 双 |
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| 作者单位： | 1.中国地质大学资源学院, 湖北武汉 430074 |
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| 基金项目： | 南岭地区燕山期深部岩浆活动与大规模成矿复杂性研究1212011121101 |
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| 摘 要： | 利用小波多尺度分解方法分离不同深源尺度花岗岩侵入体的重力异常信息, 结合视密度填图方法划分了5 km、15 km及25 km深花岗岩体分布特征, 并综合地震成像和大地电磁测深资料, 对南岭花岗岩侵入体的赋存侵位、诱发热源以及成因模式等问题进行初步探讨.研究结果表明, 以茶陵-郴州断裂为界, 区内重力场和岩体构造呈明显分区, 东南区岩体局部重力异常幅值较小, 地表出露岩体较薄, 岩浆沿着小通道上涌形成岩盖; 西北区岩体局部重力异常幅值较大, 侵位深度较深; 区内大多数岩体侵位深度不超过25 km; 深部地球物理资料还揭示诸广山和猫儿岭地区15~25 km附近存在大规模低密度、低速特征的陆壳重熔区; 诸广山地区上地幔顶部存在低速、低阻熔体特征的软流圈上涌通道, 推测来自软流圈的玄武岩浆底侵造成该区中下地壳岩石部分熔融, 并为其周围大规模成岩成矿提供热源和物质来源.
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| 关 键 词： | 布格重力异常 花岗岩侵入体 岩体边界识别 陆壳重熔 数据处理 南岭成矿带 |
| 收稿时间： | 2013-05-17 |
Characteristics of Multi-Scale Gravity Field and Deep Structures in Nanling Metallogenic Belt |
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| Abstract: | In this paper, the multi-scale wavelet decomposition method was applied to separate the Bouguer gravity anomalies of Nanling region to obtain the local anomalies of granites at different depth scales. The granite distribution is delineated at 5 km, 15 km and 25 km respectively by 3D density mapping technique. We discuss some hot issues of Nanling granitic intrusions, including their geological and geophysical model, induced heat source and genetic model, by integrating and analyzing the seismic imaging and magnetotelluric data. The results show that the gravity anomalies and granitic intrusions have apparent partition features marked by Chaling-Chenzhou fault. The local gravity anomalies in southeast region with lower amplitude indicate shallow emplacement depth of granitic intrusions, and the magma intrude into the near-surface along the small channel to form rock cover, whereas the local gravity anomalies in northwest region with higher amplitude suggest deeper emplacement depth. Most of granites' emplacement depths are no more than 25 km. The large-scale low-density and low-speed region in Zhuguangshan and Maoerling area exits near the depth range of 15-25 km. The low-speed and low-resistance region also appears at the top of mantle in Zhuguangshan area, suggesting the upwelling channel of high-temperature asthenosphere lava. Therefore, the basaltic magma underplating may cause the protolith partial melting in middle-lower crust, which also provides the heat and material sources for the large-scale mineralization in Nanling region. |
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