| 利用接收函数和大地电磁数据联合反演南迦巴瓦构造结中部地区壳幔结构 |
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| 引用本文： | 彭淼,谭捍东,姜枚,王伟,李庆庆,张立树.利用接收函数和大地电磁数据联合反演南迦巴瓦构造结中部地区壳幔结构[J].地球物理学报,2012,55(7):2281-2291. |
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| 作者姓名： | 彭淼 谭捍东 姜枚 王伟 李庆庆 张立树 |
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| 作者单位： | 1. 中国地质大学地球物理与信息技术学院, 北京 100083;2. 中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083;3. 中国地质科学院地质研究所, 大陆构造与动力学国家重点实验室, 北京 100037 |
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| 基金项目： | 中国地质调查局"青藏高原大陆动力学及资源环境效应"项目分课题，长江学者和创新团队发展计划 |
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| 摘 要： | 利用2010年布设在西藏南迦巴瓦构造结的郎嘎、崩嘎、直白和拉格四个宽频地震台所观测到的近5个月的地震记录,采用时间域迭代反褶积技术处理得到接收函数,通过筛选多条相近震中距和反方位角的高质量接收函数求取其叠加平均.对大地电磁数据做Rhoplus分析处理得到视电阻率和相位曲线.利用单台接收函数和相同位置的大地电磁视电阻率和相位联合反演地下一维壳幔结构.联合反演采用遗传算法,并通过权衡图分析大地电磁和地震数据的兼容性.理论值和实测值的对比显示两种数据能同时得到较好拟合.联合反演结果表明:(1)中上地壳为9 km至14 km厚的高阻高速层覆盖于低阻低速层之上的结构,中地壳低阻低速层可能与深部流体和局部熔融共同作用有关.(2)下地壳存在最厚达20 km的高导的壳幔过渡层,波速在4 km/s左右;上地幔约130 km至150 km以下存在软流圈.(3)上地壳的高阻高速层解释为多雄拉组混合岩化角闪岩相变质岩,而直白台所显示的低阻低速层与高压麻粒岩的少量部分熔融有关,可能源于壳幔过渡带镁铁质岩石的相变或更深处幔源岩浆底侵作用的产物.
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| 关 键 词： | 联合反演 接收函数 大地电磁测深 南迦巴瓦 遗传算法 |
| 收稿时间： | 2011-10-19 |
Joint inversion of receiver functions and magnetotelluric data: Application to crustal and mantle structure beneath central Namche Barwa, eastern Himalayan syntaxis |
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| PENG Miao
,
TAN Han-Dong
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JIANG Mei
,
WANG Wei
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LI Qing-Qing
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ZHANG Li-Shu.Joint inversion of receiver functions and magnetotelluric data: Application to crustal and mantle structure beneath central Namche Barwa, eastern Himalayan syntaxis[J].Chinese Journal of Geophysics,2012,55(7):2281-2291. |
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| Authors: | PENG Miao TAN Han-Dong JIANG Mei WANG Wei LI Qing-Qing ZHANG Li-Shu |
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| Institution: | 1. School of Geophysics and Information Technology, China University of Geosciences, Beijing 100083, China;2. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;3. State Key Laboratory for Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Science, Beijing 100037, China |
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| Abstract: | Using tele-seismograms from four stations(Langga station,Bengga station,Zhibai station and Lage station) for about five months in the central Namche Barwa,eastern Himalayan syntaxis in Tibet,we calculated receiver functions by time-domain iterative deconvolution technique and selected high-quality receiver functions with similar epicentral distances and back azimuths and then stacked them.Magnetotelluric apparent resistivity and phase curves are obtained by Rhoplus analysis of Berdichevskiy invariant of impedance tensors.The average receiver function and apparent resistivity and phase data from the same station are jointly inverted for one-dimensional Earth to infer lithospheric structure.Using genetic algorithm,we analyzed the compatibility between the magnetotelluric data and the seismic data by trade-off plots.The comparison of predicted data and measured data manifests that they coincide on both data sets.The results demonstrate:(1) In the mid-upper crust,a high resistivity,high velocity layer(9~14 km thickness) overlays a low resistivity and low velocity layer which may be related to aqueous fluids and partial melts.(2) There exists a highly conductive crust-mantle transition layer(thickness <20 km) with the S wave velocity of ~4 km/s in the lower crust,and also exists the lithosphere-asthenosphere boundary deeper than 130~150 km in the upper mantle.(3) A possible interpretation about the high resistivity and high velocity layer in the upper crust is the migmatitic amphibolite facies(Duoxiongla Formation),while the low resistivity,low velocity layer beneath the Zhibai station is associated with partial melting.And high-pressure granulite facies may originate from petrological transformation of mafic rocks in the crust-mantle transition layer or from mantle-derived magma underplating. |
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| Keywords: | Joint inversion Receiver function Magnetotellurics Namche Barwa Genetic algorithm |
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