| 青藏高原亚东—格尔木地学断面岩石圈电性研究 |
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| 引用本文：郭新峰,张元丑,程庆云,高锐,潘渝.1990.青藏高原亚东—格尔木地学断面岩石圈电性研究[J].地球学报,11(2):191-202. |
| DOI：10.3975/cagsb.xxxx.xx.xx |
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| 中文摘要:在格尔木—亚东剖面上进行了大地电磁(MT)测量，共30个测深点，获取了最大周期为1万秒的大地电磁测深数据，为深入研究青藏高原的岩石圈电性特征，为编制青藏高原GGT断面提供了有价值的资料。
木文采用二维张量阻抗对实测资料进行了数据处理，获取了沿主轴方向的E极化和H极化的两种视电阻率曲线及相应的判别参数。在考虑横向及地表电性不均匀，而产生曲线畸变的基础上，首先进行了一维形式化解释，然后用数值模拟的方法进行了二维反演，提出一种自动网格剖分技术，使有限元方法能较为灵活方便地用于复杂构造模型的数值拟合中，得到了格尔木—亚东剖面30个测点的二维地电模型。我们发现在青藏高原有一普遍存在的壳内高导层，深度在15-25 km，在雅鲁藏布江两侧还发现深度在45-70km范围变化的第二高导异常层位。文章初步探讨了某些电性特征层的成因和作用，并提出了相应的地质解释 |
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| ＭAGN ETOTELLLURIC STUDIES ALONG VADONG—GOLMUD GEOSCIENCES TRANSECT IN QINGHAI-XIZANG PLATEAU |
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| Abstract:In order to complete the GGT project and gain a better understanding of the characteristics of the lithosphere in the Qinghai-Xizang plateau, Changchun College of Geology and the Chinese Academy of Geological Sciences made another MT survey in 1988. The traverse was as long as 1.650 km from Golmud in northern Qinghai to Yadong in southern Xizang with 30 stations. The measuring period was 10-2-104 second. The traverse is perpendicular to the geological structural belt. The data collection was done with the Chinese-made GEM-2 instrument, which is supported by a in-situ data processing system. The data processing was done on each site.
Te and Tm apparent resistivities and phases, azimuths of the maximum impedences, skews and other parameters have been calculated for each site. At the shorter periods, the azimuths at all sites are approximtely parallel to the local tectonic strike or highly scattered with lower skews. At the longer periods, the azimuths are approximately parallel to the regional tectonic zones, which are roughly in the west-east direction.
The mesh-dissection method is suggested in the data interpretation.The 2-D numerical modelling of comlex electrical resistivity structure has been made using the Finite Element Method. The 2-D initial model is construted by integrating the information from the E-polarization and H-polarization pseudosection with 1-D interpretation. Trial 2-D numerical modelling of the magnetotelluric sounding data was made by using this method in 30 sites along the Yadong-Golmud profile in the Qinghai-Xizang plateau. A 2-D resistivity model of the Yadong-Golmud profile is obtained. It is discovered that there is an anomalous low resistivity layer in the earth's crust in the ,Qinghai-Xizang plateau. Its depth is between 12-25 km and resistivity is lower than 100Ω·m It is also discovered there is an anomalous conductive layer within the crust, 45-70 km deep near the Yarlung Zanbo River. The mechanism of the formation and the effects of some particular layers is dealt with and the geological significance of the magnetotelluric features of the lithosphere is also discussed tentatively in the paper. |
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