| 青藏高原亚东—格尔木地学断面岩石圈电性研究 |
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| ＭAGN ETOTELLLURIC STUDIES ALONG VADONG—GOLMUD GEOSCIENCES TRANSECT IN QINGHAI-XIZANG PLATEAU |
| 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. |
| GUO Xin-feng,ZHANG Yuan-chou,CHENG Qing-yun,GAO Rui,PAN Yu.1990.ＭAGN ETOTELLLURIC STUDIES ALONG VADONG—GOLMUD GEOSCIENCES TRANSECT IN QINGHAI-XIZANG PLATEAU[J].Acta Geoscientica Sinica,11(2):191-202. |
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