关键词: 鄂尔多斯断块, 大地电磁, 地壳结构, 低阻层, 流体

Abstract: The Ordos fault block is a stable block since the Cenozoic time.Whether low-resistivity layers exist in the middle and lower crust of this kind block is an open question.This work attempts to reveal the entire crustal structure of the Ordos fault block based on interpretation of magnetotelluric data collected along the profile across this region.The result shows that a layered structure characterizes the crust of the Ordos fault block,with a low-resistivity layer at depth of about 20km,presumably associated with fluids there.On contrast,in the areas of active tectonics in the east and west of the fault block,there is no such layered electric structure in crust,while the low-resistivity zones may be related with the detachments(or ductile-shear zones) in crust.The difference in electric structure of crust between the Ordos fault block and neighboring areas is of significance to the analysis of activity and deformation in varied blocks.

Key words: Ordos fault block, magnetotellurics, crustal structure, low-resistivity layer, fluid