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Since 1976 observations of more than forty magnetotelluric (MT) sites have been carriedout in North China, and the conductive layer at the depths of 15-25 km with the longitudinaleonduetances of several hundreds to more than one thousand siemens have been found beneathmost of the MT sites. In this region, tho depth of the conductive layer is very close to thatof the minimum velocity layer determined by DSS. Most earthquakes have occurred above thislayer, and a lot of normal faults have vanished above this layer, too. The area, where thedepth and longitudinal conductance of the conductive layer are shallow and high, has a higherheat flow and stronger tectonism during the Cenozoic time. The authors suggest that the con-duetive layer in the crust boneath the plain might result from partial melting of the felsieminerals, while that beneath the surrounding areas from dehydration of the minerals withcrystal water.
Since 1976 observations of more than than 45 magnetotelluric (MT) sites have been carriedout in North China, and the conductive layer at the depths of 15-25 km with the longitudinaleonduetances of several hundreds to more than one thousand siemens have been found beneathmost of the MT sites. In this region, tho depth of the conductive layer is very close to that of the minimum velocity layer determined by DSS. Most earthquakes have occurred above thislayer, and a lot of normal faults have vanished above this layer, too. The area, where thedepth and longitudinal conductance of the conductive layer are shallow and high, has a higherheat flow and stronger tectonism during the Cenozoic time. The authors suggest that the con-duetive layer in the crust boneath the plain might result from partial melting of the felsieminerals, while that beneath the surrounding areas from dehydration of the minerals with crystal water.