|
| | 講演要旨(英文) | | Three dimensional geophysical inversion of the long period MT data has been performed to provide a regional scale view of electrical resistivity from the middle crust to nearly the mantle transition zone of the western USA. A number of 350 USArray MT stations were acquired and analyzed for dimensionality and directionality. ModEM package was utilized to perform the inversion with several iteration of initial model to reach the minimum RMS. Results of the inversion process provide a clear subsurface image of the resistivity distribution. At the west of the study area, below Cascadia, the subducting Farallon remnant, Juan de Fuca and Gorda, lithosphere appears highly resistive. Also, oceanic lithosphere relicts are resistive, including the accreted "Siletzia" terrane beneath the Coast Ranges and Columbia Embayment, and the slab curtain beneath eastern Idaho interpreted. In the south-central region, beneath the active extensional sub-provinces, a resistive upper crust overlays the low resistivity lower crust and upper most mantle with thin lithosphere. To the east and north-east, thick sections of resistive lithosphere were imaged under the Wyoming and Medicine Hat Cratons. Results of this research, in integration with other information about the area and other geophysical data, will provide a detailed tectonic interpretation of the study area. |
|
|
|
| |
|