| Popis: |
The international Deep Probe refraction experiment is a continental-scale study of the crust and upper mantle in western North America to determine well-constrained mantle velocity-depth structures for the stable Archean Hearne and Wyoming provinces and the tectonically modified Proterozoic lithosphere of the southern Rocky Mountains and Colorado Plateau. An initial 2-D velocity interpretation for Deep Probe has been accomplished by the application of the downward-continued wave-field τ-p transform method. This approach involves two linear transforms for each shot gather from the experiment: a τ-p transform (or slant stack) of the input data followed by a downward continuation to z-p space using an appropriate velocity function. The determination of this velocity function is an iterative process which converges when the downward-continued wave field images a velocity function which is the same as that used to create it. The resulting 1-D velocity function, υ(z), from each gather is converted to a 2-D function, υ(x, z) using ray theory. Eleven profiles along the Deep Probe corridor have been analysed. The resulting functions have been combined, gridded and contoured to produce a velocity structure section for the project, which provides an initial model for the application of more advanced interpretation procedures. As a result, the lithospheric structures of three major tectonic provinces have been identified in an efficient and effective manner that did not require ‘picking’ of travel times. |
Plný text