S51B-4466:
Where has the Flat-Fattened-Farallon Slab gone?
Friday, 19 December 2014
Donald V Helmberger1, Daoyuan Sun2, Kangchen Bai1 and Michael Gurnis1, (1)California Institute of Technology, Pasadena, CA, United States, (2)University of Science and Technology of China, Hefei, China
Abstract:
It has been hypothesized that much of the Laramide orogeny producing the Rock Mountain Front was caused by dynamic effects induced by flat-slabs during a period of subducting plateaus. It has further been hypothesized that a particularly flat block containing the Shatsky Rise conjugate left a foot print from Southern California to Colorado with dimensions of about 500 km in width and 1000km in length. Here we rediscovered this block beneath the Midwest at a depth of about 660km and dipping northeastward at about 35°. This resolution was accomplished by exploiting the USArray seismic observations where detailed waveform modeling allowed both the shape and sharpness of a candidate tomographic image as box-like. This structure when migrated back in time to California (using G-plate mapping) fits the above hypothesized block quite well lending strong support for the above hypothesis.
