Subduction of the eastern Panama Basin and the seismotectonics of northwestern South America
Thesis/Dissertation
·
OSTI ID:5365517
Spreading along the Cocos-Nazca plate boundary since the break-up of the Farallon plate in the Miocene has resulted in the formation of the Panama Basin and a complex interaction of plates in and near northwestern South America. Current plate boundaries have been defined, and segments of subducted lithosphere identified through selection of hypocentral locations of earthquakes, considering only well-located events, and through focal mechanism determinations. The existence of relict plate boundaries, bathymetric features, and the Panamanian isthmus has affected the subduction process of the Nazca plate beneath South American and determined the present-day configuration of the subducting lithospheric plate. The subducted portions of the Panama Basin and old Farallon plate have become segmented into three pieces recognized in this study. The segmentation of the subducted plate can be explained by the buoyancy of bathymetric features which have been partially subducted. Shallow subduction beneath northern Peru and southern Ecuador may be due to the presence of the Nazca ridge within the subducted plate beneath Peru and another aseismic ridge, postulated to have been completely subducted beneath the Peru-Ecuador border region. The NNE direction of dip of the subducted plate beneath Ecuador is best interpreted as representing normal oceanic crust which lies between the (proposed) subducted aseismic ridge and a system of extinct spreading centers presumed to have been subducted beneath southern Colombia.
- Research Organization:
- Wisconsin Univ., Madison (USA)
- OSTI ID:
- 5365517
- Country of Publication:
- United States
- Language:
- English
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