Transtensional rifting in the late proto-Gulf of California near Bahia Kino, Sonora, Mexico / Scott Edmund Kelsey Bennett.
(Book - Regular Print)

Thesis (M.S.) submitted in partial fulfillment of the the requirements for the degree of Master of Science in the Department of Geological Sciences, University of North Carolina at Chapel Hill.

The Gulf of California rift provides an example to test the role of rift obliquity in continental rupture. Continental rifts require focused strain to rupture and form an ocean basin. Strike-slips faults are ubiquitous in highly oblique rifts and focused transtensional strain adjacent to these faults may be a catalyst for rupture. To test this hypothesis, I completed structural mapping, fault kinematic analysis, geochronology, basin analysis, and paleomagnetism of pre- and syn-rift rocks exposed in coastal Sonora, near Bahia Kino, Mexico. Transtensional sedimentary basins record -16 km of west-northwest-directed transtension across the Kino-Chueca Shear Zone. Onset of transtension in the study area is estimated to be ca. 7 Ma and lasted for approximately 1 million years. This represents a significant portion -28% of plate boundary deformation over this time interval. Dextrea shear was progressively localized withing this zone of extensional deformation, and together shear and extension acted to focus lithospheric-scale train into a narrower zone.