Lithospheric behavior with triple junction migration: an example based on the Mendocino triple junction

The northward migration of the Mendocino triple junction along the western margin of the North American plate produces a region of thin lithosphere in association with the growth of the San Andreas transform. Numerical modeling of the resultant thermal regime in conjunction with modeling of the mechanical response of the region indicate the role of lithospheric thinning in the tectonism along the western margin of North America. The geometry of the region of thin lithosphere is inherited from the previous subduction regime with resulting implications for the mechanical response. The elevation of the California Coast Ranges is maintained primarily by flexure from buoyant loading from below. Additionally, sporadic volcanism associated with the passage of the triple junction is a likely consequence of super solidus mantle emplaced at shallow depths after the removal of the subducting slab.