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P‐wave image of the Peninsular Ranges Batholith, southern California
Author(s) -
Magistrale Harold,
Sanders Christopher
Publication year - 1995
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/95gl02241
Subject(s) - batholith , geology , seismology , crust , san andreas fault , fault (geology) , mesozoic , tectonics , geophysics , paleontology , structural basin
We invert earthquake P‐wave arrival times to image the 3D distribution of P wave velocities in the Mesozoic Peninsular Ranges batholith and nearby areas in southern California. There is a 3% velocity contrast between the eastern and western Peninsular Ranges at 4 and 20 km depth (west side faster) and a 1 to 1.5% velocity contrast across the San Andreas fault zone (south side faster) in the San Bernardino region at 4 to 14 km depth. The San Andreas velocity contrast is due to the juxtaposition of different rock types by slip along the fault zone. The Peninsular Ranges batholith velocity contrast is due to a difference in rock composition across the batholith. The maximum gradient in the crustal velocities is coincident with a compositional boundary within the batholith that reflects emplacement of the batholith across juxtaposed oceanic and continental crust. Quaternary fault development has been in part concentrated at this boundary.