Regional crustal thickness variations of the Peninsular Ranges, southern California

We used the teleseismic receiver function technique to obtain a profile of the crustal thickness of the northern Peninsular Ranges, California. Depth to the Moho varies from similar to 37 inn beneath the western Peninsular Ra nges batholith to similar to 27 km at the western edge of the Salton trough , an average apparent dip of similar to 10 degrees to the west over a later al distance of 60 km, We previously obtained a similar result for a profile similar to 100 km to the south (a Moho dip of similar to 20 degrees over 3 0 km lateral distance). In both cases, the Moho depth variations do not cor relate with topography of the eastern batholith, but rather appear to paral lel the trend of a boundary that separates compositionally distinct eastern and western terranes, These observations suggest that a steeply dipping Mo ho is a regional feature beneath the eastern Peninsular Ranges, and that co mpensation is through lateral variations in crustal or upper mantle density rather than through an Airy root.