Framework and petrogenesis of the northern Peninsular Ranges batholith, southern California

Abstract

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Evolution of the Jura-Cretaceous North American Cordilleran margin: Insights from detrital-zircon U-Pb and Hf isotopes of sedimentary units of the North Cascades Range, Washington

“…Voluminous magmatism is represented by the Peninsular Ranges batholith (e.g., Silver and Chappell, 1988;Busby, 2004;Morton et al, 2014), Sierra Nevada batholith (e.g., Bateman, 1992;Coleman and Glazner, 1997;Cecil et al, 2012), Idaho batholith (e.g., Hyndman, 1983;Gaschnig et al, 2009), and plutons that form the Coast Plutonic Complex-North Cascades range (e.g., Barker and Arth, 1984;Gehrels et al, 2009;Miller et al, 2009) (Fig. 1).…”

Arc and Slab-Failure Magmatism in Cordilleran Batholiths II – The Cretaceous Peninsular Ranges Batholith of Southern and Baja California

“…Santa Rosa plutons have a limited geographical distribution in that they occur above the East Peninsular Ranges mylonite zone (Fig. 3), which is a Laramide-age, westerly vergent, shear zone (Todd et al 1988;Morton et al 2014). We cannot rule out the unlikely possibility that the plutonic rocks of the Santa Rosa suite are not genetically related to the La Posta plutons, so we use different symbols to represent them on many of our geochemical plots.…”

“…Morton et al (2014) noted that the westernmost plutons are isotropic whereas those farther east are foliated so that there is a megascopically visible deformation gradient from west to east. This gradient might reflect the deeper levels of plutonic emplacement to the east with the more westerly isotropic plutons emplaced into their own cover at no more than 2-3 kbar, whereas the foliated rocks were emplaced at pressures twice as large or greater ).…”

“…6), variably deformed, but much more so to the east, range in composition from gabbro to leucogranite, and show no directional variation in composition with time (Silver and Chappell 1988;Clausen et al 2014;Premo et al 2014b;Morton et al 2014). We use the informal name Santa Ana suite for these rocks after extensive outcrops within the Santa Ana Mountains (Fig.…”

“…We use this separation because we believe that the deformation represents a regional tectonic event and that magmatism before and after are compositionally quite different, which suggests to us that they have distinct origins. Based on a new generalized geological map of the northern Peninsular Ranges batholith showing Baird's sample locations (figure 68 in Morton et al 2014), followed up by discussions with Doug Morton, who has detailed location maps, we filtered the Lee et al (2007) data to exclude mylonitic, contact zone, sedimentary and Jurassic plutonic samples, so as to include only Santa Ana and La Posta suite samples in this study.…”