Phanerozoic Tectonic Evolution of Central California and Environs

Abstract

The use of actualistic analog models for paleotectonic reconstruction produces significant advances in our understanding of evolutionary continental tectonics. The sequential application of such models is possible in a cross section from the central California coast to Utah. This transect represents one of the best-understood Phanerozoic continental margins on Earth. Excellent exposure, detailed local studies, and regional syntheses all contribute to the choice of appropriate plate-tectonic models for successive intervals from the latest Neoproterozoic to the Quaternary. These models include craton, terrestrial rift, nascent ocean, intraplate continental margin, intraoceanic magmatic arc (both extensional and neutral), continental-margin magmatic arc (both neutral and contractional), transform continental margin, remnant ocean, suture, and successor basin. These models are useful for understanding the following stages of development of the Cordilleran margin of central California and its environs-latest Proterozoic rifting, early Paleozoic intraplate margin, Devonian-Mississippian Antler orogeny (arc-conti nent suturing), Mississippian-Pennsylvanian intraplate margin, Pennsylvanian-Permian Ancestral Rockies orogeny (Ouachita-Marathon continental suturing), Permian-Triassic Sonoma orogeny (arc-continent suturing), Triassic-Jurassic continental-margin magmatic arc, Late Jurassic Nevadan orogeny (arc-arc suturing), latest Jurassic-Late Cretaceous continentalmargin magmatic arc, latest Cretaceous-Eocene Laramide orogeny, Oligocene ignimbrite flareup, and Miocene-Holocene triple-junction migration, transform boundary, and regional exten sion of the Great Basin. The integrated result of sequential superposition of the actualistic models produces a reasonable representation of the complexity of the study area. The discipline of applying actualistic models to the evolution of this continental margin provides new insights and forces one to consider new implications of the models. The complexity of the tectonic history of this continental margin argues against simplistic general models for the growth of continental crust.

Temporal and spatial trends of Late Cretaceous-early Tertiary underplating Pelona and related schist beneath southern California and southwestern Arizona

“…Chert and basaltic rocks with mid-oceanic ridge compositional affi nities constitute up to 10% of the schist (see Haxel et al, 1987Haxel et al, , 2002Dawson and Jacobson, 1989). These lithologies are most typically associated with distal Late Jurassic to Early Cretaceous forearc strata (Ingersoll, 1983(Ingersoll, , 1997) that we have not detected in our sampling of the schist. However, we cannot discount the possibility that other sources of eugeoclinal lithologies (such as the Sierran Foothills belt) were present along the western margin of the Cretaceous arc and were underthrust and mixed with forearc strata to produce the observed mix of rock types within the schist.…”

Paleotectonics of a complex Miocene half graben formed above a detachment fault: The Diligencia basin, Orocopia Mountains, southern California

“…2 and 3), part of the regionally extensive Pelona-Orocopia-Rand (POR) Schist terrane (Jacobson et al, 2011, and references therein). The POR Schist likely formed part of a subduction complex, resulting from low-angle subduction during the latest Cretaceous-Paleogene Laramide orogeny (Dickinson and Snyder, 1978;Livaccari et al, 1981;Bird, 1984Bird, , 1988Jacobson et al, 1988Jacobson et al, , 1996Jacobson et al, , 2002Jacobson et al, , 2007Jacobson et al, , 2011Ingersoll, 1997;Grove et al, 2003;Saleeby, 2003).…”

Models for origin and emplacement of Jurassic ophiolites of Northern California

“…Rather, it is a transtensional transform boundary. In contrast, a continental-margin magmatic arc was active along the California margin throughout the period of ophiolite formation (Saleeby and BusbySpera, 1992;Dilek and Moores, 1995;Ingersoll, 1997). The useful modern analogue for California is the Sumatra arc-trench system (Hamilton, 1979), where strike-slip motion on the Barisan fault zone within the magmatic arc decouples the forearc from the backarc (Hamilton, 1979;Dewey, 1980;Saleeby, 1981;Dickinson, 1995), as probably occurred in California during the Cretaceous (Lahren and Schweickert, 1989;Schweickert and Lahren, 1990;Dilek and Moores, 1995).…”

“…This model for forearc rifting is applicable only to the initiation of new subduction zones; as Stern and Bloomer (1992) illustrated, as soon as true subduction is underway, forearc refrigeration leads to the development of strong, thick forearc lithosphere and localization of magmatism along a narrow arc axis. Thus, this model is not useful in explaining Jurassic ophiolites of California because subduction was active along the continental margin for tens of millions of years prior to their formation (Schweickert, 1976(Schweickert, , 1981Dickinson, 1981aDickinson, , 1981bSaleeby and Busby-Spera, 1992;Dilek and Moores, 1995;Ingersoll, 1997). The preponderance of lithospheric rifting in western Pacific arc-trench systems has been within or behind active arcs (e.g., Karig, 1972;Carey and Sigurdsson, 1984;Klaus et al, 1992;Marsaglia, 1995).…”

“…Conflicting models may be evaluated by using plausibility arguments based on consistency with both theoretical models for physical and chemical lithospheric processes and actualistic analogue models for modern examples of lithospheric interactions. The construction of actualistic forward analogue models (e.g., Ingersoll, 1997) illustrates a plausible scenario by which ophiolites of northern California formed and were obducted.…”