Pulling apart the Mid to Late Cenozoic magmatic record of the Gulf of California: is there a Comondú Arc?

Abstract

The composition of the lithosphere can be fundamentally altered by long-lived subduction processes such that subduction-modified lithosphere can survive for hundreds of millions of years. Incorrect petrotectonic interpretations result when spatial-temporal-compositional trends of, and source contributions to, magmatism are not properly considered. Western Mexico has had protracted Cenozoic magmatism developed mostly in-board of active oceanic plate subduction beneath western North America. A broad range of igneous compositions from basalt to high-silica rhyolite were erupted with intermediate to silicic compositions in particular, showing calc-alkaline and other typical subduction-related geochemical signatures. A major Oligocene rhyolitic ignimbrite 'flare-up' (.300 000 km 3

Chronostratigraphy of the Hottah terrane and Great Bear magmatic zone of Wopmay Orogen, Canada, and exploration of a terrane translation model

“…12 million years, Baja has been dextrally transported at least 300 km north and west of its origin (Fig. 11A: Umhoefer 2011;Sutherland et al 2012;Bennett et al 2013; also see Bryan et al 2014), while the Gulf of California evolved on top of the previous and deceased arc system (Fig. 11A;Umhoefer 2011;Bennett et al 2013).…”

“…8-10), and the fact they erupted subaerially on a plutonic basement that was unroofed within 7 Ma of crystallization, is most compatible with a suprasubduction zone environment undergoing rapid extension (Umhoefer 2011). Whether these plutonic and volcanic rocks were derived from an active subduction zone, or from a previously subduction-modified mantle, is not resolvable based on geochemistry (e.g., Bryan et al 2014). …”

“…Such an environment may result from a variety of subduction zone adjustments, including slab rollback, delamination, or flattening, or possibly the development of a pseudo-slab window from outboard ridge subduction (e.g., Dickinson 2002;Thorkelson et al 2011;Giba et al 2013). However, the suprasubduction zone geochemical signature of the rocks can also be attainted from a prior, rather than active, subduction-modified mantle (e.g., Bryan et al 2014). What we have (Fig.…”

An introduction to orogenic andesites and crustal growth

“…Three contributions to this book discuss the complex interplay between evolving tectonic parameters and rock compositions through time. Kay et al (2013) review the Miocene to Holocene arc magmatism of the central Argentine and Chilean Andes, Yoshida et al (2013) present a detailed summary of the Cenozoic evolution of the NE Japan arc and Bryan et al (2013) report the occurrence of early to middle Miocene syn-extensional andesitic magmatism in the context of the Cenozoic evolution of the Gulf of California. At the Andean margin, Neogene magmas show the influence of crustal thickening and foundering, plateau uplift and landward frontal arc migration, subduction erosion and slab -mantle mixing over a continuously changing Benioff zone (Kay et al 2013).…”

“…The NE Japan arc is characterized by clear secular changes of mode of magmatic activity and style of magma plumbing system, which affect eruption volumes and magmatic compositions in response to geotectonic evolution and mantle wedge convection (Yoshida et al 2013). In the Mexican margin, a middle Miocene phase of calc-alkaline andesite magmatism occurs in an active rift environment without evidence of concurrent plate subduction, further questioning the belief that the orogenic andesites are confined to active convergent margins (Bryan et al 2013; and also see Steiner & Streck 2013).…”