Evolution of the Guerrero Composite Terrane Along the Mexican Margin, from Extensional Fringing Arc to Contractional Continental Arc
Evolution of the Guerrero composite terrane along the Mexican margin, from extensional fringing arc to contractional continental arc Elena Centeno-García1,†, Cathy Busby2, Michael Busby2, and George Gehrels3 1Instituto de Geología, Universidad Nacional Autónoma de México, Avenida Universidad 3000, Ciudad Universitaria, México D.F. 04510, México 2Department of Geological Sciences, University of California, Santa Barbara, California 93106-9630, USA 3Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA ABSTRACT semblage shows a Callovian–Tithonian (ca. accreted to the edge of the continent during 163–145 Ma) peak in magmatism; extensional contractional or oblique contractional phases The western margin of Mexico is ideally unroofing began in this time frame and con- of subduction. This process can contribute sub- suited for testing two opposing models for tinued into through the next. (3) The Early stantially to the growth of a continent (Collins, the growth of continents along convergent Cretaceous extensional arc assemblage has 2002; Busby, 2004; Centeno-García et al., 2008; margins: accretion of exotic island arcs by two magmatic peaks: one in the Barremian– Collins, 2009). In some cases, renewed upper- the consumption of entire ocean basins ver- Aptian (ca. 129–123 Ma), and the other in the plate extension or oblique extension rifts or sus accretion of fringing terranes produced Albian (ca. 109 Ma). In some localities, rapid slivers these terranes off the continental margin by protracted extensional processes in the subsidence produced thick, mainly shallow- once more, in a kind of “accordion” tectonics upper plate of a single subduction zone. We marine volcano-sedimentary sections, while along the continental margin, referred to by present geologic and detrital zircon evidence at other localities, extensional unroofing of Collins (2002) as tectonic switching.
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