18 Crossing Borders: Large-scale tectonic models of the North American Cordillera
This session focusses on the Phanerozoic evolution of the North American Cordillera, soliciting studies that address large-scale tectonic models associated with obliquely convergent and divergent movement along the margin.
Thursday, 23 April 2026
8:00 AM - 12:00 PM
LMH, Isla Carmen
The Magdalena granites: Eocene anatexis in northern Sonora
Paper number: 18-4
Program: Technical Sessions
Time: 9:05 AM – 9:25 AM
Authors
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Carlos Gonzalez-LeonUniversidad Nacional Autonoma de Mexico, Hermosillo, SON
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Luigi SolariUniversidad Nacional Autonoma de Mexico, Queretaro, QRO
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Elizard GonzálezUniversidad Nacional Autonoma de Mexico, Hermosillo, SON
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Jonathan NourseCalifornia Polytechnic State University, Pomona, CA
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Michelle VázquezUniversidad Estatal de Sonora, Hermosillo, SON
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Teresita Sánchez NavarroUniversidad Nacional Autónoma de Mexico, Hermosillo, SON
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Rufino Lozano SantacruzUniversidad Nacional Autonoma de Mexico, Ciudad de Mexico, Ciudad de Mexico
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Ofelia Perez ArvizuUniversidad Nacional Autonoma de Mexico, Juriquilla, QRO
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Estefany Grijalva EspinozaUniversidad Estatal de Sonora, Magdalena de Kino, SON
Abstract
New geochronology, geochemistry, and field relations of the Magdalena granites in northern Sonora indicate they are distinct from the Cretaceous-Eocene Mexican (Laramide) Magmatic Arc in the northern Mexican and southern U.S. Cordillera. The Magdalena granites outcrop in the footwall of metamorphic core complexes and are predominantly Eocene (51 to 38 Ma), two-mica + garnet leucogranites. The granites were produced by water-absent to water-deficient, muscovite- to biotite-dehydration melting of metasedimentary to metaigneous crustal protoliths and are part of the North American Cordilleran Anatectic Belt. Field and petrographic relationships suggest the Magdalena granites intruded into relatively hot crust, including host rock mushes that exhibit evidence for melt infiltration and disaggregation. The cause of crustal melting in the interior of the Cordillera remains poorly understood, but is interpreted to be related to crustal thickening and development of an orogenic plateau. The anatectic granites are younger than similar granites in the southern U.S. Cordillera and suggest a southward-younging trend at odds with models for northeastward-directed, shallow subduction of an oceanic plateau or northward-directed, collisional-translational tectonic models.
Geological Society of America Abstracts with Programs. Vol. 58, No. 3
doi: 10.1130/abs/2026CD-410919
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