THE MEXICAN MOJAVE, YAVAPAI AND MAZATZAL PALEOPROTEROZOIC BASEMENT PROVINCES IN SONORA AND CHIHUAHUA: ESTABLISHING A COHERENT SW MARGIN OF LAURENTIA IN AIMS OF TESTING RODINIA RECONSTRUCTIONS

From the late sixties, and for close to four decades, the distribution of Paleoproterozoic basement provinces in northern Mexico was linked to the presence of the controversial Mojave-Sonora megashear. This Late Jurassic hypothetical left-lateral fault, that accommodated ~800–1000 km of displacement, supposedly juxtaposed older rocks from the Caborca block (1.7–1.8 Ga) on the southwest against slightly younger units of the North America block to the northeast (1.6–1.7 Ga; Pinal block).

Iriondo et al. (2004) presented the first U-Pb zircon geochronology data set for Precambrian rocks in the Quitovac area in northern Sonora and included mayor- and trace-element geochemistry and Sm-Nd whole rock determinations. This combined effort suggested that Paleoproterozoic Caborca block rocks correlated with Yavapai rocks as described in NW Arizona, whereas rocks from the North America block correlated with Mazatzal rocks as described in SE Arizona. These two basement blocks in Quitovac were sutured as part of a model of arc-arc collision that amalgamated the Yavapai and Mazatzal provinces during the Paleoproterozoic.

Iriondo and Premo (2010), based on a combination of modern U-Pb zircon geochronology and Sm-Nd determinations, presented a more regional perspective for the distribution of Paleoproterozoic basement rocks in northern Mexico and suggested the concept of the Mexican Mojave, Yavapai and Mazatzal provinces. Subsequently, Iriondo et al. (2013) and Solari et al. (2017) incorporated in-situ Hf zircon microanalysis to assess magma sources in conjunction with more U-Pb zircon geochronology to further classify these Paleoproterozoic rocks in Sonora and Chihuahua. Recently, Fragoso-Irineo et al. (2016, 2017) incorporated magnetics, gravity and magnetotelurics to pinpoint subsurface basement limits/sutures and changes in crustal thickness in NW Sonora.

All the aforementioned studies provide a new perspective on the distribution of Mexican basement provinces and, together with the currents ideas on basement distribution in California, Arizona and New Mexico, presents a more coherent SW margin of Laurentia to test influential models to assemble the supercontinent Rodinia and to explain its subsequent break up during the Neoproterozoic-Early Paleozoic.

CONACYT 82518 & 129370

PAPIIT 113906 & 116709