Poster Number 93
See more from this Division: General Discipline Sessions
See more from this Session: Precambrian Geology (Posters)
Abstract:
Sierra Los Tanques is located ~15 km SW of the border town of Sonoyta in NW Sonora. A granite unit from this area was collected just to the NE of a NW-oriented axial zone of a sinistral flower structure proposed to represent outcrops of the hypothetical Mojave-Sonora megashear. These granitic rocks form part of the Caborca block that overthrusted (NE directed) a sequence of continental arc volcanic rocks of middle to late Jurassic age of the North America block. U-Pb zircon geochronology (LA-MC-ICPMS) of this granite yields a 207Pb/206Pb age at 1100 ± 8 Ma. This crystallization age is in agreement with ages obtained for similar granites in other areas of NW Sonora (e.g., Quitovac, Sierra Prieta, Aibo, Santa Margarita) that have been found to intrude older Paleoproterozoic basement rocks with Yavapai affinities.
If the same geological relationship holds true for the Sierra Los Tanques granite, the Caborca block basement in this area may be part of the Mexican Yavapai province and should have a quite different petrogenetic signature from the rather unique Mojave signature predicted by the megashear hypothesis. Further geochemical and isotopic characterization of both, the actual ~1.1 Ga granite and its host rocks will be required to test this idea that may shed some light on one of the most controversial geological features in northern Mexico.
See more from this Division: General Discipline Sessions
See more from this Session: Precambrian Geology (Posters)