Geologic evolution of the Xolapa Complex, southern Mexico: Evidence from U-Pb zircon geochronology

Abstract

Research Article| July 01, 2004 Geologic evolution of the Xolapa Complex, southern Mexico: Evidence from U-Pb zircon geochronology Mihai N. Ducea; Mihai N. Ducea 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar George E. Gehrels; George E. Gehrels 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Sarah Shoemaker; Sarah Shoemaker 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Joaquin Ruiz; Joaquin Ruiz 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Victor A. Valencia Victor A. Valencia 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Mihai N. Ducea 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA George E. Gehrels 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA Sarah Shoemaker 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA Joaquin Ruiz 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA Victor A. Valencia 1University of Arizona, Department of Geosciences, Tucson, Arizona 85721, USA Publisher: Geological Society of America Received: 06 Aug 2003 Revision Received: 06 Dec 2003 Accepted: 12 Jan 2004 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (2004) 116 (7-8): 1016–1025. https://doi.org/10.1130/B25467.1 Article history Received: 06 Aug 2003 Revision Received: 06 Dec 2003 Accepted: 12 Jan 2004 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Mihai N. Ducea, George E. Gehrels, Sarah Shoemaker, Joaquin Ruiz, Victor A. Valencia; Geologic evolution of the Xolapa Complex, southern Mexico: Evidence from U-Pb zircon geochronology. GSA Bulletin 2004;; 116 (7-8): 1016–1025. doi: https://doi.org/10.1130/B25467.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Xolapa Complex of southern Mexico is composed of mid-crustal arc-related gneisses of poorly resolved ages, intruded by undeformed Cenozoic calc-alkaline plutons. Twelve undeformed and deformed tonalitic/granodioritic samples from three transects across the Sierra Madre del Sur (Acapulco, Puerto Escondido, and Puerto Angel) were chosen for U-Pb zircon analysis. The measurements were performed on single crystals of zircons, using a multiple-collector laser-ablation inductively coupled plasma–mass spectrometer (MC-LA-ICP-MS). About 20–30 crystals were measured from each sample. Three gneisses and migmatites from the eastern transect (Puerto Angel), located 30–42 km from the coast, yielded Grenville-aged zircons (970–1280 Ma), suggesting that the samples represent Oaxacan basement, not deformed Xolapa Complex. The central transect (Puerto Escondido) yielded Oligocene ages (25–32 Ma) on undeformed plutons as well as mid-Mesozoic and Permian ages on gneisses. Most samples along the Puerto Escondido transect contain inherited ca. 1.1 Ga xenocrystals of zircons. The western transect (Acapulco) yielded Late Jurassic–Early Cretaceous ages (160–136 Ma) on gneisses, and Paleocene (55 Ma) and Oligocene (34 Ma) ages on undeformed plutons, with no inherited Grenville ages. The older ages and xenocrystic zircons in arc-related Xolapa Complex mirror the crustal ages found in neighboring terranes (Mixteca and Oaxaca) to the north of the Xolapa Complex, suggesting an autochthonous origin of Xolapa with respect to its neighboring north-bounding terranes. The new data and previously published ages for Xolapa suggest that metamorphism and migmatization of the deformed arc rocks took place prior to the Cenozoic. Eocene and Oligocene plutons representing renewed arc-related magmatism in the area are common throughout Xolapa, and probably represent the more deeply exposed continuation of the Sierra Madre Occidental arc to the northwest. The available U-Pb data argue against the previously proposed eastward migration of magmatism between Acapulco and Puerto Angel during the Oligocene. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.