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Tracking ancient magmatism and Cenozoic topographic growth within the Northern Andes forearc: Constraints from detrital U-Pb zircon ages

2016; Geological Society of America; Volume: 129; Issue: 3-4 Linguagem: Inglês

10.1130/b31530.1

1943-2674

César Witt, M. Rivadeneira, Marc Poujol, Diego Barba, D. Beida, G. Beseme, Galo Montenegro,

earthquake and tectonic studies

Research Article| March 01, 2017 Tracking ancient magmatism and Cenozoic topographic growth within the Northern Andes forearc: Constraints from detrital U-Pb zircon ages C. Witt; C. Witt † 1Earth Science Department, Lille 1 University, UMR 8187 LOG, Avenue Paul Langevin, 59655 Villeneuve D'Ascq, France †cesar.witt@univ-lille1.fr Search for other works by this author on: GSW Google Scholar M. Rivadeneira; M. Rivadeneira 2Petroamazonas EP, Avenida Naciones Unidas E-7-95 y Avenida de los Shyris, Quito, Ecuador Search for other works by this author on: GSW Google Scholar M. Poujol; M. Poujol 3Géosciences Rennes, UMR CNRS 6118, Observatoire des Sciences de l'Univers de Rennes (OSUR), Université Rennes 1, 35042 Rennes, France Search for other works by this author on: GSW Google Scholar D. Barba; D. Barba 2Petroamazonas EP, Avenida Naciones Unidas E-7-95 y Avenida de los Shyris, Quito, Ecuador Search for other works by this author on: GSW Google Scholar D. Beida; D. Beida 1Earth Science Department, Lille 1 University, UMR 8187 LOG, Avenue Paul Langevin, 59655 Villeneuve D'Ascq, France Search for other works by this author on: GSW Google Scholar G. Beseme; G. Beseme 1Earth Science Department, Lille 1 University, UMR 8187 LOG, Avenue Paul Langevin, 59655 Villeneuve D'Ascq, France Search for other works by this author on: GSW Google Scholar G. Montenegro G. Montenegro 2Petroamazonas EP, Avenida Naciones Unidas E-7-95 y Avenida de los Shyris, Quito, Ecuador Search for other works by this author on: GSW Google Scholar GSA Bulletin (2017) 129 (3-4): 415–428. https://doi.org/10.1130/B31530.1 Article history received: 10 Mar 2016 rev-recd: 09 Sep 2016 accepted: 04 Oct 2016 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation C. Witt, M. Rivadeneira, M. Poujol, D. Barba, D. Beida, G. Beseme, G. Montenegro; Tracking ancient magmatism and Cenozoic topographic growth within the Northern Andes forearc: Constraints from detrital U-Pb zircon ages. GSA Bulletin 2017;; 129 (3-4): 415–428. doi: https://doi.org/10.1130/B31530.1 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 A comparison of detrital zircon ages from the Cenozoic forearc basins in SW Ecuador–NW Peru and those derived from the Amotapes Massif offers a singular opportunity to shed some light on the evolution of the NW Andean margin of South America. An extensive set of pre-Andean U-Pb zircon ages (older than Late Cretaceous) was obtained from 18 detrital samples coming from the Talara, Zorritos, Progreso, and Gulf of Guayaquil–Tumbes forearc basins, as well as from two metasedimentary rocks of the Amotapes Massif. U-Pb age analysis on detrital zircon grains allows a general source-to-sink scenario to be determined for this section of the Andes. These analyses give consistent insights into the early topographic growth during the modern Andean orogeny, the occurrence of proto-Andean magmatic periods in the western margin of Gondwana, and the evolution of the Amotapes Massif within the geodynamical setting of northwestern South America. Zircon ages at ca. 320 Ma and Neoproterozoic clusters for the Amotapes metasediments show significant similarities along the strike of the metamorphic belt, thus defining a common metasedimentary origin, and can be compared with previously dated rocks from the Eastern Cordillera of Peru. These strong similarities demonstrate the presence of a wide, polyphased metamorphic belt that includes the western parts of the Eastern Cordillera, the northern section of the Occidental Cordillera of Peru, and the Amotapes Massif. Detrital sediments of the forearc are marked by a major gap in Early Cretaceous–Jurassic ages and the minor presence of Ordovician (Famatinian orogeny) and Carboniferous–Permian (340–285 Ma) ages. The age spectrum is not compatible with sediment input from the eastern Andes and suggests that the external areas of the Andean chain (e.g., the Western Cordillera) were already uplifted prior to or immediately after forearc initiation during the Paleocene, thus representing a pervasive drainage divide throughout all of the Cenozoic. The Amotapes Massif or other terrains sharing the same age affinities (e.g., the Olmos terrane; Occidental Cordillera of Peru) are likely to represent the best potential sources for pre-Andean zircon grains in the forearc. Age clusters in both source and sink at ca. 600 Ma, 570–560 Ma, and 520 Ma most likely define magmatic periods and may represent first-order constraints for the difficult correlation between proto-Andean magmatic and orogenic periods to the north and south of the Huancabamba deflection. It is unlikely that the Neoproterozoic zircon grains came from the Pan African–Braziliano belts, thus suggesting the onset of significant magmatic activity in this section of the Andes at around 570–560 Ma and probably ca. 600 Ma. The 520 Ma cluster is compatible with the most prominent magmatic period in the southern Andes related to the end of the Pampean orogeny, thus suggesting the existence of a regional proto-Andean magmatic arc during Early Cambrian times. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.