Miocene volcanism and deformation in the western Cordillera and high plateaus of south-central Peru

Abstract

Research Article| August 01, 1982 Miocene volcanism and deformation in the western Cordillera and high plateaus of south-central Peru EDWIN H. McKEE; EDWIN H. McKEE 1U.S. Geological Survey, 345 Middlefield Road. Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar DONALD C. NOBLE DONALD C. NOBLE 2Department of Geological Science, Mackay School of Mines, University of Nevada–Reno, Nevada 89557 Search for other works by this author on: GSW Google Scholar Author and Article Information EDWIN H. McKEE 1U.S. Geological Survey, 345 Middlefield Road. Menlo Park, California 94025 DONALD C. NOBLE 2Department of Geological Science, Mackay School of Mines, University of Nevada–Reno, Nevada 89557 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1982) 93 (8): 657–662. https://doi.org/10.1130/0016-7606(1982)93<657:MVADIT>2.0.CO;2 Article history First Online: 01 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 EDWIN H. McKEE, DONALD C. NOBLE; Miocene volcanism and deformation in the western Cordillera and high plateaus of south-central Peru. GSA Bulletin 1982;; 93 (8): 657–662. doi: https://doi.org/10.1130/0016-7606(1982)93<657:MVADIT>2.0.CO;2 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 New radiometric ages on tuffs from south-central Peru support the postulated flare-up of volcanic activity during early Miocene time. In the region of Huancavelica, Julcani, and Lircay, lower Miocene rocks lie on folded strata of pre-Cenozoic age; the absence of units of Eocene and early Oligocene age indicates that this area remained positive after Incaic deformation in Eocene time. Conglomerate beds reflecting erosion attendant on the first pulse of late Cenozoic (Quechuan) compressive deformation do not appear in the stratigraphic record until after 21.5 m.y. B.P. In one section, beds of coarse conglomerate are underlain by tuff dated at 18.3 ± 0.6 m.y. and overlain by tuff dated at 17.3 ± 0.2 m.y. At another locality, beds of conglomerate conformably overlie tuff dated at 19.6 ± 0.8 m.y. If we incorporate published data from other areas in central and southern Peru, it appears that Quechuan deformation began in early Miocene time between 19.5 and 17 m.y. ago. A firm age for the end of the first pulse of Quechuan deformation in this region is provided by an ash-flow sheet dated at 12 to 12.5 m.y. that unconformably overlies strata of Eocene to early Miocene age. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.