The timing of the last deglaciation in Cordillera Oriental, northern Peru, based on glacial geology and lake sedimentology

Research Article| July 01, 1993 The timing of the last deglaciation in Cordillera Oriental, northern Peru, based on glacial geology and lake sedimentology DONALD T. RODBELL DONALD T. RODBELL 1Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309-0250 Search for other works by this author on: GSW Google Scholar Author and Article Information DONALD T. RODBELL 1Department of Geological Sciences, University of Colorado, Boulder, Colorado 80309-0250 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1993) 105 (7): 923–934. https://doi.org/10.1130/0016-7606(1993)1052.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation DONALD T. RODBELL; The timing of the last deglaciation in Cordillera Oriental, northern Peru, based on glacial geology and lake sedimentology. GSA Bulletin 1993;; 105 (7): 923–934. doi: https://doi.org/10.1130/0016-7606(1993)1052.3.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 The degree of soil development on moraines and radiocarbon ages indicate that the Cordillera Oriental, a part of the eastern Andes in northern Peru (7°30′-7°55′S; 77°20′-77°35′W), was last glaciated during the last glacial maximum (marine isotope stage 2). This glaciation was the most extensive late Quaternary glaciation in the area. Radiocarbondated sedimentological changes in six sediment cores from three lakes and one bog reveal that the last deglaciation is marked by a two-stepped transition from rhythmically laminated inorganic sediment to massive, organic-rich sediment. The first step of this transition commenced before 12.1 ± 0.2 ka (± 1 σ) and probably by ca. 13.5 ka. Glaciers covered less than 50% of their last glacial maximum area by 12.1 ± 0.6 ka, and cirques west of the main divide were probably ice-free by this time. A return to rhythmically laminated inorganic sediment in the lakes and the bog occurred between 12.1 ± 0.6 and 10.3 ± 0.4 ka. This may reflect an episode of increased stream discharge and glacier expansion during which glaciers reoccupied cirques above ∼3,800 m. This glacier expansion adds to widespread evidence of a late-glacial readvance in the tropical Andes. All cirques have been ice-free since between 10.3 ± 0.4 and 9.7 ± 0.5 ka. 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.