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Deglacial and postglacial sedimentary architecture in a deeply incised paleovalley-paleofjord--The Pennsylvanian (late Carboniferous) Jejenes Formation, San Juan, Argentina

2006; Geological Society of America; Volume: 118; Issue: 7-8 Linguagem: Inglês

10.1130/b25810.1

1943-2674

Mason Dykstra, Ben Kneller, Juan Pablo Milana,

Paleontology and Stratigraphy of Fossils

Research Article| July 01, 2006 Deglacial and postglacial sedimentary architecture in a deeply incised paleovalley-paleofjord—The Pennsylvanian (late Carboniferous) Jejenes Formation, San Juan, Argentina Mason Dykstra; Mason Dykstra 1Department of Geological Sciences, University of California, Santa Barbara, California 93106, USA Search for other works by this author on: GSW Google Scholar Ben Kneller; Ben Kneller 2Institute for Crustal Studies, University of California, Santa Barbara, California 93106, USA Search for other works by this author on: GSW Google Scholar Juan Pablo Milana Juan Pablo Milana 3Consejo de Investigaciones Científicas y Técnicas, Universidad Nacional de San Juan, Av. Ignacio de la Roza y Meglioli, 5401, Rivadavia, San Juan, Argentina Search for other works by this author on: GSW Google Scholar GSA Bulletin (2006) 118 (7-8): 913–937. https://doi.org/10.1130/B25810.1 Article history received: 19 Feb 2005 rev-recd: 24 Jan 2006 accepted: 30 Jan 2006 first online: 08 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 Mason Dykstra, Ben Kneller, Juan Pablo Milana; Deglacial and postglacial sedimentary architecture in a deeply incised paleovalley-paleofjord—The Pennsylvanian (late Carboniferous) Jejenes Formation, San Juan, Argentina. GSA Bulletin 2006;; 118 (7-8): 913–937. doi: https://doi.org/10.1130/B25810.1 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 Quebrada de las Lajas, near San Juan, Argentina, preserves an early Pennsylvanian deglacial-postglacial succession in a highly confined paleofjord setting. The sedimentary succession records four distinct stages in the evolution of the valley fill. Stage 1 is represented by the deposits of subglacial diamictites, ice-contact deltas, and related deep-water lacustrine environments, including several subaqueous channels. Stage 2 records a glacio-eustatic marine transgression, and a slow-down of the clastic supply into the paleofjord. Stage 3 records a sandy, confined turbidite environment. Stage 4 consists of a coarse-grained delta, which represents a significant rejuvenation of the sedimentary system in the paleofjord. The transition from stage 1 to stage 2 was abrupt and basinwide, and has proven to be a good regional correlation marker. In this paleovalley, the glacio-eustatic rise probably caused floating and consequent rapid melting of the valley glacier. This resulted in a paleovalley-wide turbidite event that is up to 5 m thick and indicates an overall waning character. The rapid sediment emplacement in this event and resulting loading of the paleovalley sediments may have helped cause widespread mass-transport events at the stage 1–2 boundary.All stages show evidence of mass-transport–related deposits, but stage 1 records the most widespread mass transport, with a large spectrum of processes represented, including coherently slumped material, rafted blocks, and completely mixed debris-flow deposits. These mass-transport deposits range from a few meters to over 50 m thick, and up to hundreds of meters wide and long. Most of the large mass-transport deposits in the lower part of the fjord fill occurred at the transition to stage 2, implicating a rise in relative sea level as a possible trigger for the slope failures. Additionally, stage 3 deposits were affected by several thrust-sense dislocations that have large offsets relative to the scale of the sedimentary succession (tens to over 50 m vertically and hundreds of meters laterally); strata associated with the dislocations exhibit growth, indicating very early movement, and they are interpreted as the frontal ramp zones of mass-transport deposits. The abundance and size of mass-transport deposits in stages 1 and 3 helped control sediment pathways throughout the paleofjord. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.