Paleosols and associated channel-belt sand bodies from a continuously subsiding late Quaternary system (Po Basin, Italy): New insights into continental sequence stratigraphy

Abstract

Research Article| March 01, 2017 Paleosols and associated channel-belt sand bodies from a continuously subsiding late Quaternary system (Po Basin, Italy): New insights into continental sequence stratigraphy Alessandro Amorosi; Alessandro Amorosi † 1Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Zamboni 67, 40126 Bologna, Italy †alessandro.amorosi@unibo.it Search for other works by this author on: GSW Google Scholar Luigi Bruno; Luigi Bruno 1Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Zamboni 67, 40126 Bologna, Italy Search for other works by this author on: GSW Google Scholar David M. Cleveland; David M. Cleveland 2ExxonMobil Development Company, 22777 Springwoods Village Parkway, Spring, Texas 77389, USA Search for other works by this author on: GSW Google Scholar Agnese Morelli; Agnese Morelli 1Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Zamboni 67, 40126 Bologna, Italy Search for other works by this author on: GSW Google Scholar Wan Hong Wan Hong 3KIGAM Korea Institute of Geoscience and Mineral Resources, 92 Gwahangro, Yuseong-gu, Daejeon Metropolitan City, Korea Search for other works by this author on: GSW Google Scholar Author and Article Information Alessandro Amorosi † 1Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Zamboni 67, 40126 Bologna, Italy Luigi Bruno 1Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Zamboni 67, 40126 Bologna, Italy David M. Cleveland 2ExxonMobil Development Company, 22777 Springwoods Village Parkway, Spring, Texas 77389, USA Agnese Morelli 1Department of Biological, Geological and Environmental Sciences, University of Bologna, Via Zamboni 67, 40126 Bologna, Italy Wan Hong 3KIGAM Korea Institute of Geoscience and Mineral Resources, 92 Gwahangro, Yuseong-gu, Daejeon Metropolitan City, Korea †alessandro.amorosi@unibo.it Publisher: Geological Society of America Received: 17 May 2015 Revision Received: 22 Aug 2016 Accepted: 07 Oct 2016 First Online: 02 Jun 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 2016 Geological Society of America GSA Bulletin (2017) 129 (3-4): 449–463. https://doi.org/10.1130/B31575.1 Article history Received: 17 May 2015 Revision Received: 22 Aug 2016 Accepted: 07 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 Alessandro Amorosi, Luigi Bruno, David M. Cleveland, Agnese Morelli, Wan Hong; Paleosols and associated channel-belt sand bodies from a continuously subsiding late Quaternary system (Po Basin, Italy): New insights into continental sequence stratigraphy. GSA Bulletin 2017;; 129 (3-4): 449–463. doi: https://doi.org/10.1130/B31575.1 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 Previous sequence-stratigraphic work has emphasized the key role of paleosols and associated sand-dominated fluvial bodies as key features for interpreting alluvial architecture. The temporal resolution of the ancient record is, however, insufficient to fully explain the complex relationship between soil formation and the evolution of fluvial systems under changing sea-level and climate conditions. In this paper, we present a detailed record of paleosol–channel belt relationships reconstructed from the subsurface of a rapidly subsiding region (Po Plain, Italy) that spans almost all of the last glacial-interglacial cycle (∼120 k.y.). The studied succession preserves a systematic bipartite zonation into a thick paleosol-bearing segment close to the basin margin and a sand-dominated interval, with vertically amalgamated channel belts, in an axial position. Individual paleosols are weakly developed and represent key stratigraphic markers that can be traced basinwide into adjacent, essentially contemporaneous, unconfined channel-belt deposits. Unlike conventional models of late Quaternary alluvial–coastal plain systems, no persistent incised valley was established in the Po system during the last glacial-interglacial cycle. Continuous accommodation was the key depositional control on alluvial stratigraphy during the prolonged (∼90 k.y.) phase of late Pleistocene sea-level fall, which led to the deposition of a thick, dominantly aggradational alluvial succession. The development of shallowly incised, short-lived valley systems took place only at the transition to glacial stages associated with substantial sea-level drop (marine oxygen isotope stage [MIS] 3-2 transition, and possibly MIS 5-4 transition). This study shows that in rapidly subsiding settings with high rates of sedimentation, incised valley systems may be replaced by aggradationally stacked, essentially nonincised fluvial bodies. In these cases, overbank packages bounded by immature paleosols represent the most likely alternative to the highly weathered interfluve paleosol predicted by classic sequence-stratigraphic models. Fourth-order sequence boundaries and lower-rank erosional surfaces may be easily confused at the ∼100 k.y. scale, and transgressive surfaces, defining the onset of retrogradation, may become the most readily identifiable sequence-stratigraphic surfaces. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.