The Stratigraphically Preserved Signature of Persistent Backwater Dynamics in a Large Paleodelta System: The Mungaroo Formation, North West Shelf, Australia

Abstract

Research Article| July 31, 2018 The Stratigraphically Preserved Signature of Persistent Backwater Dynamics in a Large Paleodelta System: The Mungaroo Formation, North West Shelf, Australia John Martin; John Martin 1Shell International Exploration and Production, Projects and Technology, Houston, Texas 77082, U.S.A. Search for other works by this author on: GSW Google Scholar Anjali M. Fernandes; Anjali M. Fernandes 2Center for Integrative Geosciences, University of Connecticut at Storrs, Connecticut 06269, U.S.A. Search for other works by this author on: GSW Google Scholar Jennifer Pickering; Jennifer Pickering 1Shell International Exploration and Production, Projects and Technology, Houston, Texas 77082, U.S.A. Search for other works by this author on: GSW Google Scholar Nick Howes; Nick Howes 1Shell International Exploration and Production, Projects and Technology, Houston, Texas 77082, U.S.A. Search for other works by this author on: GSW Google Scholar Simon Mann; Simon Mann 3Shell Malaysia, Ltd., Kuala Lumpur, KUL 50470, Indonesia Search for other works by this author on: GSW Google Scholar Katja McNeil Katja McNeil 4Shell Australia, Ltd., Perth, WA 6000, Australia Search for other works by this author on: GSW Google Scholar Journal of Sedimentary Research (2018) 88 (7): 850–872. https://doi.org/10.2110/jsr.2018.38 Article history first online: 31 Jul 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation John Martin, Anjali M. Fernandes, Jennifer Pickering, Nick Howes, Simon Mann, Katja McNeil; The Stratigraphically Preserved Signature of Persistent Backwater Dynamics in a Large Paleodelta System: The Mungaroo Formation, North West Shelf, Australia. Journal of Sedimentary Research 2018;; 88 (7): 850–872. doi: https://doi.org/10.2110/jsr.2018.38 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietyJournal of Sedimentary Research Search Advanced Search Abstract As large, deep rivers enter their coastal reaches, they are usually affected by a lengthy backwater zone. Recent studies have demonstrated pronounced geomorphic effects, such as channel deepening and decreased lateral migration rates. These observations appear to be linked to variable fluxes of sediment in rivers that characteristically vary their discharge across their backwater segments. How do such a variable sediment transport regime and its depositional effects manifest as stratigraphic architecture over geologic time? To address this question, we mapped and analyzed over 700 channel belts from a large (70,000 km2) seismic survey of the Mungaroo Formation, Northern Carnarvon Basin, Australia. Following analysis of measurements of channel-belt patterns, we propose that the Mungaroo stratigraphy was constructed by a continental-scale paleodelta and that it reveals a record of backwater-influenced deposition over a length scale of 400 km. Width measurements of the Mungaroo channel belts decay only weakly down system, in a manner similar to the lowermost reaches of the late Holocene Mississippi River, here invoked as an analogous system. In addition, significant downstream fining in the Mungaroo system is interpreted from wireline-log and lithologic core data, a trend that is also seen in the Mississippi channel belt, where bank-attached bars fine downstream due to reduced contributions of bedload. By comparing the two systems, we show that the depositional trends expressed in the 103 year record of the Mississippi River and the 106 year record of the Mungaroo paleodelta are similar, each having generated channel belts that only slightly narrow down system but transition from sand-rich to heterolithic or mud-dominated along the lower 30 to 50 percent of the backwater reach. We present a transtemporal backwater-influenced depositional model that leverages quantitative data from an analogous modern transport system for characterization of an ancient stratigraphic system. You do not currently have access to this article.