Classification for sediment gravity-flow deposits based on flow conditions during sedimentation

Research Article| April 01, 1986 Classification for sediment gravity-flow deposits based on flow conditions during sedimentation George Postma George Postma 1University of East Anglia, School of Environmental Sciences, Norwich, NR4 7TJ, England Search for other works by this author on: GSW Google Scholar Author and Article Information George Postma 1University of East Anglia, School of Environmental Sciences, Norwich, NR4 7TJ, England Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1986) 14 (4): 291–294. https://doi.org/10.1130/0091-7613(1986)14<291:CFSGDB>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 Email Permissions Search Site Citation George Postma; Classification for sediment gravity-flow deposits based on flow conditions during sedimentation. Geology 1986;; 14 (4): 291–294. doi: https://doi.org/10.1130/0091-7613(1986)14<291:CFSGDB>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 SocietyGeology Search Advanced Search Abstract The classifications of sediment gravity flows in use by geologists are based on rheology and dominant clast-support mechanism of uniform and steady sediment flow. This paper discusses a classification based on the ultimate flow character of a sediment gravity flow, which is more likely to be reflected in the deposit.Three constitutive conditions prevail during sedimentation that define the flow character of a sediment gravity flow in its final stage: (I) the flow is either laminar or turbulent; (II) the flow behavior is either plastic (cohesive) or fluidal (cohesionless); (III) its concentration is either low or high. The resulting eight theoretical rheological models are each likely to be characterized by only one type of deposit. A comparison with Lowe's (1979) classification, for example, shows that (low-density) turbidity current and cohesive debris flow correlate quite well (because the steady-flow state is not much different from their ultimate rheological state), but that liquefied flow, fluidized flow, grain flow, and modified grain flow all belong to the same rheological model—namely, laminar, high-concentration, cohesionless sediment flow. An analysis of grain-support mechanisms shows that these four types of gravity flows behave in virtually similar fashion during deposition, and all must be considered as fluidal flows. 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.