Book contents
- Frontmatter
- Contents
- List of contributors
- 1 Overview of megaflooding: Earth and Mars
- 2 Channel-scale erosional bedforms in bedrock and in loose granular material: character, processes and implications
- 3 A review of open-channel megaflood depositional landforms on Earth and Mars
- 4 Jökulhlaups in Iceland: sources, release and drainage
- 5 Channeled Scabland morphology
- 6 The morphology and sedimentology of landforms created by subglacial megafloods
- 7 Proglacial megaflooding along the margins of the Laurentide Ice Sheet
- 8 Floods from natural rock-material dams
- 9 Surface morphology and origin of outflow channels in the Valles Marineris region
- 10 Floods from fossae: a review of Amazonian-aged extensional–tectonic megaflood channels on Mars
- 11 Large basin overflow floods on Mars
- 12 Criteria for identifying jökulhlaup deposits in the sedimentary record
- 13 Megaflood sedimentary valley fill: Altai Mountains, Siberia
- 14 Modelling of subaerial jökulhlaups in Iceland
- 15 Jökulhlaups from Kverkfjöll volcano, Iceland: modelling transient hydraulic phenomena
- 16 Dynamics of fluid flow in Martian outflow channels
- Index
- Plate section
- References
12 - Criteria for identifying jökulhlaup deposits in the sedimentary record
Published online by Cambridge University Press: 04 May 2010
- Frontmatter
- Contents
- List of contributors
- 1 Overview of megaflooding: Earth and Mars
- 2 Channel-scale erosional bedforms in bedrock and in loose granular material: character, processes and implications
- 3 A review of open-channel megaflood depositional landforms on Earth and Mars
- 4 Jökulhlaups in Iceland: sources, release and drainage
- 5 Channeled Scabland morphology
- 6 The morphology and sedimentology of landforms created by subglacial megafloods
- 7 Proglacial megaflooding along the margins of the Laurentide Ice Sheet
- 8 Floods from natural rock-material dams
- 9 Surface morphology and origin of outflow channels in the Valles Marineris region
- 10 Floods from fossae: a review of Amazonian-aged extensional–tectonic megaflood channels on Mars
- 11 Large basin overflow floods on Mars
- 12 Criteria for identifying jökulhlaup deposits in the sedimentary record
- 13 Megaflood sedimentary valley fill: Altai Mountains, Siberia
- 14 Modelling of subaerial jökulhlaups in Iceland
- 15 Jökulhlaups from Kverkfjöll volcano, Iceland: modelling transient hydraulic phenomena
- 16 Dynamics of fluid flow in Martian outflow channels
- Index
- Plate section
- References
Summary
Summary
A wide variety of sedimentary structures occur in modern jökulhlaup deposits and an important question arises when trying to identify jökulhlaup deposits in the sedimentary record: which sedimentary structures are distinctive of jökulhlaup deposition? A given sedimentary structure can be formed by more than one process, and in isolation cannot be used to distinguish a jökulhlaup deposit from those formed by other fluvial and flood processes. This chapter identifies those sedimentary structures that are thought to be unique or highly distinctive in jökulhlaups. Some structures are only formed by jökulhlaups in the proglacial environment, but can be found in other fluvial environments. Distinctive sedimentary features of jökulhlaup flows may include hyperconcentrated flow deposits, thick (greater than 5m) upwards coarsening units formed by accretion during the rising stage of a flood and large gravel cross-beds (indicating formation by large gravel dunes) and flood bar deposits. Additional, non-distinctive indicators of jökulhlaup deposition include reactivation surfaces in gravel bedforms, widespread erosion surfaces and consistent palaeoflow indicators. Ice-block and rip-up clast related sedimentary structures are also non-unique, given that they can be formed under non-flood conditions, but their size and numbers are many times greater when formed by a jökulhlaup. To illustrate the points made in the review, this chapter presents a case study using ground-penetrating radar data that describe the sediments of a flood bar deposited during the November 1996 jökulhlaup in Iceland.
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- Information
- Megaflooding on Earth and Mars , pp. 225 - 242Publisher: Cambridge University PressPrint publication year: 2009
References
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