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Identification and preservation of landforms diagnostic of past ice-sheet activity on continental shelves from three-dimensional seismic evidence

Julian A. Dowdeswell, Dag Ottesen, Leif Rise and Jonathan Craig
Identification and preservation of landforms diagnostic of past ice-sheet activity on continental shelves from three-dimensional seismic evidence
Geology (Boulder) (April 2007) 35 (4): 359-362

Abstract

Ice ages have occurred a number of times in Earth's history, and are important in understanding changes in long-term climate. However, it is difficult to demonstrate the presence of ice sheets in the ancient record because their sedimentary products can resemble those from nonglacial processes (e.g., debris flows). Diagnostic large-scale glacial landforms, produced beneath ice sheets and preserved on continental shelves after deglaciation, can establish a glacial origin. Three-dimensional seismic evidence from the 2.7 Ma Naust Formation, Norwegian margin, illustrates several glacial landforms that are also commonly occurring features on modern high-latitude shelves: (1) streamlined mega-scale lineations produced by fast-flowing ice streams; (2) ploughmarks formed by iceberg keels; and (3) regularly spaced transverse ridges or push moraines formed during ice retreat. We have found, for example, buried ice-keel ploughmarks on a paleoshelf dating to ca. 2 Ma. Norwegian margin seismic stratigraphy data show that ice advanced and retreated many times, and some paleoshelf surfaces were preserved. Such paleosurfaces must survive ocean basin destruction for glacial landforms to be useful in identification of ancient depositional environments.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 35
Serial Issue: 4
Title: Identification and preservation of landforms diagnostic of past ice-sheet activity on continental shelves from three-dimensional seismic evidence
Affiliation: University of Cambridge, Scott Polar Research Institute, Cambridge, United Kingdom
Pages: 359-362
Published: 200704
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 35
Accession Number: 2007-037427
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sect., sketch map
N64°25'00" - N67°00'00", E07°00'00" - E11°00'00"
Secondary Affiliation: Geological Survey of Norway, NOR, NorwayENI Exploration and Production Division, ITA, Italy
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200720
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