Skip to Main Content
GEOREF RECORD

Early extensional detachments in a contractional orogen; coherent, map-scale, submarine slides (mass transport complexes) on the outer slope of an Ediacaran collisional foredeep, eastern Kaoko Belt, Namibia

Paul F. Hoffman, Eric J. Bellefroid, Benjamin W. Johnson, Malcolm S. W. Hodgskiss, Daniel P. Schrag and Galen P. Halverson
Early extensional detachments in a contractional orogen; coherent, map-scale, submarine slides (mass transport complexes) on the outer slope of an Ediacaran collisional foredeep, eastern Kaoko Belt, Namibia (in Uniformitarianism and plate tectonics; a tribute to Kevin C.A. Burke and John F. Dewey--L'uniformitarisme et la tectonique des plaques; hommage a Kevin C.A. Burke et a John F. Dewey, A. M. Celal Sengor (editor) and Ali Polat (editor))
Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre (November 2016) 53 (11): 1177-1189

Abstract

The existence of coherent, large-scale, submarine landslides on modern continental margins implies that their apparent rarity in ancient orogenic belts is due to non-recognition. Two map-scale, coherent, pre-orogenic, normal-sense detachment structures of Ediacaran age are present in the Kaoko belt, a well-exposed arc-continent collision zone in northwestern Namibia. The structures occur within the Otavi Group, a Neoproterozoic carbonate shelf succession. They are brittle structures, evident only through stratigraphic omissions of 400 m or more, that ramp down to the west with overall ramp angles of 1.1 degrees and 1.3 degrees with respect to stratigraphic horizons. The separations of matching footwall and hangingwall stratigraphic cut-offs require horizontal translations >20 km for each detachment. One of the detachments is remarkably narrow (5 km) in the up-dip direction, just one fourth of its translation. The other detachment is stratigraphically dated at the shelf-foredeep transition, when the passive margin was abortively subducted westward, in the direction of submarine sliding. Trenchward sliding on the foreslope occurred concurrently with deep karstification of the autochthonous carbonate succession to the east, presumably due to forebulge uplift and (or) conjectural basin-scale base-level fall. We expect that similar detachments exist in other orogenic belts, and failure to recognize them can lead to misinterpretations of stratigraphy, sedimentary facies, and paleogeography.


ISSN: 0008-4077
EISSN: 1480-3313
Coden: CJESAP
Serial Title: Canadian Journal of Earth Sciences = Revue Canadienne des Sciences de la Terre
Serial Volume: 53
Serial Issue: 11
Title: Early extensional detachments in a contractional orogen; coherent, map-scale, submarine slides (mass transport complexes) on the outer slope of an Ediacaran collisional foredeep, eastern Kaoko Belt, Namibia
Title: Uniformitarianism and plate tectonics; a tribute to Kevin C.A. Burke and John F. Dewey--L'uniformitarisme et la tectonique des plaques; hommage a Kevin C.A. Burke et a John F. Dewey
Affiliation: 1216 Montrose Avenue, Victoria, BC, Canada
Affiliation: Istanbul Teknik Universitesi, Avrasya Yerbilimleri Enstitusu, Istanbul, Turkey
Pages: 1177-1189
Published: 201611
Text Language: English
Summary Language: French
Publisher: National Research Council of Canada, Ottawa, ON, Canada
References: 53
Accession Number: 2017-006351
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., strat. cols., geol. sketch maps
S19°45'00" - S18°45'00", E13°30'00" - E14°19'60"
Secondary Affiliation: Yale University, USA, United StatesUniversity of Victoria, CAN, CanadaMcGill University, CAN, CanadaHarvard University, USA, United States
Country of Publication: Canada
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Canadian Science Publishing, NRC Research Press, Ottawa, ON, Canada. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201705
Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal