Lyell Collection
Journal of the Geological Society
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (3)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Stevenson, I.R.
Right arrow Articles by McMillan, I.K.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Journal of the Geological Society; 2004; v. 161; issue.2; p. 185-208;
DOI: 10.1144/0016-764902-003
© 2004 Geological Society of London

Original Article

Incised valley fill stratigraphy of the Upper Cretaceous succession, proximal Orange Basin, Atlantic margin of southern Africa

I.R. Stevenson & I.K. McMillan

De Beers Marine, P.O. Box 87, Cape Town 8000, South Africa (e-mail: ian.stevenson@debeersgroup.com)

Seismic stratigraphic analysis of a grid of 7860 km of shallow seismic Sleevegun data, plus lithological and biostratigraphic (foraminifera) data interpreted from core and sea-bed samples have been integrated into a detailed geological model for the Upper Cretaceous succession of the proximal Orange Basin. Emphasis has been placed on the palaeoenvironmental interpretation of incised valley fill sequences of this succession. Seismic reflection geometries for the Middle Albian to Lower Cenomanian interval show that the entire coast was dominated by aggradational fluvial braid-plain facies. The Lower Turonian to Upper Coniacian succession marks the appearance of repeated major incision into the exposed coastal plain by large fluvial drainage networks. This succession is characterized by fourth-order, fluvial-to-marine sequences, with valley incision up to 25 km wide and 70 m deep. Detailed palaeoenvironmental analysis indicates periodically waterlogged, highly reducing fluvial floodplain environments with valley systems that were flooded to create wave-dominated estuaries. Major fluvial activity during the Turonian was in an area that lies offshore of the present-day Swartlintjies to Groen River mouths in the southern part of the Orange Basin. During the Coniacian the site of fluvial activity changed to the central Orange Basin, offshore of the present-day Buffels River. These observations contradict previously published views that a dominant Orange River drainage system existed since the Albian, at a position coincident with the present-day mouth.

Key Words: South Africa • Upper Cretaceous • seismic stratigraphy • biostratigraphy • incised valleys




This article has been cited by other articles:


Home page
 Journal of the Geological SocietyHome page
B.J. Bluck, J.D. Ward, J. Cartwright, and R. Swart
The Orange River, southern Africa: an extreme example of a wave-dominated sediment dispersal system in the South Atlantic Ocean
Journal of the Geological Society, 2007; 164: 341 - 351.
[Abstract] [Full Text] [PDF]

Home page
 Journal of Sedimentary ResearchHome page
C. Grelaud, P. Razin, P. W. Homewood, and A. M. Schwab
Development of Incisions on a Periodically Emergent Carbonate Platform (Natih Formation, Late Cretaceous, Oman)
Journal of Sedimentary Research, 2006; 76: 647 - 669.
[Abstract] [Full Text] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
B. J. Bluck, J. D. Ward, and M. C. J. De Wit
Diamond mega-placers: southern Africa and the Kaapvaal craton in a global context
Geological Society, London, Special Publications, 2005; 248: 213 - 245.
[Abstract] [PDF]