Lyell Collection
Geological Society, London, Special Publications
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Full Text (PDF)
Right arrow References
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 Google Scholar
Google Scholar
Right arrow Articles by Ainsworth, R. B.
Right arrow Articles by Newall, M. J.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Geological Society, London, Special Publications; 2000; v. 172; p. 163-176;
DOI: 10.1144/GSL.SP.2000.172.01.08
© 2000 Geological Society of London

Palaeozoic-Mesozoic

Forward stratigraphic modelling of forced regressions: evidence for the genesis of attached and detached lowstand systems

R. B. Ainsworth1,2, H. Bosscher1,3 & M. J. Newall1,4

1 Shell International Exploration and Production B.V., Technology and Research Centre, PO Box 60, 2280 AB, Rijswijk, The Netherlands
2 Woodside Energy Ltd, 1 Adelaide Terrace, Perth, WA 6000, Australia
3 A/S Norske Shell, Risavikvegan 180, PO Box 40, 4056 Tanager, Norway
4 Sarawak Shell Berhad, Locked Bag No. 1, 98009, Miri, Sarawak, Malaysia

A complex series of interactions between subsidence, eustasy and sediment supply determine whether a forced regressive shoreface will be physically attached to underlying sandy deposits, or detached and encased in marine mudstone. Using a Shell-developed and proprietary forward stratigraphic modelling system, these interactions of controls on clastic depositional geometries can be simulated. Upper Cretaceous subsurface and outcrop data from the Western Interior Basin of Canada form the basis of this study. The outcrop data suggest that high frequency (200 000 years), relatively low amplitude (8 m) relative sea-level changes occurred during deposition of the studied succession. When these parameters are convolved with the Haq third-order eustatic sea-level curve and a constant rate of subsidence and sediment supply, a series of attached lowstand, forced regressive shorefaces are generated by the forward stratigraphic modelling system. In order to generate a detached lowstand shoreface a relatively large magnitude, high frequency eustatic fall or a high frequency tectonic uplift is required. The modelling studies also suggest that (i) forced regressive deposits preferentially develop as attached lowstand systems, (ii) detached lowstand systems in most cases initially develop as attached lostand systems which are subsequently detached by transgressive-regressive wave erosion, (iii) if the sequence boundary is picked below the sharp-based, forced regressive shoreface (attached and detached lowstand systems tract interpretation) or above it (falling-stage systems tract interpretation) it must remain in that position relative to the correlative down-dip, sharp-based shoreface sandbodies regardless of whether those bodies are attached or detached and (iv) the role of sediment supply as a controlling parameter in the generation of forced regressions appears to be a secondary one.