Back to List of abstracts - Conference start page - Day 1 - Day 2 - Day 3
Structural Styles associated with Fault-Propagation Folds in Salt-Influenced Rift Basins: Halten Terrace, Offshore Norway
Author(s): | Alexander J. Coleman | Basins Research Group (BRG), Department of Earth Science and Engineering, Imperial College, Prince Consort Road, London, SW7 2BP, United Kingdom |
Christopher A.-L. Jackson | Basins Research Group (BRG), Department of Earth Science and Engineering, Imperial College, Prince Consort Road, London, SW7 2BP, United Kingdom | |
Oliver B. Duffy | Bureau of Economic Geology, University of Texas at Austin, University Station, Box X, Austin, TX 78713-8924, U.S.A. |
Normal fault growth is typically associated with the development of fault-propagation folds; especially in evolving salt-influenced rift basins, whereby the presence of a ductile, evaporite-rich unit in a brittle succession may decouple folded supra-salt (cover) and faulted sub-salt (basement) strata. Cover structures and the underlying fault blocks may form hydrocarbon traps, although imaging can be poor. This study examines the along-strike variability and controls on structural styles associated with a salt-influenced fault-related fold underlain and controlled by a series of down- stepping fault blocks.
A 2000 km², high quality, 3D seismic reflection survey of Hallen Terrace, offshore Norway, has been used to understand how normal fault growth in the presence of salt controls fault-linkage, fold development, basin physiography and syn-rift stratigraphic response. Moreover, we relate fold geometry, and cover-restricted fault strike variations to salt thickness, sub-salt fault throw and polarity. Hallen Terrace forms an ideal setting as the pre-rift Triassic salt lacks the effects of extensive diapirism and is well imaged. This permits detailed mapping of salt thickness variations and deconvolution of the spatial relationship between supra- and sub-salt faults and folds.
Quantitative analysis and 3D mapping of fault geometry shows salt strongly influences fault-linkage i.e. the propagation of sub-salt faults to higher stratigraphic levels and development of fold amplitude along-strike. We have identified a series of <15 km long, <400 ms throw, N-S- to NE-SW-striking basement-restricted faults below an 18 km long, >15 km wide, NW-facing, S-plunging monocline. At the southern extent of the fault-fold system, cover-restricted faults show similar strikes and polarity to their W-dipping, NE-SW striking sub-salt counterparts and are soft- linked. In the centre, throw is focused along W-dipping, N-S hard-linked faults to the east, and fold amplitude increases with greater salt thicknesses atop ·steeper sub-salt topography. Northwards, total throw decreases and greater fault polarity and strike disparity occurs between sub- and supra-salt faults associated with cover gravity- gliding and folding over increasingly flat, wider spaced, lesser-throw fault blocks.
We illustrate how basement-involved deformation can influence the fold structural style at different stratigraphic levels producing an extensive range of structural geometries and trapping styles. These are controlled by sub- and supra-salt fault coupling, salt thickness and fault throw.
- Title:
- Structural Styles associated with Fault-Propagation Folds in Salt-Influenced Rift Basins: Halten Terrace, Offshore Norway
- Type:
- Poster (Student)
- Origin:
- Mixed
- Day:
- 1
- Session:
- 0
- Daily sequence no.:
- 07
- Affiliation(s):
- Basins Research Group (BRG), Department of Earth Science and Engineering, Imperial College, Prince Consort Road, London, SW7 2BP
- Country:
- United Kingdom
- Abstract status:
- All ok
- UID:
- 54