| Title | An alternative model of producing levee topography in the crest region of deep-water systems |
| Author | Kahn, Z A; Arnott, R; Pugin, A |
| Source | American Association of Petroleum Geologists Bulletin vol. 95, no. 12, 2011 p. 2085-2106, https://doi.org/10.1306/03281110024 |
| Year | 2011 |
| Alt Series | Earth Sciences Sector, Contribution Series 20110359 |
| Document | serial |
| Lang. | English |
| Media | paper |
| Province | British Columbia |
| NTS | 93H |
| Area | Castle Creek |
| Lat/Long WENS | -122.0000 -120.0000 54.0000 53.0000 |
| Subjects | geophysics; sedimentology; topography; geophysical surveys; seismic interpretations; seismic models; slope deposits; Isaac Formation |
| Illustrations | location maps; profiles; cross-sections |
| |
| Program | Aquifer Assessment & support to mapping, Groundwater Geoscience |
| Abstract | The crest region of deep-water levees is commonly expressed as a mound-shaped element in seismic images made up of multiple dipping seismic reflectors. These dipping reflectors are generally thought to
reflect actual stratal dip within levees. Basal contacts of levee strata in the Neoproterozoic Isaac Formation, however, show no discernible dip over hundreds of meters laterally or tens of meters vertically. Notwithstanding, mediumto thick-bedded
(10 - 100 cm [4 - 40 in.]) strata in the proximal levee change in thickness laterally away from the channel, over hundreds of meters, causing their upper surfaces to formsubtle topography. However, this topography becomes later infilled and,
accordingly, the vertical stacking of these beds does not contribute to an upward increase in stratal dip. An alternativemodel proposes that levee topography in the crest region of some systems is formed mainly by thin-bedded (<10 cm [<4 in.])
turbidites that have a tabular geometry and terminate abruptly instead of tapering laterally. The upward, progressively more channelward (backstepping) stacking of these thin beds is interpreted to form a lateral-thinning profile. This stacking
pattern is a consequence of diminishing flow magnitude, causing more limited lateral bed extent (i.e., flow runout), which in turn reflects increased channel confinement related to levee growth and reduced overspill into overbank areas. Thismodel was
then used to generate a synthetic seismic model that forms dipping reflectors similar to those observed in the crest region of some modern deep-water systems. Importantly, the reflectors produced in the model reflect a lateral change in lithofacies
and not stratal dip. Moreover, these reflectors crosscut stratigraphy. |
| GEOSCAN ID | 289883 |
|
|