Tom Wilson, Department of Geology and Geography Tom Wilson, Department of Geology and Geography Objectives for the Day • General review seismic stratigraphy exercises • Lithic surfaces versus reflection events • Edge enhancement and detection • Some additional conceptual diagrams illustrating deposition under cycles of eustatic sea level rise and fall • The Woodbine play • Synthetic tie • Identifying the sequence and internal reflection patterns associated with the Woodbine • The influence of processing • Construction the
Objectives for the Day. General review seismic stratigraphy exercises Lithic surfaces versus reflection events Edge enhancement and detection Some additional conceptual diagrams illustrating deposition under cycles of eustatic sea level rise and fall The Woodbine play Synthetic tie - PowerPoint PPT Presentation
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Tom Wilson, Department of Geology and GeographyTom Wilson, Department of Geology and Geography
Objectives for the Day
• General review seismic stratigraphy exercises• Lithic surfaces versus reflection events• Edge enhancement and detection • Some additional conceptual diagrams illustrating deposition under cycles of eustatic sea level rise and fall• The Woodbine play• Synthetic tie• Identifying the sequence and internal reflection patterns associated with the Woodbine• The influence of processing• Construction the chronostratigraphic chart
Tom Wilson, Department of Geology and Geography
Island Platform, Deep Water, Southern Bahamas
Tom Wilson, Department of Geology and Geography
In the preceding section, the platform lies to the left. The prominent seismic sequence to the right appears as a simple wedge of sediments dipping down to the right which is in turn onlapped by flatter lying sediments.
Closer inspection reveals several distinct intervals of onlap belonging to at least three different sequences.
The section reveals an earlier prograding sequence that was extensively eroded and itself followed by additional onlap against the escarpment to the left.
Subtle downlap and onlap mark locations of smaller sequences within the latest package that extends to the water bottom.
The pattern suggests presence of an earlier high stand system followed by significant sea level drop and then by gradual and relatively steady sea level rise
Tom Wilson, Department of Geology and Geography
Baltimore Canyon, East Coast, US
Erosional Truncation
A combination of prograding clinoforms followed by sealevel drop and coastal onlap (3 and above) overlie a thick sequence
characterized by predominantly parallel reflection events with some local onlap (1) above a deeper erosional inconformity
Prograding clinoforms/oblique
Tom Wilson, Department of Geology and Geography
National Petroleum Reserve, Alaska
Sigmoid clinoforms
Tom Wilson, Department of Geology and Geography
National Petroleum Reserve, Alaska
Sigmoid clinoforms
Some questions to contemplate:
1) What was the bathymetric relief between the top and base of the prograding wedge?
2) Was the wedge building upward, outward, or a combination of the two?
3) What caused the reflectors on the left (4) to become hump shaped?
Tom Wilson, Department of Geology and Geography
Central Atlantic Shelf, near the Baltimore Canyon
Prograding clastic wedge
The reflectors to the right of 1) build both out and up. The internal configuration is oblique (left) to sigmoid (near 1) and then oblique
again. The environment is prograding shelf margin.
Tom Wilson, Department of Geology and Geography
Splay, Floodplain, & Channel Environments
Flattened on the F37 reflection event
F37 Event
Manual pick of the F37 Lithic surface
Tom Wilson, Department of Geology and Geography
Splay, Floodplain, & Channel Environments
Hardage et al. (1994)The F37 “stratal” time surface
Tom Wilson, Department of Geology and Geography
Tom Wilson, Department of Geology and Geography
Enhancing Discontinuities to Resolve Depositional and Structural Features
Bahorich and Farmer, 1995
Results from an analysis of coherency between events in the seismic data set