Structural Styles

Structural StylesBrenton, David, & Ryan Normal-fault related structuresSyncline formed by growth faultingShear fold formed as fault tip displacement was lost near the surfaceNormal-fault related structuresSyncline formed by growth faultingCretaceous strata onlapJurassic faultingNigeria profileFault arrays under the Browse BasinNW continental margin of Australia

Mostly normal throws - partial inversion on the NW side of section?

Post breakup unconformity overlain by strata that onlap significant relief across the section Faulted units beneath the NW continental margin of Australia, blanketed by a post-tectonic sedimentary cover of late Mesozoic and younger age. The faults are shown here as showing normal throws. However, there may be partial inversion of these structures to create the antiformal structure on the NW side of the section. The post kinematic section lies on an erosional unconformity and onlaps significant relief across the section.

Normal-faulted clinoforms, offshore NamibiaThe stratal geometries on the shelf show progradational and aggradational geometry together with subtle slump scars. In 3D these mega forms probably trace lobes - hence the complex lap relationships. The stratal surfaces in the clinoforms (picked in blue) are cut by an array of moderately-dipping (once the excessive vertical exaggeration is removed) normal faults that do not continue to depth. These probably represent incipient failure of the stratal package upon a muddy section. These faults - which involve c. 6-700 ms (= c. 1 km) of strata may also influence the failure on the foresets.Thrust-Related Structures: Buckle folded Messinian strata, Western IonianOne of several representations of deformed strata on the floor of the western Ionian sea, just off the foot of the Malta escarpment.

Deformed Neogene strata on the floor of the western Ionian sea, just off the malta escarpment. Seismic facies tie to interpretations in the related retities links. In this interpretation the buckled layer, interpreted to be the most comptent, is likely to be massive primary gypsum - forming a distinct layer above halites and a well-layered ?clastic? sequence. This interpretation correlates with the classical Two Cycle description of Messinian evaporites from the Caltanissetta Basin of nearby Sicily (see linked papers via docs and links).Imbricate Thrust System:Glacial thrust belt, Danish North SeaIn this interpretation of line GR98-01 from the Danish North Sea, thrusts are seen, decreasing in intensity from east to west. The detachment surface for these thrusts is the min-Miocene unconformity (mMu), which is characterised by fine clays. Thrusting affects the entire section between the detachment surface and the seabed. Thrust steepen toward the surface before flattening at the tip of the thrust plane, where preserved. Note that the sediments are incised by a considerable Quaternary valley. These thrusts have been interpreted as being caused by gravity spreading ahead of advancing glaciers through ice loading with the presence of detachment surfaces.

Connors, 2009Toe of the Delta Thrust Faults, Deep Water Niger DeltaVirtual Seismic AtlasConnors, 2009Virtual Seismic AtlasFlower StructuresPositive FlowerNegative FlowerFault Imaging ChallengesJuxtaposition of different velocity rocks causes issues with seismic profiles.

Ex: Thrust faults-faster velocity rocks over slower rocksSalt Intrusions

Planar faults appear curved velocity increases with depthconstant thickness of rocks represented by smaller TWT at depth than shallower

Located between Eastern Cordillera and the undeformed foreland basin

Exploration in the mid 90's led to the discovery of 2 major fields: Cusiana and Cupiagua

BPXC - 2000km 2D sesimic - 800km2 3D

Case Study: LLanos Foothills, ColumbiaEstrada & Jaramillo (2003)Modeling showed long tails generated by overturned thrust sheets

Post stack migration caused reflectors beneath the thrust sheets to be broken up

Case Study: LLanos Foothills, ColumbiaEstrada & Jaramillo (2003)Improving quality in the over thrust belt was time consuming

2D seismic captured overall structure in the South

Structural complexity increases to the NorthReprocessing Estrada & Jaramillo (2003)Improving quality in the over thrust belt was time consuming

2D seismic captured overall structure in the South

Structural complexity increases to the NorthEstrada & Jaramillo (2003)Improving quality in the over thrust belt was time consuming

2D seismic captured overall structure in the South

Structural complexity increases to the North3D seismic Quality of 2D lines was seen as adequate for the appraisal of the Cusiana.

Wasn't possible to define the limits of the Cupiagua field

3D acquisition resulted in "step-change" in data quality

Estrada & Jaramillo (2003)Improving quality in the over thrust belt was time consuming

2D seismic captured overall structure in the South

Structural complexity increases to the NorthSeismic AttributesAn attribute is a measured characteristic taken from seismic dataCan reveal features that could easily be missed and aid in interpretationEspecially important in imaging complex fault systemsFor faults the two most important attributes are coherency and volumetric curvatureCoherencyThe measure of similarity between traces in a small analysis windowNissen, 2007Bahorich, 1995Coherency CubeVirtual Seismic AtlasReferencesBahorich, Mike, and Steve Farmer. "3-D Seismic Discontinuity for Faults and Stratigraphic Features: The Coherence Cube: ABSTRACT." The Leading Edge (1995): 1053-058.

Connors, C. D., B. Radovich, A. Danforth, and S. Venkatraman. "The Structure of the Offshore Niger Delta." Orsget (2009): 182-88.

Estrada, C. A., & Jaramillo, J. A. (2003). Making the difference: A story of pitfalls and successes in seismic imaging in a thrust belt environment.

Nissen, Susan. Using 3-D Seismic Attributes in Reservoir Charaterization. 9 Aug. 2007. Presentation. Hays, KS.

Virtual Seismic Atlas, http://see-atlas.leeds.ac.uk:8080/home.jsp