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Quantifying the origin and geometry of circular sag structures in northern Fort Worth Basin, Texas: Paleocave collapse, pull-apart fault systems, or hydrothermal alteration?
- Source :
- AAPG Bulletin. 91:1295-1318
- Publication Year :
- 2007
- Publisher :
- American Association of Petroleum Geologists AAPG/Datapages, 2007.
-
Abstract
- Three-dimensional seismic data reveal numerous subcircular sag structures in the northern Fort Worth Basin. The structures are defined by concentric faults that extend vertically upward 760–1060 m (2500–3500 ft) from the Lower Ordovician Ellenburger Group. The largest structures remained active into the lower Desmoinesian Strawn Group. Criteria are outlined for defining seismically resolvable sag structures, and a detailed quantitative analysis of the geometries of these circular features was undertaken. Results are compared and contrasted, with reviews of subsurface collapse mechanisms and strike-slip processes that are known to produce subsurface circular to subcircular sag geometries in plan view. In this manner, we develop several constraints for differentiating collapse-related sag structures from strike-slip–related sag structures. Qualitative analyses indicate that the geometries observed are strongly analogous to subsurface collapse features where material is removed at depth to create a void, into which the overburden subsequently sags and collapses. Quantitative analyses support the formation of these features by incremental collapse and suprastratal deformation above a linked system of coalesced, collapsed paleocaves within the Ellenburger Group. Observations and criteria presented herein provide valuable information in defining seismically resolvable collapse features worldwide and help distinguish sag features of collapse affinity from those of other origins.
- Subjects :
- geography
geography.geographical_feature_category
Deformation (mechanics)
Paleozoic
Energy Engineering and Power Technology
Collapse (topology)
Geology
Fault (geology)
Structural basin
Paleontology
Overburden
Fuel Technology
Geochemistry and Petrology
Carboniferous
Earth and Planetary Sciences (miscellaneous)
Ordovician
Petrology
Subjects
Details
- ISSN :
- 01491423
- Volume :
- 91
- Database :
- OpenAIRE
- Journal :
- AAPG Bulletin
- Accession number :
- edsair.doi...........cad215b3a4d6dc128bbbb5b6d4e7961d
- Full Text :
- https://doi.org/10.1306/05170706086