HR: 1340h
AN: T23B-0581    [Abstracts]
TI: Gravity Analysis of the Jeffera Basin, Tunisia
AU: * Mickus, K
EM: klm983f@smsu.edu
AF: SW Missouri State University, Dept. of Geology,, Springfield, MO 65804 United States
AU: Gabtni, H
AF: University Tunis El Manar, 1Department de G‚ologie, Facult‚ des Sciences de Tunis, Tunis, 2092 Tunisia
AU: Jallouli, C
AF: University Tunis El Manar, 1Department de G‚ologie, Facult‚ des Sciences de Tunis, Tunis, 2092 Tunisia
AB: Southern Tunisia consists of two main tectonic provinces: 1) the Saharan Platform and 2) the folded Atlasic domain, separated by the North Saharan Flexure. The Saharan Platform, which contains the Ghadames Basin and the Telemzane Arch, consists of gently dipping Paleozoic strata overlain by Triassic to Cretaceous sediments. The Atlasic domain consists of a thicker sequence of mainly Mesozoic and younger rock with less complete sequences of Paleozoic strata. Within the Atlasic domain are the still actively subsiding Chotts and Jeffera basins. The Jeffera basin, which occurs to the east of the Telemzane Arch contains at least eight kilometers of Paleozoic and younger sediment that were formed during numerous subsidence episodes since Carboniferous time. The Jeffera basin is dominated by tilted fault blocks that were formed during numerous tectonic episodes. Several unpublished seismic reflection profiles and well data exist for the Jeffera basin, however a deep structural analysis of the basin has not been published. We examined the existing gravity data in conjunction with available well and geologic data to determine structural features within the basin. The Bouguer gravity anomaly map shows that the Jeffera basin is dominated by a narrow northwest-trending gravity minimum. However, a more detailed analysis consisting of wavelength filtering and edge enhancements indicate that the structure of the basin is more complicated than indicated by the Bouguer gravity anomaly map. A residual gravity anomaly map indicates that the Jeffera basin consists of at least three and maybe four subbasins. Additionally, the Jeffera Fault marks the boundary between northwest-trending gravity anomalies to its northeast and east-trending anomalies over the Saharan Platform. The above observation is amplified by the construction of the enhanced horizontal derivatives (EHG) of both the complete Bouguer gravity and the residual gravity anomaly maps. The EHG maps highlight the lateral boundaries of subsurface density contrasts and emphasizes that the Jeffera basin is dominated by northwest-trending anomalies while the Saharan Platform consists of a series of northeast- and east-trending anomalies. The final interpretation of the gravity data will consist of constructing a series of two and one-half dimensional gravity models across the Jeffera basin.
DE: 8105 Continental margins and sedimentary basins
DE: 8109 Continental tectonics--extensional (0905)
DE: 1219 Local gravity anomalies and crustal structure
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting