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|Title: ||Neogene to Recent Displacement and Contact of Sardinian and Tunisian Margins, Central Mediterranean|
|Authors: ||Gennesseaux, Maurice G.|
Stanley, Daniel Jean
|Issue Date: ||14-Dec-1983|
|Citation: ||Smithsonian Contributions to the Marine Sciences; 23|
|Abstract: ||The seafloor between Sardinia, Tunisia, and Sicily occupies a key sector essential for understanding the geological evolution of the central Mediterranean. Although plate motion is generally considered as an explanation, this structurally complex region remains poorly defined. To interpret better the Neogene evolution, we prepared a detailed bathymetric chart and a map showing structural provinces and post-Miocene sediment patterns, which are constructed on the basis of seismic data (primarily a dense network of 30 KJ Sparker and 3.5 kHz profiles). The data suggest that the present-day configuration of the Tunisian and Sardinian margins results, in large part, from the contact of the southern part of the Corsican-Sardinian microplate with North Africa.
Several dominant structural-stratigraphic trends are recognized in this study area: (1) NNW-SSE and NW-SE trends in the northwestern part of the study area are most likely related to the formation of the Algero-Balearic Basin since the late Oligocene. (2) Pronounced NNE-SSE trending structural axes (largely normal faults) are related to the near-parallel (N-S) tilted fault blocks in the Tyrrhenian Sea east of Sardinia. One of these tectonic structures on the margin east of Sardinia may possibly extend southward (190° - 200°) onto, and across, the Tunisian margin. The largest, most obvious physiographic features south of Sardinia, including seamounts, ridges, and canyons, are associated with these trends. These features, for the most part of middle to upper Miocene age, are believed closely related to the opening and subsidence of the Tyrrhenian Sea. (3) Morphological, structural, and stratigraphic-sedimentary trends, particularly off Tunisia, suggest Pliocene-Quaternary compression (E-W trending tectonics and depositional axes), resulting from the northward movement of Africa. (4) Important NW-SE structural-depositional trends (many extensional, some strike-slip) of Miocene to Quaternary age dominate the Strait of Sicily area east of Tunisia and south of Sicily. These may be related to displacement along the Calabrian-Sicilian Arc and to a collisional regime between the arc, the Corsican-Sardinian block, and African margin.
We believe that the present configuration of the two margins resulted from plate contact and welding during several major Miocene events and also from subsidence, first, of the Algero-Balearic Basin and, then, of the Tyrrhenian Sea. In theory, the Tunisian margin and adjacent land have been subjected to compression as a result of seafloor spreading and collision. The physiographic trends and subsurface structural-stratigraphic configuration we map, however, reveal a predominance of Neogene to Recent structures, primarily of extensional origin.|
|Description: ||Files listed include high and low resolution reproductions.|
|Appears in Collections:||Smithsonian Contributions to the Marine Sciences|
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