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Seismic Stratigraphy, Subsidence History, and Tectonic Evolution of the Alboran Sea, Western Mediterranean

WATTS, A. B., University of Oxford, Oxford, United Kingdom, J. I. C. DOHERTY and E. BANDA, Institute of Earth Sciences, Barcelona, Spain, and J. PLATT, University of Oxford, Oxford, United Kingdom

Seismic reflection profile, gravity and geoid data, and well data have been used to examine the tectonic evolution of the Alboran Sea, a small basin in the western Mediterranean. Previous seismic refraction data suggest that the basin is underlain by stretched continental crust which thins from about 40 km beneath Iberia and Morocco to as much as 15 km in the basin center. According to commercial well data, the earliest sediments are lower Burdigalian, suggesting that extension was initiated during the early Miocene. The thinning is part of a sidespread extensional event that appears to have modified the crustal structure in the Balearic, Algerian, and Valencia Trough basins to the east. In the case of the Alboran Sea basin, however, the extent to which extensional processes account f r the crustal structure is obscured by the competing effects of compression due, for example, to thrust/fold loading in the flanking Betic and Rif cordillera. Seismic reflection profiles, for example, show tilted fault blocks infilled by more than 5 km of sediments as well as olistostromes fronts and inversion structures. Backstripping of commercial wells in the Iberian margin reveals an exponentially decreasing subsidence that is similar in form to that of many rift-type basins. However, DSDP Site 121, located on a basement high in the basin center, shows an accelerating subsidence that is more typical of foreland-type basins. Recent studies in the Valencia Trough, show that the relative role of extensional and compressional processes can be estimated through an integrated approach of f exural backstripping, crustal restoration, and gravity and geoid modeling along selected "transects" of a basin. Our paper presents the results of such an approach to the Alboran Sea and evaluates its implications for current models for the tectonic evolution of the basin.


AAPG Search and Discovery Article #91007© 1991 AAPG International Conference, London, England, September 29-October 2, 1991 (2009)