| 摘 要： | The last twenty-five years of geological investigation of the Mediterranean region have disproved the traditional notion that the Alpine-Himalayan mountain ranges originated from the closure of a single, albeit complex,oceanic domain-the Tethys. Instead, the present-day geological configuration of the Mediterranean region is the result of the creation and ensuing consumption of two major oceanic basins-the Paleotethys and the Neotethys-and of additional smaller oceanic basins within an overall regime of prolonged interaction between the Eurasian and the African-Arabian plates.In greater detail, there is still some debate about exactly what Tethys existed at what time. A consensus exists as to the presence of (i) a mainly Paleozoic paleotethyan ocean north of the Cimmerian continent(s); (ii) a younger late Paleozoic-Mesozoic neotethyan ocean located south of this continent, and finally ; ( iii ) a middle Jurassic ocean, the Alpine Tethys-Valais, an extension of the central Atlantic ocean in the western Tethyan domain. Additional late Paleozoic to Mesozoic back-arc marginal basins along the active Eurasian margin com-plicated somewhat this simple picture. The closure of these heterogeneous oceanic domains produced a sys-tem of connected yet discrete orogenic belts which vary in terms of timing, tectonic setting and internal archi-tecture, and cannot be interpreted as the end product of a single “Alpine“ orogenic cycle.In Neogene time. following prolonged indentation along the Alpine front, a number of small continental microterranes (Kabylies, Balearic Islands, Sardinia-Cor-sica, Calabria) rifted off the Eurooean-lberian continan-tal margin and drifted toward south or southeast, leaving in their wake areas of thinned continental crust (e.g.Valencia Trough) or small oceanic basins (Algerian,Provencal and Tyrrhenian basins). The E Mediterranean is similarly characterized by widespread Neogene exten-sional tectonism, as indicated by thinning of continental crust along low-angle detachment faults in the Aegean Sea and the periaegean regions. Overall, Neogene exten-sion in the Mediterranean can be explained as the result of roll-back of the N-dipping subducting slab along the lonian-E Mediterranean subduction zones. The complex Neogene geologic scenario of the Mediterranean is com-plicated further by the deposition of widespread evapor-ites during Messinian (late Miocene) time.
|
