| Abstract: | Reviewing the ophiolites of the Alpine chain from the Western Mediterranean to the Indian Ocean, we subdivide them into ten groups of outcrops. The geological environment through time, the internal composition and history are given for each. Emphasis is put on the variegated and successive geodynamic processes which can be reconstructed for the different ophiolitic belts since their birth as an ocean-like crust to their incorporation through accretion to a continent.One can distinguish: low versus high tholeiitic partial melting; fairly or poorly established ridges; simple ridge-type crust versus complex ridge + ensimatic arc (and even more complex) type; long-lived versus short-lived oceanic crust stages; abrupt, large-scale, pure obduction versus progressive collision-related obduction or simple progressive juxtaposition to continent.The major events through time in the Tethyan ophiolitic belts can be listed as follows: spreading ridge activity during the Jurassic (Liguria, Dinaro-Hellenides, Lesser Caucasus) and the Cretaceous (Peri-Arabic, Nain Sabzewar) with a jump of ridge in between; repeated change from ridge to ensimatic arc (Dinaro-Hellenic, Lesser Caucasus, Peri-Arabic, ? West Indian) during the latest Jurassic and Cretaceous; Upper Cretaceous (+Tertiary) collision-related obductions (Pontic-Lesser Caucasus, Liguria) squeezing out the elevated portions of these basins; lack of oceanic magmatism during the Cenozoic but progressive accretion along accretionary wedges of the elevated portions of the remaining Mesozoic crust (Van, Naïn, Sabzewar, Zahedan, MeKran). |
