The closing of the Tethys Ocean and continent-continent collision along the Alpine-Himalayan chain ultimately produced large Himalayan-type mountain belts and large plateaux, such as Tibet. Earlier stages in the collision process, however, can be seen in the Oman Mountains of eastern Arabia and the Zagros Mountains of SW Iran. In Oman, a large, intact ophiolite was emplaced onto a Mesozoic passive continental margin, largely by thin-skinned thrust processes, prior to continental collision. The ophiolite and a granulite-amphibolite-greenschist facies inverted metamorphic sole were formed in a subduction zone setting during the early stages of emplacement. Eclogites were formed by the attempted subduction of the continental margin, and its rapid expulsion back up the same subduction zone, during later stages of the orogeny. The early stages of continental collision are best seen in the Zagros Mountains where thick-skinned thrusting and simple folding has resulted in a relatively small amount of crustal shortening (50–70 km) with almost no metamorphic or magmatic consequences. Burial metamorphism may be occurring presently at deep levels of the internal zone and the Turkish-Iranian Plateau where the crust is thicker, but this remains unexposed at the surface. The collision of the Indian plate with Asia since ca. 50 Ma resulted in formation of the Himalaya along the north margin of India, and the Karakoram–Hindu Kush Mountains along the south Asian margin. Together with renewed uplift and crustal thickening of the Tibetan Plateau, this was arguably the largest continental collision in the last 450 m.y. of Earth history. The Himalayan-type orogeny involved large amounts of crustal shortening (∼500–1000 km), early ultrahigh-pressure (UHP) coesite-eclogite facies metamorphism, peak Barrovian facies kyanite and sillimanite metamorphism, and mid-crustal anatexis resulting in garnet, tourmaline, muscovite-bearing migmatites, and leucogranites. Processes involved in the construction of the Tibetan Plateau include crustal shortening and doubling the thickness of the crust to 65–90 km. High-pressure (HP) eclogite and high-temperature/high-pressure (HT-HP) granulite metamorphism may be occurring at depth today in the lower crust beneath Tibet. Widespread ultrapotassic volcanism across Tibet indicates the presence of a hot subcontinental mantle, which was progressively shifted northwards as the cold, Indian lithosphere underthrust southern Tibet. Whereas Tibet shows mainly upper crustal sedimentary and volcanic rocks at the present surface, the Karakoram Range, along strike to the west, shows mostly deep crustal high-grade metamorphic rocks, multiple granite intrusions, and over 60 m.y. of high-temperature metamorphism. This paper reviews the salient geological features of Oman-, Zagros-, Himalayan-, Tibetan-, and Karakoram-type orogenic belts. These features can be used in studies of older orogenic belts to give indications of their tectonic origins.

The late Mesozoic–early Tertiary evolution of the Mediterranean region was defined by a series of collisions between Gondwana-derived continental blocks and Eurasia as the intervening ocean basins closed. The late Tertiary–Quaternary evolution of the region was controlled by the generally northward motion of Afro-Arabia and the compressional tectonics induced by the convergence between Eurasia and Afro-Arabia. Earlier collisional events caused the formation of thick orogenic crust, high-standing plateaus, and heterogeneous mantle, and resulted in slab break-offs that were collectively crucial for the onset of postcollisional collapse of the mountain belts, tectonic extension, and magmatism. The diachronous collision of Adria (Apulia), as an appendage of Africa, with Europe along its irregular margins created the Alps, the Apennines, and the Dinaride-Albanide-Hellenide mountain belt at different times and affected the formation of the Carpathians in the east. The collision of theArabian promontory with Eurasia ca. 13 Ma facilitated the westward tectonic escape of Anatolia and caused intense deformation taken up by crustal shortening and conjugate strike-slip fault systems in a zone of ∼1000 km stretching from the Bitlis-Zagros suture zone in the south to the Greater Caucasus in the north. The Anatolia plate has been rotating counterclockwise relative to Eurasia during its escape to the west and hence has been experiencing internal deformation through a combination of strike-slip and normal faulting, including metamorphic core complex formation. Subduction roll-back along the Hellenic trench has likely been the driving force for this southwest motion of Anatolia and the extensional tectonics affecting the Aegean province in the upper plate throughout the late Tertiary. The widespread alkaline volcanism both in the Aegean extensional province and in the Turkish-Iranian plateau since the late Miocene shows chemical evidence for an enriched asthenospheric mantle melt source; in both regions postcollisional slab break-off events have played a major role in providing this asthenospheric material and weakening the orogenic crust significantly. Young basins (Tyrrhenian, Aegean?) are in the process of opening above strongly arcuate subduction zones in a broadly convergent system of the Mediterranean region. The mantle response to the discrete collisional events, the geometry of colliding continental margins, and the scale of collisions strongly controlled the syn- to postcollisional tectonics and magmatism in the Mediterranean region.