Abstract

Structural and stratigraphic relationships in the Oman Mountains developed by Late Cretaceous collision between the northern passive margin of the African continent and an island arc. Field relationships and metamorphic facies indicate that ophiolite obduction was accomplished by continental underthrusting of the fore-arc limb of an island-arc edifice at considerable depth. Uplift of the ophiolite slab resulted from both compressional shortening and isostatic interaction of the continental crust with the mantle rock it underthrust. This model may apply to many other major ophiolite areas of the world, specifically Newfoundland, Cuba, northern Venezuela, Cyprus, the Urals, eastern Celebes, New Guinea, and New Caledonia.

Events preceding the Mesozoic convergence of Africa and Eurasia and resultant Oman collision include late Paleozoic rifting in the present Turkey-Iran area, which produced a microcontinent comprising the Menderes and Kirsehir massifs of Turkey and the Rezaiyeh-Esfandagheh belt of Iran, separated from Eurasia by a northerly arm of the Tethys and from Africa by a southerly arm of the Tethys. Central Iran and central Afghanistan–southern Pamir–Karakorum are believed to have been a part of Gondwana positioned between Somalia and India. They too were affected by late Paleozoic rifting but did not reach their present position until early Tertiary time, driven north along with India by sea-floor spreading of anomaly 28 time and later.

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