ANALOGOUS TECTONIC EVOLUTION OF THE TETHYAN AND SE ASIAN REGIONS*

Abstract

The study of tectonic evolution of the Tethyan and SE Asian regions indicates that these tworegions have each passed through southwardly progressing sequences of similar tectonic events. Both regionshave experienced a southward island-arc subduction and back-arc spreading leading to continentaldetachment from Gondwanaland, with an earlier southward island arc subduction of Palaeotethys (Tethyannorthern ocean), and continental detachment (Early Devonian) which produced the Neo-Tethys Ocean and theland masses of the Tethyan region, compared with a later southward island arc subduction of Tethys II, andcontinental detachment (Permo-Triassic) which produced Tethys III, and the land masses of the SE Asianregion. The northward subduction of Neo-Tethys (Tethyan southern ocean) and formation of the AlpineOrogeny (Late Paleocene-Pliocene) in the Tethyan region was accompanied by the opening of the Red Sea to the south of the Arabian Gondwanaland. Similarly, the northward subduction of Tethys III (SE Asiansouthern ocean) (Late Oligocene-Present), and arc-continent collision in the SE Asian region wasaccompanied by the opening of the Southern Ocean to the south of the Australian Gondwanaland. In bothregions, the younger oceans are formed sequentially southward. The later occurrence of the southwardprogressing sequence of tectonic events in the SE Asian region compared with the similar sequence oftectonic events in the Tethyan region indicates an eastward global migration of tectonic events.