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ABSTRACT: The Tertiary Tectonics of the Southeast Asia

Eiichi Honza

Most of the terranes in eastern Asia appear to be relics of arcs, oceanic islands, and subduction complexes. They have collided and accreted from the inner (northwestern) side in China since the Silurian. They are characterized by three stages of Pacific and Tethys evolution. The first collision is related to the Pacific domain in the Permian in which these movements are not clearly reconstructed. The second collision is related to the closure of the Paleo-Tethys in the Late Triassic to Early Jurassic. The third is related to closure of the Neo-Tethys and the subsequent collision of India in the Tertiary.

Southeast Asia is in one of the most enigmatic plate boundaries in the world, forming many small plates, collisions, and consumptions. This complication is also suggested to be a result of the northward movement of Australia since its break-up from Gondwanaland in the Cretaceous. During their evolution, most of them have associated with arcs. These arcs also have formed superimpositions on the older exotic blocks of terranes.

They are reconstructed on the base of the regular duration on the formation of arcs and backarc basins, which can be seen in the Western Pacific Arc Chain.

AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990