Variations Around Sunda Arc

Joseph R. Curray

The Sunda Arc, which extends from the eastern Himalayan syntaxis to the Banda Arc, is the zone where the Indian-Australian or Indian and Australian plates are being subducted beneath the Eurasian, China, or Southeast Asian plate and one or more smaller secondary plates. We have studied the forearc region between Burma and Bali, both in broad reconnaissance and locally in more detail along segments of the SEATAR transects. Major variations occur around this arc, principally as a function of two variables: direction and speed of convergence across the subduction zone, and thickness of sediment on the underthrusting plate. These variables are manifested in many important variations in character of the fore-arc region, including morphology of the trench, morphology and volume of the accretionary prism/outer arc ridge, style and intensity of deformation within the accretionary prism, and tectonics of the edge of the over-thrusting plate. The latter includes terrain transport and the opening and closing of marginal basins like the modern Andaman Sea.

Understanding these variations and their apparent causes is important for the interpretation of other arcs, regions of terrane accretion, and obducted ophiolites, both extant and preserved as remnants in mountain ranges.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.