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The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract


Volume: 58 (1974)

Issue: 7. (July)

First Page: 1451

Last Page: 1452

Title: Structural Evolution of Tertiary Basins of Southeast Asia: ABSTRACT

Author(s): R. W. Murphy

Article Type: Meeting abstract

Abstract:

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Tertiary to recent basins of four main types underlie 75% of Southeast Asia's 10 million sq km. Structural style is related to: (1) basement composition; (2) petrotectonic assemblages involved; (3) relative balance between extensional, compressional, and transcurrent forces; (4) availability of preexisting fabric; (5) susceptibility to impact of changes in plate motions; and (6) sedimentary diapirism developed in overpressured clastic wedges.

Shelfal basins have continental crust on all flanks. Examples are north, central, and south Burma, central and south Sumatra, Gulf of Thailand, Sunda, west and east Java, Billiton, and Barito. Plate-margin activity is not obviously reflected in shelfal basins but may exert fundamental influence. Shelfal basins develop basement-controlled tectonic patterns except where sedimentary diapirism overprints flowage structures at shallow levels in deep-basin areas.

Continental-margin basins have continental crust on one flank and oceanic on the other. Examples include the Gulf of Martaban, Sunda outer-arc basins, Mekong, Brunei, and East Kalimantan basins. These basins mirror principal movement changes in adjacent plates, enabling fairly satisfactory tying of internal unconformities to changes in spreading direction and rate. The 10-m.y. and 26-m.y. events are particularly widespread. Outer-arc basins (continental-margin basins associated with island arcs) filled mainly by volcanosedimentary input from andesitic inner volcanic arcs and also by subduction accretion from buoyant inner trench wall wedges with fan-shaped internal structure. Structural style results from interplay of compressional and transcurrent movements.

Archipelagic island-arc basins are intraoceanic arc-basin complexes. Philippine examples include the Cagayan Valley, the Central Luzon trough, Agusan-Davao, and Cotabato. They form between intricate subparallel arc-trench systems with strong vertical mobility and relatively stable map-view configuration. Structural style is exceedingly complex.

Small ocean basins form by interarc spreading or by trapping of older oceanic crust behind newly risen intraoceanic island arcs. Examples include the Andaman Sea, South China Sea, Southeast Sulu Sea, Celebes Sea, and Banda Sea.

Transitional types of basins are known and some basins change category during evolution.

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