A Cenozoic Tectonic Model for Southeast Asia - Microplates and Basins

Kevin A. Maher

A computer-assisted Cenozoic tectonic model was built for Southeast Asia and used to construct 23 base maps 2 to 6 million years apart. This close temporal spacing was necessary to explain all the local geometric shifts in a consistent and geologically feasible fashion. More than a hundred individual blocks were required to adequately treat Cenozoic microplate processes at a basic level. The reconstructions show tectonic evolution to be characterized by long periods of gradual evolution, interrupted by brief, widespread episodes of reorganization in fundamental plate geometries and kinematics.

The model takes into account difficulties inherent in the region. First, the Pacific and Indo-Australian plates and predecessors have driven westward and northward since the late Paleozoic, towards each other and the relatively stationary backstop of Asia. Southeast Asia is therefore the result of a long-lived, complex process of convergent tectonics, compounding the difficulty of reconstructing tectonic development. This history of subduction and collision erased much of the continental margin and sea floor spreading record. In addition, convergent tectonic regimes are dominated by small-scale microplate processes with short time scales and internal deformation, taking place in rapidly evolving and more ductile buffer zones between the major rigid plate systems. These relatively ephe eral crustal blocks appear and die within the plate interaction zones, or accrete to and disperse from the margins of the major plate systems. Such microplate evolution is the dominant factor in Cenozoic basin evolution.

This detailed tectonic model aids in comprehension and prediction of basin development and hydrocarbon habitat.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995