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Abstract: Structure and Stratigraphy of South Pengchiahsu Basin, Northern Offshore Taiwan

Ta-Tsun Chen, Joel S. Watkins

The South Pengchiahsu Basin is a rifted marginal basin of the continental shelf of the East China Sea. The initial phase of basin extension occurred in the late Paleocene. Cross sections of the basin show a series of mainly asymmetrical half grabens. The basin is characterized by opposing, partly overlapping, half-graben systems linked by an interference accommodation zone in the form of a local structural high. There are three major half grabens. One is related to the main phase of extension, and the others are due to local normal faulting. The basin underwent two stages of reactivated thrust tectonic events in the middle Miocene and the late Pliocene.

A widespread angular unconformity separates synrift and postrift sequences. Fan-delta deposits in semiclosed lakes characterize the late Paleocene rift phase. A major rift phase with rising sea level and subsidence in the early Eocene was accompanied by deep-water deposition. Lowstand prograding complex-fan delta

systems were deposited in the basin with falling sea level at the beginning of the middle Eocene. Deposition of late Eocene to early Oligocene (?) deltaic sediments marks the final stage of the synrift basin.

AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994