LEE, TUNG-YI¹, CHING-HUA LO², SUN-LIN CHUNG², CHING-YING LAN³, PEI-LING WANG³, and JIAN-CHENG LEE^3
1Dept. Earth Sciences, National Taiwan Normal Univ., Taipei, Taiwan
²Dept. of Geology, National Taiwan Univ., Taipei, Taiwan
³Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan

Abstract: Tectonics of the South China Continental Margin and the Opening of South China Sea

Based on detailed plate reconstruction in South China Sea region, two continuous belts of structural highs extending from Taiwan all the way to southern Vietnam offshore can be reestablished along the South China continental margin. The inner belt consists of Con Son swell, Dongsha massif, and the Central High in Tainan Basin. The outer belt consists of Natuna high, Paracel Islands, Maclesfield Bank, Reed Bank, northern part of Palawan and Mindoro, and possibly the Tananao belt of Taiwan. The basement granites in these belts have similar chemical composition and comparable radiometric ages which may indicate that they were generated under the same tectonic setting during the Cretaceous time.

The eNd and REE data from the late Cretaceous to Paleogene basalts indicate that during the beginning of Tertiary, this area was highly attenuated. The two structural belts located on the outermost part of the stretched South China continental margin. Later on, at about 30 Ma, first identifiable marine magnetic anomaly (A11) appeared between the eastern part of these two structural highs and the spreading propagated to the southwest. However, due to the extrusion of Indochina around 28 Ma, the sea-floor spreading of the newly formed South China Sea was largely confined to the eastern part of the margin.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas