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ABSTRACT: The Gravity Field in Taiwan Strait

Su Da-Quan, Chen Xue, Liu Zu-Hui

Gravity surveys have been carried out in the western part of Taiwan Strait by South China Sea Institute of Oceanology, Academia Sinica, from 1986 to 1989. More than 3000 km of gravity profile data have been collected. The accuracy of the gravity is about ±2.5 mGal.

Based on these data, gravity maps of Taiwan Strait (1:2,000,000) have been compiled, combined with the data from University of Tokyo, Lamont-Doheny geological observatory, and the USSR, which were collected from the east and southeast parts of Taiwan Strait. The interval of contour is 5 mGal. These maps cover part of East China Sea and South China Sea, where good gravity data have been gathered. Comparing the data from different sources in the same area, we think they are in very good agreement. These maps for the first time give detailed gravity information in the Taiwan Strait. It is very useful for the tectonic study and oil exploration in this area.

The relationship between gravity anomalies and sedimentary basins has been studied in this area. Most of data show that the gravity low corresponds to the basin area and the gravity high is related to tectonic structure high. Xia-Peng depression, Wuqiuy depression, and Xinzhu depression, etc., show the gravity low. The relationship also can be seen in the gravity profiles clearly.

The general tendency of gravity in the Taiwan Strait is that the gravity values gradually increase from the south part to the north part. It can be probably explained by deep geological structures.

The relationship between gravity and geological structure units is also studied. We think the undulation of gravity anomalies is closely related to tectonic structures. Some main faults can be confirmed by the gravity maps.

AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990