New gravity and magnetic anomaly maps in the Taiwan-Luzon region and their preliminary interpretation
| Type | Article | ||||||||
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| Date | 1998-09 | ||||||||
| Language | English | ||||||||
| Author(s) | Hsu Shu-Kun1, Liu Char-Shine2, Shyu Chuen-Tien2, Liu Shao-Yung2, Sibuet Jean-Claude3, Lallemand Serge4, Wang Chensung5, Reed Donald6 | ||||||||
| Affiliation(s) | 1 : Natl Cent Univ, Inst Geophys, Chungli 32054, Taiwan. 2 : Natl Taiwan Univ, Inst Oceanog, Taipei 10764, Taiwan. 3 : IFREMER, Ctr Brest, F-29280 Plouzane, France. 4 : Univ Montpellier 2, Lab Geophys & Tecton, UMR 5573, F-34095 Montpellier 5, France. 5 : Natl Taiwan Ocean Univ, Inst Appl Geophys, Keelung, Taiwan. 6 : San Jose State Univ, Dept Geol, San Jose, CA 95192 USA. |
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| Source | Terrestrial Atmospheric And Oceanic Sciences (1017-0839) (Chinese Geoscience Union), 1998-09 , Vol. 9 , N. 3 , P. 509-532 | ||||||||
| DOI | 10.3319/TAO.1998.9.3.509(TAICRUST) | ||||||||
| WOS© Times Cited | 94 | ||||||||
| Keyword(s) | free-air gravity anomaly, Bouguer anomaly, magnetic anomaly, transverse ridge, fracture zone, transform fault, Taiwan | ||||||||
| Abstract | We have compiled new free-air gravity anomaly (FAA) and magnetic anomaly maps, shedding light on the tectonics in the Taiwan-Luzon region. To have a suitable datum level for both the available gravity and magnetic anomaly data, the set of data from an ACT cruise, conducted during May 27 to June 21, 1996, was chosen as a reference. Based on the cross-over error analysis, all the other data were adjusted accordingly. Some satellite-derived, airborne or land data were also added to the compilation to obtain better coverage. Several major new insights into the Taiwan-Luzon region are revealed by the new maps. (1) A prominent NE-SW trending belt of gravity and magnetic anomalies is present in the onshore and offshore areas of southwestern Taiwan. The Peikang High is located on this belt. (2) Located in the offshore region west of Taiwan and to the north of the belt described above, the Taishi Basin, in contrast, occupies a relatively low FAA area. It could be regarded as a flexural basin on account of the loading of a thrust-and-fold belt in western Taiwan. (3) A probable NW-SE trending old transform fault is well imaged off southwestern Taiwan, which separates the lithosphere (plate) of the South China Sea from a trapped piece of the Philippine Sea plate. (4) Located east of the Luzon Are, the Huatung Basin contains several E-W trending magnetic reversals and two N-S trending old fracture zones. The Huatung Basin is separated from the West Philippine Basin by the "123E Fracture Zone". Accordingly, the Gagua Ridge corresponds to a transverse ridge bounding the 123E Fracture Zone. (5) The Luzon Are is abnormally concave toward the Manila Trench and becomes wider toward the south. The internal deformation of the Luzon Are in terms of several NE-SW discontinuities could be related to its collision with eastern Taiwan, (6) Three previously proposed NW-SE trending strike-slip faults in the southern Okinawa Trough, west of 123.5 degrees E, are well imaged on both the FAA and magnetic anomaly maps. Post-collisional volcanism off northeastern Taiwan occurs along these NW-SE trending faults. |
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