MORPHOLOGICAL-STUDIES OF THE AYU TROUGH, PHILIPPINE-SEA CAROLINE PLATE BOUNDARY

Citation
T. Fujiwara et al., MORPHOLOGICAL-STUDIES OF THE AYU TROUGH, PHILIPPINE-SEA CAROLINE PLATE BOUNDARY, Geophysical research letters, 22(2), 1995, pp. 109-112
Citations number
16
Categorie Soggetti
Geosciences, Interdisciplinary
ISSN journal
00948276
Volume
22
Issue
2
Year of publication
1995
Pages
109 - 112
Database
ISI
SICI code
0094-8276(1995)22:2<109:MOTATP>2.0.ZU;2-W
Abstract
The Ayu Trough lies on the southern boundary between the Philippine Se a Plate and Caroline Plate. Although this trough may be the best place to study the evolution and kinematics of the Philippine Sea Plate, th e origin and evolution of this trough are poorly understood. Our geoph ysical and morphological surveys in the northern part of the Ayu Troug h revealed that the trough shares morphological similarities with slow -spreading mid-ocean ridges. The seafloor ages and an average spreadin g rate of the trough were inferred from the average length of the ridg e segments, distribution of sediment thickness, and basement subsidenc e. Based on the seismic section at 3 degrees 30'N, the opening of the trough started about 25 Ma with an average half-spreading rate 4.1 mm/ yr. This spreading rate is much slower than some previous estimates. T he present magma production rate and activity of the trough is estimat ed to be even lower than the 25 m.y. average. The seafloor depth of th e trough axis and relief of the axial valley are approximately twice a s deep as that of active mid-ocean ridges. The trough axis valley is c overed with sediment in contrast with the axial valleys of active mid- ocean ridges. Sedimentation at the trough axis shows that the spreadin g rate has been quite slow for the last 2.5 Ma.