The anomalous high transverse ridge developed along transform faults
Speaker: Yen-Fu Chen
Abstract
The main morphological feature of transform fault boundary is a narrow and elongated valley that bounded by an uplifted ridge. It is caused by differential subsidence and lateral heat flow across the transform fault. According to Nakanishi (1993), there are several ridges in the Central Pacific fracture zone, and the maximum height of ridge is 1 km. However, anomalous topographic highs are found along many large transform faults. For example, Gagua Ridge is 4 km high in the east of Taiwan and Puysegur Ridge is 3-5 km high in the south of New Zealand. Multi-beam bathymetric and geophysical data reveal influence by strike-slip deformation along the summit of two ridges. Nevertheless, the Puysegur Ridge is flanked to the west by a trench, so we suggest it formed by oblique compressive stress. We conclude that the formation of Gagua Ridge occurred 41 to 44 m.y. ago from flexural modeling. The event could be contemporaneous with a change of spreading direction which occurred about 45 m.y. ago on the West Philippine Basin and it may indicate that Gagua Ridge also formed by oblique compressive stress.
Reference
Anne E. Deschamps, Serge E. Lallemand, and Jean-Yves Collot, 1998. A detailed study of the Gagua Ridge : A fracture zone uplifted during a plate reorganisation in the Mid-Eocene. Marine Geophysical Researches 20, 403-423.
Jean-Yves Collot, Geoffroy Lamarche, Ray A. Wood, Jean Delteil, Marc Sosson, Jean-Frederic Lebrun, Mike F. Coffin, 1995. Morphostructure of an incipient subduction zone along a transform plate boundary: Puysegur Ridge and Trench. Geology 23 (6), 519-522.