Murray Ridge System
Report of the project:
Seismic image (profile SO-122-18) showing the downfaulted continental crust of the Dalrymple Trough.
Source: BGR
The NE-SW trending Murray Ridge System in the northern Arabian Sea extends about 750 km. The Murray Ridge System is divided into basins and ridges. The Murray Ridge System separates the Indian and Arabian Plates, and the Indian and Eurasian Plates, respectively.
Seismic image (profile SO-122-23) across the eastern Murray Ridge slope.
Source: BGR
The Murray Ridge System is interpreted as a transform margin of the Indian Plate, that is active since Upper Cretaceous. Stages of transpression and transtension caused negative and positive flower structures, and the development of the NE-SW trending Dalrymple Trough where more than 8 km of clastic sediments have been accumulated in the Neogene (Bild 1). The rifted continental basement is covered by volcano-sedimentary sequences (Bild 2). Magnetic modeling based on rock samples and on structural interpretation of seismic profiles gives evidence for two magmatic events. The Paleocene volcanism is correlated with a sequence of seaward (northward) dipping reflectors along the northern Murray Ridge, where Paleocene basalts of the rift phase were drilled off Karachi. In the east the basalts and the underlying continental basement of the Murray Ridge System became buried under the thrusted Eurasian Plate near the triple junction. It is concluded that this part of the Makran subduction zone is governed by continent-continent collision (Indian with Eurasian Plates), while to the west oceanic crust of the Arabian Plate is subducted below the continental Eurasian Plate. NE-SW trending transfer faults cross the Murray Ridge System and presumably extend to the Makran Accretionary Wedge. At intersections of these faults with ENE-WSW trending extensional faults of the Murray Ridge System a sub-recent volcanism created seamounts on the ocean floor.
Literature:
- Gaedicke, C., Schlüter, H.-U., Roeser, H., Prexl, A., Schreckenberger, B., Reichert, C., Clift, P. & Amjad, S. (2002): Origin of the northern Indus Fan and Murray Ridge, Northern Arabian Sea: interpretation from seismic and magnetic imaging. Former title: Structure and Origin of the crust below the northern Indus Fan and Murray Ridge System, northern Arabian Sea. Tectonophysics, 355, 127-143.