Hotspot-ridge interaction in the Gulf of Aden, East Africa
Abstract
We have conducted a mapping and sampling cruise at the Gulf of Aden along its spreading axis by Aden New Century Cruise (R/V Hakuho-maru, Dec. 2000 - Jan. 2001). The mapping was done by SeaBeam 2120 with gravity and magnetics from 45.5 degree E to 50.5 degree E that occupies the main part of the Gulf of Aden. The obtained data shows the first and clear detailed bathymetry of the spreading system of the Gulf of Aden. The data were jointly analyzed with the bathymetric data at the Tadjoura Rift at the western end of the Gulf of Aden that was obtained by a French Tadjouraden cruise in 1995. The spreading system in the Gulf of Aden is characterized with an oblique and ultraslow spreading system (2.0 cm/y for full rate with N30E direction between Arabia and Africa plates). To the east from 46 deg 20 min E, the spreading system exhibits ridge-transform system with the lengths of each segment with 30 to 60 km. To the west from 46 deg 20 min East, E-W trending Tadjoura Rift is well developed with distinct en-echelon structures in the rift. In the easternmost part of Tadjoura Rift at 45 deg 35 min E we observed shallow peaked twin mountains (Aden New Century Mountains) along the central axis of the rift with the summit depth of 500m. We recovered fresh basaltic lavas from the mountain and the mountains are surrounded by many small volcanic knolls. Based on along-axis bottom rock sampling during the cruise with the compilation of Shilling et al. (1992) data, the Aden New Century Mountains zone shows highly positive anomaly of La/Sm REE anomaly suggesting deep mantle source and we temporarily calls the volcanic zone, the Aden New Century Hotspot. Along-axis profile of bathymetry and La/Sm REE anomaly displays typical pattern of hotspot-ridge interaction with the shallowing of each segment toward the hotspot as well as the increasing geochemical anomalies. Horizontal view of the ridge-transform pattern shows increasing distortion toward the hotspot. The case of hotspot-ridge interaction in the Gulf of Aden will provide valuable information to improve our understanding the dynamics of hotspot-ridge interaction.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.T31D..13T
- Keywords:
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- 3035 Midocean ridge processes;
- 8121 Dynamics;
- convection currents and mantle plumes;
- 9305 Africa;
- 9340 Indian Ocean