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Cruise Info
| Cruise ID | MV1203 |
| Vessel | R/V MELVILLE |
| Title | Plate Tectonic and Geochemical Evolution of The Young Walvis Ridge And Implications for African Plate Motion Modeling |
| Abstract | Plate Tectonic and Geochemical Evolution of The Young Walvis Ridge And Implications for African Plate Motion Modeling: We propose that the transformation of the Walvis Ridge from an unambiguous “primary” hotspot track to diffuse volcanism is inconsistent with the classical narrow plume tail model and requires renewed scrutiny by detailed sampling and collecting a range of state-of-the-art geochronological, geochemical and geophysical data. This allows us to address the following key questions: •What is the detailed age progression of the young end of the Walvis Ridge? •Is diffuse volcanism in the young Walvis Ridge related to local extension, fracturing of the oceanic crust, or proximity to the Mid-Atlantic Ridge spreading center? •Has the hotspot been geochemically zoned over all its history? •Where is the current location of the Walvis Ridge hotspot? •Is the Walvis Ridge hotspot failing or dying? •What are the consequences of the answers to the above questions for hotspot fixity in the Atlantic, the Euler pole model for the African Plate, and global tectonic modeling? To address these questions, we propose a seagoing expedition to study the young Walvis Ridge through mapping and dredging of 40 seamounts. Geochronological and geochemical data will be acquired from recovered rocks and complemented by geophysical data to resolve the local plate tectonic history and distances of the seamounts from the Mid-Atlantic Ridge (MAR) at the time of their formation. This integrated study will provide a much better understanding of time-space-chemistry relationships between the sub-tracks, their relation to structures in the underlying oceanic crust and the local plate tectonic setting, and the geochemical evolution of the overall Walvis Ridge. Combined with a German cruise (see below) to the older part of the Walvis Ridge, our new 40Ar/39Ar dates will form the basis for a revision of global plate motion models with implications for true polar wander, mantle convectional domains, and the mantle plume model, whereas the geochemistry provides unique insights into a long-lived mantle feature changing from a LIP into a robust seamount trail and ending with extremely diminished and diffuse volcanism. |
| Starting Port | Cape Town, South Africa |
| Ending Port | Cape Town, South Africa |
| Starting Date | 2012-02-11 |
| Ending Date | 2012-03-30 |
| Principal Investigator | Koppers, Anthony |