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The extent of continental crust beneath the Seychelles
- Source :
- Earth and Planetary Science Letters. :166-176
- Publisher :
- The Authors. Published by Elsevier B.V.
-
Abstract
- The granitic islands of the Seychelles Plateau have long been recognised to overlie continental crust, isolated from Madagascar and India during the formation of the Indian Ocean. However, to date the extent of continental crust beneath the Seychelles region remains unknown. This is particularly true beneath the Mascarene Basin between the Seychelles Plateau and Madagascar and beneath the Amirante Arc. Constraining the size and shape of the Seychelles continental fragment is needed for accurate plate reconstructions of the breakup of Gondwana and has implications for the processes of continental breakup in general. Here we present new estimates of crustal thickness and V P / V S from H–κ stacking of receiver functions from a year long deployment of seismic stations across the Seychelles covering the topographic plateau, the Amirante Ridge and the northern Mascarene Basin. These results, combined with gravity modelling of historical ship track data, confirm that continental crust is present beneath the Seychelles Plateau. This is ∼ 30 – 33 km thick, but with a relatively high velocity lower crustal layer. This layer thins southwards from ∼ 10 km to ∼ 1 km over a distance of ∼ 50 km , which is consistent with the Seychelles being at the edge of the Deccan plume prior to its separation from India. In contrast, the majority of the Seychelles Islands away from the topographic plateau show no direct evidence for continental crust. The exception to this is the island of Desroche on the northern Amirante Ridge, where thicker low density crust, consistent with a block of continental material is present. We suggest that the northern Amirantes are likely continental in nature and that small fragments of continental material are a common feature of plume affected continental breakup.
- Subjects :
- geography
geography.geographical_feature_category
Plateau
Continental crust
Crust
microcontinent
Continental fragment
Plume
gravity
crustal structure
Paleontology
Gondwana
Geophysics
Oceanography
Continental margin
Space and Planetary Science
Geochemistry and Petrology
Ridge
receiver functions
Earth and Planetary Sciences (miscellaneous)
Geology
Subjects
Details
- Language :
- English
- ISSN :
- 0012821X
- Database :
- OpenAIRE
- Journal :
- Earth and Planetary Science Letters
- Accession number :
- edsair.doi.dedup.....6aaa0044090c18b5a952d907ea7d1f66
- Full Text :
- https://doi.org/10.1016/j.epsl.2013.08.023