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    Crustal structure of active deformation zones in Africa: Implications for global crustal processes

    Ebinger, C.J. and Keir, D. and Bastow, I.D. and Whaler, K. and Hammond, James O.S. and Ayele, A. and Miller, M.S. and Tiberi, C. and Hautot, S. (2017) Crustal structure of active deformation zones in Africa: Implications for global crustal processes. Tectonics 36 (12), pp. 3298-3332. ISSN 0278-7407.

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    Abstract

    The Cenozoic East African rift (EAR), Cameroon Volcanic Line (CVL), and Atlas Mountains formed on the slow-moving African continent, which last experienced orogeny during the Pan-African. We synthesize primarily geophysical data to evaluate the role of magmatism in shaping Africa's crust. In young magmatic rift zones, melt and volatiles migrate from the asthenosphere to gas-rich magma reservoirs at the Moho, altering crustal composition and reducing strength. Within the southernmost Eastern rift, the crust comprises ~20% new magmatic material ponded in the lower crust sills, and intruded as sills and dikes at shallower depths. In the Main Ethiopian rift, intrusions comprise 30% of the crust below axial zones of dike-dominated extension. In the incipient rupture zones of the Afar rift, magma intrusions fed from crustal magma chambers beneath segment centers create new columns of mafic crust, as along slow-spreading ridges. Our comparisons suggest that transitional crust, including seaward-dipping sequences, is created as progressively smaller screens of continental crust are heated and weakened by magma intrusion into 15-20 km-thick crust. In the 30Ma-Recent CVL, which lacks a hotspot age-progression, extensional forces are small, inhibiting the creation and rise of magma into the crust. In the Atlas orogen, localized magmatism follows the strike of the Atlas Mountains from the Canary Islands hotspot towards the Alboran Sea. CVL and Atlas magmatism has had minimal impact on crustal structure. Our syntheses show that magma and volatiles are migrating from the asthenosphere through the plates, modifying rheology and contributing significantly to global carbon and water fluxes.

    Metadata

    Item Type: Article
    Additional Information: This is the peer reviewed version of the article, which has been published in final form at the link above. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences > UCL/Birkbeck Centre for Planetary Sciences
    Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: James Hammond
    Date Deposited: 23 Nov 2017 08:15
    Last Modified: 13 Mar 2018 11:40
    URI: http://eprints.bbk.ac.uk/id/eprint/20360

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