Curtin University Homepage
  • Library
  • Help
    • Admin

    espace - Curtin’s institutional repository

    JavaScript is disabled for your browser. Some features of this site may not work without it.
    View Item 
    • espace Home
    • espace
    • Curtin Research Publications
    • View Item
    • espace Home
    • espace
    • Curtin Research Publications
    • View Item

    Plume-Lithosphere Interaction during Migration of Cretaceous Alkaline Magmatism in SW Portugal: Evidence from U-Pb Ages and Pb-Sr-Hf Isotopes

    152929_152929.pdf (667.0Kb)
    Access Status
    Open access
    Authors
    Grange, Marion
    Scharer, U.
    Merle, R.
    Girardeau, J.
    Cornen, G.
    Date
    2010
    Type
    Journal Article
    
    Metadata
    Show full item record
    Citation
    Grange, M. and Scharer, U. and Merle, R. and Girardeau, J. and Cornen, G. 2010. Plume-Lithosphere Interaction during Migration of Cretaceous Alkaline Magmatism in SW Portugal: Evidence from U-Pb Ages and Pb-Sr-Hf Isotopes. Journal of Petrology. 51 (5): pp. 1143-1170.
    Source Title
    Journal of Petrology
    DOI
    10.1093/petrology/egq018
    ISSN
    00223530
    School
    Department of Applied Geology
    Remarks

    This is a pre-copy-editing, author-produced PDF of an article accepted for publication in the Journal of Petrology following peer review. The definitive publisher-authenticated version [Grange, M. and Scharer, U. and Merle, R. and Girardeau, J. and Cornen, G. 2010. Plume-Lithosphere Interaction during Migration of Cretaceous Alkaline Magmatism in SW Portugal: Evidence from U-Pb Ages and Pb-Sr-Hf Isotopes. Journal of Petrology. 51 (5): pp. 1143-1170.] is available online at: http://dx.doi.org/10.1093/petrology/egq018

    URI
    http://hdl.handle.net/20.500.11937/32781
    Collection
    • Curtin Research Publications
    Abstract

    Large massifs of alkaline rocks are exposed along ∼250 km of the Atlantic coast of Portugal. Their origin is still poorly understood, including the precise timing of their emplacement and their relationships with the well-constrained alkaline magmatic rocks that occur 200–1000 km offshore. To elucidate the precise timing and origin of the alkaline magmatism in this region, magmatic rocks from the three major alkaline massifs (Sintra, Sines, and Monchique) and an isolated diorite intrusion (Ribamar, north of Sintra) have been dated by the U–Pb method on titanite and zircon and characterized based on their Pb, Sr, and Hf isotopic compositions obtained on feldspar and zircon. From north to south, the resulting ages are: 88·3 ± 0·5 Ma (95% confidence level) for Ribamar, 83·4 ± 0·7, 82·0 ± 0·7, 81·7 ± 0·4, and 80·1 ± 1·0 Ma for the Sintra complex, 77·2 ± 0·6, 77·2 ± 0·4, and 76·1 ± 1·3 Ma for the Sines massif, and 70·0 ± 2·9 and 68·8 ± 1·0 Ma for the Monchique complex.Initial isotopic compositions of Pb in feldspars are in the range of 18·522–19·299 for 206Pb/204Pb, 15·555–16·007 for 207Pb/204Pb, and 38·480–39·330 for 208Pb/204Pb. Initial 87Sr/86Sr of feldspars varies between 0·70274 and 0·70481 and initial Hf isotope ratios yield εHfi values between +3·7 and +9·6. These results, together with major, trace, and rare earth element analyses, show that the ages, (207Pb/204Pb)i, and (87Sr/86Sr)i increase northward, whereas the alkaline affinity, (206Pb/204Pb)i, and εHfi increase southward, substantiating a north–south trend of geochemical and age variation. The isotopic composition of the studied rocks can be explained by partial melting of a sub-lithospheric mantle source with an enriched DMM (Depleted MORB Mantle) signature and subsequent contamination by the metasomatized Iberian subcontinental lithospheric mantle (SCLM). The north–south age trend is in agreement with the motion of the Iberian plate between 88 and 60 Ma.The spatial and temporal variations in the isotopic signatures are explained by differences in the contribution of the two source components. The sub-lithospheric mantle-derived magmas are more contaminated by the SCLM in the northern part of the alignment, compared with the southern part of the studied region, where the rocks have isotopic signatures closer to those of enriched sub-lithospheric mantle. Our data are incorporated into a geodynamical model that explains the overall distribution of alkaline magmatism in this part of the eastern Central Atlantic, and provide new constraints on the occurrence of alkaline magmatism along the Iberian margin and the NW African plate. The spatial distribution of the magmatism is directly correlated with the motion of the Iberian plate above a deep-rooted thermal anomaly (mantle plume) that has caused magmatism since the Cretaceous.

    Related items

    Showing items related by title, author, creator and subject.

    • Early Permian intrusions of the Alai range: Understanding tectonic settings of Hercynian post-collisional magmatism in the South Tien Shan, Kyrgyzstan
      Konopelko, D.; Wilde, Simon; Seltmann, R.; Romer, R.; Biske, Y. (2018)
      © 2018 Elsevier B.V. We present geochemical and Sr–Nd–Pb–Hf isotope data as well as the results of single grain U–Pb zircon dating for ten granitoid and alkaline intrusions of the Alai segment of Kyrgyz South ...
    • Two-stage crustal growth in the Arabian-Nubian shield: Initial arc accretion followed by plume-induced crustal reworking
      Gamal El Dien, Hamed ; Li, Zheng-Xiang; Abu Anbar, Mohamed; Doucet, Luc S; Murphy, J Brendan; Evans, Noreen; Xia, Xiao-Ping; Li, Jiangyu (2021)
      Island-arc accretion during the assembly of Gondwana has been widely regarded as the main mechanism for Neoproterozoic crustal growth in the Arabian-Nubian Shield (ANS). However, processes involved to transform the newly ...
    • Evolution, source and tectonic significance of Early Mesozoic granitoid magmatism in the Central Asian Orogenic Belt (central segment)
      Li, S.; Wang, T.; Wilde, Simon; Tong, Y. (2013)
      Numerous Early Mesozoic granitoids have been recognized from the central segment of the Central Asian Orogenic Belt (CAOB). They can be broadly classified into two groups according to zircon U–Pb ages: an early-stage group ...
    Advanced search

    Browse

    Communities & CollectionsIssue DateAuthorTitleSubjectDocument TypeThis CollectionIssue DateAuthorTitleSubjectDocument Type

    My Account

    Admin

    Statistics

    Most Popular ItemsStatistics by CountryMost Popular Authors

    Follow Curtin

    • 
    • 
    • 
    • 
    • 

    CRICOS Provider Code: 00301JABN: 99 143 842 569TEQSA: PRV12158

    Copyright | Disclaimer | Privacy statement | Accessibility

    Curtin would like to pay respect to the Aboriginal and Torres Strait Islander members of our community by acknowledging the traditional owners of the land on which the Perth campus is located, the Whadjuk people of the Nyungar Nation; and on our Kalgoorlie campus, the Wongutha people of the North-Eastern Goldfields.