An isotope trace element study of the East Greenland Tertiary dyke swarm: Constraints on temporal and spatial evolution during continental rifting

Karen Hanghøj, Michael Storey, Ole Stecher

    Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

    Resumé

    Dykes of the East Greenland Tertiary dyke swarm can be divided into pre- and syn-break-up tholeiitic dykes, and post-break-up transitional dykes. Of the pre- and syn-break-up dykes, the most abundant group (Tholeiitic Series; TS) has major element compositions similar to the main part of the East Greenland flood basalts. A group of high-MgO tholeiitic dykes (Picrite–Ankaramite Series; PAS) are much less common, and are equivalent to some of the oldest lavas of the East Greenland flood basalts. Isotopic compositions of the TS and PAS dykes partly overlap with those for Iceland, but Pb isotopic compositions extend to less radiogenic values than those seen in either Iceland or North Atlantic mid-ocean ridge basalt (MORB). The isotopically depleted source required to account for this isotopic variation is interpreted as subcontinental lithospheric mantle with low 87Sr/86Sr and 206Pb/204Pb and high εNd. The post-break-up Transitional Series (TRANS) dykes are isotopically distinct from Iceland and MORB, and are interpreted as the products of contamination of Iceland plume melts with continental crust. Comparison of the Nd–Sr–Pb isotopic and trace element compositions of dykes from different segments of the East Greenland margin indicates that there is no systematic compositional change with distance from the presumed proto-Icelandic plume centre. This suggests that a northward-increasing crustal thickness observed offshore may be attributed to active upwelling rather than a systematic rise in temperature towards the plume centre.
    OriginalsprogEngelsk
    TidsskriftJournal of Petrology
    Vol/bind44
    Udgave nummer11
    Sider (fra-til)2081-2012
    Antal sider32
    ISSN0022-3530
    DOI
    StatusUdgivet - 2003

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      title = "An isotope trace element study of the East Greenland Tertiary dyke swarm: Constraints on temporal and spatial evolution during continental rifting",
      abstract = "Dykes of the East Greenland Tertiary dyke swarm can be divided into pre- and syn-break-up tholeiitic dykes, and post-break-up transitional dykes. Of the pre- and syn-break-up dykes, the most abundant group (Tholeiitic Series; TS) has major element compositions similar to the main part of the East Greenland flood basalts. A group of high-MgO tholeiitic dykes (Picrite–Ankaramite Series; PAS) are much less common, and are equivalent to some of the oldest lavas of the East Greenland flood basalts. Isotopic compositions of the TS and PAS dykes partly overlap with those for Iceland, but Pb isotopic compositions extend to less radiogenic values than those seen in either Iceland or North Atlantic mid-ocean ridge basalt (MORB). The isotopically depleted source required to account for this isotopic variation is interpreted as subcontinental lithospheric mantle with low 87Sr/86Sr and 206Pb/204Pb and high εNd. The post-break-up Transitional Series (TRANS) dykes are isotopically distinct from Iceland and MORB, and are interpreted as the products of contamination of Iceland plume melts with continental crust. Comparison of the Nd–Sr–Pb isotopic and trace element compositions of dykes from different segments of the East Greenland margin indicates that there is no systematic compositional change with distance from the presumed proto-Icelandic plume centre. This suggests that a northward-increasing crustal thickness observed offshore may be attributed to active upwelling rather than a systematic rise in temperature towards the plume centre.",
      keywords = "isotopes, trace elements, mantle sources, mantle melting",
      author = "Karen Hangh{\o}j and Michael Storey and Ole Stecher",
      year = "2003",
      doi = "10.1093/petrology/egg071",
      language = "English",
      volume = "44",
      pages = "2081--2012",
      journal = "Journal of Petrology",
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      An isotope trace element study of the East Greenland Tertiary dyke swarm : Constraints on temporal and spatial evolution during continental rifting. / Hanghøj, Karen; Storey, Michael; Stecher, Ole.

      I: Journal of Petrology, Bind 44, Nr. 11, 2003, s. 2081-2012.

      Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

      TY - JOUR

      T1 - An isotope trace element study of the East Greenland Tertiary dyke swarm

      T2 - Constraints on temporal and spatial evolution during continental rifting

      AU - Hanghøj, Karen

      AU - Storey, Michael

      AU - Stecher, Ole

      PY - 2003

      Y1 - 2003

      N2 - Dykes of the East Greenland Tertiary dyke swarm can be divided into pre- and syn-break-up tholeiitic dykes, and post-break-up transitional dykes. Of the pre- and syn-break-up dykes, the most abundant group (Tholeiitic Series; TS) has major element compositions similar to the main part of the East Greenland flood basalts. A group of high-MgO tholeiitic dykes (Picrite–Ankaramite Series; PAS) are much less common, and are equivalent to some of the oldest lavas of the East Greenland flood basalts. Isotopic compositions of the TS and PAS dykes partly overlap with those for Iceland, but Pb isotopic compositions extend to less radiogenic values than those seen in either Iceland or North Atlantic mid-ocean ridge basalt (MORB). The isotopically depleted source required to account for this isotopic variation is interpreted as subcontinental lithospheric mantle with low 87Sr/86Sr and 206Pb/204Pb and high εNd. The post-break-up Transitional Series (TRANS) dykes are isotopically distinct from Iceland and MORB, and are interpreted as the products of contamination of Iceland plume melts with continental crust. Comparison of the Nd–Sr–Pb isotopic and trace element compositions of dykes from different segments of the East Greenland margin indicates that there is no systematic compositional change with distance from the presumed proto-Icelandic plume centre. This suggests that a northward-increasing crustal thickness observed offshore may be attributed to active upwelling rather than a systematic rise in temperature towards the plume centre.

      AB - Dykes of the East Greenland Tertiary dyke swarm can be divided into pre- and syn-break-up tholeiitic dykes, and post-break-up transitional dykes. Of the pre- and syn-break-up dykes, the most abundant group (Tholeiitic Series; TS) has major element compositions similar to the main part of the East Greenland flood basalts. A group of high-MgO tholeiitic dykes (Picrite–Ankaramite Series; PAS) are much less common, and are equivalent to some of the oldest lavas of the East Greenland flood basalts. Isotopic compositions of the TS and PAS dykes partly overlap with those for Iceland, but Pb isotopic compositions extend to less radiogenic values than those seen in either Iceland or North Atlantic mid-ocean ridge basalt (MORB). The isotopically depleted source required to account for this isotopic variation is interpreted as subcontinental lithospheric mantle with low 87Sr/86Sr and 206Pb/204Pb and high εNd. The post-break-up Transitional Series (TRANS) dykes are isotopically distinct from Iceland and MORB, and are interpreted as the products of contamination of Iceland plume melts with continental crust. Comparison of the Nd–Sr–Pb isotopic and trace element compositions of dykes from different segments of the East Greenland margin indicates that there is no systematic compositional change with distance from the presumed proto-Icelandic plume centre. This suggests that a northward-increasing crustal thickness observed offshore may be attributed to active upwelling rather than a systematic rise in temperature towards the plume centre.

      KW - isotopes

      KW - trace elements

      KW - mantle sources

      KW - mantle melting

      U2 - 10.1093/petrology/egg071

      DO - 10.1093/petrology/egg071

      M3 - Journal article

      VL - 44

      SP - 2081

      EP - 2012

      JO - Journal of Petrology

      JF - Journal of Petrology

      SN - 0022-3530

      IS - 11

      ER -