Sr–Nd–Pb–Hf isotopic constraints on the diversity of magma sources beneath the Aden Ridge (central Gulf of Aden) and plume–ridge interaction

• SHINJO Ryuichi

  Department of Physics and Earth Sciences, University of the Ryukyus

• MESHESHA Daniel

  El Mining Plc

• ORIHASHI Yuji

  Earthquake Research Institute, The University of Tokyo

• HARAGUCHI Satoru

  Department of Solid Earth Geochemistry, Japan Agency for Marine–Earth Science and Technology (JAMSTEC)

• TAMAKI Kensaku

  Frontier Research Center for Energy and Resources (FRCER), The University of Tokyo

抄録

This paper presents new Sr–Nd–Pb–Hf isotopic compositions of tholeiitic basalts dredged along the Aden Ridge of the central Gulf of Aden (45.5°E–49°E). Two groups of basalts are identified based on their contrasting spatial distributions and geochemical signatures. Basalts dredged from east of 46.2°E (Group 1) are LREE–depleted but have relatively wide variations in ⁸⁷Sr/⁸⁶Sr (0.70278–0.70304) and ²⁰⁶Pb/²⁰⁴Pb (18.21–19.03) and limited ¹⁴³Nd/¹⁴⁴Nd (0.51301–0.51309) and ¹⁷⁶Hf/¹⁷⁷Hf ranges (0.283224–0.283276; εHf = 15.98–17.83), analogous to the geochemical signature of enriched to depleted normal mid–oceanic ridge basalts (N–MORB). In contrast, the basalts dredged between 45.6°E and 46.2°E (Group 2) are more enriched in incompatible elements [ocean island basalt (OIB)–like] but have little variation in ⁸⁷Sr/⁸⁶Sr (0.70323–0.70341), ²⁰⁶Pb/²⁰⁴Pb (19.33–19.49), and ¹⁴³Nd/¹⁴⁴Nd (0.51285–0.51292) and a wide variation in ¹⁷⁶Hf/¹⁷⁷Hf (0.283020–0.283155; εHf = 8.77–13.54). Isotopic and trace element variations can be attributed to the mixing of three types of mantle source: depleted MORB–type mantle (Component i), matrix mantle of the Afar plume (Component ii), and recycled oceanic crust (Component iii) occurring as blobs, streaks, or ribbons within the plume matrix. Mixing between Components i and ii would have produced Group 1 basalts, and Components ii and iii produced Group 2 basalts. Our data suggest that the Afar plume components were involved in magma genesis westward from 48°E in the Aden Ridge.

収録刊行物

• Journal of Mineralogical and Petrological Sciences

  Journal of Mineralogical and Petrological Sciences 110 (3), 97-110, 2015

  一般社団法人　日本鉱物科学会

キーワード

• Gulf of Aden
• Afar plume
• Ridge–plume interaction
• Sr–Nd–Pb–Hf isotope
• Trace element

詳細情報

• CRID: 1390001206545182336
• NII論文ID: 130005083496
• DOI: 10.2465/jmps.141211
• ISSN: 13493825
• ISSN: 13456296
• 本文言語コード: en
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可