Are the Taitao granites formed due to subduction of the Chile ridge?

Ryo Anma, Richard Armstrong, Yuji Orihashi, Shin ichi Ike, Ki Cheol Shin, Yoshiaki Kon, Tsuyoshi Komiya, Tsutomu Ota, Shin ichi Kagashima, Takazo Shibuya, Shinji Yamamoto, Eugenio E. Veloso, Mark Fanning, Francisco Hervé

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30 Citations (Scopus)

Abstract

The Taitao granites are distributed around the Late Miocene Taitao ophiolite (5.66 ± 0.33 Ma to 5.19 ± 0.15 Ma) exposed at the western tip of the Taitao peninsula, southern Chile, ~ 50 km southeast from the present day Chile triple junction. In this paper, we report sensitive high mass-resolution ion microprobe (SHRIMP) U-Pb ages for the Taitao granites to elucidate the temporal relationship between the ophiolite and granites, and discuss the origin of the granitic melts. Five intrusive bodies of the Taitao granites have U-Pb ages ranging from 5.70 ± 0.25 Ma (Tres Montes pluton in southeast) to 3.92 ± 0.07 Ma (Cabo Raper pluton in southwest). The Estero Cono, Seno Hoppner and Bahia Barrientos intrusions that fringe eastern margin of the ophiolite have U-Pb ages ranging from 5.17 ± 0.09 Ma to 4.88 ± 0.3 Ma. Recycled zircon cores are common only in the Tres Montes pluton. Our data indicate that the generation of the granitic melts started in the Tres Montes area when a short segment of the Chile ridge system started to subduct ca. 6 Ma ago. This magmatism involved contamination with sediments/basement rocks. A part of the subducting ridge center was emplaced to form the present Taitao ophiolite at ~ 5.6 Ma. Generation of granitic melts continued as the spreading center of the same ridge segment subducted, due perhaps to partial melting of the ophiolite and/or oceanic crust enhanced by heat from upwelling mantle beneath the ridge. Granitic magmas with various compositions developed during subduction of the ridge. Emplacement of the ophiolite and formation of continental crust took place almost simultaneously.

Original languageEnglish
Pages (from-to)246-258
Number of pages13
JournalLITHOS
Volume113
Issue number1-2
DOIs
Publication statusPublished - Nov 2009

Keywords

  • Chile triple junction
  • Granite
  • Ophiolite
  • Ridge subduction
  • Taitao
  • U-Pb

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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    Anma, R., Armstrong, R., Orihashi, Y., Ike, S. I., Shin, K. C., Kon, Y., Komiya, T., Ota, T., Kagashima, S. I., Shibuya, T., Yamamoto, S., Veloso, E. E., Fanning, M., & Hervé, F. (2009). Are the Taitao granites formed due to subduction of the Chile ridge? LITHOS, 113(1-2), 246-258. https://doi.org/10.1016/j.lithos.2009.05.018