Variety and origin of magmas on Shatsky Rise, northwest Pacific Ocean

Takashi Sano, Kenji Shimizu, Akira Ishikawa, Ryoko Senda, Qing Chang, Jun Ichi Kimura, Mike Widdowson, William W. Sager

研究成果: ジャーナルへの寄稿記事

36 引用 (Scopus)

抄録

Shatsky Rise consists of thick (∼30km maximum) basaltic crust with various geochemical compositions. Geochemistry data indicate that four magma types exist on the plateau; namely normal, low-Ti, high-Nb, and U1349 types. The normal type is the most abundant in volume and appears on all three large edifices of the plateau: Tamu, Ori, and Shirshov massifs. Composition of the normal type is similar to normal mid-ocean ridge basalt (N-MORB) composition, but with slight relative enrichment of the more incompatible elements. The low-Ti type is distinguished from the normal type basalt by slightly lower Ti content at a given MgO. Composition of the high-Nb type is characterized by distinctively high contents of incompatible trace elements. U1349 type basalts are composed of more primitive and depleted compositions compared with the others. The normal type basalts constitute ∼94% of the lava units of the oldest Tamu Massif and non-normal types (i.e., the other three types) basalts comprise ∼57% on the younger Ori Massif, implying that geochemical compositions may have become heterogeneous with time. Petrological examination demonstrates that compositions of the normal-, low-Ti-, and high-Nb-type basalts evolved through fractional crystallization of olivine, plagioclase, and augite in shallow magma chambers (<200MPa). Model calculations of immobile trace elements estimate that the normal type basalt can be formed by ∼15% melting of a depleted mantle source in the presence of residual garnet. This degree of melting is similar to N-MORB, but the larger effect of residual garnet during petrogenesis implies that a greater depth of melting.

元の言語英語
記事番号Q08010
ジャーナルGeochemistry, Geophysics, Geosystems
13
発行部数8
DOI
出版物ステータス出版済み - 8 1 2012

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Pacific Ocean
basalt
ocean
Chemical analysis
melting
mid-ocean ridge basalt
Melting
mid-ocean ridges
garnet
Garnets
Trace Elements
trace elements
trace element
plateau
garnets
magma
plateaus
augite
petrogenesis
massifs

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

これを引用

Sano, T., Shimizu, K., Ishikawa, A., Senda, R., Chang, Q., Kimura, J. I., ... Sager, W. W. (2012). Variety and origin of magmas on Shatsky Rise, northwest Pacific Ocean. Geochemistry, Geophysics, Geosystems, 13(8), [Q08010]. https://doi.org/10.1029/2012GC004235

Variety and origin of magmas on Shatsky Rise, northwest Pacific Ocean. / Sano, Takashi; Shimizu, Kenji; Ishikawa, Akira; Senda, Ryoko; Chang, Qing; Kimura, Jun Ichi; Widdowson, Mike; Sager, William W.

:: Geochemistry, Geophysics, Geosystems, 巻 13, 番号 8, Q08010, 01.08.2012.

研究成果: ジャーナルへの寄稿記事

Sano, T, Shimizu, K, Ishikawa, A, Senda, R, Chang, Q, Kimura, JI, Widdowson, M & Sager, WW 2012, 'Variety and origin of magmas on Shatsky Rise, northwest Pacific Ocean', Geochemistry, Geophysics, Geosystems, 巻. 13, 番号 8, Q08010. https://doi.org/10.1029/2012GC004235
Sano, Takashi ; Shimizu, Kenji ; Ishikawa, Akira ; Senda, Ryoko ; Chang, Qing ; Kimura, Jun Ichi ; Widdowson, Mike ; Sager, William W. / Variety and origin of magmas on Shatsky Rise, northwest Pacific Ocean. :: Geochemistry, Geophysics, Geosystems. 2012 ; 巻 13, 番号 8.
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