初期地球における水の役割 : 始生代の含水マントルの融解によるコマチアイトマグマ及びクラトニックペリドタイトの生成  [in Japanese] Role of water in the early Earth: formation of komatiite and cratonic peridotite by melting of the wet Archean mantle  [in Japanese]

Access this Article

Search this Article

Author(s)

    • 大谷 栄治 OHTANI Eiji
    • 東北大学大学院理学研究科地学専攻 Institute of Mineralogy, Petrology and Economic Geology, Tohoku University
    • 朝原 友紀 ASAHARA Yuki
    • 東北大学大学院理学研究科地学専攻 Institute of Mineralogy, Petrology and Economic Geology, Tohoku University

Abstract

We discuss the effects of water on important igneous processes in the Archean, i.e., the komatiite magma genesis and the formation of the cratonic peridotites based on the experimental results on the effect of water on the melting relations of model mantle peridotite at 6.5 GPa. Liquidus temperature decreases by about 100℃ and the temperature interval to produce more than 60% partial melting reduces by about 50℃ in the 1〜2 wt% water bearing system at this pressure. Garnet is the first dissolved phase and the stability field of orthopyroxene expands in the conditions of the water content of about 5 wt% at 6.5 GPa. Aluminum undepleted komatiites (AUK) can be formed by melting at 200 km depth (6.5 GPa) in a hydrous mantle at significantly lower temperatures than under the dry condition. Aluminum depleted komatiites (ADK) also can be formed by hydrous melting at higher pressure. In addition, cratonic peridotites may be formed as residues of partial melting under various water contents in the Archean mantle. The stability of the cratonic mantle, tectosphere, may be explained by dehydration hardening by removal of water due to partial melting of the wet Archean mantle.

Journal

  • Chikyukagaku

    Chikyukagaku 33(4), 235-245, 1999

    The Geochemical Society of Japan

References:  37

Codes

  • NII Article ID (NAID)
    110008679987
  • NII NACSIS-CAT ID (NCID)
    AN00141280
  • Text Lang
    JPN
  • Article Type
    REV
  • ISSN
    0386-4073
  • NDL Article ID
    4917737
  • NDL Source Classification
    ZM41(科学技術--地球科学)
  • NDL Call No.
    Z15-645
  • Data Source
    CJP  NDL  NII-ELS  J-STAGE 
Page Top