Chemical evolution of the earth's mantle over 3.5 Gyr

DOI Web Site Open Access
  • Kimura Jun-Ichi
    Department of Solid Earth Geochemistry Japan Agency for Marine-Earth Sciences and Technology

Bibliographic Information

Other Title
  • マントル35億年の化学進化
  • 授業で教えたい地球化学 マントル35億年の化学進化
  • ジュギョウ デ オシエタイ チキュウ カガク マントル 35オクネン ノ カガク シンカ

Search this article

Abstract

<p>Earth's mantle formed at 4.6 Ga and evolved through the Hadean magma ocean stage and subsequent plate tectonics stage since 3.5 Ga. Mantle convection driven by the internal heat is the major driving force of the plate tectonics with considerable tectonic roles of both oceanic and continental plates formed at mid-ocean ridges (MOR) and subduction zones (SZ), respectively. The MOR and SZ regions are the places of plate formations by intensive magma geneses where significant element fractionations between solids and melts are taking place. The MOR and SZ regions are the major factories of tectonic and geochemical mantle evolutions because their products of plates and residual mantles are mixed back into the mantle by stirring or isolated almost permanently. The geochemical fractionations in the MOR and SZ magmatism are modelled based on petrochemical mass balance and elemental and isotopic growths of the magmas and the residues are examined. These combined to enable depicting the thermal, chemical, and isotopic evolutions of the Earth's mantle over 3.5 Gyr. The present-day mantle appears to be geochemically heterogeneous and forms large mantle domains in both deep and shallow portions by Mesoproterozoic (1.7 Ga). These suggest relatively sluggish mantle convection after Mesoproterozoic due to mantle cooling.</p>

Journal

  • Chikyukagaku

    Chikyukagaku 52 (1), 29-53, 2018

    The Geochemical Society of Japan

Related Projects

See more

Keywords

Details 詳細情報について

Report a problem

Back to top