Lost primordial continents

Kenji Kawai, Taku Tsuchiya, Jun Tsuchiya, Shigenori Maruyama

Research output: Contribution to journalArticle

66 Citations (Scopus)

Abstract

We investigate the bulk density variations of some representative compositions for the lower mantle based on the pressure-volume-temperature equation of state of the constituent mineral phases. The density variations of pyrolite, harzburgite, mid-ocean ridge basalt (MORB), tonalite-trondhjemite-granodiorite (TTG), and anorthosite are studied at a temperature of 300 K and at lower mantle pressures. The density of MORB is greater than that of pyrolite throughout the lower mantle, while the density of harzburgite is slightly lower than that of pyrolite. The density of anorthosite is comparable to that of pyrolite in the lower mantle in general, and greater in the lowermost mantle, while the density of TTG is lower than pyrolite throughout the lower mantle. The above results have important implications for the fate of primordial continents, TTG and anorthosite crust. While subducted TTG might be stagnant in the mantle transition zone, dense subducted anorthositic crust could be expected to sink to the core-mantle boundary (CMB) and thus might be a major component of the D" layer immediately above the CMB. Thus, we propose that significant bodies of continental material could be present in the mantle in the transition zone and immediately above the CMB, in addition to the continents on the Earth's surface.

Original languageEnglish
Pages (from-to)581-586
Number of pages6
JournalGondwana Research
Volume16
Issue number3-4
DOIs
Publication statusPublished - Dec 2009
Externally publishedYes

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Keywords

  • Anorthosite
  • Continents
  • Core-mantle boundary
  • Density variation
  • Mantle transition zone
  • Plate tectonics
  • Tonalite-trondhjemite-granodiorite

ASJC Scopus subject areas

  • Geology

Cite this

Kawai, K., Tsuchiya, T., Tsuchiya, J., & Maruyama, S. (2009). Lost primordial continents. Gondwana Research, 16(3-4), 581-586. https://doi.org/10.1016/j.gr.2009.05.012