Formation of Paleoarchean continental crust through infracrustal melting of enriched basalt

R. H. Smithies, D. C. Champion, M. J. Van Kranendonk

研究成果査読

251 被引用数 (Scopus)

抄録

Paleoarchean rocks of the tonalite-trondhjemite-granodiorite (TTG) series require a basaltic source region more enriched in K, LILE, Th and LREE than the low-K tholeiites typical of Archean supracrustal sequences. Most TTG of the Pilbara Craton, in northwestern Australia, formed between 3.5 and 3.42 Ga through infracrustal melting of a source older than 3.5 Ga. Basaltic to andesitic rocks of the 3.51 Ga Coucal Formation, at the base of the Pilbara Supergroup, are amongst the only well-preserved remnants of pre-3.5 Ga supracrustal material on Earth, and may have formed a large proportion of pre-3.5 Ga Pilbara crust. These rocks are significantly enriched in K, LILE, Th and LREE compared to post-3.5 Ga Paleoarchean basalts and andesites, and form a compositionally suitable source for TTG. Enrichment in these basalts was not the result of crustal assimilation but was inherited from a mantle source that was less depleted than modern MORB-source and was enriched in recycled crustal components. We suggest that the formation of Paleoarchean TTG and of their voluminous mafic source regions reflects both a primitive stage in the thermal and compositional evolution of the mantle and a significant prehistory of crustal recycling. Crown

本文言語English
ページ(範囲)298-306
ページ数9
ジャーナルEarth and Planetary Science Letters
281
3-4
DOI
出版ステータスPublished - 5月 15 2009
外部発表はい

ASJC Scopus subject areas

  • 地球化学および岩石学
  • 地球物理学
  • 宇宙惑星科学
  • 地球惑星科学(その他)

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