The Archaean: Geological and Geochemical Windows into the Early Earth. 1st ed. 2014

種類:

電子ブック

責任表示:

by Andrew Y. Glikson

出版情報:

Cham : Springer International Publishing : Imprint: Springer, 2014

著者名:

• Glikson, Andrew Y.
• SpringerLink (Online service)

シリーズ名:

Modern Approaches in Solid Earth Sciences ; 9

ISBN:

9783319079080 [3319079085]    

注記:

Preface -- Field features of Archaean greenstone terrains -- Archaean Volcanism -- Archaean Plutonism -- Asteroid and comet impacts.-Archaean sedimentation -- Early life forms -- Secular geochemical trends -- Global Archaean tectonics -- Archaean crustal evolution – a synthesis.
Determinations of the age of the Earth as 4.54 ± 0.05 billion years (Ga) leave large part of its earliest history unknown. Isotopic and geochemical signatures in rocks as old as ~4.0 Ga indicate an evolutionary trend from mafic-ultramafic crust to tonalite-trondhjemite-granodiorite (TTG)-dominated micro continental nuclei. To date signatures of the 3.95 – 3.85 Ga Late heavy Bombardment (LHB), manifested by the lunar Mare, have not been discovered on Earth. Recent discoveries of near to 14 Archaean impact ejecta units up to 3.48 Ga-old intercalated with volcanic and sedimentary rocks in the Barberton and Pilbara greenstone belts, including clusters about 3.25 – 3.22 Ga and 2.63 – 2.48 Ga in age, may represent terrestrial vestiges of an extended LHB. The interval of ~3.25 – 3.22 Ga-ago emerges as a major break in Archaean crustal evolution when major asteroid bombardment resulted in faulting, large scale uplift, intrusion of granites and an abrupt shift from crustal conditions dominated by mafic-ultramafic crus

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