Early Precambrian Earth history: plate and plume tectonics and extraterrestrial controls

Abstract

The Hadean and Archean geologic history of the Earth is discussed in the context of available knowledge from different sources: space physics and comparative planetology; isotope geochronology; geology and petrology of Archean greenstone belts (GB) and tonalitetrondhjemite-granodiorite (TTG) complexes; and geodynamic modeling review to analyse plate-tectonic, plume activity, and impact processes. Correlation between the age peaks of terrestrial Hadean-Early Archean zircons and late heavy bombardment events on the Moon, as well as the Hf isotope composition of zircons indicating their mostly mafic sources, hint to an important role of impact processes in the Earth's history between 4.4 and 3.8 Ga. The earliest continental crust (TTG complexes) formed at 4.2 Ga (Acasta gneisses), while its large-scale recycling left imprint in Hf isotope signatures after 3.75 Ga. The associations and geochemistry of rocks suggest that Archean greenstone belts formed in settings of rifting, ocean floor spreading, subduction, and plume magmatism generally similar to the present respective processes. The Archean history differed in the greater extent of rocks derived from mantle plumes (komatiites and basalts), boninites, and adakites as well as in shorter subduction cycles recorded in alternation of typical calc-alkaline andesite-dacite-rhyolite and adakite series that were generated in a hotter mantle with more turbulent convection and unsteady subduction. The Archean is interpreted as a transient period of small plate tectonics.

Archean Zircons with Omphacite Inclusions from Eclogites of the Belomorian Province, Fennoscandian Shield: The First Finding

“…One of major problems to be resolved in modern geology is to answer the question: when did the present-day plate-tectonic processes, including subduction, begin on the Earth? [1][2][3][4][5][6][7][8][9][10][11][12][13]. One of the decisive indicators of convergent processes, such as subduction and collision, are crustal eclogites, mafic rocks that consist mainly of garnet and omphacite and formed at great depths at high (HP) and ultrahigh (UHP) pressures and relatively low temperatures.…”