Abstract:

The Hadean to Paleoarchean continental crust consists of both granitoid gneiss terrenes and greenstone belts. A number of investigations revealed the ~4.4 Ga oldest detrital zircon ages of continental crusts marked by granitic rocks, and the earliest tonalitic and granodioritic gneisses were formed at ~4.03 Ga as well as the oldest greenstone belts at ~3.8 Ga. The Hadean to Paleoarchean granitoid gneiss terranes are chiefly composed of TonaliticTrondhjemiticGranodioritic gneisses (TTG). The TTG gneisses still are major lithological assemblages in the Meso to Neoarchean, however, lithological compositions of granitoid gneiss terranes exhibit significant diversity, especially the late Neoarchean marked by many granodioritemonzogranitesyenogranite suites. The greenstone belts display complicated compositions, komatiitic to tholeiitic rocks dominated during the Eo to Paleoarchean associated with BIF sedimentary sequences, whereas the Meso and Neoarchean greenstone belts decrease the ratios of the utramafic to mafic komatiites but raised the ratios of tholeiitic and calcalkaline mafic to felsic volcanic compositions with BIF and detrital sedimentary sequences, locally, boninitic, Nbriched basaltic and adakitic volcanics that are generally considered as the criteria of slab subductions. Geodynamic investigations suggested that the mantle plume regime dominated in the Hadean to Paleoarchean. The mantle convections and crust/mantle interactions led to the formation and thickening of the lithosphere 3.0 Ga ago. Locally significant thickening of mafic crust in downwelling areas due to dragging of mantle convection and thrusting slice stack in upper levels, leading to granulite to eclogite facies metamorphism and partial melting in deep level, which derived the formation of TTG granitoid magmas and initially hot subductions of bottom slabs. However, the Meso to Neoarchean dynamic regimes appeared dominant modernstyle plate tectonics, which were revealed by the discoveries of more and more eclogites and calcalkaline volcanics although the mantle plume regimes still play important roles locally.

Key words: Hadean to Archean, continental crust, mantle plume, slab subduction, dynamic regimes