Formation and Differentiation of the Lower Continental Crust by Relamination
The formation and evolution of the continental crust are one of the long-term main basic scientific issues in Earth science.A simple,quantitative,and efficient model,i.e.,a relamination model,for the formation and differentiation of the lower continental crust was proposed.During slab subduction,mafic rocks become eclogites and may sink into the mantle,whereas more silica-rich buoyant rocks are transformed into felsic gneisses following decompression melting and rise to the base of the crust and form the lower continental crust.Continental refinery can occur via relamination during four subduction-zone processes:sediment subduction,intra-oceanic arc subduction,subduction erosion,and continent subduction.Numeral parametric studies of the relamination of the mafic subducting crust and the relamination styles in collisional orogens were performed,which provided a novel explanation for the secular evolution of the continental crust and important factors and dynamics for the distinguished main types of evolution regarding the fate of the subducted continental crust.Systematic lithology and geochemical investigations were performed on some island arcs to provide examples of relamination.
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