Evolution of the archaean continental crust. Insights from the experimental study of archaean granitoids.

Abstract

Experimental petrology is a valuable tool to test different models proposed to account for the origin of Archaean granitoids. However, a feasible petrogenetic model needs to be supported by studies from different disciplines. Therefore, the present article is a synthesis of experi-mental studies on the origin of Archaean granitoids (TTG and K-rich granites). Besides, a review of the published work about their origin is briefly discussed. Fi-nally, the experimental synthesis and new results, along with the review presented allow us to propose a model for the evolution of the early continental crust. The petrogenetic evolution of the Archaean crust was catalysed by progressive decrease in geothermal gradients. The thermal structure of the early Archaean down-going plates was favourable for melting the oce-anic crust at low depths (P 10 kbar) and the interaction of TTG magmas with the overlying mantle wedge. Crustal evolution at the Archaean–Proterozoic bound-ary was dominated by the generation of different sort of voluminous K-granite batholiths, the origin of which is controversial. In this study, it is considered an origin of K-granites by interaction between hy-drous sanukitoids magma and tonalitic crust. Keywords: Archaean granitoids, continental crust, experi-mental petrology, K-granites, TTG complexes. T