Sources and evolution of initial melts of Archean “Gray gneisses”: Trace-element composition and Lu-Hf isotope systematics of zircon from plagiogneisses of the Kola superdeep well and the surrounding area

The ubiquitous presence of zircon in granitoids makes the LuHf isotope system of this mineral an important indicator of granite petrogenesis. This sys tem has a high closure temperature and remains undisturbed during late stage magmatic processes and isochemical high temperature metamorphism. At the same time, the dependence of the trace element com position of zircon on the geochemical features of the initial melts [1] makes it a good proxy for deciphering the melt sources and the sequence of petrogenetic pro cesses during formation of the Earths crust.