Origin of Early Paleoproterozoic Zircons in Rocks of the Archean Eclogite Association of Gridino (Belomorian Eclogite Province)

摘要

Eclogite bodies formed as a result of Meso-Neoarchean subduction of oceanic and continental complexes are located within the Southern Kola active margin along the northeastern boundary of the Belomorian accretion orogen [1, 2]. The Belomorian eclogite province includes associations of two types, which differ in the nature of the protoliths. Eclogites of the Salma association were formed after rocks of the oceanic crust. The high-pressure processes in the Gridino association especially evident in mafic enclaves and dykes. Mineral parageneses of the eclogite facies are rarely registered in felsic rocks [3]. Eclogites of Archean age were not known for a long time, and the eclogite conditions were considered to be unreachable in the Archean crust, because of the ideas of the high geothermal gradient during the early history of the Earth. Eclogites of Archean age provide important evidence for determination of the starting point of plate tectonics and control the basic possibilities for reconstruction of geodynamic processes in the Early Precambrian.