High-pressure rocks in the serpentinite melange of the Chara zone, Eastern Kazakhstan: Geochemistry, petrology, and age

The nature of the protolith of high-pressure rocks occurring as exotic blocks in serpentinite melange in the Chara ophiolite belt, Eastern Kazakhstan, is identified based on petrological and geochemical evidence. The distribution of incompatible HFSE in these rocks suggests that their protoliths were similar to E- and N-MORB tholeiites and, more rarely, to OIB alkaline basalts. This testifies to the activity of plume magmatism in the Early Paleozoic evolution of the Paleoasian Ocean. The Ar-Ar ages of phengite and Na-amphibole from the rocks date the subduction/exhumation of high-pressure rocks in the Chara ophiolite belt at the Late Ordovician (450 ± 5 Ma).