Metamorphic evolution of the eclogites from the Neldy Formation in the HP-UHP Makbal metamorphic complex, Northern Tien-Shan, Kyrgyzstan

Abstract

The Akdjon Group is divided into the structurally lower Makbal Formation and the upper Neldy Formation. Coesite and quartz pseudomorphs after coesite included in the garnets have been found in the garnet-talc-chloritoid schists and meta-quartzites in the Makbal Formation. Eclogite blocks across occur as lenses within the meta-quartzite, garnet-talc-chloritoid schists, marbles and pelitic schists in the Makbal Formation. The Neldy Formation is composed mainly of pelitic schists (garnet-phengite-quartz-albite schists), chlorite-carbonate rocks with minor amounts of marble and meta-quartzite. Eclogites are preserved in the central parts of the garnet-amphibolite bodies are intercalated in the pelitic schists of the Neldy Formation. The metamorphism of the Neldy eclogites is divided into three events, (1) precursor metamorphic event (amphibolite facies), (2) first high-P (eclogite facies) metamorphic event, (3) second high-P (epidote amphibolite facies) events.