Mesozoic age of the Gilyui Metamorphic Complex in the junction zone of the Selenga-Stanovoi and Dzhugdzhur-Stanovoi superterranes, Central Asian fold belt

摘要

The Gilyui Complex includes sedimentary and volcanic rocks metamorphosed to amphibolite and epidote-amphibolite facies, which constitute blocks confined to the main structural sutures of the Dzhugdzhur-Stanovoi superterrane in the Central Asian fold belt. In recent stratigraphic scales, they are considered as being Neoarchean in age with Nd model age values of 1.5-3.0 Ga. The youngest detrital zircons from metamorphosed mudstone of the Gilyui Complex yield a date of 285 +/- 4 Ma, which determines the lower age limit for the formation of its protolith. The age of crystallization of rhyolites from the Gilyui Complex is determined to be 231 +/- 4 Ma. If the rhyolites form volcanic flow units or sills, the Gilyui Complex is approximately 230 Ma or 231 +/- 4 to 285 +/- 4 Ma old, respectively.