U-Pb systematics of detrital zircons from low-grade metamorphic sandstones of the Trinity Peninsula Group (Antarctica)

Abstract

U-Pb isotope analyses of detrital euhedral zircons from two Triassic metasandstones of the Trinity Peninsula Formation demonstrate that: ( i) zircons less than 125 μm in size are cogenetic; and ( ii) in a Concordia diagram, the different zircon populations define a fan-shaped area with an origin on the concordia of approximately 320 Ma. This Carboniferous age is interpreted as the final event affecting a heterogeneous population of zircons before they returned into the exogenous cycle. The U-Pb systematics of rare pink, well rounded zircons define a zircon suite with an older, Cambrian to Precambrian age information. The morphology of the dominant euhedral zircons, which reflects a granitic environment of formation, and their U-Pb data suggest that the Triassic sedimentary basin was surrounded by granitoid to migmatic rocks of Carboniferous age.