Detrital zircon ages and trace element compositions of Permian–Triassic foreland basin strata of the Gondwanide orogen, Antarctica

摘要

Detrital zircon U-Pb and trace element data provide new information on the provenance of Permian–Triassic foreland basin deposits of the Gondwanide orogen that belong to the Beacon Supergroup in Antarctica. Zircon U/Th ratios primarily point to dominantly igneous parent rocks with subordinate contributions from metamorphic sources. All three samples (two Permian and one Triassic) analyzed in this study yielded 1200–1000 Ma and 635–490 Ma zircon U-Pb age populations. The Triassic sample also yielded younger 367 Ma and 238 Ma age peaks. The combination of age and trace element proxies for rock type provides important new evidence in support of the common assertion that granitoid parent rocks of the Terra Australis and Gondwanide orogens served as a major source for the siliciclastic sediments. The results also point to smaller, but significant, contributions from Triassic (236 Ma) and Cambrian (539 Ma) mafic rocks and Ediacaran (ca. 559 Ma) alkaline source rocks from these regions.