Detrital zircon provenances for metamorphic rocks from southern S?r Rondane Mountains, East Antarctica: A new report of Archean to Mesoproterozoic zircons

摘要

The S?r Rondane Mountains in East Antarctica consist of the various metamorphic rocks and several plutonic rocks, which are related to formation of Gondwana supercontinent. In order to understand the detrital provenances, LA–ICP–MS zircon U–Pb dating were conducted from metamorphosed sedimentary rocks in southern S?r Rondane Mountains. Detrital cores with ~ 990–730 Ma ages were recognized from zircons in the pelitic gneisses and calc–silicate rocks from Menipa, Imingfjella, Mefjell and Arden, while the pelitic gneiss from Tvih?gda exhibited the Archean to Mesoproterozoic ages of ~ 2630–1060 Ma. The Neoproterozoic zircon ages are recognized not only from metamorphosed sedimentary rocks but also from metamorphosed igneous rocks distributed in the central and southern parts of the mountains. However, the Archean to Mesoproterozoic zircon ages are rare in these areas. The results imply the detrital zircons with the Neoproterozoic ages were probably derived from neighbouring igneous rocks (present metamorphosed igneous rocks), while those with Archean to Mesoproterozoic ages have clearly different provenances because of the lack in the Neoproterozoic components. This study suggests the possibility that southern S?r Rondane Mountains can be considered to be juvenile late Mesoproterozoic to Neoproterozoic terrane partly mixed with the Archean to Mesoproterozoic components.