Igneous activity and petrogenesis of Late Proterozoic (Grenville Period) intrusions in the Sor Rondane Mountains, East Antarctica

点击翻译按钮获取中文摘要

This is a detailed study of Late Proterozoic intrusion in the Sor Rondane Mountains, Antarctica. The intrusion is classified into three lithologies: strong gneissose metatonalite, weak gneissose metatonalite and metagabbro. The strong gneissose metatonalite is the main lithotype, which is geochemically categorized as low-K tholeiitic granitoid. Petrological studies suggest that the tholeiitic magma was derived from low-K basalt melting at the crustal depth, and the most plausible tectonic setting is a juvenile oceanic arc. The other two rocks are scattered as small intrusions and are geochemically regarded as calc-alkaline adakites related to oceanic slab melting. U-Pb SHRIMP zircon ages of the tholeiitic metatonalite are concentrated at 998-995 Ma, whereas the calc-alkaline adakites are younger and divided between ages 945-920 Ma and 772 Ma. Therefore, the Late Proterozoic intrusion was formed first as a juvenile arc component, followed by adakitic magmatism with oceanic slab melting.