Geochemical Characteristics, Zircon U-Pb Ages and Lu-Hf Isotopes of Pan-African Pegmatites from the Larsemann Hills, Prydz Bay, East Antarctica and Their Tectonic Implications

Prydz Bay is an important part of the Pan-African high-grade tectonic mobile belt. The focus of this investigation, by applying zircon LA-ICP-MS U-Pb geochronology, zircon Lu-Hf isotope systematics, and whole-rock geochemistry, is on Pan-African pegmatites in the Larsemann Hills of Prydz Bay, East Antarctica, their association with country rocks, and the formation conditions. Based on the obtained results, it is concluded that the pegmatites exhibit elevated levels of silica and alkali and possess peraluminous features. These pegmatites originated during the late Neoproterozoic-Early Cambrian (Pan-African) event, specifically in the D-2-D-4 stages. The D-2 stage occurred between 546 and 562 Ma, followed by D-3-stage pegmatites around 534 Ma. The pegmatites from the D-2-D-3 stages are considered to originate from Paleoproterozoic crustal materials, while there are at least two phases of pegmatites in the D-4 stage (similar to 517 Ma and similar to 521 Ma). The D4-1 pegmatite (similar to 521 Ma) suggested both Paleo-Mesoproterozoic crustal origin, perhaps connected to extension. The D4-2 pegmatite (similar to 517 Ma) originated from the crust layers. In the Larsemann Hills, Pan-African pegmatites formed in a recurring regime of tension. Therefore, the obtained data elucidate that a Pan-African stretching process might have occurred in Prydz Bay.