Whole-Rock Geochemistry, Zircon U-Pb geochronology and Lu-Hf isotopic constraints on metasedimentary rocks (Paragneisses) in Stornes Peninsula, Larsemann Hills，East Antarctica

Understanding the geological history of the Larsemann Hills and other exposures along the southeastern coast of Prydz Bay is essential for reconstructing the formation and evolution of the East Gondwana continent. This research involves analyses of the major elements, trace elements, REE, U-Pb and Lu-Hf isotopes of zircons from the metasedimentary rocks found in the Larsemann Hills. The results suggest that the provenance of the metasedimentary rocks within the Larsemann Hills is mainly Mesoproterozoic to early Neoproterozoic magmatic rocks. The age of the protolith of the metasedimentary rocks is between ~1019 and ~970 Ma. Our data show that at least two tectono-metamorphic events at ~913 Ma and ~552–555 Ma affected the metasedimentary rocks. Furthermore, Prydz Bay has been an integral whole since before the Palaeozoic era and was subsequently reactivated by Pan-African tectonic events. The thickened crust stretched and thinned, accompanied by partial melting of lithospheric mantle into the lower crust. The real Prydz Bay Pan-African collision orogenic belt should be located under the ice sheet east of the Grove Mountains and strikes close to north-northeast.厘清普里兹湾（Prydz Bay）东南海岸沿岸的拉瑟曼丘陵（Larsemann Hills）与其他露头区域的地质演化历史，对于重建东冈瓦纳大陆的形成与演化进程至关重要。本研究针对拉瑟曼丘陵产出的变沉积岩（metasedimentary rocks）中的锆石（zircons），开展了主量元素、微量元素、稀土元素（REE）、U-Pb及Lu-Hf同位素分析。研究结果显示，拉瑟曼丘陵变沉积岩的物源主要为中元古代至新元古代早期的岩浆岩。该变沉积岩的原岩形成时代介于约1019 Ma至970 Ma之间。本研究数据表明，至少两期构造-热变质事件（分别发生于约913 Ma及552~555 Ma）对该变沉积岩产生了影响。此外，普里兹湾自古生代之前便已成为完整的整体，随后泛非（Pan-African）构造事件使其再度活化。增厚的地壳发生拉伸减薄，同时岩石圈地幔的部分熔融物质注入下地壳。真正的普里兹湾泛非碰撞造山带（Pan-African collision orogenic belt）应位于格罗夫山脉（Grove Mountains）东侧的冰盖之下，其走向大致接近北东北向。