The mid-temperature thermal framework of the East Antarctic margin from 50°E–150°E: Insights from apatite Lu-Hf and U-Pb geochronology

• Large dataset of apatite geochronology for East Antarctica between 50 and 150°E. • Apatite U-Pb and Lu-Hf record the latest thermal event within three tectonic domains. • Mid-temperature record extends Kuunga footprint into the Rayner province. • Apatite U-Pb and geochemistry has potential for ice-sheet provenance in East Antarctica. East Antarctica was located at the centre of Gondwana for most of the Phanerozoic, making it a pivotal puzzle piece for reconstructing the evolution of the Gondwana supercontinent. Yet, its tectonic history has been predominantly defined by high-temperature geochronometers that may not capture the entire thermal evolution or footprint of orogenic events. Here we present an extensive dataset of 31 new in situ apatite Uranium-Lead (U-Pb) and 23 new apatite Lutetium-Hafnium (Lu-Hf) dates to complement the mid-temperature record of the more than 5000 km long East Antarctic margin and to refine the temporal framework for the tectonic processes that culminated in the amalgamation of Gondwana. While zircon U-Pb dates record a combination of metamorphic events and crustal inheritance, apatite geochronology largely records the last major thermal events that transpired along the East Antarctic margin. The apatite dates document a strong imprint of the Ediacaran to Cambrian Kuunga Orogeny (ca. 550 – 500 Ma) along the entire Indo-Antarctic margin, extending its footprint into the Rayner Province. Additionally, the second phase of the Wilkes-Albany Fraser Orogeny (1200–1150 Ma) and the Proterozoic cratonisation of the Mawson Continent (ca. 1700–1500 Ma) are recorded along the Australian sector of East Antarctica. The ‘campaign-style’ approach offers a holistic overview of the thermal history of the conjugate Antarctic-Indo-Australian margin and the opportunity to fingerprint large sections of the East Antarctic margin using apatite geochemistry. Apatite proves to be a reliable complement to high-temperature geochronometers such as zircon U-Pb or garnet Lu-Hf to resolve complex tectonic settings from limited samples in ice-covered terranes.