Permo-Triassic rift nucleation in East Antarctica revealed by low-temperature thermochronology

• New and extensive AFT ages across East Antarctica between 48 and 150°E. • East Antarctica was shaped by episodic rift phases, driven mostly by external forces. • Permo-Triassic rifting had a greater thermal impact than Gondwana breakup. • Gondwana thermal signals may be limited to the outer fringes of the rifting continent. • Rigid blocks formed during Permo-Triassic rifting and persisted as tectonic highs. The East Antarctic margin (48°-150°E) holds key information on the breakup history of Pangea and Gondwa, yet thermochronological data is scarce compared to its conjugate rifted margins in India and Australia. Here we present apatite fission track and (U-Th)/He thermochronology, revealing a pervasive record of late Carboniferous and Permo-Triassic cooling for >5000 km of the East Antarctic margin, coincident with Pangea dispersal and predating Gondwana breakup in the Cretaceous. Inverse thermal history models indicate initial rifting of Gondwana likely started in the Permo-Triassic, leading to the formation of rift basins and cooling of basin margins along the incipient margin. This rifting episode then halted and was reinitiated in the Jurassic when further extension ultimately led to continental breakup, with the latter event resulting in less than 1 km of erosion in East Antarctica. Our results demonstrate that the failed Permo-Triassic rift phase had a greater effect on the present margin’s upper crustal thermal evolution than subsequent successful lithospheric rupture in the Jurassic and Cretaceous. While detailed interpretations are limited due to Antarctica’s extensive ice-cover, we suggest that external geodynamic forces such as the rifting of the Cimmerian terrane and the opening of the Meso-Tethys or subduction roll-back along the Proto-Pacific margin of Gondwana may have shifted the extensional locus away from the Antarctic margin and are likely drivers for this multi-phase rifting development.