Finding Argoland

Argoland is a conceptual continent that broke off Australia in the Late Jurassic and drifted north towards SE Asia. Intriguingly, in SE Asia there are no intact relics of a major continent, such as India, but instead the region displays an intensely deformed, long-lived accretionary orogen that formed during more than 130 million years of subduction. However, this orogen hosts accreted continental fragments that may represent parts of Argoland. We extracted the orogenic architecture of SE Asia from literature data, and found the Gondwana-derived fragments of SW Borneo, Greater Paternoster, East Java, South Sulawesi, West Burma, and Mount Victoria Land, which collectively formed Argoland. These fragments are found between geological relics of Late Triassic to Middle Jurassic oceanic basins, which pre-date the break-up of Argoland. We reconstruct the plate tectonic and paleogeographic evolution of the plates that carried the SE Asian continental fragments from the Gondwana margin to their modern position since the Late Triassic. We systematically restore deformation within SE Asia in the upper plate system above the modern Sunda trench, use this to estimate where Gondwana-derived continental fragments arrived at this margin, and reconstruct their flight from the Gondwana margin to this restored location of accretion. Our reconstruction shows that Argoland originated at the northern Australian margin between the Birds Head in the east and Wallaby Fracture Zone in the west. During its Late Jurassic break-up to mid-Cretaceous accretion, Argoland was an archipelago, which we name Argopelago, that consisted of multiple continental fragments separated by two branches of Late TriassicMiddle Jurassic oceanic basins. During the Late Triassic break-up of Lhasa from the northern margin of Gondwana, Argoland broke up into multiple continental fragments that were surrounded by oceanic basins, similar to Zealandia offshore east Australia, and Greater Adria in the Mediterranean.