Extent, thickness and erosion of the Jurassic continental flood basalts of Dronning Maud Land, East Antarctica: A low-T thermochronological approach

Tectono-Thermal Evolution and Morphodynamics of the Central Dronning Maud Land Mountains, East Antarctica, Based on New Thermochronological Data

“…To the west of our study area, low-temperature thermochronological data have been reported from Ahlmannryggen and Annandagstoppane within the Archean Grunehogna Craton [14], and the Maud Belt between Heimefrontfjella in the southwest and Hochlinfjellet in the northeast [11,12,14,73]. Zircon (U-Th)/He analyses gave Neoproterozoic to Triassic single-grain ages, although most ages are either Permian or Ordovician, indicating that most of the samples had reached upper crustal depths either shortly after the Pan-African Orogeny or during the late Paleozoic peneplanation of western Dronning Maud Land [14].…”

“…The apatite fission track ages from western Dronning Maud Land range from Carboniferous to mid-Cretaceous. The dataset is dominated by Cretaceous and Triassic ages, with the oldest ages found at high elevations (such as Kirwanveggen), but the AFT ages also generally increase towards Hochlinfjellet in the east [11,12,14]. The apatite (U-Th)/He analyses yielded a wide range of single-grain ages, spanning from Early Ordovician to Eocene.…”

“…The apatite (U-Th)/He analyses yielded a wide range of single-grain ages, spanning from Early Ordovician to Eocene. Late Jurassic to Cretaceous ages are, however, predominant in western Dronning Maud Land [14,73]. Based on the combined apatite fission track and (U-Th)/He dataset, it has been suggested that western Dronning Maud Land was buried under up to 2 km of Jurassic continental flood basalts during Gondwana rifting [11,14].…”

“…Today, these are exposed in thicknesses up to c. 5 km within the Lebombo Monocline in southeastern Africa, whereas they are only preserved in thicknesses up to c. 1 km in Vestfjella and up to c. 400 m within the southwestern Maud Belt in western Dronning Maud Land [51,[55][56][57][58][59]. Based on thermochronological data, however, it has been suggested that western Dronning Maud Land was covered by up to 2 km of Jurassic continental flood basalts, extending at least as far east as Hochlinfjellet at c. 4 • E [11,14]. Exposures of continental flood basalts have not been reported further east in central Dronning Maud Land, but Jurassic mafic dykes in Petermannkjedene and at Schirmacheroasen have been associated with the Karoo magmatism [60,61].…”

“…Previously published thermochronological data from the area are interpreted to reflect long-lasting monotonic cooling of the basement since the last orogeny in Early Paleozoic times [8][9][10]. Similar datasets from western and eastern Dronning Maud Land have revealed a much more complex thermal evolution of the mountain range, e.g., [11][12][13][14], including Late Paleozoic-Early Mesozoic peneplanation and syn-rift reburial, either due to sedimentary basins or by emplacement of Jurassic continental flood basalts. This apparently contrasting long-term tectonic and morphodynamic evolution is puzzling, and has raised several questions: Was the basement in central Dronning Maud Land also exposed to the surface during the Late Paleozoic-Early Mesozoic?…”