Early Ordovician terrane accretion along the Gondwanian margin of the East Antarctic Craton: new Pb/Pb titanite ages from Tonalite Belt, North Victoria Land, Antarctica

• Published in: Terra Nova
• Main Authors: MUSUMECI, GIOVANNI, PERTUSATI, PIERO, KRAMERS J.
• Other Authors: Musumeci, Giovanni, Kramers, J., Pertusati, Piero
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2000
• Subjects: Pb/Pb titanite age; syntectonic magmatism; northern Victoria Land; Antarctica; Antarctic; Victoria Land; Pacific; Bowers; Murchison; Antarc*
• Online Access: http://hdl.handle.net/11568/199930; https://doi.org/10.1046/j.1365-3121.2000.00271.x

Early Palaeozoic subduction of the palaeo-Pacific plate and terrane accretion along the palaeomargin of the East Antarctic Craton is well-documented in North Victoria Land, where the Tonalite Belt is a complex of synkinematic intrusions emplaced within the Lanterman–Murchison Shear Zone at the boundary between the Wilson Terrane and the allochthonous Bowers Terrane. Stepwise leaching Pb/Pb and U–Pb studies of titanite separates carried out on two well-foliated samples of tonalites yielded ages of deformation bracketed between 490 and 480 Ma with an isochron age of 480 ±13 Myr. Ar/Ar and K–Ar ages of 477 Myr in the metamorphic rocks of accreted terranes point to fast cooling and uplift after accretion. The new titanite ages, compared with a regional distribution of magmatic and metamorphic ages, indicate an early Ordovician age for terrane collision and amalgamation. As a consequence of collision, subduction shifted to an outward position along the palaeomargin of the East Antarctic Craton.