Rodinian detrital zircons in Late Cretaceous sandstones indicate a possible Precambrian basement under southern Zealandia

• Published in: Precambrian research 2012-08, Vol.212-213, p.13-20
• Main Authors: Adams, C.J., Griffin, W.L.
• Format: Article
• Language: English
• Subjects: Detrital zircon; Precambrian, Zealandia; Provenance; Zircon geochronology
• ISSN: 0301-9268; 1872-7433
• DOI: 10.1016/j.precamres.2012.04.003

► Late Cretaceous sandstones in Zealandia have anomalously high proportions of Precambrian detrital zircons. ► These Precambrian zircons have no appropriate source within the pre-100Ma basement of Zealandia. ► A small Precambrian, Zealandia basement block beneath the Campbell Plateau is proposed. ► As a component of the Rodinia supercontinent, Precambrian Zealandia was formerly adjacent to the South China Block. U–Pb ages of detrital zircons in Late Cretaceous sandstones overlying Paleozoic basement in southernmost Zealandia have unusually high proportions (40%) of Precambrian zircons, mostly Mesoproterozoic (ca. 1100Ma) and Neoproterozoic (ca. 800Ma). The proportion of Precambrian (Rodinia), relative to early Paleozoic (Gondwana), zircon groups is anomalously high and the former cannot have been reworked from any known basement rocks within Zealandia. Since Late Cretaceous sandstones were deposited after the breakup of Gondwana, it is proposed that their Precambrian zircons originated in Precambrian basement within Zealandia, briefly exposed along its Australian/Antarctic margin during Gondwana breakup. The ca. 1100Ma and ca. 800Ma age components suggest a former juxtaposition against the South China Block, when Zealandia was located east of Australia in Meso- and Neoproterozoic time.