A hidden Rodinian lithospheric keel beneath Zealandia, Earth’s newly recognized continent
| Autor: | Keith A. Klepeis, Noreen J. Evans, Bradley J. McDonald, R.E. Turnbull, Thomas Ludwig, Joshua J. Schwartz, Marco L. Fiorentini, R. Jongens |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Geology. |
| ISSN: | 1943-2682 0091-7613 |
| Popis: | We present a data set of >1500 in situ O-Hf-U-Pb zircon isotope analyses that document the existence of a concealed Rodinian lithospheric keel beneath continental Zealandia. The new data reveal the presence of a distinct isotopic domain of Paleozoic–Mesozoic plutonic rocks that contain zircon characterized by anomalously low δ18O values (median = +4.1‰) and radiogenic εHf(t) (median = +6.1). The scale (>10,000 km2) and time span (>>250 m.y.) over which plutonic rocks with this anomalously low-δ18O signature were emplaced appear unique in a global context, especially for magmas generated and emplaced along a continental margin. Calculated crustal-residence ages (depleted mantle model, TDM) for this low-δ18O isotope domain range from 1300 to 500 Ma and are interpreted to represent melting of a Precambrian lithospheric keel that was formed and subsequently hydrothermally altered during Rodinian assembly and rifting. Recognition of a concealed Precambrian lithosphere beneath Zealandia and the uniqueness of the pervasive low-δ18O isotope domain link Zealandia to South China, providing a novel test of specific hypotheses of continental block arrangements within Rodinia. |
| Databáze: | OpenAIRE |
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