¹Anna Musolino, ¹Pierre Rochette, ^2,3Jean-Alix Barrat, ⁴Fred Jourdan, ^4,5Bruno Reynard, ¹Bertrand Devouard, ¹Valerie Andrieu, ¹Jérôme Gattacceca, ¹Vladimir Vidal
Earth and Planetary Science Letters 670, 119600 Open Access Link to Article [https://doi.org/10.1016/j.epsl.2025.119600]
¹Aix Marseille Univ, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France
²Univ Brest, CNRS, Ifremer, IRD, LEMAR, Institut Universitaire Européen de la Mer (IUEM), rue Dumont d’Urville, 29280 Plouzané, France
³Institut Universitaire de France, Paris, France
⁴Western Australian Argon Isotope Facility, School of Earth and Planetary Sciences, John de Laeter Centre for Isotope Research and C-FIGS, Curtin University, GPO Box U1987, Perth WA6845, Australia
⁵Laboratoire de Geologie de Lyon, CNRS UMR 5276, Ecole Normale Superieure de Lyon, 46, Allee d’Italie, 69364 Lyon Cedex 7, France
Copyright Elsevier

This study re-evaluates the anomalous subgroup of australites known as high Na/K (HNa/K) tektites (Chapman and Scheiber, 1969). Although previous compositional and isotopic analyses suggested a distinct origin, the group has never been formally recognized as a separate tektite strewn field. We present new data from six HNa/K tektites, complementing the eight specimens already described. We conducted a comprehensive investigation, including petrographic (optical and electron microscopy, and micro-X-ray tomography), geochemical (major and trace element compositions, Sr-Nd isotopic composition, 40Ar/39Ar dating), and spectroscopic (for the identification of inclusions) analyses. We concluded that the HNa/K tektites originated from a separate impact event compared to Australasian tektites; they have an andesitic to dacitic composition and arc-related trace element signatures. Lechatelierite (and phosphate) inclusions as well as high levels of chondritic contamination support an impact origin, for which we provide a more precise 40Ar/39Ar age: 10.76 ± 0.05 Ma. For now, Sr-Nd isotopic data and trace elements composition point to three possible sources associated with active volcanic arcs: Luzon (Philippines), Sulawesi (Indonesia), and the Bismarck region (Papua New Guinea). Systematic petrographic and geochemical differences observed between tektites from the western and eastern parts of the ∼900-km-wide hypothesized strewn field (located in Southern Australia) may help to constrain the location of the source crater, but they need to be confirmed by the study of more specimens. We propose the name “Ananguite” for this new group of tektites.