Regional implications of U/Pb SHRIMP age constraints on the tectonic evolution of New Caledonia

Abstract

U/Pb SHRIMP ages for zircons from plagiogranites indicate a Late Carboniferous age of formation for ophiolitic basement of the Koh terrane in the Central Chain Mountains of New Caledonia. Samples from ophiolites at Koh and Koua yielded ages of 302 ± 7 Ma and 290 ± 5 Ma, respectively. The similarity of these ages to those of plagiogranites in the Dun Mountain Ophiolite Belt/Maitai terrane of New Zealand, and the comparable structural positions of the two terranes, potentially constrain reconstructions of the Cretaceous SW Pacific margin. Detrital zircons from late Mesozoic sediments that overlap the Koh terrane also provide potential constraints on the location of New Caledonia prior to its break-up and dispersal from eastern Australia.