A tale of two eras: Pliocene-Pleistocene unroofing of Cenozoic and late Archean zircons from active metamorphic core complexes, Solomon Sea, Papua New Guinea

U/Pb ion microprobe analyses of zircons from gneisses and granodiorites exposed in the D'Entrecasteaux Islands, and from conglomerate sections of the Goodenough No. 1 well in the adjacent Trobriand Basin, provide constraints on the age of magmatism, peak metamorphism, and nature of rocks unroofed during initial stages of metamorphic core complex formation in the Solomon Sea. The youngest populations of zircons from felsic gneisses and granodiorites indicate late Pliocene ²⁰⁶ Pb*/ ²³⁸ U ages. In striking contrast, zircons from igneous and metamorphic clasts from the Goodenough No. 1 well indicate a single population with a ²⁰⁷ Pb*/ ²⁰⁶ Pb* age of 2781 ± 9 Ma (2σ). These results provide the first direct evidence for the existence of Archean protoliths in the basement rocks of southeastern Papua New Guinea. -from Authors