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

Abstract

Research Article| November 01, 1995 A tale of two eras: Pliocene-Pleistocene unroofing of Cenozoic and late Archean zircons from active metamorphic core complexes, Solomon Sea, Papua New Guinea Suzanne L. Baldwin; Suzanne L. Baldwin 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Search for other works by this author on: GSW Google Scholar Trevor R. Ireland Trevor R. Ireland 2Research School of Earth Sciences, Australian National University, Canberra ACT 0200, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information Suzanne L. Baldwin 1Department of Geosciences, University of Arizona, Tucson, Arizona 85721 Trevor R. Ireland 2Research School of Earth Sciences, Australian National University, Canberra ACT 0200, Australia Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1995) 23 (11): 1023–1026. https://doi.org/10.1130/0091-7613(1995)023<1023:ATOTEP>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Suzanne L. Baldwin, Trevor R. Ireland; A tale of two eras: Pliocene-Pleistocene unroofing of Cenozoic and late Archean zircons from active metamorphic core complexes, Solomon Sea, Papua New Guinea. Geology 1995;; 23 (11): 1023–1026. doi: https://doi.org/10.1130/0091-7613(1995)023<1023:ATOTEP>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract 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 206Pb*/238U ages. No inherited zircons were identified in the granodiorites, and the 206Pb*/238U ages (1.65 ± 0.18 Ma; 1.98 ± 0.08 Ma [2σ]) are interpreted as crystallization ages. These synkinematically emplaced granodiorites, intruded into actively extending continental crust, are some of the youngest known granitoids currently exposed at the Earth' surface. Zircon ages from felsic gneisses (2.63 ± 0.16 Ma; 2.72 ± 0.28 Ma [2σ]) are interpreted to date zircon growth subsequent to eclogite facies metamorphism. Felsic gneiss samples also contained zircon xenocrysts from Cretaceous-Miocene protoliths. In striking contrast, zircons from igneous and metamorphic clasts from the Goodenough No. 1 well indicate a single population with a 207Pb*/206/Pb* age of 2781 ± 9 Ma (2σ). We speculate that they are derived from basement rocks unroofed during initial stages of development of the D&Entrecasteaux metamorphic core complexes. These results provide the first direct evidence for the existence of Archean protoliths in the basement rocks of southeastern Papua New Guinea. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.