Structural evolution of the Dayman dome metamorphic core complex, eastern Papua New Guinea

Abstract

Research Article| November 01, 2011 Structural evolution of the Dayman dome metamorphic core complex, eastern Papua New Guinea Nathan R. Daczko; Nathan R. Daczko † 1Geochemical Evolution and Metallogeny of Continents Australian Research Council (GEMOC ARC) National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Sydney, Australia †E-mail: nathan.daczko@mq.edu.au Search for other works by this author on: GSW Google Scholar Peter Caffi; Peter Caffi 1Geochemical Evolution and Metallogeny of Continents Australian Research Council (GEMOC ARC) National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Sydney, Australia Search for other works by this author on: GSW Google Scholar Paul Mann Paul Mann § 2Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas 78758-4445, USA §Current address: Department of Earth and Atmospheric Sciences, University of Houston, Houston, Texas 77204-5007; pmann@uh.edu Search for other works by this author on: GSW Google Scholar GSA Bulletin (2011) 123 (11-12): 2335–2351. https://doi.org/10.1130/B30326.1 Article history received: 07 May 2010 rev-recd: 13 Oct 2010 accepted: 21 Oct 2010 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Nathan R. Daczko, Peter Caffi, Paul Mann; Structural evolution of the Dayman dome metamorphic core complex, eastern Papua New Guinea. GSA Bulletin 2011;; 123 (11-12): 2335–2351. doi: https://doi.org/10.1130/B30326.1 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 SocietyGSA Bulletin Search Advanced Search Abstract A shallow-dipping ductile mylonitic shear zone and concordant brittle detachment fault (Mai'iu fault) together make up the dominant geological structure that controls the orientation of dip slopes on the flanks of Mount Dayman, eastern Papuan Peninsula, Papua New Guinea. The dip slopes dip in all directions from the peak of Mount Dayman and form a domed landform that is much less dissected by streams compared to the adjacent Mount Suckling domed landform. The orientation of megacorrugations on the domed surface of Mount Dayman (footwall) is consistent with NNE-directed transport of the hanging-wall block, which is composed of low-grade undifferentiated volcanic and sedimentary rocks and minor ultramafic rocks. Though previously documented as a thrust surface, the geometry and style of structures and map relations presented in this study indicate an extensional origin for the domed mylonitic foliation (S1) and mineral elongation lineation (L1). The field relationships are consistent with the domed landform comprising the core of a metamorphic core complex. Observations of dominantly NNE-trending regional lineaments in aerial photography and Shuttle Radar Topography Mission (SRTM) data correlate with detailed field analysis of mineral elongation lineations (L1) in the main metamorphic core complex–bounding shear zone. Field relationships show a crosscutting sequence of structures that includes: (1) ductile S2 folia with ESE-plunging blue sodic-calcic amphibole mineral elongation lineations; (2) narrow, steeply dipping ductile D2 shear zones; and (3) semibrittle to brittle fault zones. S-C′ fabrics, asymmetric strain shadows around porphyroclasts, and fault drag indicate a top-down-to-the-NNE sense of shear for most structures. Kinematic vorticity analysis of the highest-grade ductile deformation indicates a kinematic vorticity number (Wk) between 0.34 and 0.56, suggesting general shear for the early stage of deformation (D1). The NNE-directed lineaments and L1 mineral elongation lineations are consistent with the Australia-Woodlark Eulerian pole for periods between the early Pliocene (3.6 Ma) and Pleistocene (0.52 Ma). This observation is consistent with ca. 3.3 Ma granite and monzonite intrusions that cut the mylonitic fabrics and limit the age of the mylonitic fabrics to older than 3.3 Ma on Mount Suckling. A SE-dipping sedimentary sequence (Gwoira Conglomerate) characterizes part of the hanging wall of the metamorphic core complex. Petrography of the clasts within the sedimentary rocks indicates that metabasite rocks were the dominant source. The unit is in fault contact with the metabasite footwall across prehnite-bearing D3 brittle fault zones. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.