University of Tasmania
Browse

File(s) under permanent embargo

The Tam Ky-Phuoc Son Shear Zone in central Vietnam: tectonic and metallogenic implications

journal contribution
posted on 2023-05-18, 01:17 authored by Tran, HT, Khin ZawKhin Zaw, Jacqueline HalpinJacqueline Halpin, Manaka, T, Sebastien MeffreSebastien Meffre, Lai, C-K, Lee, Y, Le, HV, Dinh, S
The Tam Ky-Phuoc Son Shear Zone (TKPSSZ) is one of the most pronounced crustal structures in central Vietnam and juxtaposes high-grade rocks of the Kontum Massif against lower grade rocks of the Truong Son Fold Belt. An internal zone comprises highly strained rocks, including ultramafic–mafic tectonites, bounded by mylonitic zones that straddle tens to hundreds of kilometers. An external zone comprises mainly high-grade metamorphic complexes (southern flank), and weakly metamorphosed siliciclastic and carbonate rocks with subordinate greenstone (northern flank). Detailed structural analysis reveals that the shear zone is a multi-deformed terrane: D1 produced a regional high grade schistosity and mylonitization; D2 generated regional northwest–southeast trending fold arrays and brittle–ductile shear zones; D3 locally produced northeast-trending folds; brittle faulting occurred during D4–D5. U–Pb dating of zircon and monazite suggests that D1 involved metamorphism and felsic magmatism at ca. 430 Ma, recording part of a regional collisional orogeny. Monazite and titanite growth at ca. 250–240 Ma in basement rocks is synchronous with widespread syn- to post-D2 magmatism between ca. 260 and 245 Ma suggesting a second major collisional event during the Indosinian Orogeny. D3 may have occurred as part of (or soon after) this Permo-Triassic event. Deformation during post-collisional stages, perhaps in response to extrusion/wedging and oroclinal rotation of terranes, led to post-D3 structures (D4–D5). The E–W trending TKPSSZ is here shown to be a continuation of the N–S trending Po Ko Shear Zone (PKSZ). Most of the significant lode gold occurrences in central Vietnam occur along this TKPSSZ–PKSZ structure and are associated with, and controlled by, D1 ductile to ductile–brittle high-strain zones. Mineralized later-stage structures support remobilization and reconcentration of ore during subsequent events at ca. 240 Ma (Re–Os molybdenite age). The TKPSSZ–PKSZ D1 structure likely represents part of a paleosuture zone, marking the closure of an ancient ocean basin through terrane assembly in the Early Paleozoic.

History

Publication title

Gondwana Research

Volume

26

Pagination

144-164

ISSN

1342-937X

Department/School

School of Natural Sciences

Publisher

Int Assoc Gondwana Research

Place of publication

Kochi Univ, Faculty Science Akebono-Cho 2-5-1, Kochi, Japan, 780-8520

Rights statement

Copyright 2014 Elsevier

Repository Status

  • Restricted

Socio-economic Objectives

Precious (noble) metal ore exploration

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC