Provenance, tectonic setting and source of Archean metasedimentary rocks of the Browns Range Metamorphics, Tanami Region, Western Australia

Nazari-Dehkordi, T., Spandler, C., Oliver, N.H.S., Chapman, J., and Wilson, R. (2017) Provenance, tectonic setting and source of Archean metasedimentary rocks of the Browns Range Metamorphics, Tanami Region, Western Australia. Australian Journal of Earth Sciences, 64 (6). pp. 723-741.

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This study combines U-Pb age and Lu-Hf isotope data for magmatic and detrital zircons, with whole-rock geochemistry of the Browns Range Metamorphics (BRM), Western Australia. The BRM are medium- to coarse-grained metasandstones that consist of angular to sub-rounded detrital quartz and feldspars with minor granitic lithic fragments. The sequence has undergone partial to extensive quartz-muscovite alteration and rare-earth-element mineralisation and has been intruded by mafic/ultramafic, syenitic and pegmatitic intrusive rock units. Uranium-Pb and Lu-Hf isotopic data on detrital zircons from the metasandstones and intruding granitic rocks yield a well-defined age of ca 3.2 to ca 3.0 Ga for all samples, with relatively radiogenic E-Hf values (E-Hf = -1.7 to 5.1) indicating derivation from Mesoarchean granite basement of juvenile origin. This is consistent with geochemical and petrological data that support deposition from a granitic source in a continental rift basin setting. The timing of sediment deposition is constrained between the ca 3.0 Ga age of the source rocks and ca 2.5 Ga age of the granitic intrusive bodies that cross-cut the metasedimentary rocks. The ca 2.5 Ga zircons from the intrusive rocks have E-Hf model ages of ca 3.4 to ca 3.1 Ga, which is consistent with formation via partial melting of the BRM, or the Mesoarchean granite basement. Zircons of the Gardiner Sandstone that unconformably overlies the BRM return detrital ages of ca 2.6 to ca 1.8 Ga with no trace of ca 3.1 Ga zircons, which discounts a significant contribution from the underlying BRM. The Mesoarchean age and isotopic signatures of the BRM zircons are shared by some zircon records from the Pine Creek Orogen, and the Pilbara, Yilgarn and Gawler cratons. Collectively, these records indicate that juvenile Mesoarchean crust is a more significant component of Australian cratons than is currently recognised. This work also further demonstrates that detrital minerals in Paleoproterozoic/Archean sedimentary rocks are archives to study the early crustal record of Earth.

Item ID: 51004
Item Type: Article (Research - C1)
ISSN: 1440-0952
Keywords: U-Pb dating, Lu-Hf isotope, Mesoarchean, Browns Range Metamorphics, Western Australia, Tanami, zircon, arkose, North Australia Craton, HREE
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A version of this publication was included as Chapter 2 of the following PhD thesis: Nazari Dehkordi, Teimoor (2018) The origin and evolution of heavy rare earth element mineralisation in the Browns Range area, Northern Australia. PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: Australian Research Council (ARC), Northern Minerals Ltd.
Projects and Grants: ARC Future Fellowship FT120100198
Date Deposited: 04 Oct 2017 07:35
FoR Codes: 37 EARTH SCIENCES > 3705 Geology > 370502 Geochronology @ 50%
37 EARTH SCIENCES > 3703 Geochemistry > 370303 Isotope geochemistry @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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