Novel dating of fluid-flow metallogenic events in East Tennant Creek region, Northern Territory, Australia: Insights from the coupled in-situ Rb-Sr and Ar-Ar geochronology of micas and feldspars
Date
2024
Authors
Alzubaidi, Osama Abdullah A
Editors
Advisors
Farkas, Juraj
Collins, Alan
Collins, Alan
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Abstract
This study investigates and contributes to a relatively underexplored mineral resources of Australia, with a specific focus on the metalliferous East Tennant Creek region in the Northern Territory. The East Tennant region is highly prospective for IOCG-style deposits hosting gold, copper, and bismuth mineralisation, like the historically productive deposits in the broader Tennant Creek Mineral Field. The conventional exploration methods, including geochemistry and geochronology, applied in this region are problematic due to the extensive cover of sedimentary rocks, which thus limits the exploration to sparse outcrops and legacy drillholes intersecting the underlying and metal-bearing bedrock. To partly address these challenges, this project employs an innovative and relatively novel and non-destructive geochronology technique based on laser-ablation or in-situ Rb-Sr dating via LA-ICP-MS/MS, which is coupled with more traditional 40Ar-39Ar dating, to investigate possible timing or ‘age’ of the local and regional metalliferous events affecting the Tennant Creek region. The combination of the above geochronological techniques, applied to K-rich minerals (micas, feldspars), helped to constrain the geological/tectonic history of the studied region and possible timing of mineralisation, thus overcoming some of the inherited limitations posed by the complex geology and limited access in the study area. The project’s findings and conclusion indicate that the Rb-Sr and 40Ar-39Ar dating in the East Tennant Creek region reveal several geological events spanning from 1315 Ma to 1846 Ma. Notably, the similar ages of Rb-Sr biotite (1846 ± 40 Ma) and 40Ar-39Ar muscovite (1837.8 ± 3.3 Ma) in sample NDIBK08.010 indicate shared metamorphism and deformation event(s) within the Murphy and Warramunga Provinces. The oldest Rb-Sr biotite age (1846 ± 40 Ma) suggests IOCG mineralisation occurred between 1840 and 1860 Ma, in agreement with published studies. Sample NDIBK10.008's 40Ar-39Ar biotite age (1867.7 ± 5.5 Ma) and U-Pb zircon age (1867.5 ± 4.8 Ma) marks the original metamorphic stages, supported by U-Pb dating aligning with the Barramundi Orogeny (1880–1850 Ma), a period of significant crustal reworking and high-grade Au-Cu-Bi deposit formation. Subsequent tectonic reactivations occurred at ~1777 to 1723.6 ± 8.9 Ma after the Barramundi Orogeny, indicating additional tectonic and thermal events that influenced the geological and mineralisation history of the region. Finally, younger Rb-Sr ages (1315 ± 27 Ma, 1437 ± 160 Ma, 1539 ± 78 Ma, and 1575 ± 114 Ma) acquired from micas (sericite) and K-feldspar point to much younger or secondary (Mesoproterozoic) thermal/hydrothermal events, thus significantly postdating the main mineralisation phase (~1840 to 1860 Ma) in the East Tennant Region.
School/Discipline
School of Physics, Chemistry and Earth Sciences
Dissertation Note
Thesis (MPhil) -- University of Adelaide, School of Physics, Chemistry and Earth Sciences, 2024
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