Protracted Neoarchean high-temperature–moderate-pressure metamorphism recorded in the granulite-facies Katanning Gold Deposit, Southwest Yilgarn Craton, Western Australia

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The 1.33 Moz Katanning Gold Deposit (KGD) is hosted by Neoarchean granulite-facies volcanosedimentary rocks of the Katanning Greenstone Belt (KGB), Southwest Yilgarn Craton, Western Australia. The pressure–temperature-time (P-T-t) evolution of these high-grade metamorphic rocks remains poorly constrained, limiting our understanding of the tectono-thermal framework in which gold mineralisation developed. We present P-T estimates and in situ Lu-Hf garnet geochronology for mafic, felsic, and metasedimentary migmatites to establish the timing and conditions of metamorphism across the KGD. Mafic samples yield slightly lower pressures and higher apparent thermal gradients (4.4–6.4 kbar; ∼135–210°C/kbar) than felsic (6.5–7.5 kbar; ∼140–110°C/kbar) and metasedimentary samples (∼5.5 kbar; ∼140°C/kbar). The P-T estimates at the KGD reflect high-temperature–moderate-pressure, granulite–facies conditions (780–930°C; 4.4–7.5 kbar), with modelled melt fractions from ∼0–25 vol% and approximate burial to mid-crustal paleodepths (∼22 km), in agreement with estimates for the Corrigin Tectonic Zone (CTZ). Almandine-rich garnets display subdued yttrium-rich cores and flattened major-element compositional zoning, including Y-Cr-Mn enrichment in narrow rims, consistent with prograde growth followed by intracrystalline diffusion and continued garnet growth during prolonged granulite-facies residence. These garnets yield an in situ Lu-Hf weighted mean age of 2702 ± 15 Ma, interpreted to record the time-integrated garnet growth from prograde through peak metamorphic conditions. Maximum depositional and Lu-Hf garnet ages of metasedimentary migmatitic gneiss indicate apparent burial rates for the KGB consistent with active tectonic burial. The high-temperature thermal regime that affected the KGD was relatively long-lived, initiating shortly after or coeval with the KGB volcanosedimentary deposition (∼2710–2680 Ma) and culminating at ∼2650 Ma with the cooling of anatectic melts. This event overlaps locally with the emplacement of a TTG intrusion at ∼ 2670 Ma and, regionally, with widespread high-Ca TTG magmatism between ∼2680–2660 Ma across the Yilgarn Craton, the UHT metamorphism in the Narryer Terrane (∼2690–2660 Ma), and the low- to high-temperature metamorphism in the Kalgoorlie Terrane (∼2680–2665 Ma). The high to ultrahigh apparent thermal gradients and older metamorphic ages obtained for the KGD are consistent with the involvement of diverse heat sources during a dynamic and protracted Neoarchean tectono-metamorphic evolution throughout the Yilgarn Orogeny (∼2730–2630 Ma).

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