High-strain deformation and fluid infiltration diachronism of the middle crust: New Devonian–Permian Alice Springs ages (365–290 Ma) of shear zones in the Strangways Metamorphic Complex, Central Australia

Glimmerite: A product of melt-rock interaction within a crustal-scale high-strain zone

“…Notably, the most significant 658 age peak from the kernel density estimation occurs at c. 451 Ma (Fig. 14b), consistent with U-659 Pb monazite ages from similar shear zones of the Strangways Range (Möller et al, 1999;660 Howlett et al, 2014;Fournier et al, 2016). This timing reflects the earliest onset of the Alice 661 Springs Orogeny recorded regionally (Mawby et al, 1999;Raimondo et al, 2014), perhaps 662 suggesting a peak in melt-rock interaction and the replacement or resetting of inherited 663 monazite driven by large-scale changes to deep crustal architecture and basin dynamics that 664 initiated at this time.…”

Pressure–temperature–time constraints on gneiss dome formation in an intracontinental orogen

“…This juxtaposition reflects substantial thinning of the HRG, with a present-day structural thickness of $6 km compared with an original stratigraphic thickness of 20-35 km (Figure 11c; Maidment et al, 2013;Tucker et al, 2015). On a regional scale, the distribution of ages in country rocks of the EGC align more closely with the episodic record of prograde metamorphism in hydrated crustalscale shear zones of the adjacent Strangways Metamorphic Complex (SMC; Figure 1b) (Ballevre et al, 2000;Bendall, 2000;Fournier et al, 2016;Piazolo et al, 2020) and periods of syn-orogenic sedimentation (Haines et al, 2001), particularly at c. 380, c. 360, c. 340, and c. 330-310 Ma. The overlap in timing of metamorphism and partial melting in the EGC (Figure 2) and meltpresent deformation in shear-zones of the adjacent SMC suggests that pre-orogenic hydration played an important role in crustal fertility and sustained deformation along the eastern margin of the Alice Springs Orogen.…”

“…The Entia Gneiss Complex (EGC) is located in the Harts Range, central Australia (Figure 1a,b) and represents the exhumation of Paleoproterozoic granulite facies basement that underwent hydration and recrystallization at amphibolite facies conditions during the Palaeozoic intracontinental Alice Springs Orogeny (ASO; 450-300 Ma) (Buick et al, 2008;Fournier et al, 2016;Hand, Mawby, Kinny, & Foden, 1999;Piazolo et al, 2020;Prent et al, 2020;Silva et al, 2018). The EGC crops out in an approximately elliptical domal structure that is 25 Â 15 km in diameter along its major and minor axes, respectively, and contains two antiformal culminations referred to as the Inkamulla and Huckitta sub-domes (Figure 2).…”