Fig. 8. Tectonomagmatic evolution of the Waroonga greenstone belt (WGB) and the Yilgarn lithosphere.

Cartoon outlining the tectonomagmatic evolution of the WGB and the Yilgarn lithosphere in the Meso- to Neoarchean. Note the change of scale from (a) to (b). a Long-term plate configuration characterized by the convergence between the Narryer (NT) and the Youanmi-Eastern goldfields terranes (YT and EG, respectively). Volcanism with an arc signature occurred in the Murchison⁴¹ (Mu), Marda⁶³ (Md) and Cosmos⁶¹(Cs) areas. b The pre-orogenic period (until c.2750 Ma⁴⁰) reflects the accumulation of a thick greenstone pile dominated by mafic–ultramafic volcanic rocks interlayered with BIFs, devoid of any clastic input⁴⁰. The WGB developed at c. 2820 Ma, in the vicinity of the proto-Ida Fault. c Synmagmatic shearing along large-scale, east-dipping contractional structures, together with subaerial volcanism and development of high-energy sedimentary basins above a regional unconformity, mark the onset of the Neoarchean orogeny. Meanwhile, the WGB was buried to lower-crustal depths (12–13 Kbar³⁵), along the Ida Fault, and subsequently partly exhumed to mid-crustal levels (7 kbar). Coeval volcanism with arc affinity occurred in the Cosmos area (Cs)⁶¹.d Mafic–ultramafic magmatism along the eastern margin of the Youanmi Terrane produced the Kalgoorlie Group greenstone sequence¹⁰ (KG). Asthenospheric magma (pictured in dark blue) was likely channelled along the main crustal-scale structure in the area, the Ida Fault. e Late-orogenic exhumation of the WGB took place along the Waroonga shear zone³⁵, which channelled the emplacement of the syntectonic Waroonga Gneiss, transporting slivers of the WGB to their present position.