Tectono‐metamorphic evolution of the Mary Kathleen fold belt, northwest Queensland: A reflection of mantle plume processes?

Abstract

The Proterozoic Mary Kathleen Fold Belt is one of the most intensely deformed fold belts within the Mt Isa Inlier (northwest Queensland), and contains key evidence for both extension and shortening, as well as a protracted thermal history culminating in a high temperature, low pressure amphibolite facies metamorphism. An early phase of extension (1780–1730 Ma) may have initially been responsible for basin development, and was subsequently associated with intense ductile shearing and multiple magma injection in a lower plate, and minor folding, extensional fracturing and emplacement of discrete intrusions in a more brittle upper plate. The subsequent regional deformation (D2) and metamorphism (1600–1500 Ma) involved east‐west directed compression, locally producing a variety of fold interference patterns by overprinting of F1 folds. This deformation resulted in tight folding of the early zone of high D1 strains into a large anticlinorium (the Wonga Belt). East of this zone, the effects of D2 dominate. The ...