Characterization of a proposed Palaeoproterozoic suture in the crust beneath the Curnamona Province, Australia

Abstract

We use constrained forward and inverse modeling of Bouguer gravity data to investigate a regional positive gravity anomaly that defines, but is not confined to, the eastern margin of the Curnamona Province. Best-fit results imply that the positive gravity values are sourced from a relatively dense terrane (+ 0.04 Mg m − 3 with respect to surrounding crust) located at middle crustal levels (16–27 km depth), which is likely dismembered and offset into discrete slivers by later tectonism. Consideration of pre-1500 Ma plate reconstructions of the Australian continent correlates this terrane with an interpreted buried suture in the Mount Isa Inlier of northern Australia, where allochthonous crust was amalgamated to the Australian margin at ca. 2.20–1.85 Ga. Bouguer gravity forward and inverse modeling also delineates a shallow, west-dipping crustal-scale structure that possibly represents a primary boundary between Precambrian basement of Australia and the eastern fold belts accreted to the Precambrian margin during the Palaeozoic.