Lithospheric architecture of a Phanerozoic orogen from magnetotellurics: AusLAMP in the Tasmanides, southeast Australia

摘要: Abstract We present a resistivity model of the southern Tasmanides southeastern Australia using Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) data. Modelled lower crustal conductivity anomalies resemble concentric geometries revealed in upper crust by potential field and passive seismic These are key part architecture predicted Lachlan Orocline for evolution Tasmanides, which proterozoic Selwyn Block drives oroclinal rotation against eastern Gondwana margin during Ordovician period. For first time, we image these structures three dimensions (3D) show they persist below Moho. include conductor largely following northern margin. Spatial association between conductors both Paleozoic to Cenozoic mafic intermediate alkaline volcanism gold deposits suggests genetic i.e. fluid flow into resulting deposition conductive phases such as hydrogen, iron, sulphides and/or graphite. The 3D resolves different pattern lithospheric mantle, including northeast trending model. Three correspond leucitite volcanoes along Cosgrove mantle hotspot track likely map metasomatised source region volcanoes. northeasterly alignment correlates with variations lithosphere-asthenosphere boundary (LAB) direction plate movement, may be related movement an irregular LAB topography over asthenosphere. By revealing tectonic Phanerozoic orogen overprint more recent tectono-magmatic events, our enhances understanding geodynamic processes southeast Australia, demonstrating ability magnetotelluric data geological time.