‘Boomerang’ migratory intraplate Cenozoic volcanism, eastern Australian rift margins and the Indian-Pacific mantle boundary

The Tamar Trough revisited: correlations berween sedimentary beds, basalts, their ages and valley evolution, North Tasmania

“…This is compatible with a proposed model for quasi-continuous, but episodic Tasmania volcanism that resulted from lithospheric drift of eastern Australia over an extended Tasman Sea plume zone (Sutherland et al 1989). Furthermore, precise Tasmanian basalt ages (Sutherland et al 2004, Everard et al 2004b) and better-controlled Australian plate motion paths back to 80 Ma (Sutherland 2003) now allow more detailed testing of the Tasman margin magma source model for Tasmanian volcanism. A fuller development will be given elsewhere, but for this Tamar Trough study a simplified model that relates the Tamar basalts to migratory links through eastern Victoria is presented in figure 8.…”

“…2004. The lithosphere here lies on the outskirts of a dormant mantle plume in the asthenosphere under Bass Basin, which acted as a trigger for hotspot volcanism along eastern Australia (Sutherland 2003) and is imaged down to ~ 650 km depth (Montelli et al 2004). The crust here, however, is presently under compression with a mean horizontal stress maximum along a WNW-ESE direction (Clark & Leonard 2003).…”

“…The origin of this HIMU imprint in southern Australasia and Antarctic basalts is uncertain, but may relate to mantle events around 80-100 Ma; it possibly stems from a large plume head or a series of small plumes developed with late Gondwanan break-up (see Lanyon et al 1993, Lanyon 1994, Sutherland 1994, Crawford et al 1997. The HIMU character in some basalts within Tasmania and in the Tasmanian seamounts (p. 19-20.3;Ewart et al 1988, Lanyon et al 1993, Lanyon 1994, Crawford et al 1997, Sutherland 2003, Zhang et al 2006) becomes more pronounced in many Antarctic basalts (p. > 20.5; Rochell etal. 1995, Panter etal.…”

“…Whatever the precise origins of the HIMU-and garnet-bearing sources for the Tamar alkaline basalts, the Tamar tholeiites also reflect variations in source inputs. Tasmanian olivine tholeiites include co-existing types that differ in trace element and Pb isotope signatures, even at similar Mg-values and compatible element contents (Sutherland 2003, Sutherland et at. 2004.…”

Late Neogene and Quaternary Vertical Motions in the Otway Coast, Southeast Australia (II): Epeirogenic Uplift Driven by Lithospheric Flexural Deformation

“…The up-down motion in lithospheric flexure is described by stretching of the lithosphere and subsequent upwelling by isostatic compensation between the lithosphere and the asthenosphere. Possible causes vary for example, localized isostasy, a set of faulting in the lithosphere, convecting anomalously hot mantle, and igneous material injection like a mantle plume (Sutherland, 2003;Demidjuk et al, 2007). Herein, this study provides geophysical analyses such as gravity anomaly, tectonic structure and in-situ stress field to explain the nature and possible mechanism for the neotectonic movements in the Otway Ranges, SE Australia.…”