摘要
The Early–mid Cretaceous marks the confluence of three major continental-scale events in eastern Gondwana:(1)the emplacement of a Silicic Large Igneous Province(LIP)near the continental margin;(2)the volcaniclastic fill,transgression and regression of a major epicontinental seaway developed over at least a quarter of the Australian continent;and(3)epeirogenic uplift,exhumation and continental rupturing culminating in the opening of the Tasman Basin c.84 Ma.The Whitsunday Silicic LIP event had widespread impact,producing both substantial extrusive volumes of dominantly silicic pyroclastic material and coeval first-cycle volcanogenic sediment that accumulated within many eastern Australian sedimentary basins,and principally in the Great Australian Basin system(>2 Mkm^(3)combined volume).The final pulse of volcanism and volcanogenic sedimentation at c.105–95 Ma coincided with epicontinental seaway regression,which shows a lack of correspondence with the global sea-level curve,and alternatively records a wider,continental-scale effect of volcanism and rift tectonism.Widespread igneous underplating related to this LIP event is evident from high paleogeothermal gradients and regional hydrothermal fluid flow detectable in the shallow crust and over a broad region.Enhanced CO_(2)fluxing through sedimentary basins also records indirectly,large-scale,LIP-related mafic underplating.
