Abstract
Details of the Late Cretaceous–Cenozoic migration of the Australian continent have been sources of contention since the 1960s. Two types of apparent polar wander paths (APWPs) have emerged from previous paleomagnetic studies: one group based on sedimentary and lateritic data that includes relatively linear northward motion of Australia away from Antarctica, and a second group, based on basaltic and lateritic data, that includes significant longitudinal movement of the Australian continent. This study compares the migration and evolution of the Australian plate over the past 100 m.y. using these two competing paths. Our animated reconstructions illustrate the relative motion of the Australian plate, the formation of Cenozoic volcanic provinces in eastern Australia, the opening of the Coral and Tasman Seas, and the docking of the Ontong Java Plateau with the Solomon Islands. The reconstructions incorporate new 40 Ar/ 39 Ar and previously published geochronology data from Late Cretaceous to Cenozoic east Australian mafic to felsic volcanism in order to evaluate potential relationships between volcanism, changes in the motion of the Australian plate, and the opening of the Tasman and Coral Seas. We conclude that the APWP that includes significant longitudinal movement is more compatible than the linear path with both observable geological features (such as volcanic tracks) and the global moving hotspot reference frame. Our reconstructions reveal little correspondence between opening of the Tasman and Coral Seas and eruption of east Australian lava fields. However, the reconstructions and new 40 Ar/ 39 Ar geochronology illustrate that the formation of east Australian Late Cretaceous to Cenozoic central volcanoes and lava fields were closely linked, both temporally and spatially, and we suggest that edge-driven convection was an important process in the generation of both types of east Australian volcanic provinces.
Highlights
The generation of basalts is frequently ascribed to the processes of rifting and hotspot activity (e.g., Wilson, 1963; White and McKenzie, 1989)
We compared the linear apparent polar wander paths (APWPs) of Idnurm (1985), the longitudinal APWP of Embleton and McElhinny (1982), and synthetic virtual geomagnetic poles (VGPs) derived from the global moving hotspot reference frame (GMHRF) model of Doubrovine et al (2012; Fig. 10)
Based on the overall fit of the GMHRF synthetic VGPs to the APWPs and the approximate relative plate speeds, we find that the GMHRF is more similar to the longitudinal APWP than the linear APWP
Summary
The generation of basalts is frequently ascribed to the processes of rifting and hotspot activity (e.g., Wilson, 1963; White and McKenzie, 1989). The Late Cretaceous through Cenozoic magmatic history of eastern Australia is possibly somewhat unique in that it includes periods of what have been previously described as both rift-related and hotspot-related basaltic magmatism that overlapped in time and space (e.g., Fig. 1; Wellman and McDougall, 1974a). A series of onshore and offshore, age-progressive, bimodal shield volcanoes that decrease, at least in part, in both age and volume to the south have been attributed to the northward motion of Australia over stationary and irregularly active (but primarily waning) mantle plumes (e.g., Wellman and McDougall, 1974a; Cohen et al, 2007; Sutherland et al, 2012; Jones and Verdel, 2015). An apparent late Oligocene to early Miocene period of significant plate slowdown has previously been linked to docking of the Ontong Java Plateau (OJP; Fig. 2) with the Solomon Islands (Knesel et al, 2008)
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