Animated reconstructions of the Late Cretaceous to Cenozoic northward migration of Australia, and implications for the generation of east Australian mafic magmatism

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 vol canism 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 edgedriven convection was an important process in the generation of both types of east Australian volcanic provinces.

Animated reconstructions of the Late Cretaceous to Cenozoic northward migration of Australia, and implications for the generation of east Australian mafic magmatism: REPLY

“…The global APWP of Besse and Courtillot (2002) is, in some ways, similar to the "longitudinal" Australian APWPs discussed in Jones et al (2017), in that they both show a period of westward divergence of the Australian plate between 25 and 20 Ma (Fig. 1A).…”

“…We appreciate the opportunity to discuss our paper on the Cenozoic mafic magmatism of eastern Australia and potential relationships to plate motion and are thankful to Musgrave and Schmidt (2019) for bringing the uncertainties and inconsistencies of Jones et al (2017) to our attention. The comments from Musgrave and Schmidt (2019) focus on the paleomagnetic record of Australian plate motion, so, to begin, we note that Jones et al (2017) did not include new paleomagnetic data. Instead, the paper presented new 40 Ar/ 39 Ar results from east Australian mafic rocks and evaluated them in light of tectonic reconstruction circuits compiled by Seton et al (2012).…”

“…When directly comparing APWPs and the GMHRF, reconstructed points were rotated using poles derived from the longitudinal APWP of Embleton and McElhinny (1982) and the "linear" APWP of Idnurm (1985). Because error margins are unavailable for the poles of Embleton and McElhinny (1982), the longitudinal reconstruction also utilized a combination of the smoothed bands of Embleton (1981), as described in the methodology of Jones et al (2017). To determine poles, we adopted a method similar to that proposed by Embleton (1981), whereby the ages of poles that satisfy the criteria of Besse and Courtillot (2002) were used with a sliding time window to calibrate the approximate age.…”

“…The errors in the figures are primarily due to misaligned overlays that occurred during the transfer from the reconstructions to the figures. A procedure similar to that used in the construction of figures 11 and 13 of Jones et al (2017) was used to determine the location of the GMHRF reference poles in figure 10 of Jones et al (2017), but with a reversed angle of rotation. Finite rotation poles were used in GPLATES (www.…”

Animated reconstructions of the Late Cretaceous to Cenozoic northward migration of Australia, and implications for the generation of east Australian mafic magmatism: COMMENT

“…A change in the age distribution of the shield volcanoes during the early Miocene and a corresponding deflection in the trends of the seamount chains were attributed by Knesel et al (2008) to a reduction in the rate and a change in the direction of Australian plate motion caused by its collision with the Ontong Java Plateau. In their paper, Jones et al (2017) examined changes in the significance of the age and direction trends of the eastern Australian shield volcanoes by comparing them to predictions for the absolute motion of the Australian plate defined by two competing apparent polar wander paths (APWPs) and the global moving hotspot reference frame (GMHRF) of Doubrovine et al (2012). We believe that significant errors have been made in the plate motion analysis, expressed as inconsistencies within and between their figures 10 through 13, which also invalidate the second of their two animated reconstructions for Australian plate motion.…”