Melanesian back-arc basin and arc development: Constraints from the eastern Coral Sea

Abstract

The eastern Coral Sea is a poorly explored area at the northeastern corner of the Australian 24 Tectonic Plate, where interaction between the Pacific and Australian plate boundaries, and 25 accretion of the world's largest submarine plateau-the Ontong Java Plateau-has resulted in 26 a complex assemblage of back-arc basins, island arcs, continental plateaus and volcanic 27 products. This study combines new and existing magnetic anomaly profiles, seafloor fabric 28 from swath bathymetry data, Ar-Ar dating of E-MORB basalts, palaeontological dating of 29 carbonate sediments, and plate modelling from the eastern Coral Sea. Our results constrain 30 commencement of the opening of the Santa Cruz Basin and South Rennell Trough to c. 48 31 Ma and termination at 25-28 Ma. Simultaneous opening of the Melanesian Basin/Solomon 32 Sea further north suggests that a single > 2,000 km long back-arc basin, with at least one 33 triple junction existed landward of the Melanesian subduction zone from Eocene-Oligocene 34 times. The cessation of spreading corresponds with a reorganization of the plate boundaries 35 in the area and the proposed initial soft collision of the Ontong Java Plateau. The correlation 36 between back-arc basin cessation and a widespread plate reorganization event suggests that 37 back-arc basins may be used as markers for both local and global plate boundary changes.

Rapid, semi-automatic fracture and contact mapping for point clouds, images and geophysical data

“…It is common in the geosciences to bring interpretations from multiple types of data into a single synthesis (e.g. Seton et al, 2016;Blaikie et al, 2017), especially when using geophysical datasets such as gravity and magnetics. Limiting factors during such data synthesis include both the time required and the highly subjective nature of multi-data-type interpretations, so a method for rapidly quantifying the extent to which different datasets support an interpretation serves as an important addition.…”

Geophysical and geological characterisation of dredge locations from RV Southern Surveyor voyage ss2012_v06 (ECOSATI): hotspot activity in northern Zealandia

“…The multibeam data were used for targeting of dredge site locations and to determine seafloor morphology. The swath data were combined with the existing Geoscience Australia bathymetry grid of the region to complete coverage, as presented in Seton et al (2016a). Slope and azimuth grids were derived for each dredge site location using GMT's gradient function (Wessel et al, 2013).…”

“…4b). As a sensitivity study, this process was repeated using a regional bathymetry compilation (Seton et al, 2016a), which included the detailed swath data from our dredge sites. As expected, our results show negligible difference in the resultant crustal thickness estimates between the two datasets, consistent with the small difference observed along profiles at the dredge sites ( Fig.…”

“…One hypothesis consistent with these observations is that mantle upwelling associated with the Lord Howe trail is genetically related to upwelling beneath the South Rennell Trough spreading centre. When spreading at the South Rennell Trough ceased due to the soft collision of the Ontong Java Plateau (Seton et al, 2016a), the upwelling could no longer find an outlet at a divergent plate boundary and switched into an intraplate hotspot mode.…”

Magma production along the Lord Howe Seamount Chain, northern Zealandia

“…Specifically, we investigate the relationship between the Lord Howe Seamount Chain and the South Rennell Trough, and whether some of the plateau and ridge features in the Coral Sea are likely candidates for the ultimate source of the age-progressive volcanism within eastern Australia and Zealandia. This paper can be considered a companion to Seton et al (2016) and Mortimer et al (2018).…”