The historic
Indo-Australian plate and the
Pacific plate have had oblique
convergence. This is when two
tectonic plates come together and collide at an odd angle rather than head-on, as has been the case, from the time the basin was formed. An example of oblique convergence would be if a plate moving north collided with another plate moving east, which results in a
transpressional regime. The overwhelming drag of the overriding Pacific plate caused the Solomon microplate to break away from the Indo-Australian plate, producing a mega shear zone between the two plates made up of at least two microplates. This shear zone has been named the
Nubara Fault, Nubara faults or
Nubara Transform Fault which is along the eastern part of the Woodlark Rise that separates at least two microplates, being the Solomon Sea plate and the Woodlark plate. The passive rifting and seafloor spreading in the Woodlark Basin has produced the Woodlark plate in the northern part of the basin, as a separate microplate from the present
Australian plate. The western end of the Woodlark Basin is still rifting towards the edge of
New Guinea. The Pocklington Rise and Plockington Trough separate the Woodlark Basin from the old subduction and spreading centers in the Australian plate from before 20 million years ago. A distinctive feature of the Woodlark Basin that scientists and researchers explored is the transition from continental rifting to sea floor spreading. The rifting at the western end of the basin has split the Woodlark Rise from the Pocklington Rise. It is one of few ocean basins that has been completely systematically mapped, resulting in tectonic model refinement over the last 50 years. Geological samples from the dark smoking chimneys showed the lack of the typical enrichment in gold or lead found in vents in back-arc settings (i.e. in contrast to the much older hydrothermal vents in the very western parts of the basin) and is consistent with basalt related hydrothermal fields along mid-oceanic ridges elsewhere.
Sediments The Woodlark Basin is very young and only started spreading around 3 million years ago, so that there is very little sediment in the basin relative to most
oceanic basins. These can have thousands of meters of sediment fill close to continental margins. The basin has a maximum thickness of 1500 meters of sediment fill in the deepest section of the North Moresby graben, however most of the basin is covered in less than 1000 meters of sediment. From the Cheshire Seamount in the western Woodlark Basin samples had been intensely hydrothermally altered from precursor andesitic to
rhyolitic composition with quartz growth, from over time
magmatic processes,
silicification,
chloritization, formation of
illite,
sericitic alteration, replacement of
plagioclase by
albite, and
sulfidation associated with concentration of
precious metals and other minerals. the relative light plate made of recent oceanic type basalt stays shallow. It is presumably being melted on mantle contact and producing the many arc volcanoes of the western Solomon Islands. The most recent change in spreading direction of the Woodlark Basin spreading center occurred about 450,000 years ago with a slowing in rate of divergence about 200,000 years ago. The Woodlark Basin originally began to open as a with a pole near the tip of eastern Papua about 20 million years ago. This spreading rift marks the southern boundary of the Solomon Plate, which is bounded by subduction zones in the north and east (the
New Britain and northern Solomon's trenches (e.g. North Solomon Trough) respectively), and in the west by a combination strike-slip rifting (dip-slip) boundary in eastern Papua (New Guinea). A vector triangle solution near the Solomons Trench-Woodlark Rift triple point gives underthrusting of the Solomons Plate beneath the North Solomon Trough in a northeasterly direction at about 11 centimeters per year. Even so, the Nubara Transform Fault to the north of the basin is accommodating of movement, In between the Woodlark Basin is subducted northeast beneath the
New Georgia Islands but here the deformation front lacks a flexed outer rise and bathymetric trench. In the Woodlark Basin the active low angle normal faults have a dips between 15°-35°, and are all located in the small range of 150.5° E to 152.5° E. This is the area in the Woodlark Basin where
seafloor spreading makes the transition to continental
rifting. The spreading centers are offset by transform faults, creating five segments, It is also known that prior to 4 million years ago seafloor spreading in the Woodlark Basin was up to east of the Simbo Transform where it ends today. ==Natural resources==