3-D Plate Tectonic Reconstructions of New Guinea Since the Triassic

Abstract

Understanding the tectonic evolution of an area is critical for assessing its hydrocarbon potential, such as predicting heat flow and maturity, sediment type/distribution and structural style. We use time-dependent 3D plate reconstruction and mantle flow modeling to study the geodynamic evolution of New Guinea in a regional and global context. Detailed regional plate reconstructions in this area are difficult because no seafloor is preserved, while remnants of multiple generations of back-arc and intra-oceanic subduction systems are dismembered along many suture zones in remote parts of New Guinea. However, decades of sampling and mapping can be synthesized with the geological record of neighboring regions, including Southeast Asia and the Southwest Pacific, to generate self-consistent plate motion models. We apply a modern plate reconstruction approach using GPlates to model evolving topological plate boundaries resulting from a synthesis of geological and geophysical constraints. The plate reconstructions act as surface boundary conditions for numerical mantle flow simulations using CitcomS, enabling us to track the time-dependent trajectory of subducted slabs in the mantle, as well as the vertical deflection of the surface from convection in the mantle (i.e., dynamic topography). We test alternative scenarios for the emplacement of the Central Ophiolite Belt in Jurassic times, which was likely obducted following the accretion of the Sepik composite terrane by Late Eocene times. In addition, we implement a scenario of Caroline Arc accretion on the New Guinea margin from Miocene times, resulting in double-vergent subduction of the Solomon Sea Plate. The onset of widespread shallow marine carbonate deposition from Late Oligocene times is consistent with New Guinea overriding “slab burial grounds” that we reproduce in our geodynamic modeling workflow, validated using the distribution of slab material interpreted from P- and S- wave seismic tomography. Our approach, which enables progress beyond simple schematics and continental drift concepts by harnessing data-driven geodynamic modeling of the plate-mantle system, is powerful for frontier hydrocarbon exploration. Future work will use velocities extracted from the plate reconstructions to guide regional numerical models of the fold and thrust belt using realistic rheologies to better constrain the nature and chronology of deformation in New Guinea and surrounding regions.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015