Mesozoic Ocean Basins of the Circum-Arctic; Linking plate Tectonics and Mantle Dynamics

Grace Shephard

One of the most elusive aspects of global plate reconstructions since the breakup of Pangea is the tectonic evolution of the circum-Arctic. The kinematic complexity of region is largely driven by the opening and closing of ocean basins, including the South Anuyi, Oimyakon, Cache Creek, Panthalassa and Amerasia basins. Evaluating and refining plate kinematic models of the Arctic within a broader regional context is essential in analysing the formation and evolution of regional sedimentary basins and mountain belts and to provide a consistent large-scale framework of tectonic events. Here, we have integrated key observations from publicly available geological and geophysical datasets, and present a new plate tectonic reconstruction for the circum-Arctic and adjacent regions since the start of the Jurassic. We present a refined three-plate model for the opening of the Amerasia Basin, incorporating seafloor spreading between at least 142.5 and 120 Ma, a “windshield” rotation for the CA Basin and opening orthogonal to the Lomonosov Ridge for the northern Makarov and Podvodnikov basins. The time-dependent location of subduction, age of subducted lithosphere, convergence rates and intermittent ridge subduction as predicted by our model hold significant implications for the evolution of overriding plates and of the mantle structure. We use our new plate tectonic reconstruction of the circum-Arctic, embedded within a global plate model, to drive forward geodynamic models of mantle flow from which we can analyse the spatio-temporal evolution of subducted slab volumes, compare the present-day prediction of our model with P and S-wave tomography models and compute the spatio-temporal evolution of dynamic topography. We find that subducted slabs inferred from seismic velocity anomalies from global P and S wave tomography models can be linked to various episodes of Arctic subduction since the Jurassic, in particular to the destruction of the South Anuyi Ocean. Our workflow illustrates that analysing surface and mantle structure through predictions of subduction zones is a useful tool in refining plate tectonic models.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013