Building Global Kinematic Plate Reconstructions Through the Phanerozoic: Testing Alternative Models for the Amalgamation of Pangea

Abstract

Kinematic plate models that reconstruct the positions of tectonic plates and their boundaries through time are useful in elucidating the geological and tectonic history of a region—essential knowledge in determining regional resource potential. We are using the open-source GPlates software to develop global Phanerozoic kinematic plate reconstructions. The models include continuously closing plate boundaries, whose construction is helpful for testing the consistency of any given model with the rules of plate tectonics. As we extend our models back through the Paleozoic, and data constraints become more sparse, the integration of disparate data sets and the strict adherence to the rules of plate tectonics become essential in producing geologically sound global pre-Pangea plate models. The position of Laurussia relative to Gondwana prior to the amalgamation of Pangea is a major on-going controversy, with different scenarios implying distinct histories of passive margin evolution and basin formation. Models based primarily on paleomagnetic data tend to require large dextral strike-slip motions (up to 8400 km) to bring Laurussia into its Pangea configuration during the Devonian–Carboniferous Variscan Orogeny. These models of the orogeny involve multiple terranes, representing portions of present-day Spain, France and Germany, each with distinct motions, and multiple ocean basins separating them. Models more strongly biased towards honouring the juxtaposition of faunal and geological provinces, as well as geochronological data, involve more orthogonal collision during the Variscan Orogeny, and imply most or all of the European terranes remained connected to Gondwana until Pangea dispersal. We investigate these end-member models using alternative plate reconstructions that are consistent with paleomagnetic data. Strike-slip amalgamation requires Laurussian plate velocities up to 18 cm/yr, which is unreasonably high for a plate comprising a large continent, whereas orthogonal convergence implies velocities more consistent with the rules of plate tectonics. Other testable predictions from the kinematic models of each scenario are compared with geological and paleomagnetic data. Iteratively applying this approach allows us to expand the global model both in regional detail, and further back through time. Future work will extend the model back to Rodinia, and will add in complexity, such as deforming regions within a global tectonic framework.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015