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Evaluating the Consistency of Plate Models With Geologic Observations

Abstract

Paleogeographic reconstructions, and the plate models that underlie them, are fundamental tools in hydrocarbon play assessment. However, a multitude of current plate models exist with substantive differences in their implications for a given hydrocarbon system. Here we present a method involving a series of tests for evaluating the consistency of a plate model with a standardized set of geologic and geophysical observations. Using applicable tests, a user can make an objective selection of a plate model for a given geographic area and technical objective. Plate models can be evaluated based on their ability to reproduce oceanic fracture zones, hotspot tracks, paleolatitude observed via paleomagnetism, intracratonal deformation, timing of rift initiation, and crustal thickness in the incipient rift zone. Least squared residuals between model predictions and geologic observations are used to assess the models' accuracy. Tolerances are based on the standard deviation of the following criteria: average crustal thickness, 95% confidence ellipses for Paleomagnetic data, Ar39/Ar40 age uncertainties for rift associated magmatism, and azimuthal deviation of linear modeled features from observed linear features (fracture zones, hotspot tracks, and intracratonal geologic lineaments). A test application of this method to 6 different academic and commercial plate models along the south Atlantic margin demonstrates major discrepancies between models in paleo latitude, pre rift crustal thickness, timing of rift initiation, and intracratonal deformation. However, some models do pass all of the listed tests. We suggest that these models support the most likely predictions regarding hydrocarbon system elements, based on their ability to also reproduce known geologic features.