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Flexural Modeling of the Colville Foreland Basin, Northern Alaska
  • Muhammad Hassan Quddusi,
  • Mortaza Pirouz
Muhammad Hassan Quddusi
The University of Texas at Dallas

Corresponding Author:[email protected]

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Mortaza Pirouz
The University of Texas at Dallas
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Abstract

In this study, we model the flexure of the Colville foreland basin in northern Alaska and calculate the effective elastic thickness (Te) of the Arctic Alaska terrane with a simple 3D flexural model. Previous studies show that the elastic thickness of northern Alaska is 65 km; however, the wavelength of the Colville foredeep is considerably shorter for such an elastic thickness and indicates a thinner elastic thickness for the area. Seismicity of crust, as a direct indicator of the mechanical strength, reduces considerably at a depth of 25 km in northern Alaska. We address these contrasting observations with a 3D flexural model to better understand elastic thickness constraints for the north of the Alaska lithosphere. We constrained Colville basin geometry with a structural map of the foredeep, where the maximum depth reaches 8 km towards the southwest of the basin. The flexural deflection model of northern Alaska considers various parameters, and results are compared to the observed data to obtain the best fit model. We applied basin and topographic loads, including a crustal root load with a ratio of 3.4-4.5 times to modern topography. Our obtained elastic thickness value is 13-16 km, with less than a 3% average misfit between the model and the observation. The results of this study indicate that the Colville basin geometry is mainly controlled by loads of the Brooks Range and basin deposits, and additional loads or density anomalies in the crust are not required for the deflection of the basin.