Crustal-scale evolution of northern Alaska

Principal Investigators:

Catherine L. Hanks
Wesley K. Wallace

Participating scientists:

Robert Lillie (Oregon State University)
Brian Whiting (College of William and Mary)

The North Slope of Alaska is a major hydrocarbon-producing region of North America, but its geologic setting is still incompletely understood. This is in part due to the tectonic history of northern Alaska, where there is a complex interplay between the formation of the Brooks Range collisional orogen and the development of the nearby north Alaska rifted continental margin. Understanding the crustal-scale evolution of the Brooks Range, Colville basin and Arctic margin can provide new constraints on the initiation and growth of both the mountain belt and the adjacent foredeep, as well as the depositional and thermal history of the basin.

This is a multidisciplinary study that uses existing gravity data and models of the present-day crustal architecture of the Brooks Range in combination with regional balanced cross sections to develop and test models for the kinematic evolution of northern Alaska. These models begin before collision and proceed forward in time to the present day in order to develop a dynamic image of how the mountain belt, adjacent foredeep, and new continental margin developed through time. Estimates of the amount and timing of uplift and unroofing within the range are incorporated into the models in order to evaluate the effect of erosion and isostatic rebound on the gravity signature and resulting crustal models, and the effect of sediment loading on the subsequent growth of the Colville basin.

The resulting crustal-scale model of the evolution of the Brooks Range and adjacent Colville basin provide a regional model for the geologic development of this part of the Cordillera, and an important conceptual framework for future petroleum exploration in northern Alaska. The results of the study can yield new insights into several key areas of interest to hydrocarbon exploration, including: the timing, location and magnitude of unroofing and burial events in northern Alaska; the timing and geometry of major depositional sequences within the Colville basin; the timing and geometry of regional dip changes and the subsequent implications for hydrocarbon migration; and the timing and distribution of potential trapping mechanisms.

Phase 1 of the study use existing geophysical and geological databases to develop three balanced, kinematic crustal-scale geologic models of the central Brooks Range along a transect parallel to the Dalton Highway. These geologic models were tested by sequential gravity models of the central Brooks Range. The results of the gravity modeling were published as an OSU Masters thesis by J. Williams.

This research has been supported by industry sponsors of the Tectonics and Sedimentation Research Group, including ARCO Alaska, BP Exploration, FINA and Union Texas.

If you would like more information about this project, please contact

Dr. Catherine Hanks or

Dr. Wesley K. Wallace

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