--> Abstract: Piercing Points and Extensional Domain Analysis for the Plate Tectonic and Paleogeographic Restoration of the Amerasia Basin of the Arctic, by Elizabeth Miller; #90177 (2013)

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Piercing Points and Extensional Domain Analysis for the Plate Tectonic and Paleogeographic Restoration of the Amerasia Basin of the Arctic

Elizabeth Miller

The opening history of the Amerasia Basin of the Arctic has eluded us because the basin lacks magnetic anomalies and there are conflicting constraints on its age(s) and direction(s) of rifting. Regional piercing points (tie points) allow one to approximately restore the Arctic to its pre-rift configuration, but these data carry little information about the plate translations, timing or kinematics/dynamics of basin formation. A concerted effort to integrate geologic piercing points with data on the timing and direction of extensional rifting is helping us to move closer to a kinematic opening model. Geologic efforts, detrital zircon geochronology and dredging in the Amerasia Basin have established piercing points that need to be honored in restoring the basin to its pre-rift paleogeography: N. Alaska restores to the Canadian Arctic margin, eastern and western Chukotka to a position near the Lomonosov Ridge/Barents Shelf, east of the Caledonides and west of the Urals; the N. Siberian Islands restore to Taimyr and the Chukchi Borderland to near Pearya and Svalbard. Extensional domain analysis on land and within the Amerasia Basin helps constrain kinematics of opening. Continental extensional provinces provide timing based on crosscutting relations and geochronologic and thermochronologic data as well as kinematic information. These suggest a long-lived and complex opening history for the Amerasia Basin, perhaps spanning ~ 130 to 60 Ma. Initial opening may have been orthogonal to the Lomonosov Ridge and orthogonal to the length of the Brooks Range, Alaska, rifting continental fragments and arc systems towards the paleo-Pacific continental margin between ~130 and 100 Ma. Rifting continued, but the direction of extension changed to ~ N-S (present coordinates) and became increasingly focused in the Bering Strait region, mostly ending at ~ 80 Ma. Basins such as the N. Chukchi, S. Chukchi, Hope, Norton and Anadyr developed across this region due to a component of N-S extension into the early Tertiary. The CA Basin may have opened late rather than early in this rift history. This compiled data set provides useful constraints for restoring the Amerasia Basin back to its pre-rift configuration, yields a rough idea of the extension needed to do so, and forms the basis of hypotheses for further testing.

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