Biostratigraphic Interpretations Influenced by Structural Complexities; Nansen Formation, Ellesmere Island
The Carboniferous to Permian aged Nansen Formation is a cyclic carbonate shelf deposit and potential hydrocarbon reservoir. This formation is the thickest, most widespread carbonate sequence in the Sverdrup Basin. Deformed during the Eurekan Orogeny, the Nansen Fm. is topographically prominent and responsible for the rugged topography on Axel Heiburg and Ellesmere Island.
The type section for the Nansen Fm. is located on the
north side of Hare Fiord, along Girty Creek. At this location there is an
estimated stratigraphic thickness of 2 km. More work has been completed on
sections exposed by glaciers, that run parallel to Girty Creek, due to easier
access. Extensive biostratigraphy has been completed on a glacier section to
the west, however, in a glacier section to the east of Girty Creek, structural
complexities appear to be repeating sections of the formation. Here, the Nansen
formation is bounded by two regional assumed thrust faults. This has produced
duplex structures, with clearly exposed stacked horses, footwall synclines, and
truncations. By projecting the structures observed in the east glacier section
to the west glacier section that was used for biostratigraphy, it is clear that
these structures would affect biostratigraphic interpretations. It has been
previously noted by biostratigraphers that thrust faults appear to be repeating
sections of the Nansen formation. However by correlating all observed faults
with the biostratigraphy, we can determine the extent to which the faulting has
affected the interpretations, and whether all faults or stratigraphic
repetitions have been accounted for.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California