Ellesmerian Tectonism: a Critical Appraisal from a Circum-Arctic Perspective
Stephen Rippington and Robert Scott
CASP, University of Cambridge, Cambridge, United Kingdom.
Evidence for Late Devonian to Early Carboniferous tectonism is widely reported for the circum-Arctic. Regional unconformities associated with contractional and transpressional deformation have been documented in Alaska, the Canadian Arctic, North and East Greenland, Svalbard and Severnaya Zemlya. In Alaska, Canada and Severnaya Zemlya, magmatism occurred in conjunction with this tectonism. In many instances, this tectonomagmatic event has been attributed to the Ellesmerian Orogeny. However, the full extent, precise timing, and geodynamic cause of this putative orogeny are unclear. Furthermore, the relationship of Ellesmerian tectonism to the preceding Caledonian Orogeny is poorly constrained.
Immediately following Ellesmerian tectonism, some of the Arctic’s most important hydrocarbon-bearing sedimentary basins were initiated (e.g. Alaskan North Slope, Sverdrup Basin, Barents Shelf). Understanding the extent, timing, cause and development of the tectonism is therefore important to constrain the geological and geomorphological framework in which these hydrocarbon-bearing basins developed, as well as offering the potential to help constrain the source areas, compositions and transport-pathways of the sediments which filled these basins. In a wider context, the locations of rocks affected by Caledonian and Ellesmerian tectonism in the circum-Arctic may be used as markers to constrain Arctic Ocean reconstructions.
In this study, published field data, geological maps and cross-sections of areas reportedly affected by Ellesmerian tectonism have been compiled to construct a GIS-based structural database. The first stage of this ongoing study concerns Svalbard and North Greenland. Later stages will deal with the Canadian Arctic and Alaska. The GIS-database has allowed published evidence for Ellesmerian tectonism to be properly evaluated. This process has highlighted how much “data” on the geology of the region is actually interpretation or assumption. Considering only the concrete evidence, the database shows that minor contractional tectonism of Ellesmerian age occurred, but there is a lack of evidence to support the hypothesis of a Late Devonian to Early Carboniferous Orogen.
AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia