Topography in the Arctic-North Atlantic Realm (TOPOREAL) - Northern Ellesmere Island (Eurekan Orogeny) and its Polar Margin and the Conjugate Margins of Davis Strait
Randell Stephenson1, Søren B. Nielsen2, and Eoin McGregor1
1School of Geosciences, University of Aberdeen, Aberdeen, United Kingdom.
2Earth Sciences, University of Aarhus, Aarhus, Denmark.
Tectonics and erosion are the driving forces of topography evolution, but resolving their relative contributions remains a fundamental scientific problem in relation to the understanding of geodynamic and surface processes, in particular, in the presence of a changing climate. In the Arctic-North Atlantic realm, the most recent active margin and continental collision/convergence tectonism dates back to the early Palaeozoic closure of the Iapetus and related oceans and Caledonide-aged collision between the Precambrian continents of Baltica and Laurentia, with commensurate accretion at that time of new or strongly reworked continental lithosphere between them. Subsequently, the Arctic-North Atlantic realm was affected by rifting and plate break-up (Labrador Sea-Davis Strait-Baffin Bay, North Atlantic) in (mainly) the Cretaceous and Palaeogene and related intraplate shortening leading to the Eurekan Orogen in the Palaeogene. The high topography of this realm occurs in three settings: (1) built on “Palaeozoic” lithosphere adjacent to rifted areas (east Greenland-Scandinavia), (2) on Precambrian lithosphere adjacent to rifted areas (west Greenland-Baffin Island) and (3) on Palaeozoic and Precambrian lithosphere clearly affected by Cenozoic shortening (Ellesmere Island and adjacent Greenland). The origin and age of Arctic-North Atlantic topography is undoubtedly important for understanding the petroleum systems of adjacent sedimentary basins and, in regard to the first two settings, has attracted much interest in terms of postulated Neogene tectonic rejuvenation/uplift by unknown mechanisms. There is, nevertheless, a growing consensus that the high topography of the first of these represents, at least in part, the remains of the ancient Caledonian orogenic belt. Here, we present results of various studies being undertaken regarding the topography of west Greenland and Baffin Bay on the margins of Davis Strait and the topography of Ellesmere Island and northwesternmost Greenland. Numerical subsidence and thermal history models, constrained by stratigraphy and paleothermometry, are presented for the former, including new AFT results for the mountains of Cumberland Peninsula on Baffin Island, and the results of analogue models of intraplate convergence (Eurekan Orogeny), constrained by potential field and limited seismic data, for the latter. Our provisional conclusions are that Neogene uplift, for which there exists no robustly demonstrated mechanism in any case, is not required to explain the high topography of the margins of Davis Strait whereas in Ellesmere Island, where Cenozoic tectonics are very well documented, present-day topography is easily explicable as the consequence of these superimposed on the ancient Caledonian orogenic belt.
AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.��������������������