Synchronous exhumation events around the Arctic including examples from Barents Sea and Alaska North Slope

Abstract

In many areas of the Arctic, sedimentary sequences have been exhumed from significantly greater depths during the Cenozoic, with 2 km of section or more removed in some areas. Implications for exploration include enhanced maturity levels, possible loss of reservoired hydrocarbons as a result of seal breach, and phase changes due to pressure reduction. While the importance of Cenozoic exhumation to hydrocarbon prospectivity in individual basins is widely recognized, less well recognized is the regional synchroneity in the main phases of Cenozoic exhumation over wide areas of the Arctic and North Atlantic. Thermal history reconstruction studies in the Barents Sea and the Alaskan North Slope, based on application of apatite fission track analysis and vitrinite reflectance, reveal three main episodes of exhumation, in Paleocene, Eocene–Oligocene and Miocene times, and correlative exhumation episodes have been identified in a number of published studies in these and other areas. Previous attempts to explain these episodes of exhumation have been focussed on local mechanisms. However, our results reveal a pattern of regionally synchronous exhumation over a wide region, not only of the Arctic but also in many areas around the European North Atlantic margin, suggesting that events in each area are a regional response to events at plate boundaries, perhaps coupled to imbalances of crustal forces at continental boundaries. To date, no convincing mechanism has been put forward for producing such regional exhumation episodes, despite the fact that in many areas they exert critical control on regional hydrocarbon prospectivity. We suggest that serious attention should be directed to investigating the underlying mechanisms.