The Jameson Land basin (east Greenland): a fission track study of the tectonic and thermal evolution in the Cenozoic North Atlantic spreading regime

Abstract

The Late Mesozoic and Cenozoic thermal history of the Jameson Land basin is constrained by new apatite and zircon fission track (FT) data of surface Permian to Jurassic sedimentary rocks. The results show a general regional thermal evolution related to burial to temperatures close to and in excess of the maximum temperatures of the apatite annealing interval (∼125°C) followed by cooling mainly due to Cenozoic uplift and erosion. Faulting and differential movements in the basin generally occurred after cooling below the apatite partial annealing zone (PAZ: ∼75–125°C). However, in the northern part of the basin the data suggest a thicker sediment cover or localized heating related to an earlier fracture zone. Both apatite FT analysis and vitrinite reflectance values reveal a postmature signature for the studied rocks in the northeastern Jameson Land and premature to mature for the western, central and southern Jameson Land rocks with respect to generation of hydrocarbons. The chemical variations of apatite enhance the possibility of recognizing sample positions near maximum temperatures in the PAZ. Furthermore, the Pb–Zn mineralization pattern closely follows the Tertiary maturity trend given by the FT data. The type and distribution of mineralization suggest that it was influenced by the regional thermal evolution of the basin. In the northeast domain, circulating fluids may have overprinted the regional thermal record before ca. 20Ma. Basaltic dyke and sill intrusions (55–45Ma) locally caused resetting of apatite FT ages, but generally the direct influence from upper crustal magmatic activity played only a minor role. The thermal evolution in northeast Jameson Land is related to the late tectonic evolution of the Northeast Atlantic involving a change in ridge position at ca. 25Ma which followed the passage of the proto-Icelandic mantle plume at 63–40Ma.