The Caledonian foreland basin in Scandinavia: constrained by the thermal maturation of the Alum Shale

Various palaeotemperature estimates from preserved Palaeozoic sedimentary r ocks in Sweden indicate the existence of a considerably higher temperature in the past. Earlier workers have suggested that the reason for this higher palaeotemperature was due to the development of a foreland basin which bur ied the sediments, during the Caledonian orogeny. Palaeotemperature estimat ions from vitrinite reflectance are indicating a maximum palaeotemperature of approximately 165 degrees C for the autochthonous Alum Shale in Jamtland and 100 degrees C for the Alum Shale in Vastergotland. These palaeotempera ture estimations converted to burial depths are used as boundary conditions in the modelling of the Caledonian mountain range and the connected forela nd basin. This study suggests, that to accommodate a basin fitting palaeote mperature constraints, a mountain chain similar to the Himalayas must have occurred, which implies a flexural rigidity of the lithosphere in the order of 4X10(24) Nm. The heat flow is assumed to have been approximately 60 mW/ m(2). The model is used to estimate the overthrusted load of the Caledonian mountain range from calculated burial effects of an elastic lithosphere an d does not include any other heat producing sources, i.e. fluid flow or ign eous intrusions on a regional scale.