Evolución termal mesozoica de la Cuenca Prebética (Sierra de Segura) inferida mediante análisis de huellas de fisión en apatitosresultados preliminares

Abstract

Apatite fission-track techniques have been applied to Lower Cretaceous sands and sandstones of the Prebetic continental margin in order to unravel its evolution since the Mesozoic until present. Preliminary results show that sediment source for the Aptian-Albian sandstones were likely the Triassic sandstones that by Cretaceous times where already cropping out. Modeling performed in two different grain age populations in one of the samples show main cooling-heating episodes. The first could be related to the Tethys opening and correspond to a Triassic rifting followed by a Jurassic extensional stage controlled by thermal subsidence. The second could be related to the Atlantic opening; which took place during the Portlandian-Neocomian. Mathematical models show a relatively fast cooling during this Portlandian-Neocomian episode, which does not agree with the classical thermal models of rifting. Following this stage a thermal subsidence episode, during which maximum burial was attained by the end of the Cretaceous time and was likely less then 2 km, occurred. Final inversion of the Cretaceous basin is represented by a cooling stage beginning around 20 Ma ago, which is the age of the extensional collapse of the internal zones of the Betic orogen.