Mesozoic thermal history of the Prebetic continental margin (southern Spain): Constraints from apatite fission-track analysis

Abstract

Apatite fission-track analysis was applied to Triassic and Cretaceous sediments from the South-Iberian Continental Margin to unravel its thermal history. Apatite fission-track age populations from Triassic samples indicate partial annealing and point to a maximum temperature of around 100-110°C during their post-depositional evolution. In certain apatites from Cretaceous samples, two different fission-track age populations of 93-99 and around 180 Ma can be distinguished. Track lengths associated with these two populations enabled thermal modelling based on experimental annealing and mathematical algorithms. These thermal models indicate that the post-depositional thermal evolution attained temperatures ≤ 70°C, which is consistent with available vitrinitereflectance data. Thermal modelling for the Cretaceous samples makes it possible to decipher a succession of cooling and heating periods, consisting of (a) a late Carboniferous-Permian cooling followed by (b) a progressive heating episode that ended approximately 120 Ma at a maximum T of around 110°C. The first cooling episode resulted from a combination of factors such as: the relaxation of the thermal anomaly related to the termination of the Hercynian cycle; the progressive exhumation of the Hercynian basement and the thermal subsidence related to the rifting of the Bay of Biscay, reactivated during the Late Permian. Jurassic thermal evolution deduced from the inherited thermal signal in the Cretaceous sediments is characterized by progressive heating that ended around 120 Ma. This heating episode is related to thermal subsidence during Jurassic rifting, in agreement with the presence of abundant mantle-derived tholeiitic magmas interbedded in the Jurassic rocks. The end of the Jurassic rifting is well marked by a cooling episode apparently starting during Neocomiam times and ending at surface conditions by Albian times.

Long-term thermo-tectonic evolution of the Montes de Toledo area (Central Hercynian Belt, Spain): constraints from apatite fission-track analysis

“…The origin of this heating might therefore be related to far-field effects of the rifting process, which opened the Tethys Ocean. Thermal his tories obtained by modeling apatite fission-track data (Barbero et al 2001(Barbero et al , 2002) from samples of Albian (108 96 Ma) sediments from the external Betics (the southern Iberian paleomargin), are very similar to those recorded in the Montes de Toledo area (Fig. 4).…”

“…This is particularly evident in the surrounding sedimentary basins on the basis of subsi dence curves (Schwentke and Kuhnt 1992;Gdife and Wiedmann 1993;Ziegler et al 1995;Stapel et al 1996, Martin-Chivelet 1997 and has also become evident by a heating period exhibited by fission-track-based thermal models in the external Betics (Barbero et al 2001(Barbero et al , 2002. This heating period is also shown by the thermal models based on AFT data in the Montes de Toledo area and confirms that the Cretaceous subsidence event took place on the whole Iberian plate scale.…”

“…Finally, the regional cooling event at about 20 Ma suggested by thermal models not only in the Montes de Toledo area, but also all around the Iberian plate (Reicherter and Pletsch 2000;Barbero et al 2001Barbero et al , 2002 marks the onset of the extensional collapse related to the collision between the African and European plates (Sosson et al 1998). A thin sheet of Miocene conglom erates overlies part of the study area.…”

Thermal history of the Sabero Coalfield (Southern Cantabrian Zone, NW Spain) as revealed by apatite fission track analyses from tonstein horizons: implications for timing of coalification

“…3), which is consistent with the Cainozoic uplift of the Cantabrian Mountains and the last phase of erosion (Alonso et al 1995). The enhanced exhumation in the last 20-40 Ma is also supported by the cooling pattern in other parts of the Variscan basement (Barbero et al 2001(Barbero et al , 2002(Barbero et al , 2005.…”

Mesozoic and Cenozoic exhumation history of the SW Iberian Variscides inferred from low-temperature thermochronology

“…The post-Paleozoic vertical movements of the SW Iberian Variscides are poorly known mainly due to the scarce low-temperature geochronological data available and the nearly absence of post-Paleozoic sediments. However, those data point to a complicated evolution of the region, with exhumation occurred at Triassic-Early Jurassic times in a rifting episode related to Pangea break-up (Stapel, 1999;Barbero and López-Garrido, 2006;Juez-Larré and Ter Voorde, 2009, and references therein). These ages contrast with the fact that local relief in the Sierra Morena can reach 500 m and streams show V-shaped deep incised valleys, which point to recent tectonic-and exhumation-activity.…”