Exhumation of the Sierra de Cameros (Iberian Range, Spain): constraints from low-temperature thermochronology

Abstract

We present new fission-track and (U–Th)/He data from apatite and zircon in order to reconstruct the exhumation of the Sierra de Cameros, in the northwestern part of Iberian Range, Spain. Zircon fission-track ages from samples from the depocentre of the basin were reset during the metamorphic peak at approximately 100 Ma. Detrital apatites from the uppermost sediments retain fission-track age information that is older than the sediment deposition age, indicating that these rocks have not exceeded 110 °C. Apatites from deeper in the stratigraphic sequence of the central part of the basin have fission-track ages of around 40 Ma, significantly younger than the stratigraphic age, recording the time of cooling after peak metamorphic conditions. Apatite (U–Th)/He ages in samples from these sediments are 31–40 Ma and record the last period of cooling during Alpine compression. The modelled thermal history derived from the uppermost sediments indicates that the thermal pulse associated with peak metamorphism was rapid, and that the region has cooled continuously to the present. The estimated palaeogeothermal gradient is around 86 °C km−1 and supports a tectonic model with a thick sedimentary fill (c. 8 km) and explains the origin of the low-grade metamorphism observed in the oldest sediments.

Unraveling Multiple Thermotectonic Events Accommodated by Crustal‐Scale Faults in Northern Iberia, Spain: Insights From K‐Ar Dating of Clay Gouges

“…The Río Grío Fault played a major role during that time, with important transpression documented by the present‐day geometry of the Cameros Basin, where Cenozoic compressional structures strike E‐W to NW‐SE and the footwall of the main thrust consists of up to 4 km thick Eocene molasse of the Ebro Basin (Muñoz‐Jiménez & Casas‐Sainz, ). Furthermore, the reactivation of the Río Grío Fault during the Eocene is supported by a 40 ± 5 Ma K‐Ar illite date (Mantilla Figueroa et al, ) and by apatite (U‐Th)/He and fission‐track data indicating that the main part of the Cameros Basin was exhumed at 40 Ma (Del Río et al, ). The crystallization of illite‐1M d in the clay gouge of the Vallès‐Penedès Fault at about 47 Ma is coeval to the exhumation of a few Variscan granitoids in the Catalan Coastal Range that provided a time interval of 40–48 Ma based on low‐temperature thermochronological data (Juez‐Larré & Andriessen, ).…”

“…Available fission‐track data on zircon and apatite and U‐Th/He ages on apatite for the Iberian Plate record the last period of cooling during the Alpine compression. Moreover, they suggest slow cooling throughout the Jurassic and thermal stability during the Late Cretaceous for the Iberian Chain and Catalan Coastal Range (De Bruijne & Andriessen, ; Del Río et al, ; Juez‐Larré & Andriessen, ).…”

Drainage reorganization and divide migration induced by the excavation of the Ebro basin (NE Spain)

“…The Cameros subbasin to the NW represents a Late JurassicEarly Cretaceous trough almost exclusively filled by continental siliciclastic deposits (Martín-Chivelet et al, 2002 and references therein;Del Rio et al, 2009). Shortening in the Iberian Range occurred from the Late Cretaceous to the early Miocene, along inherited Hercynian NW-SE structures (Gutiérrez-Elorza and Gracia, 1997;Guimerà et al, 2004;Gutiérrez-Elorza et al, 2002).…”

Apatite thermochronology in modern geology

“…Schaer et al 1975;Wagner et al 1979;Grundmann & Morteani 1985;Hurford 1986;, most of the world's young orogenic belts were studied (e.g. Parrish 1983;Seward & Tulloch 1991;Corrigan & Crowley 1992;Hendrix et al 1994;Blythe et al 1996;O'Sullivan & Currie 1996;Sorkhabi et al 1996;Dunkl & Demény 1997;Kamp 1997;Sanders et al 1999;Fayon et al 2001;Spiegel et al 2001;Glasmacher et al 2002b;Reiners et al 2002;Thomson 2002;Willet et al 2003;Van der Beek et al 2006;Gibson et al 2007;Vincent et al 2007;Glotzbach et al 2008Glotzbach et al , 2009del Río et al 2009;Ruiz et al 2009). …”