Alpine exhumation of the central Cantabrian Mountains, Northwest Spain

Abstract

The Cantabrian Mountains extend along the Atlantic coast of northern Spain and are known to have experienced an Alpine phase of deformation, reactivating well-expressed Variscan structures. They form the westward continuation of the Pyrenean range and were similarly uplifted consequently to the convergence between the Iberian and European plates. Nevertheless, due to the scarcity of syntectonic sediments and structural markers in a large outcrop of Variscan basement, little is known about the precise timing and amount of the Alpine exhumation phase in the Cantabrian Mountains. We present a new low-temperature thermochronology data set, composed of nine apatite fission track (AFT) and six zircon (U-Th)/He (ZHe) ages, sampled along structurally well-constrained N-S profiles through the central part of the Cantabrian Mountains and complemented by 3-D thermokinematic modeling. The occurrence of Eocene-Oligocene AFT and ZHe ages in the center of the profiles allows us to frame the period of Alpine exhumation from 39 to 29 Ma, at a rate of 0.24-0.3 km Myr À1 . Moreover, the reset ZHe ages imply significant burial of the samples, by up to 8-10 km in the center of the range. Therefore, the Alpine exhumation phase was significant, and synchronous to the main phase of exhumation in the central Pyrenees, although exhumation rates were an order of magnitude lower. Three-dimensional thermokinematic modeling of the data confirms the timing of uplift of this area, but its resolution is limited by the relatively small number of reset ages over a large area.

Tectonothermal Evolution of the Cameros Basin: Implications for Tectonics of North Iberia

“…As shown in Figure e, AFT grains of the CMR1 sample, previously annealed, cooled below the 110 °C isotherm, recording a late Eocene to Oligocene exhumation. This period signs a main exhumation phase in the Pyrenees, in the Cantabrian belt (Fillon et al, ; Fitzgerald et al, ), and in the Cameros basin at 35–25 Ma (Figure ). A total exhumation of 1.5 km is estimated for this period in the Cameros basin.…”

“…Existing low‐temperature data sets and constraints on time‐temperature evolution in northern Iberia. (a) In situ apatite fission‐track (AFT) age data from Yelland (), Morris et al (), Fitzgerald et al (), Juez et Andriessen (), Jolivet et al (), Maurel et al (), Del Río, Barbero, and Stuart (), Grobe et al (), Fillon and Van Der Beek (), Fillon et al (, ), Herman et al (), Botor and Anczkiewicz (), Bosch et al (), Mouchene (), and Vacherat et al (). In situ zircon fission‐track (ZFT) age data from Maurel et al (2008) and Sinclair et al ().…”

The Spanish‐Portuguese Central System: An Example of Intense Intraplate Deformation and Strain Partitioning

“…However, it was during the late Chattian to Burdigalian (Late Oligocene to Early Miocene) that it reached a maximum within the Iberian interior, clearly registered by coeval deformation in the Iberian Chain (to the E; de Vicente et al, 2009) and in the Lower Tagus basin (to the W; e.g., Curtis, 1999). Apatite fission track data show an important cooling event in the Cameros area between 31 and 40 Ma (del Río, 2009), also registered in the SPCS (Spanish sector; De Bruijne & Andriessen, 2002) and in the westernmost part of the Cantabrian Pyrenees (Fillon et al, 2016). At the same time, a NW-SE trending compressional stress field is registered in the Spanish sector of the SPCS.…”

Unraveling the Mesozoic and Cenozoic Tectonothermal Evolution of the Eastern Basque‐Cantabrian Zone–Western Pyrenees by Low‐Temperature Thermochronology

“…Temperature offset between samples in subvertical profiles in the western Axial Zone and Chaînons Béarnais also point to mean geothermal gradients of 25 °C/km, with no major variation throughout the Paleogene (Bosch et al, ). Finally, these are also the range of geothermal gradient values used by Fillon et al () in their thermochronologic study of the central Cantabrian Mountains, allowing a direct comparison of results between both zones.…”

“…(b) Apatite fission track (AFT) data from northern Spain and southern France. Squares are the AFT ages obtained in this work and circles are AFT ages from the literature (Beamud et al, ; Bosch et al, ; Carrière, ; Del Rio et al, ; Fillon et al, , ; Fillon & van der Beek, ; Fitzgerald et al, ; Gibson et al, ; Grobe et al, , ; Jolivet et al, ; Juez‐Larré & Andriessen, ; Labaume, Meresse, Jolivet, & Teixell, ; Labaume, Meresse, Jolivet, Teixell, & Lahfid, ; Martín‐González et al, ; Maurel et al, ; Metcalf et al, ; Morris et al, ; Mouthereau et al, ; Pérez‐Arlucea et al, ; Rahl et al, ; Rat et al, ; Rushlow et al, ; Sinclair et al, ; Vacherat et al, , ; Yelland, ).…”