Low-temperature exhumation history of Variscan-age rocks in the western Cantabrian Mountains (NW Spain) recorded by apatite fission-track data

• Verfasst von: Grobe, René Wilhelm [VerfasserIn]
• Verfasst von: Alvarez-Marrón, Joaquina [VerfasserIn]
• Verfasst von: Glasmacher, Ulrich A. [VerfasserIn]
• Verfasst von: Menéndez-Duarte, Rosana [VerfasserIn]
• Titel: Low-temperature exhumation history of Variscan-age rocks in the western Cantabrian Mountains (NW Spain) recorded by apatite fission-track data
• Verf.angabe: René W. Grobe, Joaquina Alvarez-Marrón, Ulrich A. Glasmacher, Rosana Menéndez-Duarte
• E-Jahr: 2010
• Jahr: 18 April 2010
• Umfang: 15 S.
• Fussnoten: Gesehen am 25.05.2023
• Titel Quelle: Enthalten in: Tectonophysics
• Ort Quelle: Amsterdam [u.a.] : Elsevier, 1964
• Jahr Quelle: 2010
• Band/Heft Quelle: 489(2010), 1, Seite 76-90
• ISSN Quelle: 1879-3266
• DOI: doi:10.1016/j.tecto.2010.04.006
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: Apatite fission-track data
• Sach-SW: Exhumation history
• Sach-SW: Thermochronology
• Sach-SW: Western Cantabrian Mountains
• K10plus-PPN: 1846228913

Abstract

This paper presents the first regional study of apatite fission-track (AFT) thermochronology to be undertaken in the western termination of the Cantabrian Mountains (NW Spain). The mountains reach elevations of over 2600m along the northern coast of Spain and are comprised of a Variscan crustal section uplifted due to Cenozoic shortening along the northern Iberian Plate. The study constrains the pattern and history of exhumation within the Paleozoic bedrock over the past c. 240Ma. Twenty-one apatite fission-track samples range in age from 246.7 (±26.9) Ma to 78.1 (±3.7) Ma, with mean track lengths between 10.4 (±1.8) µm and 12.4 (±1.4) µm. Time-temperature path modelling of the data indicates that different rates of continuous cooling took place during the three main tectonic events that affected the area. A rapid cooling event that ended by the Late Jurassic corresponds to topographic decay during unroofing of the Variscan orogen and the break-up of Pangea, and is responsible for the largest amount of exhumation. Westernmost samples cooled coinciding with rifting in the North Atlantic and Bay of Biscay during the Late Jurassic to Early Cretaceous. By about 100-80Ma most samples had reached, or passed through, the upper boundary of the apatite partial annealing zone, which indicate that regional denudation has not exceeded c. 1.7km since then, for geothermal gradients ≥27°C/km and a surface temperature of 15°C. Only three samples next to fault escarpments in the west cooled below 70°C since 80Ma, reaching below 65°C before initiation of incipient subduction along the northern Iberian Margin by 46Ma. An average cooling rate of ≤1°C/Ma reflects latest denudation as the new mountainous relief developed since then due to shortening and incipient subduction associated with convergence along the northern Iberian Plate. The Cantabrian Mountains are one of the few natural examples of a coastal orogen in a juvenile stage of evolution.