%0 Journal Article
%A Barbero González, Luis C.
%A Glasmacher, U. A.
%A Villaseca González, Carlos
%A López García, José Ángel
%A Martín Romera, Cristina
%T Long-term thermo-tectonic evolution of the Montes de Toledo area(Central Hercynian Belt, Spain): constraints from apatite fission-trackanalysis
%D 2005
%@ 1437-3254
%U https://hdl.handle.net/20.500.14352/49582
%X Abstract In the Montes de Toledo area, located in theaxial part of the Central Hercynian zone, a long-termthermo-tectonic evolution can be deduced from apatitefission-track (AFT) data in conjunction with tight geologicalconstraints derived from the knowledge of regionalgeology and other independent chronometers.The area is composed of two different blocks separatedby the Toledo Shear Zone (TSZ). The northern block isa granulite facies anatectic terrane. The southern blockis composed of greenschist facies Paleozoic sedimentsintruded by a late Hercynian granitic pluton. A total of13 samples have been recovered for AFT analysis. AFTages in both blocks cluster around 189–221 Ma, withmean confined track lengths between 11.4 lm and12.4 lm. Modeling of the AFT data indicates that thethermal history is broadly similar in both blocks, whichconstrains the main movement of the TSZ, as essentiallybefore the Upper Permian. AFT ages in the TSZ clusteraround 124–164 Ma, and the track lengths vary between11.4 lm and 12.4 lm. These data reveal that the faultmust have been affected by a later thermal overprint asAFT ages are significantly younger than those of thefootwall and hangingwall blocks. This differential thermalresetting is likely related to the advection of localizedhydrothermal fluids that are responsible for thewidespread Pb–Zn mineralization along the TSZ. Theseresults give an example of resetting AFT data byhydrothermal events. The long-term evolution suggests alack of important Alpine tectonism in the Montes deToledo block, in clear contrast to other nearby Hercynianareas such as the Sierra de Guadarrama, where theimportant effect of Alpine tectonism has almost totallyerased the previous thermal signal in the AFT system.
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