Abstract The Variscan segment of the Pyrenees is well suited to study the timing of crustal-scale deformations as crustal flow and gneiss dome formation. This has been constrained from a synthesis of available structural and geochronological data of intrusive rocks, as well as new zircon U–Pb age determinations via laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). After a stage of moderate thickening by fold–thrust belt development in the upper crust between 323 and 308 Ma, the Variscan segment of the Pyrenees experienced crustal flow at c. 306 Ma and then gneiss dome formation at c. 304 Ma. Localization of the deformation along reverse-dextral shear zones occurred at c. 300 Ma. The Variscan segment of the Pyrenees recorded a high-temperature regime, which allowed crustal flow of the middle crust, but with limited amounts of heat which induced rapid cooling. The development of this enigmatic orogenic segment of the Variscan belt is closely contemporaneous with the formation of the Cantabrian Orocline and could correspond to a lithospheric-scale shear zone that accommodated buckling of the orocline. Late Variscan lithospheric delamination and asthenospheric upwelling associated with buckling in the core of the Cantabrian Orocline could explain the short-period high-temperature regime in the Variscan segment of the Pyrenees. Supplementary material: Review of published U–Th–Pb, Ar–Ar and K–Ar ages of granites from the Axial Zone of the Pyrenees; LA-ICP-MS U–Pb dating methodology (Clermont-Ferrand, France); and zircon LA-ICP-MS U–Pb data for Ax-les-Thermes, Carançà, Mont-Louis and Cauterets granites are available at http://www.geolsoc.org.uk/SUP18729 .

Abstract Most Palaeozoic magmatic rocks in Spain were produced during the Variscan orogeny, and there are excellent and abundant examples of both volcanic and plutonic lithologies. Volcanic units include those in the world-famous Iberian Pyrite Belt, and plutonic rocks exposed in the Iberian Massif include some of the largest and best granite outcrops in the European Variscides. Magmatic rocks are present in all the Iberian tectonostratigraphic zones into which the Variscan orogen in Spain has been classically divided. In addition to these Variscan igneous rocks, there is also evidence for earlier magmatism, including widespread exposures of Neo-proterozoic–Cambrian (Cadomian) age, and the diatreme-like breccias linked to the origin of the remarkable mercury mineralization at Almaden. In this chapter we deal initially with Palaeozoic volcanic rocks, with special emphasis on the volcanism related to the generation of the Iberian Pyrite Belt. With regard to the Variscan granitoid rocks we have grouped these according to compositional features and relative age, rather than by tectonostratigraphic zones (the latter approach does not contribute to a better understanding of the magmatism because the emphasis is on differences and not on similarities). However, Variscan granites of the Iberian Massif are described separately from other granitic massifs in the Pyrenees and Catalonian Coastal ranges, because of their geographic separation and the lack of obvious direct links between them. Outcrops of distinctive mafic and ultramafic rocks, mostly related to granitoids of the appinite–granodiorite association (cf. Pitcher 1997 ), are treated separately, not least because of their importance in international

Abstract The paper presents a geodynamic interpretation of the deep structure and active tectonics of the northern Tien Shan, with particular emphasis on strike-slip motions, which produced a pull-apart in the centre of the Issyk-Kul basin. The study is based on a detailed interpretation of satellite imagery, fault plane solutions of earthquakes, seismic, and geodetic data. Seismic and magnetotelluric studies show tectonic layering of the Tien Shan lithosphere, with several nearly horizontal viscoelastic layers and the lower layer underthrust northward in the northern Tien Shan. This active process may be responsible for the intricate present-day tectonic framework of the northern Tien Shan. The recent tectonics of the northern Tien Shan inherits the earlier structure: The lens-shaped Issyk-Kul microcontinent comprising Precambrian-Palaeozoic metamorphic and magmatic rocks is surrounded by thick shear zones which have been involved in the activity over most of the Cenozoic. In the Quaternary the strain propagated as far as the central part of the Issyk-Kul basin.