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Variscan migmatites cropping out in the eastern Pyrenees were dated together with Late Variscan plutonic rocks. Upper Proterozoic-Lower Cambrian series were migmatized during a thermal episode that occurred in the interval 320-315 Ma coeval with the main Variscan deformation event (D 1 ). The calc-alkaline Sant Llorenç-La Jonquera pluton and the gabbro-diorite Ceret stock were emplaced during a later thermal episode synchronous with the D 2 deformation event. A tonalite located at the base of La Jonquera suite intruded into the upper crustal levels between 314 and 311 Ma. The gabbro-diorite stock was emplaced in the middle levels of the series in two magmatic pulses at 312 and 307 Ma. The thermal evolution recorded in the eastern Pyrenees can be correlated with that of neighbouring areas of NE Iberia (Pyrenees-Catalan Coastal Ranges) and SE France (Montagne Noire). The correlation suggests a NW-SE-trending zonation where the northeasternmost areas (Montagne Noire and eastern Pyrenees) would occupy relatively more internal zones of the orogen than the southwesternmost ones.

Geochronological U-Pb (LA-ICP-MS), geochemical and isotopic data from metavolcanic felsic rocks of the Canigó and Cap de Creus massifs in the Eastern Pyrenees provide evidence of an Ediacaran magmatic event lasting 30 m.y. in NE Iberia. Data also constrain the age of the Late Neoproterozoic succession in the Cap de Creus massif, where depositional ages range from 577 to 558 Ma, and in the Canigó massif, where the data (575 to 568 Ma) represent minimum ages. Geochemistry indicates that the rocks were formed in a back-arc environment and record a fragment of a long-lived subduction-related magmatic arc (620 to 520 Ma) in the active northern Gondwana margin. The homogeneity shown by all these crustal fragments along this margin suggests that the individualization of the Pyrenean basement from the Iberian Massif started later, probably during its transition from an active to a passive margin in Cambro-Ordovician times.

International audienceDuring the Late Palaeozoic Variscan Orogeny, Cambro-Ordovician and/or Neoproterozoic metasedimentary rocks of the Albera Massif (Eastern Pyrenees) were subject to low-pressure/hightemperature (LPHT) regional metamorphism, with the development of a sequence of prograde metamorphic zones (chlorite-muscovite, biotite, andalusite-cordierite, sillimanite and migmatite). LPHT metamorphism and magmatism occurred in a broadly compressional tectonic regime, which started with a phase of southward thrusting (D1) and ended with a wrench-dominated dextral transpressional event (D2). D1 occurred under prograde metamorphic conditions. D2 started before the P–T metamorphic climax and continued during and after the metamorphic peak, and was associated with igneous activity. P–T estimates show that rocks from the biotite-in isograd reached peak-metamorphic conditions of 2.5 kbar, 400 C; rocks in the low-grade part of the andalusite-cordierite zone reached peak metamorphic conditions of 2.8 kbar, 535 C; rocks located at the transition between andalusitecordierite zone and the sillimanite zone reached peak metamorphic conditions of 3.3 kbar, 625 C; rocks located at the beginning of the anatectic domain reached peak metamorphic conditions of 3.5 kbar, 655 C; and rocks located at the bottom of the metamorphic series of the massif reached peak metamorphic conditions of 4.5 kbar, 730 C. A clockwise P–T trajectory is inferred using a combination of reaction microstructures with appropriate P–T peudosections. It is proposed that heat from asthenospheric material that rose to shallow mantle levels provided the ultimate heat source for the LPHT metamorphism and extensive lower crustal melting, generating various types of granitoid magmas. This thermal pulse occurred during an episode of transpression, and is interpreted to reflect breakoff of the underlying, downwarped mantle lithosphere during the final stages of oblique continental collision

Keywords:Pre-Variscan Late Ordovician magmatism SHRIMP geochronology U-Pb zircon

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Livingston Island contains several, distinctive sedimentary and volcanic sequences, which document the history and evolution of an important part of the South Shetland Islands magmatic arc. The turbiditic, late Palaeozoic–early Mesozoic Miers Bluff Formation (MBF) is divided into the Johnsons Dock and Napier Peak members, which may represent sedimentation in upper and lower mid-fan settings, respectively, prior to pre-late Jurassic polyphase deformation (dominated by open folding). The Moores Peak breccias are formed largely of coarse clasts reworked from the MBF. The breccias may be part of the MBF, a separate unit, or part of the Mount Bowles Formation. The structural position is similar to the terrigenous Lower Jurassic Botany Bay Group in the northern Antarctic Peninsula, but the precise stratigraphical relationships and age are unknown. The (?) Cretaceous Mount Bowles Formation is largely volcanic. Detritus in the volcaniclastic rocks was formed mainly during phreatomagmatic eruptions and redeposited by debris flows (lahars), whereas rare sandstone interbeds are arkosic and reflect a local provenance rooted in the MBF. The Pleistocene–Recent Inott Point Formation is dominated by multiple, basaltic tuff cone relicts in which distinctive vent and flank sequences are recognized. The geographical distribution of the Edinburgh Hill Formation is closely associated with faults, which may have been reactivated as dip-slip structures during Late Cenozoic extension (arc splitting).