The plutonic rocks of the Antarctic Peninsula magmatic arc form one of the major batholiths of the circum-Pacific rim. The Antarctic Peninsula batholith is a 1350 km long by < 210 km wide structure which was emplaced over the period -240 to 10 Ma, with a Cretaceous peak of activity that started at 142 Ma and waned during the Late Cretaceous. Early Jurassic and Late Jurassic-Early Cretaceous gaps in intrusive activity probably correspond to episodes of arc compression. In a northern zone of the Antarctic Peninsula, the batholith intrudes Palaeozoic-Mesozoic low-grade meta-sedimentary rocks, and in a central zone it intrudes schists and ortho-and paragneisses which have Late Proterozoic Nd model ages and were deformed during Triassic to Early Jurassic compression. In a southern zone the oldest exposed rocks are Permian sedimentary rocks and deformed Jurassic volcanic and sedimentary rocks. All these pre-batholith rocks formed a belt of relatively immature crust along the Gondwana margin. With few exceptions, Jurassic plutons crop out only within the central zone: many are peraluminous, having 'S-like' mineralogies and relatively high 87 Sr/ 86 Sr i . They are considered to consist largely of partial melts of upper crust schists and gneisses and components of mafic magmas that caused the partial fusion. By contrast, Early Cretaceous plutons crop out along the length of the batholith. Few magma compositions appear to have been affected by upper crust, the bulk being compositionally independent of the type of country rock they intrude. They are dominated by metaluminous, calcic, Si-oversaturated, 1-type granitoid rocks with relatively low "Sr/^Sr,, intermediate-silicic compositions (< 5 % MgO). We interpret these to represent partial melts of basic to intermediate, igneous, locally garnet-bearing, lower crust. Contemporaneous mafic magmas (e.g. syn-plutonic dykes) form a more alkaline, Si-saturated series having higher 143 Nd/ 144 Nd at the same 87 Sr/ 86 Sr than the intermediate-silicic series, to which they are not petrogenetically related. The change from limited partial fusion of upper crust in Jurassic times to widespread partial fusion of lower crust in Early Cretaceous times is considered to be a result of an increasing volume of basaltic intrusion into the crust with time.

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In the Central Iberian Zone there are several large thermal domes in which small bodies of ultramafic, mafic and intermediate rocks appear intimately associated with crustal granites and migmatites. The closest spatial association between the ultramafic, mafic and intermediate rocks and migmatites is in the Toledo Anatectic Complex, where field relationships suggest that these rocks are coeval and have an age close to 340 Ma. This, and the recent discovery in the neighbouring Ossa Morena Zone of a large mid-crustal seismic reflector interpreted as a 335-350 Ma mafic sill, reinforce the hypothesis that heat for crustal melting was supplied from early Variscan mantle magmas emplaced in the middle crust. However, precise ionmicroprobe U-Pb zircon dating and Ti-in-zircon thermometry in Toledo do not support this idea. Whereas the mean age of four mafic bodies is 307 AE 2 Ma, the migmatites are c. 25 Ma older. The migmatites hosting ultramafic, mafic and intermediate bodies have the same age and Ti-in-zircon temperatures as migmatites far from any mafic intrusion. These data reveal that ultramafic, mafic and intermediate magmas are late Variscan; they were emplaced in already cooling anatectic zones once the extensional collapse was initiated, and their thermal impact on the mid-crustal Variscan anatexis of Central Iberia was negligible.

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How and why magmatic systems reactivate and evolve is a critical question for monitoring and hazard mitigation efforts during initial response and ongoing volcanic crisis management. Here we report the first integrated petrological results and interpretation provided to monitoring authorities during the ongoing eruption of Cumbre Vieja, La Palma, Canary Islands, Spain. The first eruptive products comprised simultaneous Strombolian fountain-fed lava flows and tephra fall from near-continuous eruption plumes. From combined field, petrographic and geochemical analyses conducted in the 10 days following sample collection, we infer low percentage mantle melts with a variably equilibrated multimineralic crystal-cargo and compositional fractionation by winnowing during eruptive processes. Hence ‘rapid response’ petrology can untangle complex magmatic and volcanic processes for this eruption, which combined with further study and methodological improvement can increasingly assist in active decision making.

Terra Nova, 22, 341–346, 2010 Abstract The abnormally elevated abundance of inherited zircon (locally up to 80–90% of zircon grains contain pre‐magmatic cores) in the Cambro‐Ordovician magmatic rocks of Central Iberia made possible an estimation of the distribution of ages of their source rocks. The comparison of inherited U–Pb ages and whole‐rock Nd model ages with those of three main North African Neoproterozoic terranes reveals that the Iberian magmas can only have been generated from a crust similar to that of the East African Orogen west of the Arabian–Nubian Shield. Such crust is currently found in the three Precambrian inliers of the Western Desert of Egypt east of the Archaean terranes of Gebel Kamel. Palaeontological evidence also indicates that the Ordovician fauna of Central Iberia is similar to that of the region between eastern Algeria and Arabia; therefore, we conclude that during the Ordovician Iberia was not attached to north‐west Africa near Morocco, as is usually assumed, but instead to the East African Orogen in northern Egypt.

Mg-K mafic intrusive rocks are commonly observed during the late stages of the evolution of orogenic belts. The Variscan French Massif Central has many outcrops of these rocks, locally called vaugnerites. Such magmas have a mantle-derived origin and therefore allow discussion of the role of mantle melting and crust-mantle interactions during late-orogenic processes. In the Southern Velay area of the French Massif Central, LA-ICPMS U-Pb dating on zircons and monazites from three vaugnerites and four coeval granites reveals that the two igneous suites formed simultaneously, at c. 305 Ma. This major igneous event followed after an early, protracted melting stage that lasted for 20-30 My and generated migmatites, but the melt was not extracted efficiently and therefore no granite plutons were formed. This demonstrates that widespread crustal anatexis, melt extraction and granite production were synchronous with the intrusion of vaugneritic mantle-derived melts in the crust. The rapid heating and subsequent melting of the crust led to upward flow of partially molten rocks, doming and collapse of the belt.