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Bora-Baricha-Tullu Moye is a Late Quaternary volcanic system in the Main Ethiopian Rift, characterised by products of both explosive and effusive volcanic eruptions. The petrological and geochemical characteristics of the volcanic products are investigated using a combination of petrography, major and trace element whole rock analyses and in-situ major element analyses of phenocryst phases, matrix glass and melt inclusions. The bulk rock compositions vary from basalt to peralkaline rhyolite (comendite and pantellerite), and the chemical variability can largely be explained by fractional crystallisation processes with minor crustal assimilation and magma mixing. The dominant mineral phases such as clinopyroxenes and feldspars show a tendency for Fe and Na enrichment respectively from the basalts towards the pantellerites. The comendite and pantellerite deposits show systematic variations towards more evolved glass and mineral composition with the stratigraphy. The combination of thermometry (i.e. clinopyroxene-liquid, feldspar-liquid, olivine-liquid and clinopyroxene-only) and barometry (i.e. clinopyroxene-liquid and clinopyroxene-only) modelling suggests that the basaltic magmas are stored at high temperature (1070–1190 °C) at mid-to-deep-crustal levels (∼7–29 km). The peralkaline rhyolite melts are stored at lower temperature (i.e. 805–900 °C for comendite; 700–765 °C for pantellerite) at shallow crustal levels (∼4 km). The conditions of pre-eruptive storage as recorded in the comendite and pantellerite rocks in combination with stratigraphic constraints, suggests a progressive temporal evolution of the magma reservoirs to cooler storage temperatures., SCOPUS: ar.j, info:eu-repo/semantics/published

Constraining the duration of magmatic activity on the Moon is essential to understand how the lunar mantle evolved chemically through time. Determining age and initial isotopic compositions of mafic lunar meteorites is a critical step in defining the periods of magmatic activity that occurred during the history of the Moon and to constrain the chemical characteristics of mantle components involved in the sources of the magmas. We have used the in situ Pb-Pb SIMS technique to investigate eight lunar gabbros and basalts, including six meteorites from the Northwest Africa (NWA) 773 clan (NWA 2727, NWA 2700, NWA 3333, NWA 2977, NWA 773, and NWA 3170), NWA 4734, and Dhofar 287A. These samples have been selected as there is no clear agreement on their age and they are all from the dominant low titanium chemical group. We have obtained ages of 2981 +/- 12 Ma for NWA 4734 and 3208 +/- 22 Ma for Dhofar 287. For the NWA 773 clan, four samples (the fine-grained basalt NWA 2727 and the three gabbros NWA 773, NWA 2977, NWA 3170) out of six yielded isochron-calculated ages that are identical within uncertainties and yielding an average age of 3086 +/- 5 Ma. The age obtained for the fine-grained basalt NWA 2700 is not precise enough for comparison with the other samples. The gabbroic sample NWA 3333 yielded an age of 3038 +/- 20 Ma suggesting that two distinct magmatic events may be recorded in the meteorites of the NWA 773 clan. The present study aims to identify and assess all potential issues that are associated with different ways to date lunar rocks using U-Pb-based methods. To achieve this, we have compared the new ages with the previously published data set. The entire age data set from lunar mafic meteorites was also screened to identify data showing analytical issues and evidence of resetting and terrestrial contamination. The data set combining the ages of mafic lunar meteorites and Apollo rocks suggests pulses of magmatic activity with two distinct phases between 395

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 (D1). The calc-alkaline Sant Llorenç–La Jonquera pluton and the gabbro–diorite Ceret stock were emplaced during a later thermal episode synchronous with the D2 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., Ministerio de Ciencia e Innovación, Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, FALSE, pub

Growth of continental crust involves the complex interplay of subduction zone magmatism, to generate the crust, followed by stabilization through crustal thickening, magmatism and ultimately isolation from the active plate margin. The Jinshajiang orogenic belt, SW China, provides an exceptional record of continental development as the result of closure of the Paleo-Tethys seaway and ensuing collision. A compilation of U-Pb age and geochemical data for the plutonic and volcanic rocks within the southern part of the Jinshajiang orogenic belt, including new high-precision ages for the Ludian granitoid batholith of 231 to 220 Ma, enables us to explore the interaction between magmatism and orogeny in the context of the Paleo-Tethys closure and continental amalgamation. These age and geochemical constraints, in conjunction with other geologic evidence, suggest that subduction of the Paleo-Tethys ocean dominated local tectonics prior to the Triassic, creating a volcano–plutonic arc along the eastern margin of the Qamdo-Simao terrane. Following consumption of the ocean, collision zone magmatism, dated at 247 to 237 Ma, was manifested by eruption of voluminous volcanic rocks in a suture-parallel zone. Crustal anatexis was contemporaneous with the earliest phases of collision, producing high-silica rhyolites of Early Triassic age (ca. 247-246 Ma). Between 245 and 237 Ma, the local tectonic regime switched from compression to extension, probably due to strain partitioning caused by oblique convergence, which led to the development of rift-basins and extensive syn-tectonic bimodal volcanism associated with deep-water sediments. From 234 Ma to 214 Ma, the emplacement of high-K, calc-alkaline granodiorites-monzogranites occurred prior to, or during, isostatic uplift and extension, probably caused by breakoff of the subducted slab. The resultant exhumation brought deep-seated granitoid batholiths to the surface, and was contemporaneous with intrusion of ultramafic-mafic melts. Oph

El presente trabajo discute aspectos de la evolución volcano-magmática de la isla Decepción en Antártida, sobre la base del reordenamiento estratigráfico y análisis geoquímico de los distintos eventos acaecidos. La isla Decepción se encuentra en el eje del rift que separa las islas Shetland del Sur de la península Antártica correspondiente al estrecho de Bransfield. En ella, numerosos investigadores llevaron a cabo estudios geológicos existiendo actualmente controversias respecto al orden lito y cronoestratigráfico de los afloramientos. Se analiza en detalle el sector occidental de la isla, donde están representadas todas las unidades de la columna estratigráfica. A partir del relevamiento geológico de detalle del área y el levantamiento de perfiles estratigráficos, se correlacionaron las distintas unidades presentes, y de acuerdo a este reordenamiento estratigráfico, se analiza la evolución magmática a partir de la caracterización geoquímica de la secuencia. This work discusses the different aspects of the volcanic-magmatic evolution of the Deception Island in Antarctic, based on the stratigraphic reorganization and the geochemical analysis performed in several events. This island constitutes the rift axis that separates the South Shetland from the Antarctic Peninsula along the Bransfield Strait. Several investigators performed geological research on Deception Island. Some controversy exists regarding the lito- and chronostratigraphy of the rocks. Here, we analyze in detail, the westernl sector of the island, where the entire stratigraphic column is represented. From this detailed geological study of the area and the stratigraphic profiles collected, the different units were correlated. According to this stratigraphic reorganization based on the geochemical characteristics of the sequence, the magmatic evolution is analyzed.