Coral Patch and Ormonde seamounts as a product of the Madeira hotspot, Eastern Atlantic Ocean

New detailed swath bathymetry and bottom samples from Coral Patch and Ormonde seamounts provide constraints on the emplacement of the Madeira hotspot in the Eastern Atlantic Ocean. Swath bathymetric data document that Coral Patch is a composite structure, made up of at least nine distinct volcanic centres. Lithified pelagic carbonates infilling fissures in lava blocks constrain a minimal age for the volcanism in the Early Miocene and represent the first documentation of Coral Patch acting as an offshore terrigenous-starved seamount. At Coral Patch, as already observed at the Ormonde seamount, volcanism was emplaced on top of a pre-existing relief resulting from the regional tectonic compressive regime

Magma emplacement at anomalous spreading ridge: constraints due to plagioclase phenocrysts from basalts of Marsili seamount (Southern Tyrrhenian back-arc).

Plagioclase crystals from four basalt samples dredged from different portions of the Marsili seamount (Southern Tyrrhenian, Italy) provide a detailed record of the changes occurring in the surrounding magma during its ascent in the crust. The textural features and chemical zoning (i.e., An content and Fe, Mg, Sr and Ba concentrations) of the plagioclases from each sample show that aggregation of various generations of crystals occurred in the host melt prior to eruption. Plagioclases resulting from crystallisation in small sill intrusions, where local flotation of plagioclase may have occurred, are ubiquitous. Instead, large (up to 1 mm) homogeneous An-rich plagioclases are rare and have only been found in two of the studied basalts, recovered from the northern and southern portions of the volcano, respectively. These crystals record crystallisation events occurring long before eruption, and probably derive from deep-seated crystalline material. At the highest An values, the Sr and Ba concentrations of the studied plagioclases also indicate the existence of two distinct mafic magmas within the lower crustal plumbing system of the Marsili volcano, one with lower Sr and Ba contents than the other. Three of the four stud- ied basalts came from magma with low Sr and Ba, whereas the fourth, which erupted from the southern portion of the volcano, sampled magma richer in Sr and Ba. The ascent of magma caused resorption of the previously formed plagioclase crystals and regrowth of normally or inversely zoned portions, depending on the water-saturated or water-undersaturated conditions of the surrounding magma, respectively. Small shallow magmatic reservoirs may be located under the southern part of the Marsili volcano, as testified by the resorbed sodic cores (An52–57) found in the two basalt samples from this portion

Origin of the southern Tyrrhenian back-arc magmas: evidence for african mantle propagation.

Not availabl

The Messinian volcaniclastic layers of the Northern Apennines: evidence for the initial phases of the Southern Tyrrhenian spreading?

A petrological investigation has been carried out on the Late Miocene (around 5.5 Ma) volcaniclastic layer interbedded in the uppermost Messinian deep-water sediments of the Northern Apennines foredeep basin. The studied samples derive from five sections located on a 200 km long area and reveal that the volcaniclastic layer corresponds to centimetric- to metric-thick turbiditic sequence, essentially composed of lapilli to ash-sized glass shards and scarce (<5%) mineral fragments. The homogeneous chemical composition of the glass shards (calc-alkaline rhyolite) and crystals (plagioclase, sanidine, biotite) suggests a cogenetic origin for the studied samples. In these samples non-volcanic detritus is absent and the morphology of the glass shards is indicative of an origin by an explosive magmatic eruption. Morphological, geochemical and sedimentological features suggest that the volcaniclastic layer can be considered as «primary monomagmatic turbidite» resulting directly from the eruptive vent of a calc-alkaline rhyolitic volcanic arc system. None of the coeval outcropping volcanoes, up to a distance of 1500 km from the studied sections, can be considered as the possible source of this layer. Nevertheless, tectono-magmatic evidence suggests that it may represent the witness of the activity of a calc-alkaline submarine volcanic arc located northwestward of the Aeolian Arc, and related to the first rifting-spreading episode of the Southern Tyrrhenian regio

The heterogeneous nature of the Southern Tyrrhenian mantle: Evidence from olivine-hosted melt inclusions from back-arc magmas of the Marsili seamount

International audienc

Time scales of open-system processes in a complex and heterogeneous mush-dominated plumbing system

The architecture of a mush-dominated plumbing system in active volcanic areas conditions the magma pathways feeding eruptions. Open-system processes along these pathways and the associated time scales are directly related to monitoring data and eruptive behavior. Despite crystal mush–dominated systems being common in active volcanoes, previous studies have not focused on the integration of data from the mush sectors feeding different eruptions, supply- ing a partial view of the pre-eruptive magmatic processes and hindering the interpretation of the monitoring signals during unrest periods. We focus on the Marsili seamount (Tyrrhenian Sea), where the mineral data document processes within a magmatic system vertically extended throughout the local oceanic crust and made of a mush framework spotted with eruptible melt- and crystal-rich pockets. We undertook a study of Marsili olivine crystals that constrains the time scales of three pre-eruptive scenarios, dominated by open-system processes: (1) disag- gregation of the deep Marsili volcano mush zone that occurred over a time scale of years prior to the eruption; (2) rapid ascent (days) of mantle-derived basaltic magma that, in some cases, intercepts shallow plagioclase-rich pockets; and (3) multiple mixing events between melt- and crystal-rich mush zones occurring approximately 1–2 mo and 0.5–3 yr before the eruption. Our results highlight the importance of contemporaneously studying eruptions in different locations on a volcano edifice for a better comprehension on how mush-dominated plumbing systems work as a whole and how this must be considered during the interpretation of monitoring data

MAPPER - MAterie Prime essenziali Per l'Emilia Romagna

Caratterizzazione geochimica e mineralogica di residui solidi da termovalorizzazione per la ricerca di "Critical Raw Minerals" che secondo la EC avranno un ruolo chiave per il sostegno allo sviluppo tecnologico della nostra società. Queste materie prime sono gli elementi dei gruppi delle Terre Rare e del platino, litio, argento, cobalto e (semi)metalli come gallio, germanio, tellurio ed indio. Il progetto co-finanza una borsa di dottorato