Quartz-bearing rhyolitic melts in the Earth's mantle.

The occurrence of rhyolite melts in the mantle has been predicted by high pressure-high temperature experiments but never observed in nature. Here we report natural quartz-bearing rhyolitic melt inclusions and interstitial glass within peridotite xenoliths. The oxygen isotope composition of quartz crystals shows the unequivocal continental crustal derivation of these melts, which approximate the minimum composition in the quartz-albite-orthoclase system. Thermodynamic modelling suggests rhyolite was originated from partial melting of near-anhydrous garnet-bearing metapelites at temperatures ~1000 °C and interacted with peridotite at pressure ~1 GPa. Reaction of rhyolite with olivine converted lherzolite rocks into orthopyroxene-domains and orthopyroxene + plagioclase veins. The recognition of rhyolitic melts in the mantle provides direct evidence for element cycling through earth's reservoirs, accommodated by dehydration and melting of crustal material, brought into the mantle by subduction, chemically modifying the mantle source, and ultimately returning to surface by arc magmatism.

A Middle Pleistocene wolf from central Italy provides insights on the first occurrence of Canis lupus in Europe.

Here, we describe a partial cranium of a large canid dated at 406.5 ± 2.4 ka from the Middle Pleistocene of Ponte Galeria (Rome, Italy). The sample represents one of the few Middle Pleistocene remains of a wolf-like canid falling within the timeframe when the Canis mosbachensis-Canis lupus transition occurred, a key moment to understand the spread of the extant wolf (Canis lupus) in Europe. CT-based methods allow studying the outer and inner cranial anatomy (brain and frontal sinuses) of a selected sample of fossil and extant canids. Morphological and biometric results allowed to: (I) ascribe the cranium from Ponte Galeria to an adult Canis lupus, representing the first reliable occurrence of this taxon in Europe; (II) provide the content for a biochronological revision of the Middle Pleistocene record of European wolves.

Experimental measurements of the viscosity and melt structure of alkali basalts at high pressure and temperature.

Volcanic eruptions are shallow phenomena that represent the final stage of density- and viscosity- driven processes of melt migration from source rocks at upper mantle depths. In this experimental study, we investigated the effect of pressure (0.7-7.0 GPa) and temperature (1335-2000 °C) on the viscosity and the atomic melt structure of a synthetic anhydrous primitive alkaline basalt, an analogue of the pre-eruptive magma that likely feeds the Campi Flegrei Volcanic District at present day. Obtained viscosities (0.5-3.0 Pa s), mobility (0.1-0.4 g cm3 Pa-1 s-1) and ascent velocity (1.5-6.0 m yr-1) are presented to support geochemical and geophysical observations of Campi Flegrei as a critical volcanic district currently undergoing gradual magma recharge at depth.

Environmental evolution, faunal and human occupation since 2 Ma in the Anagni basin, central Italy.

We present the study of a composite, yet continuous sedimentary succession covering the time interval spanning 2.6-0.36 Ma in the intramontane basin of Anagni (central Italy) through a dedicated borecore, field surveys, and the review of previous data at the three palaeontological and archaeological sites of Colle Marino, Coste San Giacomo and Fontana Ranuccio. By combining the magneto- and chronostratigraphic data with sedimentologic and biostratigraphic analysis, we describe the palaeogeographic and tectonic evolution of this region during this entire interval. In this time frame, starting from 0.8 Ma, the progressive shallowing and temporary emersion of the large lacustrine basins and alluvial plains created favorable conditions for early hominin occupation of the area, as attested by abundant tool industry occurrences and fossils. This study provides new constraints to better interpret the hominin migratory dynamics and the factors that influenced the location and spatial distribution during the early occupation of this region.

Neandertals on the beach: Use of marine resources at Grotta dei Moscerini (Latium, Italy).

Excavated in 1949, Grotta dei Moscerini, dated MIS 5 to early MIS 4, is one of two Italian Neandertal sites with a large assemblage of retouched shells (n = 171) from 21 layers. The other occurrence is from the broadly contemporaneous layer L of Grotta del Cavallo in southern Italy (n = 126). Eight other Mousterian sites in Italy and one in Greece also have shell tools but in a very small number. The shell tools are made on valves of the smooth clam Callista chione. The general idea that the valves of Callista chione were collected by Neandertals on the beach after the death of the mollusk is incomplete. At Moscerini 23.9% of the specimens were gathered directly from the sea floor as live animals by skin diving Neandertals. Archaeological data from sites in Italy, France and Spain confirm that shell fishing and fresh water fishing was a common activity of Neandertals, as indicated by anatomical studies recently published by E. Trinkaus. Lithic analysis provides data to show the relation between stone tools and shell tools. Several layers contain pumices derived from volcanic eruptions in the Ischia Island or the Campi Flegrei (prior to the Campanian Ignimbrite mega-eruption). Their rounded edges indicate that they were transported by sea currents to the beach at the base of the Moscerini sequence. Their presence in the occupation layers above the beach is discussed. The most plausible hypothesis is that they were collected by Neandertals. Incontrovertible evidence that Neandertals collected pumices is provided by a cave in Liguria. Use of pumices as abraders is well documented in the Upper Paleolithic. We prove that the exploitation of submerged aquatic resources and the collection of pumices common in the Upper Paleolithic were part of Neandertal behavior well before the arrival of modern humans in Western Europe.