Search results for " MAntle"
showing 10 items of 75 documents
Potassic and sodic igneous rocks from eastern Paraguay: their origin from the lithospheric mantle and genetic relationships with the associated Paran…
1997
3 DIPARTIMENTO DI SCIENZE DELLA TERRA, UNIVERSITY OF TRIESTE, VIA E. WEISS 8, I-34127 TRIESTE, ITALY 4 INSTITUTO DE GEOCIENCIAS, UNIVERSIDADE DE SAO PAULO, C.P. 30627, 01051 SAO PAULO, SP, BRAZIL 5 DIPARTIMENTO DI SCIENZE DELLA TERRA, ‘LA SAPIENZA’ UNIVERSITY, PIAZZALE ALDO MORO 5, I-00185, ROME, ITALY 6 ISTITUTO DI MINERALOGIA, PETROGRAFIA E GEOCHIMICA, UNIVERSITY OF PALERMO, VIA ARCHIRAFI 36, I-90100,
A two-component mantle source feeding Mt. Etna magmatism; insights from the geochemistry of primitive magmas.
2014
The major elements, trace elements and Sr and Nd isotopes of selected Etnean primitive rocks (b15 ky BP) were studied in order to characterize their mantle source. The noble-gas geochemistry of fluid inclusions in minerals fromthe same lavaswas also investigated. Themajor element compositions ofwhole rocks and minerals showed that these products are among the most primitive atMt. Etna, comprising 6.3–17.5 wt.% MgO. The variable LREE (Light Rare Earth Elements) enrichment relative to MORB (Mid-Ocean Ridge Basalt) (Lan/Ybn = 11–26), togetherwith the patterns of certain trace-element ratios (i.e., Ce/Yb versus Zr/Nb and Th/Y versus La/Yb), can be attributed to varying degrees of melting of a c…
Carbon concentration increases with depth of melting in Earth’s upper mantle
2021
Carbon in the upper mantle controls incipient melting of carbonated peridotite and so acts as a critical driver of plate tectonics. The carbon-rich melts that form control the rate of volatile outflux from the Earth’s interior, contributing to climate evolution over geological times. However, attempts to constrain the carbon concentrations of the mantle source beneath oceanic islands and continental rifts is complicated by pre-eruptive volatile loss from magmas. Here, we compile literature data on magmatic gases, as a surface expression of the pre-eruptive volatile loss, from 12 oceanic island and continental rift volcanoes. We find that the levels of carbon enrichment in magmatic gases cor…
Proterozoic melting in the northern peridotite Massif, Zabargad Island: Os isotopic evidence
1999
The geodynamic history of the three Zabargad peridotite bodies is the key to their significance as samples of the upper mantle. Currently, there are two main hypotheses that differ greatly in their implications for the origin and age of the peridotite complex as a whole. In the first, the Zabargad peridotite bodies all represent young asthenospheric mantle that was juxtaposed with ancient crustal gneisses during the opening of the Red Sea. In the second, the complex may represent a single package of residual mantle and lower crust of Pan-African age that was uplifted during the Miocene. In order to distinguish between these two models, we have analysed five samples of Zabargad peridotite an…
Carbonatites from the Southern Brazilian platform: I
2020
We present a comprehensive overview of the geochemical characteristics and evolution of the carbonatites from the southern Brazilian Platform (Paraná Basin). The carbonatites from different complexes display large compositional variability in terms of abundances of incompatible and rare earth elements. This is in agreement with an origin from heterogeneous lithospheric sources, as confirmed by isotopic data (see Speziale et al., this issue). The characteristic major and trace element abundances of these carbonatites present compelling evidence for invoking liquid unmixing as the main mechanism of their formation and evolution albeit few exceptions. We propose an evolutionary trend for the B…
Phytosociological and phytogeographical considerations on the orophilous alliance Berberido aetnensis-Crataegion laciniatae (Rhamno-Prunetea)
2011
Re-enrichment of cratonic lithospheric mantle beneath an evolving rift: Mantle xenoliths from East Antarctica
2006
The ecological role of Pyrus Spinosa Forssk. in the ecosystem recovery and land restoration of Mediterranean woodlands
2021
In the Mediterranean basin, large areas still call for active reforestation, having a very low woody cover, thus resulting less resistant and resilient to climate change and suffering from a higher risk of soil degradation processes. Knowing the effects on soil fertility and carbon sequestration of single woody species can be of great practical importance, although being rarely tested. We aimed to assess the effect of Pyrus spinosa on soil fertility (soil carbon and nitrogen), microbial biomass and carbon sequestration (in aboveground stems) of Mediterranean pasturelands. The research was carried out in Ficuzza Nature Reserve (NW Sicily), where large areas are composed of extensive pasturel…
The transition between the Marsili oceanic crust and the W Calabria rifted margin: rifting and drifting in the upper plate of the Ionian subduction z…
2012
The western Calabria continental margin forms the transition between the Late Pliocene to Recent Marsili spreading center and continental Calabria. Integrating highpenetration and -resolution upper crustal seismic images with seafloor morphology, ODP well data and geological/geophysical constraints we provide a detailed reconstruction of the architecture of the distal portion of the W Calabria rifted margin and of the adjacent Marsili “oceanic” domain (Fig. 1) and develop a scheme for the Pliocene to present rifting and drifting of the upper plate of the Ionian subduction zone. Our seismic data document the presence of stretched and thinned continental crust, less than 10 Km thick into the …