Search results for "Xenoliths"
showing 5 items of 15 documents
New evidence of mantle heterogeneity beneath the Hyblean Plateau (southeast Sicily, Italy) as inferred from noble gases and geochemistry of ultramafi…
2012
Abstract We analyzed major and trace elements, Sr and Nd isotopes in ultramafic xenoliths in Miocenic age Hyblean diatremes, along with noble gases of CO2-rich fluid inclusions hosted in the same products. The xenoliths consist of peridotites and pyroxenites, which are considered to be derived from the upper mantle. Although the mineral assemblage of peridotites and their whole-rock abundance of major elements (e.g., Al2O3 = 0.8–1.5 wt.%, TiO2 = 0.03–0.08 wt.%) suggest a residual character of the mantle, a moderate enrichment in some incompatible elements (e.g., LaN/YbN = 9–14) highlights the presence of cryptic metasomatic events. In this context a deep silicate liquid is considered the me…
CHLORITE/SMECTITE - ALKALI FELDSPAR METASOMATIC XENOLITHS FROM HYBLEAN MIOCENIC DIATREMES (SICILY, ITALY): EVIDENCE FOR EARLY INTERACTION BETWEEN HYD…
2006
Upper-Miocene tuff-breccia pipes from the Hyblean area (south-eastern Sicily) bear a number of ultramafic and mafic xenoliths (spinel-peridotites, pyroxenites, gabbroic rocks) whose study has led to conclude that the Meso-Caenozoic carbonatic and volcanic succession stands upon a fossil oceanic core-complex, probably connected with the adjacent Ionian crust. Evidence for hydrothermal metasomatism is common in the Hyblean ultramafic and mafic xenoliths. In some cases, extreme metasomatic transformation and shearing have deleted original mineralogy and textures yielding unusual rocks, hereafter called “metasomatites”. These rocks generally exhibit cataclastic texture, their hydrothermal miner…
The heterogeneity of the Mexican lithospheric mantle: Clues from noble gas and CO2 isotopes in fluid inclusions
2022
The abundance of mantle-derived rocks and lavas, in combination with its tectonic evolution, render Mexico a perfect laboratory to investigate the chemical and the isotopic heterogeneity of the lithospheric mantle. New data on the composition of noble gases and CO2in Mexican mantle xenoliths and lavas is reported. Our samples consist of six ultramafic nodules from the Durango Volcanic Field (DVF) and the San Quintin Volcanic Field (SQVF), monogenetic complexes belonging to the Mexican Basin and Range province; and four lavas from the Sierra Chichinautzin (SCN), a Quaternary monogenetic volcanic field located in the Mexican volcanic arc. Ne and Ar isotopes in fluid inclusions reveal mixing b…
Cognate xenoliths in Mt. Etna lavas: witnesses of the high-velocity body beneath the volcano
2013
Various xenoliths have been found in lavas of the 1763 (“La Montagnola”), 2001, and 2002–03 eruptions at Mt. Etna whose petrographic evidence and mineral chemistry exclude a mantle origin and clearly point to a cognate nature. Consequently, cognate xenoliths might represent a proxy to infer the nature of the high-velocity body (HVB) imaged beneath the volcano by seismic tomography. Petrography allows us to group the cognate xenoliths as follows: i) gabbros with amphibole and amphibole-bearing mela-gabbros, ii) olivine-bearing leuco-gabbros, iii) leuco-gabbros with amphibole, and iv) Plg-rich leuco gabbros. Geobarometry estimates the crystallization pressure of the cognate xenoliths between …
Micro-thermometry and minerochemical composition of ultramafic xenoliths and minerals from Mt. Vulture volcano (southern Italy)
2022
Here minerochemical composition and micro-thermometric data of ultramafic xenoliths (wehrlite) and loose xenocrysts (olivine and Cr-diopside) from the last melilitite-carbonatite explosive volcanic activity of Mt. Vulture volcano. In addition, some geometrical parameters of pelletal lapilli are reported.