Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Extreme Differentiation Along Multiple Liquid Lines Of Descent In Strongly Peralkaline Magma Series At Pantelleria (Italy), John C. White, Ray Macdonald, Bogusław Bagiński, Katarzyna M. Liszewska
Extreme Differentiation Along Multiple Liquid Lines Of Descent In Strongly Peralkaline Magma Series At Pantelleria (Italy), John C. White, Ray Macdonald, Bogusław Bagiński, Katarzyna M. Liszewska
EKU Faculty and Staff Scholarship
The liquid line of descent from trachyte to pantellerite is controlled primarily by fractional crystallization of alkali feldspar, with whole rock compositions following a fractionation path along the ‘thermal valley’ in the peralkaline haplogranite system Qz-Ab-Or-Ac-Ns and terminating at a minimum on the feldspar-quartz cotectic. Although whole-rock compositions for different pantelleritic suites follow nearly identical paths in a Qz-Ab-Or projection that terminate near the experimental minimum (Qz40.5Or34.5Ab25 at 100 MPa, projected from Ac-Ns), matrix glass from samples with near-minimum compositions record extreme differentiation and form a ‘cotectic delta’ beyond the terminus of the ‘thermal valley’. Although each glass trend shows …
Experimental And Thermodynamic Constraints On Mineral Equilibrium In Pantelleritic Magmas., Pierangelo Romano, Bruno Scaillet, John C. White, Joan Andujar, Ida Di Carlo, Silvio G. Rotolo
Experimental And Thermodynamic Constraints On Mineral Equilibrium In Pantelleritic Magmas., Pierangelo Romano, Bruno Scaillet, John C. White, Joan Andujar, Ida Di Carlo, Silvio G. Rotolo
EKU Faculty and Staff Scholarship
Crystallization experiments on two pantellerites from Pantelleria, Italy, provide new evidence for the relation-ships between mineral phases in pantelleritic rocks as well as the influence of temperature and redox conditionson mineral assemblages. Experiments were performed at 1 kbar with temperature ranging between 750–900°C,andfluid saturation conditions with XH2O (=H2O/H2O+CO2) between 0 and 1. Redox conditions were fixed at, or slightly below, the FMQ buffer. Results show that at temperature of 900 °C pantelleritic magmas are well above the liquidus regardless their water content; we also observed a decrease in liquidus temperature (800°C) with increasingly reducing conditions. Mineral assemblages of the natural …
Volatiles And Trace Element Contents In Melt Inclusions From The Zoned Green Tuff Ignimbrite (Pantelleria, Sicily): Petrological Inferences., Pierangelo Romano, John C. White, Alessandro Ciulla, Ida Di Carlo, Claudia D'Oriano, Patrizia Landi, Silvio G. Rotolo
Volatiles And Trace Element Contents In Melt Inclusions From The Zoned Green Tuff Ignimbrite (Pantelleria, Sicily): Petrological Inferences., Pierangelo Romano, John C. White, Alessandro Ciulla, Ida Di Carlo, Claudia D'Oriano, Patrizia Landi, Silvio G. Rotolo
EKU Faculty and Staff Scholarship
The island of Pantelleria is one of the best known localities of bimodal mafic-felsic magmatism (alkali basalt and trachyte-pantellerite). Among the felsic rocks, the coexistence in a single eruption of products of both trachyte and pantellerite compositions is limited to few occurrences, the Green Tuff (GT) ignimbrite being one of these. The GT is compositionally zoned from pantellerite (70.1 wt% SiO2, mol Na+K/Al = 1.86, 1871 ppm Zr) at the base to crystal-rich (>30 vol%) comenditic trachyte (63.4 wt% SiO2, mol Na+K/Al = 1.10, 265 ppm Zr) at the top, although the pantellertic compositions dominate the erupted volume. We …
Peralkaline Felsic Magmatism At The Nemrut Volcano, Turkey: Impact Of Volcanism On The Evolution Of Lake Van (Anatolia), Ray Macdonald, Mari Sumita, Hans-Ulrich Schmincke, Boguslaw Baginski, John C. White, Slawomir S. Ilnicki
Peralkaline Felsic Magmatism At The Nemrut Volcano, Turkey: Impact Of Volcanism On The Evolution Of Lake Van (Anatolia), Ray Macdonald, Mari Sumita, Hans-Ulrich Schmincke, Boguslaw Baginski, John C. White, Slawomir S. Ilnicki
EKU Faculty and Staff Scholarship
Nemrut volcano, adjacent to Lake Van (Turkey), is one of the most important peralkaline silicic centres in the world, where magmatism for ~570,000 years has been dominated by peralkaline trachytes and rhyolites. Using onshore and Lake Van drill site tephra samples, we document the phenocryst and glass matrix compositions, confirming a complete spectrum from very rare mafic to dominantly silicic magmas. Magma mixing has been common and, along with the multi-lineage nature of the magmas, indicates that Nemrut has been a very open system where, nevertheless, compositionally zoned caps developed during periods of relative eruptive quiescence. Geothermometry suggests that the …
Variations In Mineralogy, Temperature, And Oxygen Fugacity In A Suite Of Strongly Peralkaline Lavas And Tuffs, Pantelleria, Italy., John C. White, Minghua Ren, Don Parker
Variations In Mineralogy, Temperature, And Oxygen Fugacity In A Suite Of Strongly Peralkaline Lavas And Tuffs, Pantelleria, Italy., John C. White, Minghua Ren, Don Parker
EKU Faculty and Staff Scholarship
Eight samples of pantelleritic lava and tuff and a lithic inclusion of trachyte from Pantelleria, Italy, have been thoroughly analyzed with an electron microprobe. These samples reveal five different mineral assemblages if classified by the presence of fayalite, aenigmatite, ilmenite, and magnetite: (1) augite + fayalite + ilmenite + magnetite, (2) augite + fayalite + ilmenite, (3) hedenbergite or sodian hedenbergite + fayalite + ilmenite + aenigmatite + quartz, (4) sodian hedenbergite or aegirine-augite + ilmenite + aenigmatite + quartz ± ferrorichterite, and (5) aegirine-augite + aenigmatite + quartz. Alkali feldspar (Or35–37) is present as the dominant phyric phase in …