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RESEARCH PROGRAM

italiano - inglese
Research Units
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Keywords
PANTELLERIA; PERALKALINE MAGMAS GENESIS AND DIFFERENTIATION; MAGMA CHAMBER PROCESSES; ERUPTIVE DYNAMICS; DEPOSITIONAL MECHANISMS; RADIOGENIC ISOTOPES; PHYSICAL PROPERTIES OF MAGMAS; CHEMCAL PROPERTIES OF MAGMAS

Genesis, evolution, eruptive dynamics and depositional processes of peralkaline magmas at Pantelleria.

Università degli Studi di Napoli "Federico II"
Abstract
The island of Pantelleria, the type locality for pantellerite, is characterised by the close association of weakly-alkaline basalts, and peralkaline rhyolites and trachytes. The peralkaline eruptions span over a wide range of size and style. As a consequence, Pantelleria offers a good opportunity to study the genesis and differentiation of peralkaline magmas, magma chamber processes, eruption dynamics, transport and depositional mechanisms, and their relationships. All these scientific topics are still strongly debated in the international literature. The debate also arises from the limited knowledge of the rheological and thermodynamic properties of the peralkaline magmas, less diffuse than magmas of other composition. To contribute to the solution of the open problems at Pantelleria and, more in general, at all peralkaline volcanoes, the present project includes a detailed volcanological study of three volcanoes, each representative of one of the different types of volcanoes on the island: a pumice cone, a shield volcano and a partially collapsed edifice. To define the peralkaline magma genesis we will study also the basaltic magmas of Pantelleria. A field survey will be carried out and followed by collection of rock samples on which sedimentological, geochemical (major and trace elements, volatile content), isotope (at a different scale: whole rock, minerals, single mineral, core-rim of selected minerals) analyses will be performed. Furthermore, we will also measure or >>>

Principal Investigator
Lucia CIVETTA Università degli Studi di NAPOLI "Federico II"
Research Objectives
The present research project has as main objective the definition of the history of peralkaline magmas at Pantelleria, from source, through magma chamber and eruption, to deposition. Achievement of this goal will contribute to the understanding of magmatological and volcanological processes involving peralkaline magmas, very poorly addressed or strongly debated in the volcanological literature. Particular objectives are the definition of: a) genesis of peralkaline magmas and their differentiation processes; b) possible effects of crustal contamination on mantle-derived magmas; c) shallow magma chamber processes; d) pre-eruption volatiles content; e) P and T of crystallisation; f) rheological properties of peralkaline magmas; g) eruption dynamics, and transport and deposition mechanisms of the products of eruptions building up small volcanic edifices.
Furthermore, the island is one of the eight Italian active volcanoes with a widespread fumarole activity. The last eruption has taken place in 1891, few miles away from the northern coast, in the Sicily Channel. The island is home for about 10,000 people and population increases during summer. Persistent activity of the volcanic system and population exposed to the volcanic hazards in case of renewal of volcanism, make the volcanic risk of the island quite significant. In this framework it is important to assess the type of hazards which could occur investigating the eruption dynamics and the characteristics of the >>>

Timescale
24 months
National and international background
Genesis of pantelleritic magmas and relationships among pantelleritic magma rheology, eruption dynamics, and transport and deposition mechanisms are topics still debated in the literature. As a matter of fact, the rheological properties of pantelleritic magmas are poorly known and the controversy on their genesis by crystal fractionation from a basaltic parental magma or partial melting of gabbroic cumulate or underplated basalts is still alive.
The island of Pantelleria, the type locality for pantellerite, is characterised by a bimodal association of mildly alkalic basalts and peralkaline trachytes and rhyolites, and by eruptions of peralkaline magmas covering a wide range of intensity and style. Therefore, it offers a good opportunity to investigate pantelleritic magma genesis and differentiation, magma rheology, eruption dynamics, transport and deposition mechanisms, and their relations.
The island is the emergent portion of a volcanic edifice that rises about 1,000 m above sea floor, in the Sicily Channel. Pantelleria is composed dominantly of volcanic rocks which include lavas and pyroclastic deposits, varying in compositions from pantellerite, through pantelleritic trachyte and comenditic trachyte, to mildly alkalic basalt, in order of decreasing abundance (Civetta et al., 1998). Felsic rocks range in age from 324 to 4 ka (Mahood and Hildreth, 1986; Civetta et al., 1984; 1988), whereas exposed mafic rocks are dated at about 118, 83, 29 and less than 10 ka >>>