Geochronology of the Aeolian Islands (S. Italy)

The full details of this project on the IAPETUS2 webpage (https://www.iapetus2.ac.uk/) will be available shortly. To apply for this position, use the following link www.gla.ac.uk/ScholarshipApp

For further information please contact: Rob Ellam (SUERC, University of Glasgow) [Email Address Removed].

The project student will join the Caledonian Geochronology & Geochemistry Research Group (https://www.scottishisotopes.co.uk/) and be based fulltime at SUERC (https://www.gla.ac.uk/research/az/suerc/). Further project details can be found here: https://www.scottishisotopes.co.uk/postgraduate

PROJECT SUMMARY:

The main aim of this studentship is to provide the best yet reliable chronology for the eruption history of the Aeolian Islands, Southern Italy. For the active volcanoes (Stromboli and Vulcano) the new information will inform volcanic hazard planning but geochronology for these and the other extinct volcanoes on other islands (Alicudi, Filicudi, Lipari, Salina and Panarea) this will be the first state-of-the-art attempt to develop an absolute chronology for Aeolian volcanism. Most radiogenic geochronometers (e.g. Ar-Ar) were only suited to dating material older than a few million years.

Radiocarbon could date wood fragments engulfed by relatively low temperature pyroclastic deposits but, until the advent of accelerator mass spectrometry, required sample sizes of a few grammes. U-series isotopes operate over the correct timescale, but when ages have been generated, they tend not to be eruption ages because the processes that set the isotopic clocks predate eruption.

The Cassignol or unspiked K-Ar method was developed specifically to date young volcanic rocks. However, the Cassignol method has tended to produce conflicting ages and does not deliver high precision. Consequently, the Cassignol method has not been widely embraced by the geochronological community.

Recent advances in Ar-Ar mass spectrometry have achieved performance in two respects: (i) Ar-Ar is now able to date much younger rocks and (ii) the precision on those ages is greatly improved. Now, with absolutely state-of-the-art instrumentation, we can date rocks that are a few tens of k.a. old with a precision of a few hundred years. The youngest rocks we have dated are only a few thousand years old and, critically, we have demonstrated concordance with radiocarbon and luminescence dating. There is now a seamless transition from the radiocarbon working age range to that of Ar-Ar.

Reliable volcanic chronologies can be (literally) vital to the populations of habited volcanoes. The seven Aeolian Islands are calc-alkaline to potassic subduction-related volcanoes. They define an island arc from Stromboli in the east to Alicudi in the west. However, in the centre of the arc, three islands, Vulcano, Lipari and Salina, are aligned roughly north-south. These three islands appear to be located along a rift bounded by the Tindari-Letojanni faults.

Objective 1: Hazard Mitigation: a better knowledge of the lengths and periodicity of the various ancient volcanoes will inform hazard assessment models.

Objective 2: Absolute Age Determinations: With the advent of high precision Ar-Ar geochronology being extended to young volcanic rocks and the increased availability of small sample 14C by accelerator mass spectrometry (AMS) and the new positive ion mass spectrometry (PIMS) method it is, for the first time, possible to build a detailed chronology.

Objective 3: From Chronology to Tectonics: With greatly improved chronology it will also be possible to address some puzzling tectonic questions. In particular, the student will assess whether the suggested migration of magmatism from west to east along the arc is genuine. There seems no obvious reason why typical arc magmatism shouldn’t be simultaneous along the arc. However. The Aeolian islands are not a typical island arc; there is no longer oceanic crust between Africa and Europe in Sicily although there is a Wadati-Benioff zone.

STUDENT

The project requires a student from a geological background who has a desire to combine field observations with precise and accurate laboratory measurements (geochemistry and geochronology). Experience of field mapping, numerically literate and demonstrable ability to work with isotope data are key. The student will be immersed in the Caledonian Geochronology & Geochemistry Research Group at the Scottish Universities Environmental Research Centre (SUERC), which currently includes 6 PhD students, 2 post-doctoral researchers and 4 research technicians.