Resolving the Pantescan tephrostratigraphy using trace elements
Tephra samples have been recovered from many drill cores around the Mediterranean Sea, both from offshore locations as well as onshore lakes and caves. Since they represent isochrons (horizons of the same age) they have been used to date palaeo-environmental and archaeological records; and the stratigraphy and dataset of Mediterranean tephras is constantly being refined with a view to help understand the timing and rates of environmental transitions.
The island of Pantelleria, Italy, is the source for many key marker tephras in the Mediterranean record. Recent work on the stratigraphy of the island has developed the first complete spatial and temporal pre-46 ka volcanic history of the island. This work reveals that continusous, small-scale background activity is punctuated by 9 ignimbrite-forming eruptions. Five caldera collapse events have been identified, 3 more than previously defined. While it may appear that a large number of proximal-distal tephra correlations for Pantelleria have already been suggested in the literature this is because Pantelleria’s chemistry is unique in the greater Mediterranean area and easy to identify. However, very few distal tephras have up to now been related to specific eruptions due to a lack of proximal stratigraphic and geochemical data. Thus, there is a need to revisit the tephrochronology record in light of the new island stratigraphy.
Correlating tephras from drill cores with onshore deposits relies on a number of characteristics such as stratigraphic position, age (if available), crystal content (if any) and geochemical composition. The more information is available the better for achieving a reliable correlation. Increasingly, tephrochronology has moved from bulk-rock to single shard analysis and from major element to trace element analysis, e.g. via laser ablation ICP-MS.
This project will contribute to ongoing work to establish a comprehensive Pantescan tephrochronological framework. Existing correlations of tephra horizons and Pantescan eruptions are being reviewed in light of the new stratigraphy published by Jordan et al. (2018). Our main aim is to define the geochemical composition of the nine ignimbrite formations on Pantelleria, and to correlate with distal equivalents. This project will focus on defining the tephras using trace element analysis on the LA-QQQ-ICP-MS at the University of Hull.
The successful candidate will have experience which includes volcanic successions and handling geochemical data. The successful candidate will be able to access a variety of training. They will develop skills in the use of the LA-QQQ-ICP-MS and analysing geochemical data sets in excel and R.