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Tracing the source in the volcanic field

The collation of whole-rock major and trace element data has led to the development of a method to correlate volcanic ash samples to their source volcanic centres.

The method produces reasonable results based on major element signatures alone but the use of trace element signatures strengthens correlations.

By linking volcanic ash fragments (tephra) to their source centres in volcanic fields, the eruptive history and fragment dispersal patterns can be revealed, along with potential hazards.

Tephra-derived glass compositions have been compared with past and new data for the entire field.

The results show that incompatible trace element ratios vary widely across the field. However, there is a more restricted range within samples from a single volcanic centre.

The findings suggest that each volcanic centre does not have a unique geochemical signature in the field as a whole. Additional criteria have been utilised to further constrain the source centres, including age, eruption scale, and location.

The combination of tephra correlation, dating and stratigraphic constraints allow – for the first time – the relative and absolute ordering of 48 of 53 volcanic centres. A relationship between short quiet periods and close eruption sites has also been found for several centres.

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Multi-criteria correlation of tephra deposits to source centres applied in the Auckland Volcanic Field, New Zealand. Cover
Multi-criteria correlation of tephra deposits to source centres applied in the Auckland Volcanic Field, New Zealand.

Bulletin of Volcanology

Publication Date: 28/06/2017