Publication Date:
2019-02-01
Description:
Volcanic ash has long been recognized in marine sediment, and given the prevalence of oceanic and continental arc
volcanism around the globe in regard to widespread transport of ash, its presence is nearly ubiquitous. However, the
presence/absence of very fine-grained ash material, and identification of its composition in particular, is challenging
given its broad classification as an “aluminosilicate” component in sediment. Given this challenge, many studies of ash
have focused on discrete layers (that is, layers of ash that are of millimeter-to-centimeter or greater thickness, and their
respective glass shards) found in sequences at a variety of locations and timescales and how to link their presence with
a number of Earth processes. The ash that has been mixed into the bulk sediment, known as dispersed ash, has been
relatively unstudied, yet represents a large fraction of the total ash in a given sequence. The application of a combined
geochemical and statistical technique has allowed identification of this dispersed ash as part of the original ash
contribution to the sediment. In this paper, we summarize the development of these geochemical/statistical
techniques and provide case studies from the quantification of dispersed ash in the Caribbean Sea, equatorial Pacific
Ocean, and northwest Pacific Ocean. These geochemical studies (and their sedimentological precursors of smear slides)
collectively demonstrate that local and regional arc-related ash can be an important component of sedimentary
sequences throughout large regions of the ocean.
Type:
Article
,
PeerReviewed
Format:
text
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