Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6445430 | Quaternary Science Reviews | 2016 | 19 Pages |
Abstract
Despite the widespread application of tephra studies for dating and correlation of stratigraphic sequences ('tephrochronology'), questions remain over the reliability and replicability of tephra records from lake sediments and peats, particularly in sites >1000Â km from source volcanoes. To address this, we examine the tephrostratigraphy of four pairs of lake and peatland sites in close proximity to one another (<10Â km), and evaluate the extent to which the microscopic (crypto-) tephra records in lakes and peatlands differ. The peatlands typically record more cryptotephra layers than nearby lakes, but cryptotephra records from high-latitude peatlands can be incomplete, possibly due to tephra fallout onto snow and subsequent redistribution across the peatland surface by wind and during snowmelt. We find no evidence for chemical alteration of glass shards in peatland or lake environments over the time scale of this study (mid-to late- Holocene). Instead, the low number of basaltic cryptotephra layers identified in distal peatlands reflects the capture of only primary tephra-fall, whereas lakes concentrate tephra falling across their catchments which subsequently washes into the lake, adding to the primary tephra fallout received in the lake. A combination of records from both lakes and peatlands must be used to establish the most comprehensive and complete regional tephrostratigraphies. We also describe two previously unreported late Holocene cryptotephras and demonstrate, for the first time, that Holocene Icelandic ash clouds frequently reached Arctic Sweden.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
E.J. Watson, G.T. Swindles, I.T. Lawson, I.P. Savov,