Research group NG| Stockholm University Quaternary Tephra Studies (SUQuaTeSt)
Volcanic ashes (tephra) buried in sediments or glacier ice are a useful material for geochronological applications. At Stockholm University, tephrochronology has been used in geological research over the course of the last few decades.
Quaternary tephra studies
Tephra is the unconsolidated pyroclastic material ejected into the atmosphere during an explosive volcanic eruption. To put it in simple terms: it's the stuff that shoots up when a volcano goes "boom". The finest particles of this is the volcanic ash, and it can spread far by wind in a short amount of time. Most of it settles on the surfaces of the Earth within a few weeks at the most, which in geological terms is very quick.
Tephra that has become properly buried in sediments or glacier ice therefore becomes a very precise time-marker for the eruption event. This works as a dating method in climate reconstructions and as a correlation tool between studies where the same tephra has been identified at different locations. Tephrochronology is the method where volcanic ashes are used for chronological applications, and it is useful in various disciplines of geology, palaeontology and archaeology.
Group description
The tephra studies performed at Stockholms University today were initiated by professor Stefan Wastegård around the turn of the millenium, but its roots go further back. The term "tephra" as used to describe volcanic ashes in geology and "tephrochronology" for the chronological applications of volcanic ashes were coined by Sigurdur Thorarinsson in 1944, in his disseration at Stockholms högskola (Stockholm University College). The more recent research has involved several PhD students and postdocs as well as collaborators from other institutions.
The field equipment and laboratory facilities at the Department of Physical Geography allow for field sampling and laboratory extraction of tephra in sediments. Detection of ash particles is performed via microscopy, while adequate geochemical analysis requires equipment currently not hosted at Stockholm University. The recent and current research mainly has a Quaternary geology and palaeoclimate focus, but methodological and other aspects of tephra studies and their advancement are also of interest.
Group members
Group managers
Stefan Wastegård
Professor of Quaternary Geology with a specialisation in Quaternary Stratigraphy
Members
Simon Larsson
Postdoctoral researcher
Stefan Wastegård
Professor of Quaternary Geology with a specialisation in Quaternary Stratigraphy