Characteristics and Possible Source of a 1479 A.D. Volcanic Ash Layer in a Greenland Ice Core

Abstract

A microparticle concentration peak in a GISP2 ice core contains volcanic glass shards of rhyolitic composition that correspond in age to the 1479-1480 A.D. Mt. St. Helens Wn eruption. These glass shards are compositionally similar to the Wn tephra and constitute 83% of the total particle population. The shards are very coarse-grained (up to 40 μm diameter), suggesting rapid transport from their source to Greenland. A major sulfate peak in the ice occurs approximately 4 months after deposition of the glass shards. This difference in depositional timing suggests primarily tropospheric transport of the ash and stratospheric transport of the sulfate aerosol. Large-scale climatic perturbations following this eruption were evidently negligible. Glaciochemical seasonal indicators suggest a late-fall to early-winter 1479 A.D. eruption.

Recognition of Santorini (Minoan) Tephra in Lake Sediments from Gölhisar Gölü, Southwest Turkey by Laser Ablation ICP-MS

“…Analysis of single glass shards may also provide more information, and hence greater confidence, on the identification and sourcing of disseminated or low mass-loading tephras in lake sediments and ice-cores (cf. Fiacco et al, 1993;Zielinski et al, 1995;Zielinski & Germani, this volume).…”

Volcanic ash layers from the Last Glacial Termination in the NGRIP ice core

“…This extends the chemical range of young Icelandic rhyolites to include the NGRIP ash layers. However, more distant volcanic areas of Alaska and Japan erupt tephra with a low potassium composition and 40 mm ash shards from the AD 1479 Mount St. Helens eruption were reported in the GISP2 ice core (Fiacco et al, 1993). 1519.1 m: basaltic ash layer, Tv-1 (I-THOL-2)…”

“…The volcanic conductivity and sulphate signals are relatively distinct during warm periods but during glacial conditions the measured background signal increases drastically, making the detection of potential volcanic signals much more uncertain. Volcanic ash particles in the ice cores are less ambiguous and chemical analysis of the juvenile shards may result in the identification of the source volcano as well as correlation with ash layers from other ice, marine and terrestrial records (De Angelis et al, 1985;Palais et al, 1991Palais et al, , 1992Fiacco et al, 1993;Grö nvold et al, 1995;Zielinski et al, 1997;Haflidason et al, 2000).…”

Tephrological implications of beam size—sample‐size effects in electron microprobe analysis of glass shards

“…Bogaard et al, 1994;Turney et al, 1997;Turney, 1998;Caseldine et al, 1999). The widespread application of crypto-tephra analysis has resulted in the establishment of Holocene tephrostratigraphical frameworks and the mapping of tephra distributions in diverse and widely separated environments (Lowe, 1988;Kvamme et al, 1989;Sejrup et al, 1989;Sjøholm et al, 1989;Begét et al, 1992;Blackford et al, 1992;Hall, 1992, 1996;Fiacco et al, 1993;Merkt et al, 1993;Austin et al, 1995;Bennett et al, 1993;Grö nvold et al, Hall et al, 1995;Juvigne et al, 1995;Newnham et al, 1995;Oldfield et al, 1997;Pilcher et al, 1995;Zielinski et al, 1995;Lacasse et al, 1996;Dwyer and Mitchell, 1997;Eastwood et al 1999;Haflidason et al, 2000;Turney et al, in press;Wastegård et al, 2000).…”