Trace element analysis of Late Holocene tephras from Greenland ice cores

Locating and geochemically characterising cryptotephra in polar ice cores is critical for identifying the sources of volcanic markers that the ice cores contain. Trace element analysis of tephras is an important compliment to major element analysis as trace element composition can help differentiate volcanic sources and provide insights into the processes that generated the tephra. Here, we examine the trace element composition of selected tephras from Greenland ice cores using laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) in an attempt to verify their sources. Our results support the attribution of the ~1641 BCE acid layer in Greenland ice to Aniakchak, but we demonstrate that an eruption from an unidentified source was coeval with the Millennium Eruption of Changbaishan in 946 CE. We find that small shard size and the presence of multiple tephra populations pose particular challenges to the successful analysis of sparse tephra layers in the ice.