The provenance of Icelandic volcanic sand: Significance of black sand origin and implications for sampling Mars regolith

• Main Author: Norman, Angela Michelle
• Other Authors: Barnes, Calvin G., Karlsson, Haraldur R., Sylvester, Paul
• Format: Thesis
• Language: English
• Published: 2017
• Subjects: Iceland; Provenance
• Online Access: http://hdl.handle.net/2346/73127

About one-fifth of Iceland’s surface is characterized by basaltic volcanic sand deposits. The provenance of the sands, the factors that lead to enrichments from one volcanic source or another, and whether the detritus is representative of the local or regional bedrock is not well understood. Also, basaltic sand regolith is widespread on Mars, and has the potential to provide important information about Mars’ regional volcanic geology, with a more detailed understanding of the sampling and analysis strategies that might be most effective, based on the Iceland sands results. This study investigates the provenance of ten Icelandic volcanic sand surface deposits collected from beach, dune, river levee and glacial outwash settings across the island. This is achieved by analyzing individual grains of sand, and comparing their chemical compositions to samples from the various volcanic systems on Iceland using published and unpublished data sets. The dominant grain types in each sand deposit are basaltic volcanic glass, plagioclase, clinopyroxene, olivine and siliceous volcanic glass. Some or all of these grain varieties have been analyzed from each sample for major and minor elements via electron microprobe analyses (EMPA). The majority of the grains analyzed by EMPA have been analyzed further for trace element concentrations via laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). All ten Icelandic sand samples have also been analyzed in bulk for major, minor, and trace elements via solution inductively coupled plasma optical emission spectrometry (ICP-OES), or inductively coupled plasma mass spectrometry (ICP-MS), depending on the element. The results of the study show that the individual sand grains are commonly linked to two or more relatively proximal (within ~100km) volcanic sources. The volcanic glasses appear to be particularly distinctive provenance indicators. Individual mineral grains are found to be much less distinctive, at least in terms of the major element composition, and generally ...