Trace elements in quartz - a combined electron microprobe, secondary ion mass spectrometry, laser-ablation ICP-MS, and cathodoluminescence study

We present electron microprobe, secondary ion mass spectrometry, and laser ablation inductively coupled mass spectrometry data for common trace elements (Li, Al, Ti, Na, K, Fe) in quartz. Our samples from both magmatic and hydrothermal environments all show heterogeneity at the single grain scale. ConcentrationsofAlandTi determinedbyEPMA,SIMS,andLA-ICP-MSareinroughagreementandconfirmtherobustnessof these analytical methods. The highest precision data were obtained from SIMS, but this is outweighed by the lack of a high quality quartz reference sample for calibrating this technique. Due to its large sampling volume, laser ablation analyses gave only average values for trace elements in zoned quartz. Because of its better spatial resolution in conjunction with the ability to combine spot analyseswithcathodoluminescenceimaging EPMAprovedthemost reliable insitu methodfor obtainingquantitativetraceelement dataofquartzatconcentrationsinexcessof afew10' sofppmandatthe<10µ mscale.However,oursamplecontainedfewelements at such high concentration levels. We found in our samples a positive correlation between CL signature and the observed Ti contents for the samples investigated. In particular, blue luminescing zones were found to have elevated Ti concentrations as compared to other nearby domains. Using a mathematical spectral deconvolution weshow thehighlycomplex natureof CL emission- it appearsthat other trace elementmight play a less pronounced role in this process. Our examples demonstrate the value of CL for documenting multi-phase alteration in quartz. In agreement with previously proposed models, we confirm a significant correlation between mono- and tri-valent cation concentrations in quartz. A very strong correlation in alkali metal contents is particularly obvious. Ti was found to be universally present in magmatic quartz, but at much lower abundance in hydrothermal quartz.