Trace element distributions in the chalcopyrite wall of a black smoker chimney: insights from laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS)

The thin walls of young black smoker chimneys experience steep physico-chem ical gradients during active venting of hydrothermal fluid, and these gradi ents control trace element precipitation within those walls. Here, we utili se a combination of high sensitivity ICPMS and UV laser ablation (resolutio n of better than 30 mu m) to demonstrate the existence of non-random V, Ag, In, Te, Ba, Au, Pb and U distributions within the chalcopyrite wall of an immature black smoker chimney. The data are the first of their kind to be p roduced for black smoker chimney walls. Distributions of In and Te are attr ibuted to preferential incorporation into lattices at elevated temperature. Enrichments of U and V derived from seawater are the product of redox immo bilisation on sulphide surfaces. The distributions of Au, Ag, Pb and Ba may be related to interactions at the hydrothermal fluid-seawater mixing front ; however, comparison of distribution data with reaction-transport models o f chimney walls suggest a possible pH control on precipitation. These data illustrate the power of the LA-ICP-MS method, and such spatially resolved d ata have the potential to constrain models of element precipitation both in chimneys and in associated mounds, (C) 1999 Elsevier Science B.V. All righ ts reserved.