Chemical analyses of hydrothermal deposits and associated material from Transform fault 'A' on the Mid-Atlantic Ridge, FAMOUS area

Sampled hydrothermal deposits from Transform fault 'A' on the Mid-Atlantic Ridge have been classified into two main categories according to the relative proportion of the black Fe-Mn concretions with respect to the clay-rich fraction: clay-rich hydrothermal material and black Fe-Mn concretions (nodules). These materials have been analysed for their chemical composition by arc spectrometry using an ARL quantometer were made at the University of Strasbourg. This method consists of melting the sample in a mixture of lithium tetraborate and then introducing the melt into in a glycolated solvent prior analysis. Trace elements were determined using graphite discs . Na and K were determined by emission spectrometry (precision of +- 2.0%).