Two basement holes were drilled during Ocean Drilling Program (ODP) Leg 206. Hole 1256C penetrates 88.5 m into basement and Hole 1256D, ~30 m to the south, penetrates 502 m into basement (Wilson, Teagle, Acton, et al., 2003, doi:10.2973/odp.proc.ir.206.2003). Recovered cores consist of basalts exhibiting the effects of low-temperature alteration by seawater. As part of a larger study of alteration effects, a study of the secondary mineralogy was undertaken. This data report presents the major and some minor element compositions of secondary minerals. Analyses focus on the major secondary phases, phyllosilicates, and less abundant feldspars, but also include limited analyses of carbonates and apatite. Different occurrences of secondary minerals are included (e.g., veins and vesicles replacing olivine and plagioclase) as well as variations with depth.

Supplement to: Alt, Jeffrey C; Laverne, Christine (2006): Data report: Chemical compositions of secondary minerals from Site 1256 basement, ODP Leg 206. In: Teagle, DAH; Wilson, DS; Acton, GD; Vanko, DA (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 206, 1-16