Data report : trace element, Sr isotope, and Ge/SI composition of fluid and sediments in ridge-flank low-temperature hydrothermal environments

The data presented in this report demonstrate significant improvements\ud in the ability to constrain trace element and Sr isotopic\ud concentrations in sediments overlying ridge-flank hydrothermal\ud systems. Improved sampling methods orchestrated by the Integrated\ud Ocean Drilling Program (i.e., advanced piston coring and\ud anoxic sample processing) enabled the collection of reactive pore\ud water species with minimal alteration and sampling artifacts.\ud Improved methods of high-resolution inductively coupled\ud plasma–mass spectrometry trace element analysis, including the\ud use of the 8-hydroxyquinoline functional group to extract and\ud preconcentrate rare earth elements and other trace metals, were\ud used to compile a data set of 28 trace element concentrations and\ud ⁸⁷Sr/⁸⁶Sr ratios. From this extensive data set, we were able to increase\ud the current understanding of how redox-reactive species respond\ud to diagenic processes. Near-basement trends were used in\ud combination with the known composition of hydrothermal fluids\ud that exit Baby Bare Springs to asses our ability to predict basement\ud fluid compositions using sediment pore water profiles collected\ud by deep-sea drilling. The results show that prediction of basement\ud fluid composition is possible for many trace elements, provided\ud the near-basement concentration gradients are minimal. In order\ud to place the Ge/Si systematics in a broader context, pore water\ud and borehole fluid Ge and Si data are presented from additional\ud sites across the Juan de Fuca Ridge flank and from two additional\ud ridge-flank settings. These data show that Ge concentrations and\ud Ge/Si ratios are much higher in the basement fluids than in the\ud basal sediments because of increased mobilization of Ge relative\ud to Si within the basement hydrothermal reservoir. Solid-phase\ud sediment data are presented, highlighted by the occurrence of\ud Mn- and carbonate-rich layers