A suite of 41 serpentinite muds was analyzed onboard the JOIDES Resolution using the JY 2000 inductively coupled plasma–atomic emission spectrometer (ICP-AES). Another suite of 22 serpentinite mud samples, along with 14 of the larger metamorphic clasts from South Chamorro and Conical Seamounts, was analyzed for major and some trace elements using a direct coupled plasma–atomic emission spectrometer (DCP-AES) at the University of South Florida (USF), Tampa, Florida (USA). Sample digestions for major and some trace elements (Cr, Ni, V, Co, Sc, Zn, Cu, Sr, Ba, and Mn) were performed on LiBO2 fluxed fusions, followed by DCP-AES measurements at USF. Concentrations of the elements of interest were accurate within ~10%, based on monitoring of replicates of certified U.S. Geological Survey (USGS) standards: DTS-1, BIR-1, AGV-1, and G-2.
Lithium abundances were measured by DCP-AES following HF: HClO4 (4:1) sample digestion using the procedures of Ryan and Langmuir (1987). All Li determinations were performed by the standard addition method, using a gravimetric Li standard made from 99.999% pure Li2CO3. Reproducibility obtained for Li determinations was ±5% down to 1 ppm Li. Boron abundances were measured in 17 serpentinite mud and 12 metamorphic schist samples at USF by DCP-AES following a Na2CO3 fluxed fusion in Pt crucibles, a method modified from that of Ryan and Langmuir (1993) in that, as a final step, all solutions were neutralized with ultra-pure HNO3 and no column preconcentration procedures were used. Because the majority of the measured serpentinite muds and all of the metamorphic clasts have boron abundances >10 ppm, DCP-AES reproducibility for all samples was ±5%.
A subset of serpentinite muds and metamorphic clasts were analyzed for rare earth elements (REE)—Y, Sr, Li, Be, Rb, Cs, Pb, As, Sb, U, Th, Nb, Ta, Hf, Zr, Sc, V, Ga, Cu, and Zn—at the VG Elemental PlasmaQuad II ICP-mass spectrometer (MS) facility at the Department of Earth Sciences of Boston University, Boston, Massachusetts (USA). Samples were digested in HNO3:HF (3:1) mixtures, following procedures described by Kelley et al. (2003). Gravimetric calibration standards were matrix-matched to sample solutions by adding ~150 ppm Mg from a 1000-ppm Mg standard solution (SPEX, Metuchen, New Jersey). Based on replicate analyses of the certified standards JB-3, BIR-1, AGV-1, JP-1, and DTS-1, reproducibility was about ±2% for all of these elements. Accuracy was about ±5% for higher-concentration elements and about ±10% for the lowest-concentration elements such as As, Sb, and Be.