DATA

Detailed petrographic descriptions including modal analyses on MS and FV samples are documented by Mackie (2000) and Gilmore (2000) in their University of Queensland honors theses, which are available in electronic form upon request. Here, we present and discuss mineral major element compositional data on MS, GS, and FV samples and whole-rock major element and selected trace element data on MS, BN, and FV samples.

Major and minor element compositions (Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P, Cr, and Ni) of olivine, plagioclase, clinopyroxene, orthopyroxene, amphibole, and Fe-Ti oxides were analyzed on polished thin sections using a JEOL Superprobe JXA-8800L at The University of Queensland. Analytical conditions were optimized for standard silicates and oxides at 15-kV accelerating voltage with a 20-nA focused electron beam for all the elements, with the exception of Na and K, for which a broader beam (10 µm) was used. Routine analyses were obtained by counting for 30 s at peak and 5 s on background. Repeated analysis of natural and synthetic mineral standards yielded precisions better than 2% for all the major element oxides analyzed. For the minerals in Hole 735B samples analyzed, the precisions are better than 2% for SiO₂, TiO₂, Al₂O₃, FeO, MgO, and CaO; 5% for MnO, Na₂O, Cr₂O₃, and NiO; and 10% for K₂O and P₂O₅, depending on mineral types and elemental abundances. Instrumental drift was minimal over an analytical session of 2-3 days but corrected for when present by repeatedly analyzing standards as unknowns during the run. The analytical data are given in Tables T2 (olivine), T3 (plagioclase), T4 (clinopyroxene), T5 (orthopyroxene), T6 (Fe-Ti oxides), and T7 (amphiboles).

All MS, BN, and FV samples for whole-rock compositional analysis involved a thorough cleaning procedure. The pen marks, saw marks, sticker residues, and other suspicious surface contaminants were ground off all samples that were collected on board. The samples were then reduced to 1- to 2-cm size using a percussion mill with minimal power production. These centimeter-sized rock pieces were then ultrasonically cleaned in Mili-Q water, dried, and powdered in a thoroughly cleaned agate mill.

Major element oxides (SiO₂, TiO₂, Al₂O₃, FeOt, MnO, MgO, CaO, Na₂O, K₂O, and P₂O₅) for MS and BN samples were analyzed using a Varian Liberty 200 inductively coupled plasma-atomic emission spectrometer (ICP-AES) at Queensland University of Technology, following the procedure of Kwiecien (1990). Precision (1 ) for most elements based on U.S. Geological Survey (USGS) standards (BCR-1, BIR-1, AGV-1, and G2) is better than 1% with the exception of TiO₂ (~1.5%) and P₂O₅ (~2.0%). Loss on ignition (LOI) was determined by placing 1 g of sample in a furnace at 1000°C for several hours, cooling in desiccator, and reweighing. These same major element oxides were analyzed for FV samples using a Perkin Elmer Optima 3300 DV inductively coupled plasma-optical emission spectrometer (ICP-OES) at The University of Queensland with the analytical precisions similar to the above. No LOI was determined for the FV samples because of small sample size. The analytical data along with calculated CIPW norms are given in Table T8.

Minor and trace element (Li, Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, and Nb) abundances in these same samples were analyzed on a Fisons PQ2⁺ inductively coupled plasma-mass spectrometer (ICP-MS) at The University of Queensland with the analytical conditions and procedures following Niu and Batiza (1997) and Eggins et al. (1997) except for sample digestion, which was done using high pressure bombs to ensure complete digestion/dissolution of ilmenite, zircon, and other refractory phases in gabbroic rocks (vs. basalts). Precisions (1 ) are better than 1%-2% for Li, Ga, Sr, Y, Zr, and Nb and are better than 2%-4% for Sc, V, Cr, Co, Ni, Cu, Zn, and Rb based on repeated analyses of highly depleted basaltic samples like USGS reference rock standard BIR-1. The analytical data are given in Table T8.