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doi:10.2204/iodp.proc.335.201.2015

Methods and materials

Electron microprobe analysis

Major element concentrations of minerals were determined using a Cameca SX100 equipped with five spectrometers and the operating software “Peak Sight” at the Institut für Mineralogie (University of Hannover, Germany). All data were obtained using a 15 kV acceleration potential, Kα or Kβ emission for all elements, and the matrix correction “PAP” according to Pouchou and Pichoir (1991). Calibration material includes natural wollastonite (Si and Ca), albite (Na), orthoclase (K), halite (Cl), strontium fluoride (F), and synthetic Al₂O₃, Fe₂O₃, MgO, TiO₂, Mn₃O₄, V₂O₃, and Cr₂O₃. Thallium acid phthalate (TAP) single crystal was used as the diffracting crystal for Na, Mg, Si, Al, and F; pentanerythritol (PET) single crystal for Ca, Cr, K, Ti, V, and Cl; and lithium fluoride (LIF) single crystal for Fe and Mn. Most of the data were obtained using a 15 nA beam current and static (focused) beam. Counting times were 10 s for major elements, 40 s for Ca in olivine, 30 s for Cr in pyroxenes, and 60 s for F and Cl in hydrous minerals. Core and rim analyses were obtained using a focused beam.

Samples

Microanalytical data were collected from six thin sections of granoblastic dikes recovered during Expedition 335 in Hole 1256D, covering 1507–1521 meters below seafloor (mbsf). The samples were drilled in situ (one sample) or collected from reverse circulation junk baskets (RCJB; 4 samples) and from external junk baskets (EXJB; one sample). An overview of sample information is presented in Table T1. Further details about the samples and about the hole cleaning tools, including the junk baskets, can be found in Teagle, Ildefonse, Blum, and the Expedition 335 Scientists (2012).

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