Proc. IODP, 309/312, Data report: petrography and phase analyses in lavas and dikes from Hole 1256D (ODP Leg 206 and IODP Expedition 309, East Pacific Rise)

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Chapter contents Abstract Introduction Methods and materials Petrographic results Microanalytical results Proxenes Plagioclase Fe-Ti oxides Mineral downhole variations Differentiation trend Acknowledgments References Figures F1. Simplified lithostratigraphy. F2. Clinopyroxene compositions. F3. Clinopyroxene vs. bulk rock. F4. Type I relict pigeonite. F5. Relict pigeonite. F6. Sector zoning. F7. Microprobe profile. F8. Groundmass plagioclase. F9. FeOtot vs. An content. F10. Oxide cluster. F11. Magnetites and ilmenites. F12. An, FeOtot content, and Mg#. F13. Mg# vs. An content. Tables T1. Textural features. T2. Average mineral compositions. PDF file			Previous \| Next doi:10.2204/iodp.proc.309312.201.2008 Petrographic results Petrographic results are presented in Table T1. As phenocrysts, only clinopyroxene and plagioclase were identified. Olivine seems to have been completely altered to secondary minerals, as we only identified possible olivine pseudomorphoses. In spite of careful investigation by both optical microscope and backscattered electron (BSE) imaging combined with energy-dispersive X-ray (EDX) analyses, we were not able to find fresh olivine in our samples. The primary groundmass is composed of plagioclase, clinopyroxene, and Fe-Ti oxides, and anhedral clinopyroxene fills the interstices between the mostly euhedral plagioclase laths. Top of page \| Previous \| Next

Petrographic results