The procedures and methods for metamorphic descriptions of the core during Leg 179 generally follow those adopted during Leg 147 (Shipboard Scientific Party, 1993a), Leg 153 (Shipboard Scientific Party, et al., 1995), and Leg 176 (Shipboard Scientific Party, 1999). VCDs of metamorphic characteristics were compiled together with igneous and structural documentation of the core. This information was recorded to provide two types of information: (1) the extent of replacement of igneous minerals by metamorphic or secondary minerals and (2) the extent to which metamorphic or alteration minerals contribute to any subsolidus fabric found in the core. These data were recorded together with igneous descriptions in the igneous/metamorphic core log (see Table AT2.XLS in the "Appendix" contents list) and are summarized in the VCDs. To ensure accurate core descriptions, thin-section petrography of representative samples was integrated into the VCDs. Identification of mineral phases was, when possible, confirmed by XRD analyses according to ODP standard procedures outlined in previous Initial Reports volumes (e.g., Volume 118; Shipboard Scientific Party, 1989a). Terminologies adopted for metamorphic rock types, metamorphic textures and fabrics, metamorphic facies, etc., follow conventional usage (Williams et al., 1982). Metamorphic mineral assemblages and alteration intensities are included in the comments column of the igneous/metamorphic core log (see Table AT2.XLS in the "Appendix" contents list). Alteration intensity was classified as negligible (<2%), slight (2%-10%), moderate (10%-40%), high (40%-80%), and pervasive (80%-100%). Portions of pieces where primary textures were ambiguous or obliterated by secondary minerals were termed patches. For those patches where thin-section analysis was available, their mineralogies are recorded (see the "Core Descriptions" contents list).
Where metamorphic minerals are included in fabric elements such as shear zones, cataclastic fabrics, foliations, textures and associated minerals were recorded in the structure log (see Table AT3.XLS in the "Appendix" contents list). For samples affected by crystal-plastic deformation, textural features noted included identities and abundances (in volume percent) of porphyroclasts and their alteration products, neoblasts, and other minerals associated with and defining the fabric.
Breccias were defined as intervals of angular fragments in which clast rotation could be documented. Portions of the core crosscut by dense vein networks may appear to be brecciated; however, if adjacent clasts separated by the veins were not visibly rotated, they were described as net or mesh veined. Characterization of breccias included clast lithology and secondary phase mineralogy, matrix mineralogy, and abundances of clasts and mineral phases.
Detailed petrographic descriptions were made aboard ship to aid in identification and characterization of metamorphic and vein mineral assemblages. Stable mineral parageneses were noted, as were textural features of minerals indicating overprinting events (e.g., coronas, overgrowths, and pseudomorphs). Mineral abundances were visually estimated. These data are recorded and summarized (see the "Core Descriptions" contents list). The modal data allowed accurate characterization of the intensity of metamorphism and aided in establishing the accuracy of the macroscopic visual estimates of the extent of alteration.