The structural features described in the cores recovered during Leg 192 are summarized on the hard-rock VCD forms. For each section, we provided more detailed structural information, such as crosscutting relationships and the apparent and true orientations of veins and fractures, using a separate structural geology description form. These forms are available upon request from the ODP Data Librarian (see the "Related Leg Data" contents list). Structural data are tabulated in the vein/structure logs for each site. The site summary gives more detailed observations. The structural data entered into the vein/structure logs include hole, core, section, piece number, meters below the seafloor for the top of each section, oriented samples (yes or no), and structural identifiers (vein). The data were entered in accordance with a checklist (Table T7).
Veins are indicated as V1...Vn from the first (top) to the last (bottom) vein. We recorded the interval over which a structural feature occurs on the split core surface. Vein compositions and abbreviations we used are defined in "Alteration". Widths of structures are recorded in millimeters. Wall-rock lithology is described by the abbreviations SED (sediment) or BAS (basalt). We determined the orientation of planar features by the values of two apparent-dip measurements, which are used to calculate strike and dip. In addition, we documented the continuity and geometry, thickness, alteration halos, offsets, and crosscutting relationships. We calculated fracture density as number of fractures per meter and vein abundance from vein width as millimeters per meter of core.