The recovered sediments from all three holes at Site 1217 were seriously affected by coring disturbance, downhole debris, and flow-in associated with chert fragments blocking the core liner. In addition to this general coring disturbance throughout the cored interval, one stratigraphic interval was highly disturbed or not recovered in all three holes (~37-49 mbsf), thus preventing the recovery of a complete continuous sedimentary section. Nevertheless, it was possible to generate a spliced, but discontinuous, record in the upper 90 m of the section. Below 90 mbsf (Cores 199-1217A-12H through 15H; 89.70-129.66 mbsf), there was negligible recovery because of difficult drilling conditions associated with an extensive (~40 m thick) chert-rich interval. Approximately 1.5 m of good-quality quasicyclical claystone and chalk were recovered in Core 199-1217A-16X (129.66-137.70 mbsf), but this interval is omitted from further discussion because it was not cored in Holes 1217B and 1217C and is too stratigraphically removed from the shallower intervals.
Multisensor track (MST) and color reflectance data were collected from Holes 1217A, 1217B, and 1217C. Magnetic susceptibility (MS), P-wave velocity, and color reflectance data were collected at 2-cm intervals and gamma ray attenuation (GRA) bulk density data at 4-cm intervals on all core sections recovered from Holes 1217A to 1217C that were not entirely filled by chert fragments (see "Physical Properties" and "Lithostratigraphy" for details about MST and color reflectance data). Table T4 lists intervals from Holes 1217A to 1217C that are interpreted to be disturbed and are excluded from further discussion.
Figure F12 illustrates the MST and color reflectance data from Site 1217 on the mbsf depth scale, after culling MST data from the disturbed intervals listed in Table T4. The interhole correlation of the upper ~40 mbsf is straightforward as the result of a strong and clear variation of MS data as well as a clear decreasing pattern in the natural gamma ray (NGR) data that was also observed at Sites 1215 and 1216. Coring in Holes 1217B and 1217C began below 20 mbsf; thus, no data are available from these holes to aid in composite-depth construction in the upper 20 mbsf. Therefore, no depth adjustment was made to Cores 199-1217A-1H, 2H, and 3H.
A continuous composite record can be constructed from the top of Core 199-1217A-3H (15.00 mbsf; 15.00 meters composite depth [mcd]) down to the base of Core 199-1217B-3H (39.00 mbsf; 41.50 mcd), which corresponds to the middle of Core 199-1217A-5H (a disturbed interval in Hole 1217A). Figure F13 shows the MST and color reflectance data after adjusting to a common depth scale, and Table T5 lists the offsets that were applied to the top of each core. Below 42 mcd (Core 199-1217B-3H), several cores can be placed into a composite depth framework (i.e., correlated to each other), but a continuous section cannot be constructed and it was not always possible to establish the true stratigraphic position of cores. For example, data from Cores 199-1217B-4H and 199-1217C-3H can be correlated to each other. In Figure F13, this interval is plotted between ~42.5 and 45.8 mcd, but the position of these cores is not constrained with respect to Hole 1217A or the other intervals above or below in any of the holes. This uncertainty also applies to the relative position of other core segments below 49 mcd (Core 199-1217A-6H).
With the understanding that the composite depth scale aligns features within continuously cored segments but does not represent the relative sediment thickness across unconstrained intervals, one can construct a partially spliced record as defined by the splice table (Table T6) and shown in Figure F14. The interhole correlation developed here is consistent with radiolarian biostratigraphic datums (see "Biostratigraphy") and paleomagnetic data (see "Paleomagnetism").