LOGGING PLANUnder the primary operations plan, logging will be carried out at Sites SHAT-5C, 2B, and 3 (Table 2). We cannot expect exceptionally high rates of recovery in hard-soft interlayered intervals, even with double XCB/MDCB coring. Logging of these holes will provide critical information that will enable us to interpret some of the most fundamental questions we are addressing, even with poor core recovery.
Three tool strings will be run at the logged sites: the triple combo (resistivity, density, porosity, and natural gamma logs); the Formation MicroScanner (FMS)/sonic (resistivity image, acoustic velocity, and natural gamma logs); and the geologic magnetic tool (GHMT) (magnetic field, susceptibility, and natural gamma logs). The first two tool strings are the main priority. Small-scale features can be identified in the FMS image log; for example, Röhl and Abrams (2000) used FMS image logs to detect unrecovered ash layers in the uppermost Paleocene section of Site 1001 in the Caribbean and to correlate between holes. The thickness and position of black shales should be clearly identifiable in the natural gamma logs. Chert bands will appear as spikes in most of the logs. The acoustic velocity logs can be used to create a depth-traveltime curve to determine how much of the seismic section has been penetrated, and they can also be used in the generation of synthetic seismograms. The GHMT logs will probably provide a magnetic polarity stratigraphy, and magnetic susceptibility is usually the best parameter for core-log integration. In summary, a complete set of logs will be used to interpret the stratigraphy of unrecovered intervals at all of the logged sites.
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