Sampling Strategy | Table of Contents


Core Logging and Archiving Strategy
Multiple hole coring aims to fill coring gaps from one hole with recovered sequences from another hole. Ideally, the stratigraphic correlator will able to tell the driller (or core technician) at what depth the drill string should be placed for shooting the third hole, based on the correlation of the top cores from the first two holes. The multisensor track (MST) core logging often lags many hours behind at that point, and full MST logging runs are too slow to provide the quick feedback required to guide coring.

To address this issue, we tentatively plan to install a specialized (non-ODP) track with a magnetic susceptibility loop to perform quick "scratch" measurements for the sole purpose of rapidly determining the required coring interval. We will attempt to run this specialized track immediately after core sections are cut on the catwalk, at a rate of ~1 min per core section (under the guidance of the stratigraphic correlators).

An important part of the shipboard measurements at each site will be the near-real time construction of a composite depth section from multiple holes (for purposes of later sampling) and an alternate spliced section as complete as possible (for purposes of ODP archiving) for the multi-hole intervals at all sites. Two dedicated stratigraphic correlators will operate the whole-core MST, retrieve the relevant data from the database, and correlate cores from multiple holes by vertical whole-core depth shifting. The MST sampling program will be set to optimize measurement time (within constraints of adequate data quality and depth resolution) for the overall time available. In typical operations, about 60-90 min will be available to process one core (~10 m), which will also set the core processing rate for all other laboratory stations.

After MST measurements are completed, the cores will be split. Working halves will be transferred to the paleomagnetics laboratory, followed by sampling noted below. Archive halves will be imaged using the new ODP core imaging system that will be deployed and tested during Leg 198. These high-resolution R-G-B image data may not yet be fully integrated into the JOIDES Resolution's database system during Leg 202 and data transfer protocols may have to be created ad hoc. Following digital imaging, routine color reflectance measurements will be taken with the automated Minolta CM2002 after the cores are split and can be used to refine the hole-to-hole correlation. The imaging and color reflectance tracks will be operated by the sedimentology group. Under ideal core processing conditions, these core logging data should be available ~2 hr after the full core measurements. Archival photography will be completed using standard ODP film photography.

Sampling Strategy | Table of Contents