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Laboratory Methods

Core Description

Lab Documentation

After the cores (up to 9.5 m-long) are recovered on the rig floor, they are carried to the catwalk just forward of the rig floor. On the catwalk, the core is labelled and cut into 150 cm sections. In addition, samples for hydrocarbon safety monitoring (headspace and vacutainer) and whole round samples (interstitial water, physical properties, etc.) are also taken on the catwalk.

The core sections are then moved into the Core Lab where they are permanently labelled and information related to the core just obtained is entered into a database to initiate the curation and core sample tracking process (meters cored and recovered, depths below seafloor, etc). After the cores equilibrate to room temperature, the whole-round core sections are subjected to thermal conductivity measurements and then passed through the Multi-sensor Track (MST). The MST measures bulk density, P-wave velocity, magnetic susceptibility, and natural gamma radiation for each core section (Fig. 1; also see Physical Properties)

After the thermal conductivity and MST measurements, the core sections are delivered to the core splitting room (Fig. 2). The cores are cut into Archive and Working halves. The Archive half is used for non-destructive description and analyses such as for visual core descriptions (VCD's), whole-core and close-up photography, and paleomagnetic analysis. The Working half is used for Physical Properties and Paleomagnetic measurements and then sampled for shipboard and postcruise scientific research.

After the Archive and Working halves are finished being described, analyzed and photographed, each section is placed in a plastic "D-tube" and then assembled in shipping boxes. The boxes with cores are stored in the large core refrigerator until the end of the cruise when they are shipped to one of the ODP Core Repositories.

Core Description

The Core Description area is located between the Physical Properties and Paleomagnetism Labs. Its most prominent feature are two large tables for assembling the archive and working half sections of each core. This is where the Sedimentologists, Petrologists, and Structural Geologists make comprehensive visual descriptions of the recovered cores. The lab contains all materials for smear slide preparation as well as a few microscopes (more are located in the microscopy lab). A digital color spectrophotometer is used for high-resolution color profiles of each core section (Fig. 3). Computers are provided for preparing generalized digital visual core description of each core for publication.

Sampling Table

The Sampling Table is where nearly all the core samples are identified and extracted from the cores, and is located between Core Description and the Physical Properties Lab. The ODP Curatorial Representative is responsible for all aspects of core curation and sampling. The Curatorial Representative provides training and guidance for the scientists, since they are the ones who actually take the samples (Fig. 4).

Photography Table

A photographic table for whole core photography and a copy stand for close-up photography is located adjacent to the Paleomagnetism Lab. ODP technicians take whole-core color and B&W high resolution (4x5) photographs of each archive section of all split cores. In addition, the ODP Photographer will take a limited (~17/day) of B&W close-up photographs of cores intended for publication. The copy stand and training are provided to individual scientists who wish to take their own color and/or B&W close-ups (scientists must provide their own film). Postcruise scientists can request 35 mm color slides or B&W prints of whole core photographs or B&W 35 mm slides or prints of close-up photographs (Fig. 5).

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