OverviewScientific participants are invited to perform particular jobs that need to be completed to ensure the success of the cruise. An individual's scientific expertise is taken into account as much as possible during job assignments. There may not always be a one-to-one relationship between an individual's expertise and objectives and the required job. In such a case, shipboard scientists should be aware that they are responsible for contributing to the overall leg objectives as outlined in the Prospectus in the most effective way possible prior to completion of auxiliary science Information on shipboard laboratories.
Core DescriptionCore describers may have expertise in a wide variety of fields including sedimentology, petrography, petrology, or structural geology. The optimal mix of expertise is determined by the leg objectives and the individuals selected by the Co-chiefs, the Manager of Science Services, and the Staff Scientist. Core description may involve the following tasks:
macroscopic visual description of split cores, entered in the core description database which generates the "barrel sheets" (sediments) or in more detailed core section graphic templates (igneous rocks);
microscopic observations from smear slides and/or thin sections are written to word processing files and, in some cases, added to the macroscopic description forms;
acquisition of physical property data with the split-core track, including diffuse color reflectance, magnetic susceptibility, and digital images; may also be done by the individual in the physical properties position;
preliminary interpretation of depositional, diagenetic, magnetic, or deformational processes;
selection of samples, in consultation with other scientists, for carbonate, XRD, or XRF analysis;
analysis of XRD and/or XRF data, if the appropriate expertise exists (otherwise don't bother collecting these data on the ship); may also be done by the individual in the geochemistry position.
Stratigraphic CorrelationStratigraphy correlators are key positions on legs where complete stratigraphic sections (achieved by coring multiple holes at a site) are an essential component of the leg objectives. Completion of a meters composite depth (mcd) depth scale in near-real time guides coring operations and ensures complete stratigraphic coverage. For maximum efficiency, two correlators are needed to cover a 24 hour period and to guarantee feedback within hours. Correlation is achieved using a Sun workstation and the customized program "Splicer." Precruise training is required for inexperienced correlators. The position typically also includes operation of the multisensor track since the main data sets used are magnetic susceptibility, natural gamma radiation, and gamma-ray attenuation density from whole-core logging. Other data may be needed to improve correlation such as color reflectance logs, macroscopic descriptions from split cores, or biostratigraphic information.
BiostratigraphyShipboard micropaleontologists provide age data and an age/depth model for each site. This is done using (a) core-catcher samples as soon as possible after a core is recovered, and (b) additional samples, up to one per section, in at least one hole per site. For nannofossils, and sometimes diatoms, toothpick samples may be taken from the open ends of core sections on the catwalk. For other microfossil groups, samples taken in addition to the core catcher samples have to be taken from the split core working halves. Some stratigraphic boundaries may be analyzed in higher detail on ship, using samples taken from the split working half cores. Full assemblage analysis is not necessary on ship; rather, identification of useful microfossil datums for constructing age/depth plots and sedimentation/ accumulation rate curves is the primary emphasis. Microfossil datums are also used for integration with multisensor track data for core/core correlation and construction of spliced composite sections. Paleoenvironmental or bathymetric data, principally from benthic foraminifers, may also be of primary importance on certain legs. Shipboard micropaleontologists process their own samples, and have a fully equipped processing lab with two acid hoods for this purpose. A variety of slides, mounting media, and maceration chemicals are available for all major microfossil groups. A reference library with texts, journals, and reprints is available to help shipboard paleontologists identify microfossils. Because of limited shipboard space, this library is not comprehensive, and micropaleontologists should check with ODP before their leg to see what references are available. Micropaleontologists are advised to bring their own set of references to supplement the shipboard library. A computer image database of nannofossils is also available on a PC in the paleontology lab. Micropaleontology Reference Collections (MRC) are available at a number of institutions worldwide, that contain reference slides of planktonic foraminifers, diatoms, calcareous nannofossils, and radiolarians from DSDP and ODP cores. Scientists may visit these collections to view material before sailing. Check the MRC webpage for information about using these collections.
MagnetostratigraphyPaleomagnetists conduct or supervise paleomagnetic measurements and reduction of paleomagnetic data to intensities and direction of magnetization. Paleomagnetists also provide absolute orientation data for deformational structures measured in the core, if appropriate. Some additional rock magnetic properties can be acquired on the ship, which can be particularly useful if the magnetic properties are (partly) ephemeral (post-recovery dissolution, reduction, or oxidation of magnetic minerals). For detailed information, see ODP Technical Note 18 or the paleomagnetism lab.
Physical PropertiesScientists assigned to this job usually determine the following properties:
moisture content and grain density on core samples
P-wave velocity on split cores and/or core samples
thermal conductivity on full cores or split cores, if appropriate
vane shear strength on split cores, if appropriate
In addition, they oversee and document the overall physical properties measurement program in consultation with other scientists, including the full core and split-core logging systems. They also ensure that calibrations and control measurements are carried out according to protocol to ensure data quality control. For detailed information, see the physical properties handbook (ODP Technical Note 26).
GeochemistryOrganic chemists monitor cores for hydrocarbon content. They advise the Operations Manager, LPM, and Co-chiefs when hydrocarbon levels in cores may constitute a potential safety or pollution hazard. Inorganic geochemists conduct elemental analysis on interstitial water and/or solid sediment or rock samples and provide preliminary interpretations. For detailed information, see ODP Technical Note 15). ODP marine laboratory specialists assist in geochemical analyses.
Downhole Logging, GeophysicsThis job includes the following:
advise the co-chief scientists on the logging program for the cruise;
work closely with the Lamont-Doherty Earth Observatory logging scientist in designing, implementing, and interpreting the logging program; and
assist the Schlumberger field engineer with data acquisition if required.
This position often includes responsibility for other geophysical tasks, such as:
acquisition, analysis, and presentation of downhole temperature measurements;
seismic data acquisition and presentation (site surveys);
construction of synthetic seismic profiles.
On rare occasions, specialists may sail to perform more specialized measurements, which may include:
microbiological sampling and analysis;
installation of CORKs;
vertical seismic profiling.