Paleontology (PAL)
Paleo Samples (PAL) – CORE CATCHER
If paleontologists are onboard the platform they receive material from the core catcher for initial biostratigraphic dating of the core.
Experience from detailed stratigraphic correlation on paleoceanographic ocean drilling expeditions in the past showed that usually 10-15 % of sediment between two cores is missing.
A core catcher in general is stratigraphically (more or less) intact (strongly depending on the quality!) in relation to the overlying section. This would mean by removing the complete up to 25 cm long core catcher for offshore analyses and consume ALL of it would add ANOTHER 5 % of missing section between two adjacent cores!
Therefore, a model for curation of the core catcher sample on the platform/drillship is recommended so that at least an archive half will be kept!
Once onboard the core catcher sample is extruded into a short piece of plastic liner, capped, taped (with absolutely NO handling of acetone for gluing end-caps if the porewater whole round sample has to be taken from the core!!!), and labelled with a black marker. The core catcher is treated as a separate section below the last core section. It can be up to 23-25 cm long.
According to the various micropaleontological disciplines and to the volumes compiled from the IODP Sample, Data, And Obligations Policy, where general guidelines are given for volumes of material generally required for various kinds of analyses), an expedition-specific estimate of what could be required for shipboard scientists will be made.
The CC sample should be recorded as a sample code PAL in offshore DIS.
Macro- and Micropaleontological analyses of smear slides, thin sections and other materials will be carried out in the microscope lab. A number of diverse microscopes are available. Please note that we will try to organize any microscope for your special requirement.
The lab is equipped with a hot plate under hood, a variety of permanent mounting media, and supplies (petrographic slides, cover glasses, sieves, sampling tools, etc.) for the preparation of smear slides.
Smear slides
Study of this tutorial will help core describers develop and apply solid skills
in the identification and semiquantification of mud components.
IODP video (Feb 2017): A Guide To Smear Slides
Marsaglia, K., Milliken, K., and Doran, L., 2013. Smear Slides of Marine Mud
for IODP core description, Volume I. Part 1: Methodology and Atlas of
Siliciclastic and Volcanogenic Components. IODP Technical Note 1.
doi:10.2204/iodp.tn.1.2013
Smear Slide Digital Reference for Sediment Analysis of Marine Mud. Part 2:
Methodology and Atlas of Biogenic Components. IODP Technical Note 2.
doi:10.14379/iodp.tn.2.2015
1. cover glass (24 x 40 mm) - #1 thickness
2. toothpick
3. water dropper
4. glass petrographic slide (25 x 75 mm)
5. permanent mounting medium
6. glass rod
7. hot plate
8. tweezers
9. pencil with new eraser
10. slide label
The hot plate is located under a hood. The hot plate should be set constantly on "low." A small beaker or uncapped bottle of mounting media is usually kept on (if appropriate, to reduce its viscosity) or near the hot plate under the hood at all times.
To prepare a smear slide take a cover glass in hand and place a few drops of distilled water in its center. Collect a tiny fraction of the sample with the flat end of the toothpick, and mix it into the water on the cover glass. Spread the wet sediment with the flat end of the toothpick until it forms a thin translucent coat across the entire cover glass, and then place the cover glass (with the sediment smear up) on the surface of the hot plate to dry.
While the smear on the cover glass dries, place a slide label on the glass petrographic slide, and label it with the expedition site, hole, core, core, type, section, and sample interval data. Place a few drops of mounting medium in the center of the petrographic slide with the glass rod, and set
it on the surface of the hot plate to warm. When the smear on the cover glass is dry, use the tweezers to place the cover glass (with the sediment smear down) on the mounting medium on the petrographic slide. Press down and slowly rotate the cover glass with the clean eraser-end of the pencil
to spread the mounting medium across the petrographic slide and to expel gas bubbles. If there is not sufficient mounting medium to cover the entire smear, use a clean toothpick to drip one or two drops of mounting medium
onto the petrographic slide at the edge of the cover glass, where they will be drawn by capillary action under the cover glass. Finally, return the smear slide to the hot plate for 3-5 minutes to allow it to cure.