Cruise participant: Antoon Kuijpers

Antoon Kuijpers is a marine geologist specialised in marine sediment transport processes and late Quaternary (paleo)oceanography/climatology. Presently, his research focus is the Labrador Sea and adjacent Greenland waters, the Baltic Sea and the Caribbean. Previously, he also worked in the Barents Sea, North Sea, Northeastern and (sub)tropical Atlantic, and Indian Ocean.

Freeze drying samples

For some of the analyses (e.g. micropaleontological census, elemental analyses, grain size, etc.) it is preferable that the sediment is freeze dried rather than oven dried. The process of freeze drying (also known as lyophilization) is preferable to oven drying because it removes the water content without greatly altering the physical structure of the sediment. As a result, sediments containing clay are much easier to handle as they remain friable, foraminifera abreakage resulting from contraction of the sediment during drying is also reduced as it is the formation of carbonate agregates on the surface of calcareous microfossils due to carbonate re-precipitation.

Cruise participant: Christof Pearce

I am a Ph.D. student at the Centre for Past Climate Studies of the Department of Geosciences at Aarhus University in Denmark. My research is on the reconstruction of past sea-surface conditions (temperature and sea-ice variability) in the North Atlantic Subpolar gyre region. For this I am using sedimentological, geochemical and micropalaeontological data with the main focus on diatom analysis.

Diatoms are unicellular algae and are generally the main constituents of the phytoplankton. As primary producers in the upper layers of the ocean, they play a vital role in the marine food web. The cell walls of diatoms have characteristic shapes and ornamentations depending on the species and are made up of silica, resulting usually in excellent preservation in the sediments. Because of the wide variety in species, all with their own ecological preferences (e.g. temperature, salinity, nutrient availability), diatom remains in sediments are ideal indicators of past sea-surface conditions.

At the moment I am studying a gravity core from offshore Newfoundland, that encompasses the Late Glacial to Early Holocene time period (from 12500 to 9500 years ago). In the core, the transition from glacial times to the current Holocene epoch is not smooth and is associated with numerous big climatic fluctuations such as the Younger Dryas, a cold interval when temperatures dropped almost back to glacial levels. The diatom assemblages clearly reflect these changes as variations in sea-surface temperatures and sea ice presence.

The results will be combined with analysis of benthic foraminifera and geochemical parameters to achieve a more comprehensive record. The study of these fluctuations is important to improve our understanding of past and present natural climate variability and will contribute to better future predictions.

Sampling the cores

After the cores arrived to the CORESTORE laboratory we split them longwise. Then we packed, labeled and deposited them in the cold room.

All the working halves* were taken to the GEOLOGICAL WELL SAMPLE LABORATORY. Here, with the help of Sebastian a Geology and Geography undergrad student working in the lab, we sliced each half section every 1 cm.

Dark gray layer: volcanic ashes?

The sediment composing the cores is high in carbonate content, hence the light color, however on the cores’ surface it was possible to distinguish some darker layers that we think are volcanic ashes. Some of these layers appear gray while others look greenish. The analysis of the elemental composition of the sediments will tell us why the difference in color and will confirm if those are, in fact,  pyroclastic particles.

Sebastian showing a slice of the core sediment

We use a CD to slice the cores. The physical and chemical characteristics of the polymer plastic use to produce CDs prevents the sticking of the sediment to   the CD surface, making the slicing process (that is already time consuming and a little tedious) much easier than when using aluminium or regular plastic cutters.

Each of the sample-slices was divided in 3, and each of these subsamples will be used for something different:

1. Elemental analysis (composition of the sediment) and magnetic susceptibility
2. Planktic and benthic foraminifera (assemblage changes, stable isotopes, etc)
3. Sediment characteristics (granulometric analysis)

At the end, the linning is empty and we have 265 x 3 little bags full of mud.

The end of the core, finally!!!

*The half of the core that is used for all the analyses is commonly referred as the Working half. The half that is keep intact and preserved in the cold room is the Archive.

A little more about our project

Cruise rute from Tuxpan (Mexico) to the Yucatan Strait

The cruise's focal objective was to obtain sediment samples—by gravity and box core retrieval—from depths between 500 and 2000m along the Yucatán Strait,which is an ocean channel extending for 217 km between Cabo Catoche (Mexico) and Cabo San Antonio (Cuba). This strait represents the boundary between the Caribbean Sea and the Gulf of Mexico.
Oceanographically speaking, this is a very interesting area, where water masses advecting from the Caribbean Current, derived from the North and South Equatorial Current, enter the Gulf of Mexico to form the Loop Current, outlining the foundation of the Gulf Stream. Thus, sediments from the Strait of Yucatan may contain a record of the past oceanographic variability that affected the strength and characteristics of the Gulf Stream in previous times.

With sediment from our cores, we are working towards generating a multi-proxy record of high resolution to reconstruct past climate and oceanographic variability in this region.

Finalcial support from this cruise was provided by the Dansk Center for Havforskning (Danish Center for Marine Research)  in their 2010 applicatuion for ship-time funding.

NEWS

After some months without any updates on the blog it's time to start posting again. We've started the analyses of the recovered cores and it's now time to tell you about it. Also,  we have made some changes to the blog:

1. To make it easier for everybody to understand what we did during the cruise, we've decided to translate all entries regarding the trip to English (you can still find the original version, in Danish, German or Spanish, as a comment to each particular entry) .

2. We are also starting a series of notes about each one of the participants. Once a week I'll post some info about one researcher or student, telling you about them, what they do and where are they now.

3. You will also find new pictures from before, during and after the cruise. We plan to change this pictures at least one a month.

The adventure is finished

A nice view of Tuxpan from the B.O. Justo Sierra

We arrived back in Tuxpan at midnight of March 29th.

Next morning all the equipment was load back in the container and we started to say goodbye to the crew, to our other fellow students and scientits and to the warm weather.

I hope the container will arrived in Denmark without delays or problems and we´ll have samples to work on for a long time.

y nos dieron las 10 y las 11... y a las 12, llegamos a puerto.

The Justo Sierra just after our arrival

Finally here... back in Tuxpan

Y las muestras, estuvieron a bordo...

In the last station, at which we arrived last night, it was possible to obtain very good samples from both the box and the gravity corers.

Once the work was finished we had much time to spare before arriving to the port of Tuxpan, thus the whole research group gathered for a photo shoot ...

Status pt

We're now traveling back to Tuxpan with a lot of CTD profiles and one good gravity core + a small piece recovered from a 2000 m depth. I must admit, though it probably sounds a little nerdy, I’m a bit in awe of that little lump of clay.

We’re now sailing with the current (instead of against it) and there is not more sea surface chaos, so sailing it’s definitively a greater pleasure. The water is blue and the sun shines, and a part of me wants to go on deck to enjoy the sun and the fresh breeze much more than during the way over.  At 9:00 pm we’ll arrive at our last station, and here we bring all the guns to get as many samples as possible. Both the gravity core, box core, CTD' and perhaps even de Van Veen excavating will be sent out. We wait in excitement and hope for a lot of mud! :)