What is a rock library?
A rock library is where rock collections and geology samples are stored.
What does the rock library at Ifremer contain?
Geological research requires samples. On-land, a good pair of boots and a hammer may suffice, but at sea, things are not as easy. The seabed is composed of rocks and sediment and specific tools are deployed from research ships for sampling.
For rocks, we use a dredger, the equivalent of a trawl net but stronger, which drags along the bottom removing fragments of rock.
The sediment of the ocean bed is soft and to recover samples, we use a grab to sample the superficial layer and other tools which penetrate the sediment to recover a sample as intact as possible. The depth of penetration may be several centimetres (core boxes, multi-tubes) or several tens of metres when a corer is used. For deeper rock and sediment samples borers are used.
Why archive geological samples from the bottom of the sea?
This is an important question as archiving a sample requires a significant budget and financial commitment over several years. However, several considerations plead in favour of systematic and automatic archiving of samples made by oceanographic research ships :
• An ocean-going expedition is complex, long and costly to obtain and organize. Generally, its takes several years to plan and finalize an expedition. It is therefore of utmost importance that the samples collected are stored in optimal conditions as the opportunity to return to the same site is extremely unlikely.
• A sample is always made with a scientific objective. For the purposes of the project, the sample is generally not used in its entirety and may therefore be used later or for other projects 5, 10 or many years later.
• Analysis techniques and methods evolve and improve permanently. What may be analysed now may not have been 30 years ago ; what cannot be analysed now may be in 30 years time. A sample collected in the past or today has unseen potential for research and analysis.
• The annual cost of archiving and maintaining the quality of a sample is minute.
How are samples archived?
All samples are listed and identified in the database BIGOOD - Biology and GeOlogy Ocean Database) with information such as its geographical position (GPS point), the sample tool used, its weight and length, the ship used, the name of the expedition and of course the exact place of storage of the sample.
At the Ifremer rock library the samples are stored in cases and drawers at room temperature. Sediment samples are water saturated and require storage conditions which will prevent them drying and deteriorating. They are stored in airtight containers at a temperature of 4°. Every case, drawer and container is identified and all the information transferred to the database.
How to access the samples?
Archiving involves making the samples accessible to the scientific community, which must above all be informed of the existence of these samples.
The information on the database BIGOOD (SISMER department at Ifremer) is available on the internet via a cartographic portal. The data may be filtered by its type (sediment or rock), the tool used, the name of the expedition, GPS coordinates, with a link to a web page. Information is available on the storage location and the procedure to obtain the sample. This page may also contain data acquired on the sample.