EuroMARC Ocean Drilling
Oceans serve as our climate
regulators, cover the sites of fundamental geodynamic, geochemical and
biological processes, and offer high-resolution records of the Earth's history.
Scientific marine drilling and coring can shed light on both the deep and
shallow (sub-) seafloors to advance our knowledge in the Earth and
environmental sciences.
The European Science Foundation's European Collaborative Research (EUROCORES) program EuroMARC is a tool to boost European planning of international marine coring expeditions and the preparation of IODP (Intergrated Ocean Drilling Program) or IMAGES (International Marine Past Global Change Study) proposals. The program consists of seven collaborative research projects with principal investigators from nine countries. Fossil reef and carbonate mounds cores are extracted to reconstruct sea-level and environmental changes. Current ocean dynamics and sediment fluxes are investigated with the help of sediment traps, and hydrothermal processes of deep biosphere at mid-ocean ridges get explored.
But how does coring work, and what actually is done on the cruises?
International marine coring expeditions are divided into several parts – the pre-, cruise and post-cruise activities. It's crucial to be 100 percent prepared for the coring, which means advance planning, starting with getting a slot on one of the few coring and drilling ships, obtaining territorial drilling permits, making sure all the required equipment is on board, and getting a good scientific team together. "We had organizational meetings even before EuroMARC started," explains Catherine Kissel from the French Atomic Energy Commission, who was the chief scientist of the AMOCINT (Atlantic Meridional Overturning Circulation during Interglacials) cruise that took place this past summer.
Often, a site-survey cruise precedes the main cruise to identify the best spots for the actual coring, and to get the drill sites approved by bodies like IODP. In order to map the topography of the seafloor, a multi-beam echo sounder system is used, which is similar to a fanlike beam covering a huge swath of the seafloor. Additionally, sediment penetrating systems are employed, which shoot signals with varying energy pulses and wavelengths that hit the bottom, and are differently reflected depending on the density of the layers, thus giving a detailed impression of the layering of the sediments.
Besides the seismics, autonomous underwater vehicles often are used for more local surveys. "To make sure we won't damage any living ecosystem, we drop an underwater camera to see the nature of the seafloor just around the potential drilling site," reveals Gilbert Camoin, chair of EuroMARC's scientific committee. Especially in the case of coral reefs, the regulations for drilling are very strict, and pictures are taken before and afterwards. "There is no impact at all. When you pull up the pipes, the hole just collapses, and it's even impossible to find it again," assures Camoin, who investigates coral reefs in both Tahiti and the Great Barrier Reef.
On the main cruise, the coring itself takes place, as well as first measurements and part of the sampling, provided the type of ship allows for it. The cores are extracted in different ways, at different water depths and of different lengths, depending on the sediments and the objectives. Short cores of less than 5 feet often are used to drill coral reefs, and if there are high sedimentation rates going back in time, long cores are required. Box coring is used for taking surface samples, as is the so-called multicores instrument with four short cores, where even the water above the sediment is captured.
Marine coring and drilling is a challenging endeavor. Needless to say, a good recovery of the cores is essential, however, sometimes the sediment is lost when pulling out the core, and the so-called core-catcher at the bottom doesn't shut. The prevailing weather conditions are another crucial success factor; storms, for example, make operations nearly impossible. At times, failures of cruises are more man-made, and can range from difficulties in receiving territorial approval before strict deadlines to failed orders for indispensable drilling equipment.
The European Science Foundation's European Collaborative Research (EUROCORES) program EuroMARC is a tool to boost European planning of international marine coring expeditions and the preparation of IODP (Intergrated Ocean Drilling Program) or IMAGES (International Marine Past Global Change Study) proposals. The program consists of seven collaborative research projects with principal investigators from nine countries. Fossil reef and carbonate mounds cores are extracted to reconstruct sea-level and environmental changes. Current ocean dynamics and sediment fluxes are investigated with the help of sediment traps, and hydrothermal processes of deep biosphere at mid-ocean ridges get explored.
But how does coring work, and what actually is done on the cruises?
International marine coring expeditions are divided into several parts – the pre-, cruise and post-cruise activities. It's crucial to be 100 percent prepared for the coring, which means advance planning, starting with getting a slot on one of the few coring and drilling ships, obtaining territorial drilling permits, making sure all the required equipment is on board, and getting a good scientific team together. "We had organizational meetings even before EuroMARC started," explains Catherine Kissel from the French Atomic Energy Commission, who was the chief scientist of the AMOCINT (Atlantic Meridional Overturning Circulation during Interglacials) cruise that took place this past summer.
Often, a site-survey cruise precedes the main cruise to identify the best spots for the actual coring, and to get the drill sites approved by bodies like IODP. In order to map the topography of the seafloor, a multi-beam echo sounder system is used, which is similar to a fanlike beam covering a huge swath of the seafloor. Additionally, sediment penetrating systems are employed, which shoot signals with varying energy pulses and wavelengths that hit the bottom, and are differently reflected depending on the density of the layers, thus giving a detailed impression of the layering of the sediments.
Besides the seismics, autonomous underwater vehicles often are used for more local surveys. "To make sure we won't damage any living ecosystem, we drop an underwater camera to see the nature of the seafloor just around the potential drilling site," reveals Gilbert Camoin, chair of EuroMARC's scientific committee. Especially in the case of coral reefs, the regulations for drilling are very strict, and pictures are taken before and afterwards. "There is no impact at all. When you pull up the pipes, the hole just collapses, and it's even impossible to find it again," assures Camoin, who investigates coral reefs in both Tahiti and the Great Barrier Reef.
On the main cruise, the coring itself takes place, as well as first measurements and part of the sampling, provided the type of ship allows for it. The cores are extracted in different ways, at different water depths and of different lengths, depending on the sediments and the objectives. Short cores of less than 5 feet often are used to drill coral reefs, and if there are high sedimentation rates going back in time, long cores are required. Box coring is used for taking surface samples, as is the so-called multicores instrument with four short cores, where even the water above the sediment is captured.
Marine coring and drilling is a challenging endeavor. Needless to say, a good recovery of the cores is essential, however, sometimes the sediment is lost when pulling out the core, and the so-called core-catcher at the bottom doesn't shut. The prevailing weather conditions are another crucial success factor; storms, for example, make operations nearly impossible. At times, failures of cruises are more man-made, and can range from difficulties in receiving territorial approval before strict deadlines to failed orders for indispensable drilling equipment.
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