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Drill results reveal the global climatic influence on basin waters in small fractures



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IMAGE: This is the Fugro Synergy drill ship prepared for IODP Expedition 381 in the port of Corinth, Greece.
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Credit: C. Cotterill (ECORD / IODP)

The new rift basins, such as the Gulf of Corinth, are known as sensitive recorders of past climate and sea changes and the chemical and biological conditions of the waters they contain. However, the changes observed in the Gulf of Corinth, published in the magazine Nature, were more dramatic and complex than expected. The volume of sediments that filled the raft raft increased drastically when the Earth experienced glacier conditions compared to the periods in which the Earth was not glaciated.

This is an important discovery to understand the impact that global climate fluctuations have on the sedimentation history, especially for the earliest sediments deposited as new oceanic basins are formed. The continental rifting process is essential for the formation of new ocean basins and these basins are the source of a large proportion of the Earth's hydrocarbon resources. Therefore, its sedimentation history informs how hydrocarbons are formed and where they can be collected.

The results come from a new oceanic scientific drilling expedition conducted as part of the International Ocean Discovery Program (IODP) and are published this week in the journal Scientific Reports in an article entitled "The high resolution registry reveals environmental and sedimentary climate-oriented changes to an active bend ". The IODP Expedition 381 went to the sea from October to December 2017 on the Fugro Synergy drilling vessel and the sediment rings and recovered well data were analyzed in February 2018 by a team of 35 scientists from international geology. The Expedition and new publication was directed by Professor Lisa McNeill of Southampton University, United Kingdom and Professor Donna Shillington of the Land Observatory of Lamont-Doherty, University of Columbia, United States.

"This is the first log of sediments of long and high resolution of the initial failure process that has already been obtained," comments Lisa McNeill. "In a single site, an expanded section of 700 meters records the last 800,000 years of the rift basin's history." The nuclei revealed how conditions changed as the global climate and the growth of ice sheets reduced sea levels and isolated the Corinth basin from the open ocean. The reduced salinity severely restricted the variety of organisms that can inhabit the waters under such stressed conditions. These fluctuations occurred once every 100,000 years as the global climate changed.

The most surprising result is that the rate of sediment flow in the bowl increases by 2-7 during global glacial periods in relation to non-glacial periods. This is recorded in the relative thicknesses of the sedimentary filling in the rift bowl during these different periods. Donna Shillington explains: "We argue that this change is not caused by increased precipitation and erosion during glacial times, but by reducing vegetation coverage and a change in the type of vegetation during the glacial periods that lead to improved erosion." This is an important outcome to understand the climate of the eastern Mediterranean at this time and to the impact of global climate fluctuations on the rate of filling of sedimentary basins. These basins are the source of a large proportion of the Earth's hydrocarbon resources and its sedimentation history, particularly in the initial phase of rifting, informs how hydrocarbon sources and rocks of the reservoir are being developed.

The scientific team also found that the sedimentation rates in the Holocene (the last 10,000 years) were much higher than the non-glacial periods of the past. This can probably be due to human impacts on the landscape of mainland Greece, deforestation of the landscape and increase in coastal erosion rates over a period of approximately 4000 years.

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Notes to publishers

1. The Science of the International Ocean Discovery Program (IODP) Expedition 381 included 35 scientists from different disciplines of geosciences in Australia, Brazil, China, France, Germany, Greece, India, Norway, Spain, United Kingdom and United States. , nine of them sailed aboard the Fugro Synergy from October to December 2017 in the Gulf of Corinth, Greece, to collect the data and data. After the offshore phase, the entire science team met at the IODP Bremen Core Repository (BCR), located at the MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany, in February 2018 to divide, analyze and test nuclei and analyze the collected data. The scientists continue to analyze the nuclei and samples in the next 2 to 4 years to extract more information from this new set of data.

2. The four main issues of the expedition are:

  • Natural hazards – As one of the most seismic areas in Europe, what are the implications for earthquake activity in a break in development?
  • Structural evolution: how is the rift evolving and growing and in what time scale? How has the activity changed over time?
  • Surface processes: how does the landscape react to tectonic and climatic changes?
  • Reconstruction of the paleoclimate – What was the climate in the eastern Mediterranean and in the middle of the rift basin in the last 1 to 2 million years?

4. The expedition is conducted by the European Consortium for the Drilling of Oceanic Investigations (ECORD) as part of the International Ocean Discovery Program (IODP). The International Ocean Discovery Program (IODP) is an international maritime research program supported by 23 countries, which explores the history and structure of the Earth recorded in sediments and rocks at the bottom of the sea and monitors the submarine environments. Through multiple platforms – an exclusive feature for the IODP – scientists show the depth of the biosphere and the underwater ocean, the environmental change, the processes and the effects and the solid earth cycles and dynamics.

5. The University of Southampton drives the original thinking, converts knowledge into action and impact and creates solutions to the challenges of the world. We are among the first one percent of the institutions worldwide. Our academics are leaders in their fields, forging links with high-profile companies and international organizations and inspire an exceptional community of 24,000 people from more than 135 countries around the world. Through our high quality education, the University helps students on a discovery journey to realize their potential and join our global network of more than 200,000 alumni. http: // www.Southampton.acUnited Kingdom

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