IODP Expedition 381 Corinth Rift: FEC Co-Chief Scientist Duties and Post-Moratorium Research

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The discovery of plate tectonics in the 1960's has provided geologists with insight into the causes of earthquakes and the continued re-organisation of the continents. An important part of plate tectonic theory is continental rifting and breakup, the process that begins the process of breaking apart a continent and ultimately can result in the formation of a new ocean. There are many continental margins on Earth where we know rifting has acted in the past and these margins are the source of much of the world's oil and gas resources, but there are limited places where we can witness the active processes that presently characterise the formation of a rift valley. Of the relatively small number of places on Earth where the process of continental rifting is just starting, the Gulf of Corinth, Greece stands out as a rare location of earthquake activity, high rates of the plate being split apart and a record of the rifting process contained in the sediments now filling the rift basin. Therefore it holds vital clues as to how a tectonic plate stretches and splits into two. The Corinth Rift has been studied for several decades, with scientists investigating its rift deposits and active fault traces exposed on land. But much of the activity is hidden below the inland sea of the Gulf of Corinth and in order to investigate this part of the rift, researchers have used marine geophysics to image the faults and sedimentary layers below the seafloor. They have also sampled the shallowest sediments using coring techniques. The has allowed us to see how faults have developed to create the basin and cause it to gradually subside as the rifting process evolves. We can also see how the sediment, eroded from the land surrounding the basin, has gradually filled the subsiding basin and records the movement of the faults through time. What has been lacking is direct sampling of these sediments over a significant part of the time since rifting began. This would enable us to determine how old the different sedimentary layers are and therefore how fast the faults are moving and how quickly the rift is opening and changing. Sampling and investigating the plants and animals living within and around the basin would also tell us the environment of the basin - was it a marine sea, a freshwater lake, or a series of river and delta systems and how has this changed as the rift has developped? These flora and fauna would also tell us about the local climate of this part of the Eastern Mediterranean and how this related to changes in the global climate in the last 1-2 million years, and how climate might have affected how and how much sediment was eroded and transported into the basin.The Integrated Ocean Discovery Program (IODP) will be drilling 3 boreholes in order to sample these rift basin sediments to answer the problems and questions raised above. This method, using a drillship, is the only way these sediments can be accessed. Approximately 32 scientists of a wide range of geoscience disciplines will analyse the cores and log data (which give information on the physical properties of the sediments) together over a period of 3 months offshore and onshore and then over a period of 3-4 years after the expedition. In addition, McNeill will take some of the drilling results and compare them with the already collected marine geophysical data to get a better idea of how fast faults are slipping, the basin is opening up, and how fast it has been subsiding, which can tell us how much the continental crust of the plate has thinned since the start of rifting. The results will be very relevant to understanding the potential for earthquake hazards in the region (how fast faults move is a major control on earthquake potential) and also to understanding how and where hydrocarbon resources collect within the earliest and deepest part of a rift system.