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

20世纪60年代板块构造的发现使地质学家对地震的成因和大陆的持续重组有了深入的了解。板块构造理论的一个重要组成部分是大陆的裂谷和分裂，这一过程开始于大陆分裂的过程，并最终导致新海洋的形成。地球上有许多大陆边缘，我们知道这些边缘过去曾发生过裂谷作用，这些边缘是世界上大部分石油和天然气资源的来源，但我们能见证裂谷形成的活跃过程的地方有限。在地球上相对少数几个大陆裂谷过程刚刚开始的地方，希腊的科林斯湾（Gulf Of Corinth）是一个罕见的地震活动地点，它的板块分裂率很高，而且现在充满裂谷盆地的沉积物中包含了裂谷过程的记录。因此，它为构造板块如何伸展并分裂成两部分提供了重要线索。科学家们对科林斯裂谷进行了几十年的研究，调查其裂谷沉积物和陆地上暴露的活动断层痕迹。但大部分活动都隐藏在科林斯湾的内海之下，为了调查这部分裂谷，研究人员利用海洋地球物理学对海底以下的断层和沉积层进行了成像。他们还利用取心技术对最浅的沉积物进行取样。这让我们看到了断层是如何形成盆地的，并在裂谷作用的过程中使盆地逐渐下沉。我们还可以看到，从盆地周围的土地上侵蚀下来的沉积物是如何逐渐填满下沉的盆地的，并记录了断层随时间的运动。缺少的是在裂谷开始以来的大部分时间里对这些沉积物的直接采样。这将使我们能够确定不同沉积层的年龄，从而确定断层移动的速度以及裂谷打开和变化的速度。对生活在盆地内部和周围的动植物进行取样和调查，还可以告诉我们盆地的环境——它是海洋、淡水湖，还是一系列河流和三角洲系统，以及随着裂谷的发展，这些环境是如何变化的？这些动植物也会告诉我们东地中海这部分地区的气候，以及这与过去1-2百万年全球气候变化的关系，以及气候如何影响沉积物被侵蚀和输送到盆地的方式和数量。综合海洋发现计划（IODP）将钻3个钻孔，以便对这些裂谷盆地沉积物进行取样，以回答上述问题。这种使用钻井船的方法是获取这些沉积物的唯一方法。大约32名来自不同地球科学学科的科学家将在海上和陆上的3个月时间里分析岩心和测井数据（提供有关沉积物物理性质的信息），然后在考察结束后的3-4年时间里进行分析。此外，麦克尼尔将把一些钻探结果与已经收集到的海洋地球物理数据进行比较，以更好地了解断层滑动的速度、盆地张开的速度和下沉的速度，这可以告诉我们板块的大陆地壳自裂谷开始以来变薄了多少。这些结果对于了解该地区潜在的地震危险（断层移动的速度是地震可能性的主要控制因素）以及了解裂谷系统最早和最深部分的油气资源是如何和在哪里聚集的非常重要。

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.