High-resolution time variability of the tectonic stress field associated to continental rifting in the Gulf of Corinth (IODP Expedition 381)

大陆裂谷作用是一个关键的板块构造过程，最终导致大陆裂解和洋盆形成。然而，由于裂谷岩石的埋藏很深，与裂谷有关的变形的样式和变异性很难受到约束。年轻的(&lt；5 Ma)活跃的科林斯湾裂谷(希腊)提供了一个独特的机会来研究早期裂谷的沉积记录，并推断这一鲜为人知的过程的重要制约因素，因为它具有原始的、更容易接近的同裂谷序列。IODP探险381将从科林斯同裂带层序中恢复沉积物，目的是在高时空分辨率上解决早期裂谷系统中的断层如何演化和形变如何重新分布的问题。这些目标将主要通过建立同裂谷层序的高分辨率年龄模型并将其与已知的地下裂谷结构和陆上地层学相关联来实现。虽然了解这个裂谷系统中的变形是如何进行的是至关重要的，但重建与裂谷形成有关的构造应力场的性质、方向和大小是解决鲜为人知的控制大陆裂谷的原因和机制的另一个关键步骤。在这个项目中，我们将使用磁化率各向异性(AMS)分析，这是最有效的古应力研究技术之一。AMS是一种岩石组构工具，通常用于确定岩石中颗粒(即组构)的优先取向，并重建产生这种组构的古应力场的样式、方向和强度。对IODP 381探险中发现的科林斯同裂带序列进行的AMS分析将有助于首次重建控制科林斯裂谷系形成的构造应力的方向和强度的变化。此外，通过进行轨道调整，将获得那些经典生物地层学技术可能失败的间隔的更准确的年代测定。通过对特定参数或化学元素进行时间序列分析而识别的天文周期将使沉积物的年龄达到20-50ka的分辨率。

Continental rifting is a key plate tectonic process, which ultimately leads to continental breakup and ocean basin formation. The style and variability of rift-associated deformation is, however, poorly constrained due to deep burial of stn-rift rocks. The young (< 5 Ma), active Gulf of Corinth rift (Greece) offers a unique opportunity to investigate the sedimentary records of incipient rifting and infer important constraints on this poorly understood process, due to its pristine, more accessible syn-rift sequence. IODP Expedition 381 will recover sediments from the Corinth syn-rift sequence with the aim to resolve at a high temporal and spatial resolution how faults evolve in an incipient rift system and how deformation is re-distributed. These goals will be achieved mainly by producing a high-resolution age model of the syn-rift sequence and correlate it to the know sub-surface rift structure and onshore stratigraphy. While understanding how deformation progressed in this rift system is crucial, reconstructing the nature, orientation, and magnitude of the tectonic stress field associated to rift formation represents an additional, key step to resolve the poorly known cause and mechanism that controlled continental rifting.In this project we will use anisotropy of magnetic susceptibility (AMS) analysis, which is one of the most effective techniques for paleo-stress investigations. AMS is a petrofabric tool commonly used to determine the preferred orientation of grains (i.e. fabric) in rocks and reconstruct the style, orientation, and intensity of the paleo-stress field that produced that fabric. AMS analysis of the Corinth syn-rift sequence recovered during IODP Expedition 381 will help in reconstructing for the first time the variation in orientation and intensity of the tectonic stresses that controlled the formation of the Corinth rift system. Furthermore, a more precise dating of those intervals where classical biostratigraphic techniques may fail, will be obtained by performing orbital tuning. Astronomical cycles recognised through a time series analysis on specific parameters or chemical elements will allow to tight the age of the sediments with a resolution of 20-50 ka.