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重要的板块构造过程，它最终导致大陆裂解和洋盆的形成。然而，由于深埋的裂谷岩石，裂谷相关变形的样式和可变性受到很大限制。年轻（< 5 Ma），活动的科林斯裂谷湾（希腊）提供了一个独特的机会，调查沉积记录的早期裂谷和推断重要的限制，这一鲜为人知的过程，由于其原始的，更容易同裂谷序列。IODP远征381将恢复科林斯同裂谷序列的沉积物，目的是以高时空分辨率解决断层如何在早期裂谷系统中演变以及变形如何重新分布。这些目标将主要通过制作同裂谷序列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相关联来实现。虽然了解如何变形在这个裂谷系统的进展是至关重要的，重建的性质，方向，和规模的构造应力场与裂谷的形成代表了一个额外的，关键的一步，以解决鲜为人知的原因和机制，控制大陆裂谷。在这个项目中，我们将使用磁化率各向异性（AMS）分析，这是古应力研究最有效的方法之一。AMS是一种岩石组构工具，通常用于确定岩石中颗粒（即组构）的优选取向，并重建产生该组构的古应力场的样式、取向和强度。AMS分析的科林斯同裂谷序列恢复在IODP远征381将有助于重建的方向和强度的变化，控制科林斯裂谷系统的形成构造应力的第一次。此外，将通过轨道调整获得经典生物地层学技术可能失败的那些间隔的更精确的年代测定。通过对特定参数或化学元素的时间序列分析识别的天文周期将允许以20-50 ka的分辨率确定沉积物的年龄。

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.