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

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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.