Abstract
The primary objective of International Ocean Discovery Program Expedition 381 was to retrieve a record of early continental rifting and basin evolution from the Corinth rift, central Greece. Continental rifting is fundamental for the formation of ocean basins, and active rift zones are dynamic regions of high geohazard potential. However, the detailed spatial and temporal evolution of a complete rift system needed to understand rift development from the fault to plate scale is poorly resolved. In the active Corinth rift, deformation rates are high, the recent synrift succession is preserved and complete offshore, earlier rift phases are preserved onshore, and a dense seismic database provides high-resolution imaging of the fault network and of seismic stratigraphy around the basin. As the basin has subsided, its depositional environment has been affected by fluctuating global sea level and its absolute position relative to sea level, and the basin sediments record this changing environment through time. In Corinth, we can therefore achieve an unprecedented precision of timing and spatial complexity of rift-fault system development, rift-controlled drainage system evolution, and basin fill in the first few million years of rift history. The following are the expedition themes: High-resolution fault slip and rift evolution history, Surface processes in active rifts, High-resolution late Quaternary Eastern Mediterranean paleoclimate and paleoenvironment of a developing rift basin, and Geohazard assessment in an active rift. These objectives were and will be accomplished as a result of successful drilling, coring, and logging at three sites in the Gulf of Corinth, which collectively yielded 1645 m of recovered core over a 1905 m cored interval. Cores recovered at these sites together provide (1) a longer rift history (Sites M0078 and M0080), (2) a high-resolution record of the most recent phase of rifting (Site M0079), and (3) the spatial variation of rift evolution (comparison of sites in the central and eastern rift). The sediments contain a rich and complex record of changing sedimentation, sediment and pore water geochemistry, and environmental conditions from micropaleontological assemblages. The preliminary chronology developed by shipboard analyses will be refined and improved during postexpedition research, providing a high-resolution chronostratigraphy down to the orbital timescale for a range of tectonic, sedimentological, and paleoenvironmental studies. This chronology will provide absolute timing of key rift events, rates of fault movement, rift extension and subsidence, and the spatial variations of these parameters. The core data will also allow us to investigate the relative roles of and feedbacks between tectonics, climate, and eustasy in sediment flux and basin evolution. Finally, the Corinth rift boreholes will provide the first long Quaternary record of Mediterranean-type climate in the region. The potential range of scientific applications for this unique data set is very large, encompassing tectonics, sedimentary processes, paleoenvironment, paleoclimate, paleoecology, geochemistry, and geohazards.
Highlights
How rifting initiates and evolves to continental breakup and ocean basin formation is a major unanswered solid earth/plate tectonic question; continental rifting is the first stage of this process.Numerical models indicate that strain rate is a key parameter controlling the style and magnitude of extension, but spatial and temporal patterns in strain rate are very poorly known for most extensional systems due to scarce chronological constraints, other than over short timescales
Key questions include the following: What controls rift geometry and evolution? How does activity on faults change with time? What does rift evolution and fault activity tell us about crustal rheology? What are the implications of changing fault activity for earthquake activity in a developing rift fault system? Over the last ~15 years, important insights have been derived from numerical models (e.g., Burov and Poliakov, 2001; Lavier and Buck, 2002; Lavier and Manatschal, 2006; Huismans and Beaumont, 2007, 2011; Olive et al, 2014) and from observations at mature, magma-poor passive margins where activity has ceased (e.g., Manatschal et al, 2001; Whitmarsh et al, 2001; Osmundsen and Ebbing, 2008; Van Avendonk et al, 2009; Bayrakci et al, 2016)
The Corinth rift is an ideal target for studying rift processes because it is opening orthogonally at high strain rates (e.g., Briole et al, 2000), extension is focused with well-constrained initial conditions, it lacks volcanism, and there is almost no tectonic overprinting
Summary
How rifting initiates and evolves to continental breakup and ocean basin formation is a major unanswered solid earth/plate tectonic question; continental rifting is the first stage of this process. Early synrift stratigraphy is often difficult to image and sample due to deep burial and tectonic overprinting, making it difficult to examine the earliest stages of rifting Instead, this project studies the young, seismically active Corinth rift with a unique existing data set to resolve at high temporal and spatial resolution how rift faults initiate and link and how strain is distributed over time. Recent models predict that surface processes will strongly influence rift development by modifying the thermal structure (Bialas and Buck, 2009) and by redistributing mass through erosion and deposition (Olive et al, 2014), all of which can influence fault evolution and strain localization Addressing all of these questions, determining driving mechanisms, and resolving the interplay between processes requires a detailed record of climate, tectonics, and sedimentation in a young rift basin. During International Ocean Discovery Program (IODP) Expedition 381 we drilled, sampled, and logged a significant part of the synrift sequence of the Corinth rift to constrain in space and time the deformation rate, absolute timing of rifting processes, subsidence and sediment flux, changing paleoenvironment and depositional conditions, and the interaction of rift development and climate on surface processes and sediment flux
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
