Geophysical, structural, geochronological and geomorphological data indicate that the Psatha, East Alkyonides, Skinos and Pisia faults are Holocene-active structures whereas the status of the West Alkyonides, Strava, Perachora and Loutraki faults is less certain. We see no evidence for significant lateral surface fault growth. New data for late Pleistocene footwall uplift of the Psatha fault are comparable with previously estimated Holocene rates. Pre-Holocene stratigraphic sequences in the Alkyonides Gulf allow calculation of vertical displacement on the Skinos fault of 1.42–1.60 km over a period of >0.6 Ma. Previous palaeoseismological studies indicate comparable displacement rates extrapolated to 0.61–2.20 Ma, whereas extrapolation of previous geodetic data indicate a range of 0.17–0.46 Ma. The latter is too short given the evidence of the stratigraphic record, signifying either that these data may not be representative of longer-term rates, or that significant deformation has taken place elsewhere, for example, on offshore antithetic faults. A case is established for uniform late Quaternary (post-MIS 7) uplift of the Perachora peninsula at rates of c. 0.2–0.3 mm a–1. The lack of regional tilting over Perachora–Corinth–Isthmia is in marked contrast to the situation in the Alkyonides–Megara basins to the east

New evidence for uplift of the southern margin to the Corinth rift, one of the world's most rapidly extending continental regions, defines an area of uniform uplift separating a more rapidly uplifting western rift flank from a slowly backtilting eastern flank. This major tectonic boundary coincides with geophysical evidence for a junction between flat underlying subducted oceanic plate and steep subduction. We propose that trench rollback by the Anatolian plate over the subducting African plate has led to differential uplift and possible migration of active faulting at the southern rift margin in the last few million years.

The cyanobacterium Rivularia haematites has calcified to form unusually large (up to 10 m high) bioherms in the Pleistocene Gulf of Corinth. Today R. haematites calcifies only in freshwater environments but these Gulf of Corinth bioherms have a brackish affinity, limited areal extent, and occur within marine deposits. Field relations and preliminary U‐series dating suggest a marine isotope stage (MIS) 5e age for the bioherms. This age is compatible with published MIS 5e ages for corals in the marine sediments above the bioherms and is consistent with their current elevation based on average uplift rates. Bioherm growth during MIS 5e constrains their formation during a time of near sea‐level highstand when the Gulf of Corinth was marine. Growth cavities in the bioherms are encrusted by brackish tolerant coralline algae. Field mapping of the MIS 5e highstand palaeoshoreline shows the bioherms grew in water <16 m deep. Mg contents of the bioherm calcites, and associated coralline algal skeletons, are both much lower than expected for marine MIS 5e carbonates. They are best explained if the calcites precipitated from brackish fluids with Mg/Ca ratios below 2, implying at least 60% input of freshwater with low Mg/Ca ratio. Sr isotopes confirm a strong input of groundwater that had partially equilibrated with Mesozoic limestones. The limited areal extent of the bioherms and their close association with karstified fault scarps suggest that they formed in shallow sea water where freshwater submarine springs delivered CaCO3 saturated water that promoted rapid calcification of cyanobacteria. Rapid calcification and strong degassing of CO2 from the spring water resulted in disequilibrium stable isotope compositions for the calcites.

No abstract

No abstract