Quaternary Elevation Change of the Gulf of Corinth in Central Greece
Dramatic elevation changes have occurred since early Pleistocene time in and around the Gulf of Corinth sedimentary basin in central Greece, which is actively extending at a maximum rate of ca. 2 mm a-1. Shoreline deposits younger than 1 million years are found at up to ca. 1200 m elevation south of the Gulf, with sediment from an older Plio-Pleistocene basin above 1750 m. The Gulf floor, in the hanging-wall of normal faults along its southern coast, has subsided up to ca. 1650 m on the same timescale. However, other hanging-wall localities such as the Corinth isthmus - east of the Gulf - have uplifted instead. During the past million years the Gulf has alternated between marine and lacustrine environments in response to glacially induced sea-level variations. This study establishes its chronology of marine and lacustrine terraces for the past half million years, allowing lateral variations in uplift to be investigated. To explain the observed elevation changes, it is suggested that ca. 0.9 million years ago the previously lacustrine Gulf became flooded by ca. 80 m during an interglacial marine highstand. The resulting ca. 0.8 MPa increase in lithostatic pressure at the base of the brittle upper crust caused southward lower-crustal flow to beneath the older Plio-Pleistocene basin. Isostatic adjustment uplifted this basin, creating unstable topography that enabled rapid erosion. This lower-crustal flow, which since been maintained by the sediment load in the Gulf that results from this erosion, also causes the hanging-wall uplift of the Corinth isthmus and other `anomalous' localities. The Gulf of Corinth is thus an important case study locality for revealing the existence of lower-crustal flow during continental extension.
Proceedings of the Royal Society of London Series A
- Pub Date:
- May 1996