Tectono-sedimentary evolution of the western Corinth rift (Central Greece)

Abstract

The Corinth rift (Greece) is one of the world's most active rifts. The early Plio-Pleistocene rift is preserved in the northern Peloponnese peninsula, south of the active Corinth rift. Although chronostratigraphic resolution is limited, new structural, stratigraphic and sedimentological data for an area >400 km² record early rift evolution in three phases separated by distinct episodes of extension rate acceleration and northward fault migration associated with major erosion. Minimum total N–S extension is estimated at 6.4–7.7 km. The earliest asymmetrical, broad rift accommodated slow extension (0.6–1 mm a⁻¹) over >3 Myrs and closed to the west. North-dipping faults with throws of 1000–2200 m defined narrow blocks (4–7 km) with little footwall relief. A N-NE flowing antecedent river system infilled significant inherited relief (Lower group). In the earliest Pleistocene, significant fluvial incision coincided with a 15 km northward rift margin migration. Extension rates increased to 2–2.5 mm a⁻¹. The antecedent rivers then built giant Gilbert-type fan deltas (Middle group) north into a deepening lacustrine/marine basin. N-dipping, basin margin faults accommodated throws <1500 m. Delta architecture records initiation, growth and death of this fault system over ca. 800 ka. In the Middle Pleistocene, the rift margin again migrated 5 km north. Extension rate increased to 3.4–4.8 mm a⁻¹. This transition may correspond to an unconformity in offshore lithostratigraphy. Middle group deltas were uplifted and incised as new hangingwall deltas built into the Gulf (Upper group). A final increase to present-day extension rates (11–16 mm a⁻¹) probably occurred in the Holocene. Fault and fault block dimensions did not change significantly with time suggesting control by crustal rheological layering. Extension rate acceleration may be due to strain softening or to regional tectonic factors.