Temporally Constant Quaternary Uplift Rates and Their Relationship With Extensional Upper‐Plate Faults in South Crete (Greece), Constrained With 36Cl Cosmogenic Exposure Dating

Abstract

In order to investigate how active upper-plate faults in Crete influence uplift above the Hellenic subduction zone we mapped deformed Late Quaternary marine terraces along 17 profiles, across strike of the South Central Crete Fault (SCCF), identified and dated palaeoshorelines using in-situ 36Cl exposure dating on wave-cut platforms, correlated them with the Quaternary sea-level curve and calculated uplift rates. We identified 16 distinct palaeoshorelines from field observations and study of digital elevation models (DEMs), located along the footwall and hangingwall of the SCCF and the footwall of the offshore Ptolemy ‘trench’ fault. Cosmogenic dating constrains the ages of three palaeoshorelines as 76, 100 and 125 ka. We use these dates to guide a correlation of other mapped palaeoshorelines with Quaternary sea-level highstands between 200 and 980 ka with results implying that the uplift rate is constant through time at each of the 17 profile locations. Elastic half-space modelling implies that uplift in both the hangingwall and footwall of the SCCF is influenced by uplift related to offshore upper-plate faults, in addition to background regional uplift, perhaps from the subduction interface. By correlating palaeoshorelines across the active South Central Crete Fault, we derive a throw-rate of 0.41 mm/yr for this fault which can also be expressed as a slip rate of 0.58 mm/yr. The fault-specific earthquake recurrence interval, assuming repetition of 1.1 m slip events, is approximately 2700 years for the SCCF.