High-resolution architecture of late Holocene highstand prodeltaic deposits from southern Spain: the imprint of high-frequency climatic and relative sea-level changes

The stratigraphic architecture and recent evolution of two late Holocene prodeltas (Guadalquivir and Guadalhorce rivers) from the south of Spain are compared on the basis of a high-resolution seismic stratigraphic analysis. These sedimentary bodies display a similar internal architecture, being characterised by a thin transgressive systems tract at their bases and an overlying thick, wedge-shaped highstand systems tract (HST). The internal structure of the HST deposits shows the repetition of two progradational/aggradational cycles, whose generation seems to be related to the influence of high-frequency climatic changes during the last 6–7 ka. Those changes probably involved small amplitude (<3–4 m) sea-level oscillations and associated changes of sediment supply, conditioning the development of delta switching processes. Small differences in the distribution and characteristics of the seismic units in each area are attributed to local factors, such as physiography of the coastal plains, the wave climate and increased sediment supplies conditioned by anthropic actions.