Origen de la laminación en las facies intermareales del canal estuarino del río Guadalquivirconsideraciones climáticas

Abstract

The Guadalquivir estuarine cannel extends from the town of Sevilla to its mouth in front of Sanlúcar de Barrameda, bordering Doñana National Park along its southeastern margin. This estuarine zone is characterizaed by its mesotidal character and the presence of high-sloped intertidal margins. The channel margins mainly develop muddy facies with a clearly visible parallel lamination dipped to the channel. The study of 10 short sediment cores allowed an approximation to the origin of this lamination. So this work demonstrates that their origin is not tidal but related with seasonal oscillations in the supply of fluvial sediment and the environmental conditions to the microscopic organisms. In this way, each year, a couple of layers are deposited, including a light-grey muddy layer and a dark-grey organic layer. The relationships between the thickness and the grey tone of these laminae with the curves of fluvial input and interannual climatic curves would be used as a climatic marker. So we can extend the climatic curve to the periods previous to the instrumental records.