Publication: Sequence stratigraphy of Holocene incised-valley fills and coastal
evolution in the Gulf of Cádiz (southern Spain)
Loading...
Full text at PDC
Publication Date
1999
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
Royal Geological and Mining Society of the Netherland
Citations
Exportar
Abstract
This first sedimentary interpretation of two incised-valley fills in the Gulf of Cádiz (southern Spain), which
accumulated during the last fourth-order eustatic cycle in response to fluvial incision, changes of sea level, and
correlative deposition, relates the filling of the estuarine basins and their barriers with four regional progradation
phases, H1 to H4. The cases studied are the wave-dominated Guadalete, and the mixed, tide and wave-dominated
Odiel-Tinto estuaries. The sequence boundary is a type-1 surface produced during the lowstand of the Last Glacial
period ca. 18 000 14C yr BP. No fluvial lowstand deposits were found in the area. Due to rapid transgression the
valley fills consist of transgressive and highstand sediments. The maximum landward advance of the estuarine
barriers occurred ca. 6500–6000 14C yr BP during the maximum of the Flandrian transgression, but there is no
evidence of sea level rising appreciably above the present. A large part of the estuaries was filled during H1 (ca.
6500–4400 14C yr BP) but ravinement by shifting tidal inlets destroyed most of the coeval barriers. During the
H2 phase (ca. 4200–2550 14C yr BP) sedimentation was favoured by arid conditions and concentrated in the axial
estuarine zones and the barriers. Between H2 and H3 prevailing winds changed from W to WSW, increasing spit
growth to the east and south-east. Progradation of bay-head deltas and flood-plains during H3 (ca. 2300–800 14C yr
BP) and H4 (500 yr ago to the present) further reduced the accommodation space in the largely-filled valleys, and
sediment by-passed the estuaries and accumulated in the estuarine barriers as fast-growing spits. Arid conditions
and increasing human activity have caused rapid coastal modifications.