Interpretación paleoambiental de los sedimentos holocenos de la ría de Suances (Cantabria) a través de su estudio micropaleontológico y geoquímico

Resumen

Benthic foraminiferal assemblages, palynological and heavy metal contents in the Holocene sedimentary record of the Suan- ces estuary (Cantabria) have been analyzed from a borehole (17 m) taken at a supratidal area in the middle estuary. The results obtained have allowed the identification of three sections, which can be associated with the depositional sets that constitute the typical stratigraphic sequence of the Cantabrian estuaries during the Holocene marine transgressive cycle: (1) a basal section (lowstand systems tract or LST) formed by fluvial facies without foraminifera and low palynological content; (2) an intermediate section (transgressive systems tract or TST) that consists of muddy estuarine sediments deposited during the flooding of the river valley due to sea level rise (7.980 - 7.380 ± 30 years BP); and (3) after a stratigraphic hiatus, an upper section (highstand systems tract or HST) formed by recent sediments corresponding to a strongly anthropized salt- marsh, including increased concentrations of heavy metals as a consequence of the intensive mining and industrial activities since mid-19th century, as well as the presence of exotic pollinic taxa (Eucalyptus sp.).