Facies laminadas en la secuencia sedimentaria del lago de Montcortés (Lleida) durante los últimos 6.000 años

Abstract

The different sedimentological, geochemical and geophysical analysis performed in the Montcortés lake sedimentary record (Pre-Pyrenees, Lleida) helps to interpret the sedimentary evolution of this karstic lake during the last 6.000 years. The deposition of lacustrine varves is continuous during, at least, the last 3.500 Cal. yr BP. This fine lamination is punctuated by massive clastic facies corresponding to turbidite events. A total of 9 litostratigraphic units were recognized corresponding to three different depositional environments that alternate throughout the record; i) a shallow, meromictic lake with very high bioproductivity (unit VI: 6.000- 3.500 Cal. yr BP), ii) a deep, meromictic lake with high bioproductivity (units V, III and I; 3.500-1.250, 500-180 Cal. yr BP and last decades) and iii) deep, meromictic lake with higher clastic inputs (units IV and II; 1.250-500 and 180 Cal. yr BP- last decades). Several slumps deposits have been recognized within the sequence (units A, B and C)