Palaeobotanical study of the vallesian (Neogene) outcrop of Salanca ravine (la Cerdaña, Lérida, Spain). Palaeoecological aspects

Abstract

An integral palaeobotanical study (macro- and microflora) has been done of the Salanca ravine outcrop. This place is located in the región of la Cerdaña (Lérida province, Spain), which constitutes an Upper Miocene lacustrine basin from Eastern Pyrenees. The sediments of the Salanca ravine outcrop consist of diatomites and grey mudstones. They have been interpreted as being deposited in distal lacustrine zones. In a palynological study, 79 taxa have been identified. They belong to the divisions Pteridophyta, Pinophyta and Magnoliophyta. The recorded assemblages allow us to reconstruct the vegetation of la Cerdaña during the Vallesian, though the problem of overrepresented taxa exists. The macrofloristic study has revealed the presence of 36 taxa through foliar remanís and winged seeds. The recorded assemblage presents plant remains of the divisions Pinophyta and Magnoliophyta. The best represented remains are leaves of dicotyledonous angiosperms because of their wind transport. The high percentage of angiosperm foliar remains in the sediments of the Salanca ravine outcrop revealed calm water conditions in the neogene lake. The palaeoclimatology deduced from the palynological study and the physiognomic study of macroflora indicates that températe conditions existed in which mixed mesophitíc forest developed where the families Pinaceae, Betulaceae and Fagaceae dominated.