Notes sur la Géologie et la paléontologie du Miocène de Lisbonne. XVIII - Coupe de Palença, rive gauche du Tage: stratigraphie et micropaléontologie (Coccolithoforidés)

Abstract

Key words: Stratigraphy - micropaleontology - Tagus basin Palen{: a - Miocene - coccolithophorids. This note deals with the stratigraphical and paleontological study of the Palen9a section on the southern bank of the river Tagus, Portugal, and specially with its coccolithophorids. Three main lithostratigraphical units may be recognized: the lowest one does correspond to the upper 'part of COTTER's division II, the intermediate one to divisions III and IV-a, the third corresponding to pratically the whole division IV-h, However other and higher levels are also represented. Higher beds are also represented in the same sections; they are less well exposed and were not studied in detail. Caracterisation of biozones on the basis of Coccoliths so far found at Palen9a section is difficult since MARTINI's zones have becn defined mainly by forms of Discoaster and other genera that are wanting. However we can recognize that the richest assemblage (from beds 17-18, the uppermost layers of blue clays IV-a) may correspond to NN4. This is not in opposition to the results of the study of planctonic foraminifera, that are characteristic of BLOW's N7. Coccoliths from lower beds do not allow at present any valid comparisons.