Biostratigraphie et paléoécologie des peuplements d'ostracodes dans le Domerien du Bassin Lusitanien, Portugal

Abstract

Key-words: Ostracods; Domerian; Biostratigraphy; Palaeoecology; Lusitanian Basin; Portugal. The Domerian sections from the Lusitanian Basin of Sao Pedro de Mue!, Raba9al and Tomar have provided us with more than 1100 Ostracods belonging from 18 genus and about 48 species. The faunal diversity and density of the associations decrease in space (from Tomar to Raba9al and Sao Pedro de Mue!) and time, with favourable environments for the proliferation of Ostracods at the lower part of the sections (Stokesi subzone) and more hostile at the upper part (Ragazzonii subzone). The Monestieri and Nitescens horizons and the Subnodosus subzone are characterized by a typical assemblage of Ostracods. The palaeoecological Ostracod indexes reveal the fluctuations of the oxygenation, temperature, depth and hydrodynamism of the water, on the different sections and on the whole platform. They display a diachronous cooling in the Lower Domerian series. In the Upper part ofthe Middle and in the Upper Domerian, the deeper, less oxygenated and cooler waters prevent the development of the Ostracod faunas.