First report of late Messinian Lago-Mare micropaleontological assemblage in northeastern Algeria (Beni Fouda Basin)

Abstract

This study presents the first detailed micropaleontological investigation of Late Messinian Lago-Mare facies in the Beni Fouda Basin (Northeastern Algeria). Analyzing 20 samples from four stratigraphic sections (KAL, KAU, KAM, DH), our findings reveal an oligotypic micropaleontological assemblage comprising six ostracod taxa (five genera) alongside dominant charophytes, with Sphaerochara miocenica being the only species formally identified. The assemblage, characterized by euryhaline Cyprideis species and freshwater taxa like Ilyocypris gibba and Candona angulata, indicates transitional lagoonal environments with significant fluvial influence. Here, we report the first documented occurrence of the genus Zonocypris in North Africa, contributing new data to our understanding of its biogeographic distribution.

A major contribution of this study is the stratigraphic positioning of Lago-Mare deposits above the Turolian Amama 2 vertebrate level, which significantly reduces the estimated hiatus between the Turolian and Pliocene in northeastern Algeria. This finding refines the regional stratigraphic framework and highlights regional variations in Lago-Mare environments. Unlike the Chelif Basin, the Beni Fouda Basin is characterized by a persistent freshwater influence, the absence of marine planktonic microfossils, and a lack of evidence for the Messinian Erosional Surface, emphasizing the influence of local factors on Messinian paleoenvironments. Furthermore, the presence of Paratethyan-affinity taxa supports the hypothesis that the paleo-Sicily Channel allowed faunal exchange between the Eastern and Western Mediterranean during the Late Messinian. This first report of Lago-Mare species in northeastern Algeria provides significant new insights into the stratigraphy and the Messinian-Pliocene transition in the region.