Sedimentation argileuse et phosphatee au Dahomey

Abstract

The distribution of argillaceous facies relative to arenaceous facies in the Cretaceous- Tertiary sequence of the coastal sedimentary basin of Dahomey (west Africa) confirms the importance of clay sedimentation, with two major phases of deposition of attapulgite and with abundant development of montmorillonite, during the lower Eocene in Africa. Attapulgite is not represented in facies that contain phosphate and glauconite, but montmorillonite frequently accompanies the attapulgite and is equally common in phosphatic beds. The phosphate and glauconite facies correspond to agitated conditions of sedimentation, the attapulgite to calm conditions.

Mineralogy and geochemistry of Upper Cretaceous Mazıdağı Phosphorite Deposits from the Northern Arabian Plate (Mardin, Turkey)

“…Sepiolite/palygorskite minerals in Tertiary rocks occur widely as diagenetic, pedogenic, and newly formed minerals and were formed in different sedimentary environments (e.g., lake, lagoon, and sea) (Singer 1979;Singer and Galan 1984). In marine environments, phosphate-related palygorskite minerals were first studied in the Eocene deposits of the West African coastal basins (Slansky et al 1959), and it is widely accepted that these clays were formed by authigenic processes in the deep oceanic environment (Bowles et al 1971;Couture 1977;Church and Velde 1979;Tlili et al 2010;Nathan and Soudry 2018). The observation of sepiolite/palygorskite and smectite minerals in the pores and the matrix by SEM has supported interpretations regarding their authigenic precipitation (millot 1970;Singer 1979;Weaver 1984;Isphording 1984;Estéoule-Choux 1984;Chahi et al 1993;Torres-Ruiz et al 1994;Yalçın and Bozkaya 1995).…”

Origin of lower Eocene palygorskite clays in the Côte d'Ivoire-Ghana Transform Margin, eastern equatorial Atlantic

“…Western African coastal basins and, in particular, the northern shelf of the Gulf of Guinea are classical areas for the study of palygorskite in Paleocene-Eocene sediments. Skansky (1958) and Skansky et al (1959) described the stratigraphy and clay mineralogy of exploration wells in the Côte d'Ivoire basin, which is the proximal part of the Côte d'Ivoire-Ghana Transform Margin, and in the Dahomey-Togo basin, some 600 km to the northeast. In the Côte d'Ivoire basin, they report the occurrence of abundant palygorskite and sepiolite throughout 500 m of Paleocene to lower middle Eocene shallow marine sediments.…”