Late Cretaceous to Early Eocene dinoflagellate cysts from the “12 frères” borehole, Fresco, southwestern Côte d’Ivoire: Biostratigraphy and paleobiogeographic implication

Paleoenvironmental and paleogeographic characterization of the 12 frères borehole, fresco, southwestern Côte d’Ivoire: Palynological implication

“…The preparation of palynological slides in the laboratory is done in three steps as described by [1][2]: (1) sampling and physical treatment, (2) chemical attacks (HCl 10%, HF 40%) to dissolve the mineral matter and preserve the organic matter contained in the sediments, (3) mounting of the collected organic matter between slide and coverslip for microscopic study. The determination of the paleoenvironment is based on the relative proportions of dinocysts (marine organisms) to spores and pollen grains (continental organisms) in the palynological assemblage [15].…”

“…The present study, which is a continuation of the one already published on the biostratigraphy of the "12 Frères borehole" [1], deals with the paleoenvironment and paleogeography that prevailed during the emplacement of its sediments.…”

“… The tropical to subtropical or Tethyan province with the "Malloy suite" type association is characterized by the abundance of species of the genera Andalusiella, Cerodinium, Lejeunecysta and Senegalinium. Assemblages of this suite have been observed in Campanian to Danian deposits of the peri-Mediterranean basins [18,21,[46][47][48][49], in Côte d'Ivoire [1,8,[50][51][52], in Senegal [53], in equatorial zones [50,51,54,55], in the southeastern United States of America [32,[56][57][58], in the Caribbean [59], and in Caribbean Mexico [60].  The temperate province with the "Williams suite" type association is characterized by species of the genera Alterbidinium, Chatangiella (small forms), Isabelidinium, Spinidinium and Trithyrodinium.…”

“…Côte d'Ivoire is a West African country that for oil interests has focused its biostratigraphic studies on the Cretaceous and neglected the Paleogene which is also very poorly known. In spite of some palynological studies on the basin in the framework of thesis of Diploma of Advanced Studies [3][4][5], Doctorate [6][7] and rare publications [1,[8][9][10][11][12][13][14], this basin remains still badly known from the palynological point of view.…”

“…Assemblages of peridinioid dinoflagellate cysts observed in the Maastrichtian-Danian interval of the 12 Frères borehole according to the paleo-provinces associations defined by[45] The Malloy suite of Lentin and Williams[45], has been demonstrated in Campanian, Maastrichtian and Danian sediments of the Tethyan regions[18,21,[46][47][48][72][73][74], in Ivory Coast[1,8,[50][51][52], in Senegal[53], under the Equator[54,55,75], in the Southeastern United States of America[32,[56][57][58], and in India[76].…”