Distribution of dinoflagellates in a subsurface marine Wilcox (Paleocene‐eocene) section in southwest louisiana

Abstract

Fifty conventional core samples from the Ragley Lumber # 1 well located in Allen Parish Louisiana (Sec 29, T5S, R7W) were analyzed for palynomorphs. Dinoflagellate cysts, not considered to be recycled, were present in all samples along with abundant to very abundant pollen, spores and fungal spores. Dinoflagellate cyst abundances varied considerably from sparse (< 20 cysts per sample) to abundant (> 100 cysts per sample). Preservation also displayed considerable range, even within the same sample.

Biostratigraphically useful taxa include: Adnatosphaeridium multispinosum, Apectodinium homomorphum, Areosphaeridium dictyoplokus, Deflandrea phosphoritica, Spinidinium sagittula, Lingulodinium machaerophorum, Muratodinium fimbratum, Palaeocystodinium golzowense, and Hafniasphaera septata. Other taxa described include: Achomosphaera alcicornu, Cleistosphaeridium diversispinosum, Cordosphaeridium inodes, Diphyes colligerum, Operculodinium centrocarpum, Polysphaeridium subtile, Trichodinium hirsuitum, and Senegalinium sp. 1. In addition to the indigenous flora, a recycled flora was also encountered. These specimens were assignable to the following genera: Muderongia, Dinogymnium and Odontochitina.

Based on abundances of Spiniferites and Cleistosphaeridium types and general scarcity of peridiniacean dinoflagellate cysts and Impagidinium species an outer neritic water depth is postulated. Benthic foraminiferal data from a section of the core generally support this interpretation.