Abstract

Fifty conventional core samples from the Ragley Lumber #D1 well located in Allen Parish, Louisiana (Sec 29, T5S, R7W) were analysed for terrigenous palynomorphs. The sediment was deposited during the Sabinian in a marine environment as evidenced by the presence of in situ dinocysts and acritarchs in every sample. One hundred twenty-nine terrigenous taxa are recognized as compared with marine palynomorph diversity of 46 taxa. Single sample diversity among the terrigenous palynomorph component ranged from 23 to 65 taxa, while single sample marine palynomorph diversity ranged from 7 to 25 taxa. High terrigenous diversity intervals possibly indicate sourcing from multiple onshore environments or a single onshore environment with a very diverse flora. Because the terrigenous component is reworked from the onshore environments to the offshore ones, intervals of terrigenous abundance possibly indicate deltaic progradation associated with changes in sediment supply or sea-level. Confirmation of this interpretation awaits regional studies. The subdivision of the section into palynofacies based on the terrigenous portion of the palynoflora shows general correspondence with the palynofacies of Gregory (1991) based on the total palynoflora. In general, mean percentages of palynomorphs used in the process of discrimination were lowered by the exclusion of the marine portion of the palynoflora. The Sabinian-Claibornian boundary is not present in the cored interval, based on consistent occurrences of Thomsonipollis magnifica (Thomson & Pflug 1953) Krutzch 1960 at the top of the core. The absence of diagnostic middle and late Paleocene indicator pollen, such as Momipites dialatus (Fairchild) Stover et al. 1966 and Holkopollenites chemardensis (Fairchild) Stover et al. 1966 along with other characteristic palynomorphs, suggests that the entire Sabinian is not present in the core as was previously believed based on lithostratigraphic studies (Lowery, 1987). Due to the lack of regionally significant taxa with restricted temporal distributions, a biozonation for the Ragley Lumber #D1 well is proposed base on the constrained palynomorphs from the principle components and discriminant function analyses.

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