Use of palynofacies analysis to define Lower Jurassic (Sinemurian to Pliensbachian) genetic stratigraphic sequences in the Wessex Basin, England

Abstract

Quantitative palynological and palynofacies analyses allow the Lower Jurassic succession of the Dorset coast (Wessex Basin, southern England, UK) to be placed within a genetic sequence stratigraphic framework. The multifaceted approach employed utilizes various palynological criteria adopted from previous publications (e.g. both relative and absolute particle abundance data, allochthonous versus autochthonous palynomorphs ratios, phytoclast type, etc.), and suggests new parameters which may be studied in this context (e.g. ratios of acritarch spine length). Interpretation of palynofacies trends within the studied succession enables the identification of eight genetic sequences informally described as Genetic Stratigraphic Sequences I-VIII. Genetic stratigraphic sequence boundaries are placed at the following horizons: Mongrel, Grey Ledge, Pavior, the Coinstone, Hummocky, the Belemnite Stone, Day's Shell Bed and the margaritatus Stone.These results compare well with sequence stratigraphic frameworks for published for the British Lower Jurassic interval both in Dorset and elsewhere, suggesting that the maximum flooding events recognized are likely to have been of inter-regional extent.

Triassic to Middle Jurassic stratigraphy of the Kerr McGee 97/12-1 exploration well, offshore southern England

“…The most important and relevant publications for the UK, and in particular the Wessex Basin, are those by Ainsworth et al (1998a), Cole and Harding (1998), Davey (1980), Orbell (1973), Powell (1992), Riding (1984aRiding ( ,b, 1987, Riding and Thomas (1992), Wall (1965), Warrington (1977aWarrington ( ,b, 1978Warrington ( , 1982Warrington ( , 1997Warrington ( , 2005 and Woolham and Riding (1983).…”