Sedimentology and palynofacies analysis of Jurassic rocks Eriksdal, Skåne, Sweden

Sammanfattning: A sedimentlogical and palynological study of samples from the Middle Jurassic Fuglunda Member, Mariedal Formation at Eriksdal, Skåne, Sweden, has been carried out. The section is dominated by sandstone with minor units of coal, claystone, siltstone and conglomerate. The depositional environment has been interpreted as a coastal setting, perhaps a delta system with mixed influences of fluvial, tidal and wave processes. Twenty-four samples processed for the palynological study revealed rich and well-preserved assemblages of dispersed organic matter but their composition varies significantly. Forty-two pollen and spore species were identified. Wood remains, amorphous organic matter, cuticles and fungal spores were also recorded in the samples. The coal samples have almost the same palynomorph content as samples from adjacent clastic sediments, except 23A and 23B, which are devoid of pollen and spores. The Fuglunda member palynoflora is dominated by gymnosperms, most notably Perinopollenites elatoides. Most of the species are long-ranging; however, a few species are stratigraphically significant (Neoraistrickia gristhorpensis, Todisporites minor, Callialasporites microvelatus). These index taxa suggest that the studied samples are of Bajocian–Bathonian (Middle Jurassic) age. The occurrence of the key environmental indices Gleicheniidites senonicus, Cyathidites, Classopollis and Perinopollenites suggests a warm and humid palaeoclimate for the Eriksdal area. The composition of the Fuglunda member palynoflora, together with its Thermal Alteration Index (TAI = 2) and Spore Colour Index (SCI = 4), reveal that the organic matter is gas-prone and is immature to produce hydrocarbons.