Early-Late Cretaceous (Aptian-Cenomanian) Palynomorphs

Abstract

Abstract. Samples from 12 wells situated mainly in the northern part of the Cyrenaica Shelf of northeast Libya have yielded palynomorph assemblages of Aptian, Albian or Cenomanian aspect. The Aptian assemblages are dominated by land-plant remains and contain relatively few dinoflagellate cysts. By contrast, the latter are generally common in those from the Albian and Cenomanian samples. Deposition in near-shore marine environments is indicated for most of the Aptian succession whereas more open marine conditions are generally suggested for the younger strata. In places, however, a substantial terrestrial input was maintained during the accumulation of the Albian sediments.Dinoflagellate cysts typically recorded from Aptian palynological preparations include Aptea anaphrissa, Cyclonephelium sp. 1, Hystrichosphaerina schindewolfii, Muderongia simplex microperforata and Occisucysta spp. Several species of Cribroperidinium, but especially C. edwardsii and C. orthoceras, usually form an important part of the Albian assemblages; Kiokansium hydra is also often present. Skolochorate cysts referable to Coronifera and Florentinia are abundant in both these and the Cenomanian preparations, with Palaeohystrichophora infusorioides and several species of Canningia, Cyclonephelium, Oligosphaeridium, Spiniferites and Subtilisphaera being among the most numerous of the associated forms. In general the assemblages compare closely with those of similar age described by Below (1981, 1982) and Williams (1978) from onshore and offshore Morocco respectively.Although miospores are common in the Aptian preparations, they show relatively little morphological diversity. Smooth walled triradiate specimens, Classopollis and Inaperturopollenites are often the dominant forms. Angiosperm pollen grains are generally scarce and bisaccates only rarely encountered. A few of the Albian . . .