Article: Wealden occurrence of an isolated Barremian dinocyst facies

Records of occurrence are presented in the form of two new taxa of peridinioid dinoflagellate cysts and twenty-three comparison records from Upper Wealden strata of Barremian age in the British Geological Survey's Warlingham Borehole, Surrey. Because these well-preserved dinocysts are not accompanied by any other dinocyst palynomorphs, their presence is interpreted as a short-lived and local record of very low palaeo-salinity. Other occurrences at different levels in the Wealden usually contain three or four dinocysts of known marine taxa, and appear to represent more widespread and perhaps stronger marine incursions. Palynofacies, ostracods, and clay minerals are briefly discussed in connection with the possibility that these new dinocysts may represent the earliest known occurrences of non-marine dinoftagellates to produce fossilisable cysts.