The Barremian-Aptian arid phase in western Europe
Abstract Evidence is presented from nine areas in western Europe (Speeton, Yorkshire; southern North Sea; Channel and Weald Basins, southern England; Jeanne d'Arc, Lusitanian and Aquitanian Basins of the North Atlantic continental margins; Lower Saxony Basin, north Germany; the Paris Basin and southern France) for a phase of aridity which began during the Hauterivian-middle Barremian and continued to dominate the climate of the region until the mid-Aptian, although conditions during this period were not uniformly dry throughout. Criteria for recognising arid environments include the occurrence of evaporites, abundances of carbonate-rich sediments, red beds, firmgrounds, carbonate nodules and pyrite concretions, depletion of kaolinite, spore assemblages of limited morphological diversity, and the presence of numerous coniferalean and cheirolepidiacean pollen grains. The change from generally humid to dry climates during the Barremian is thought to have been linked to a lowering of sea-level. The arid phase clearly falls within the time span of the first Cretaceous Oceanic Anoxic Event.