Sequence stratigraphy and inferred relative sea-level change from the onshore British Jurassic

摘要

Sequence stratigraphy - the subdivision of successions into facies packages bounded by surfaces representing major shifts in depositional environment - has provided a systematic methodology for inference of relative sea-level change from vertical facies successions. In the present review, sequence stratigraphic work on exposures of British Jurassic successions is summarized. Resultant inferred relative sea-level curves for Early Jurassic and early Mid Jurassic successions show some strong similarities at the scale of ammonite zones between widely separated basins, implying sea-level change of at least regional extent or, alternatively, regionally co-ordinated changes in sediment supply. Also well developed are coeval stage-level influxes of sandy sediments into widely separated marine basins during the Late Pliensbachian, Late Toarcian-Aalenian and Oxfordian. Similarly, widespread synchronous shifts to more offshore facies are evident in the Early Pliensbachian, Early Toarcian, Early Callovian and Early Kimmeridgian.