A facies analysis of Middle-Upper Jurassic boundary beds, i.e. Callovian-Oxfordian Stage boundary beds, has been carried out on numerous sections across Europe, with the aim of constructing relative sea-level curves for each geographic area. Accurate correlation of the various epeiric-sea, sedimentary successions has been achieved using ammonite zonations. The comparison of twelve relative sea-level curves has led to the recognition of regional sea-level events in Europe during the Callovian-Early Oxfordian interval. A regional sea-level rise occurred during the Middle and Late Callovian, reaching its greatest extent in the latest Callovian (lambert; Zone), and highstand conditions and incipient sea-level fall characterized the Early Oxfordian. A literature review of Callovian-Oxfordian boundary beds in six further regions from four other continents has shown that a Middle Callovian sea-level rise and Late Callovian-Early Oxfordian phase of high sea-level can be recognized on a global scale. The European regional sea-level changes are, therefore, considered to be eustatic in origin, and are a response to a third, or possibly second-order, eustatic cycle of 6-1 0 Ma. A "Norris eustatic curve" has been constructed and compared with two published eustatic curves. It differs markedly from that of Hallam (1988), also based on the facies analysis technique, but is very similar to that of Haq el al. (1987), based on sequence stratigraphic concepts. However, the systems tracts and coastal onlap curve of the Haq ct al. (1987) chart are at odds with the facies interpretations made in this study, reflecting the inadequacy of the sequence stratigraphy model in addressing the Jurassic epicontinental sea successions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:539902 |
| Date | January 1993 |
| Creators | Norris, Michelle Samantha |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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