Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9463034 | Palaeogeography, Palaeoclimatology, Palaeoecology | 2005 | 17 Pages |
Abstract
The available data of ostracod ranges for the Cenomanian, Campanian and Maastrichtian stages of the Late Cretaceous of the northern part of the Anglo-Paris Basin were examined and combined with new data from the Turonian, Santonian and Coniacian stages. A new cumulative species diversity curve is presented for the Ostracoda of the Late Cretaceous of Britain. The results obtained challenge the method of chronoecologic charts to determine sea-level from diversity. When a more complete data set is applied, and compared with published sea-level curves, the result is the inverse of that previously predicted by employing chronoecologic charts. A model is presented of changing sea-levels in S.E. England from the Cenomanian through to the Santonian, which integrates the new diversity data with published sea-level changes and curves of stable isotopes of oxygen and carbon. In the earliest Cenomanian, low diversity is associated with a deeper water depositional environment and warmer temperatures. The mid-Cenomanian diversity maximum corresponds to a regressive trough and cooler water. Over the Cenomanian-Turonian boundary interval the diversity minimum is correlated with global sea-level and temperature maxima. The proportion of ostracods possessing eye tubercles falls to a minimum over this period. After the diversity crash, the Cenomanian fauna was replaced by the new Turonian fauna; east-west migrations into the Anglo-Paris Basin were facilitated by the sea-level rise overcoming marginal basin highs. The pattern seen in the mid-Cenomanian is also present at the Turonian-Coniacian boundary interval; that of high diversity corresponding with a regressive trough on a long-term regressive trend with cooling conditions. The model for this northern part of the Anglo-Paris Basin then associates high diversity with regressive cooler conditions, and low diversity with deeper and warmer water.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Earth-Surface Processes
Authors
Ian J. Slipper,