Climate and sea-level fluctuations across the Cretaceous-Tertiary (K-T)
transition in Tunisia were examined based on bulk rock and clay
mineralogies, biostratigraphy and lithology in five sections (El Melah,
El Kef, Elles, Ain Settara and Seldja) spanning from open marine to
shallow inner neritic environments. Late Campanian to early Danian
trends examined at El Kef and Elles indicate an increasingly more humid
climate associated with sea-level fluctuations and increased detrital
influx that Culminates at the K-T transition. This long-term trend in
increasing humidity and runoff in the Tethys region is associated with
middle and high latitude cooling. Results of short-term changes across
the K-T transition indicate a sea-level lowstand in the latest
Maastrichtian about 25-100 ka below the K-T boundary with the regression
marked by increased detrital influx at El Kef and Elles and a short
hiatus at Ain Settara. A rising sea-level at the end of the
Maastrichtian is expressed at Elles and El Kef by deposition of a
foraminiferal packstone. A flooding surface and condensed sedimentation
mark the K-T boundary clay which is rich in terrestrial organic matter.
The P0-P1a transition is marked by a sea-level lowstand corresponding to
a short hiatus at Ain Settara where most of PO is missing and a period
of non-deposition and erosion in the lower part of P1a (64.95 Ma). At
Seldja, PO and possibly the topmost part of CF1 are missing. These
sea-level fluctuations are associated with maximum humidity. These data
suggest that in Tunisia, long-term environmental stresses during the
last 500 ka before the K-T boundary and continuing into the early Danian
are primarily related to climate and sea-level fluctuations. Within this
long-term climatic trend the pronounced warm and humid event within the
latest Maastrichtian Zone CF1 may be linked to greenhouse conditions
induced by Deccan volcanism. The absence of any significant clay mineral
variations at or near the K-T boundary and Ir anomaly suggests that the
bolide impact had a relatively incidental short-term effect on climate
in the Tethys region. (C) 2002 Elsevier Science B.V. All rights
reserved.