SOURCE: http://www.FORAMS2010.uni-bonn.de/sites/sessions/C3.php
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Session Session Title Convenor(s)
C3 Biozonation by means of larger benthic foraminifera
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Summary

A biozonation of benthic marine organisms represents a tool to correlate or subdivide the events of Earth History according to evolutionary mechanisms. They permit to calibrate the lithological and lithochemical signals in the sedimentary sequences because they are independant from the factors conditioning the facies.
A Shallow Benthic Zonation (SBZ) of the Tertiary was updated and modernized with a numbering system by Serra et al. (1998) and Cahuzac et al. (1998). This zonation is extended here to cover the Late Cretaceous during which perforate-lamellar benthics produce for the first time in Earth History highly specialized, large-sized shells (Orbitoidiforms, Siderolitids, Sulcoperculinids, Rotaliids), shells that reflect their evolution by channeled morphological change, in parallel to imperforate benthics such as Larger Miliolids, Alveolinids, Meandropsinids and some agglutinated groups.
The Middle Cretaceous has produced only imperforate larger foraminifera, fusiform and axially compressed Alveolinids with porcelaneous and Orbitolinids with agglutinated shells. Their potential for a zonation will have to be discussed in the light of the Global Maturation Cyles (GCM) repeating analogous types of shell morphology in subsequent slices of geologic time. Earlier epochs of the Mesozoic have produced only agglutinated foraminiferal families that might be used for a zonation, in particular the conical Orbitolinids in the Lower Cretaceous and the Anchispirocyclinids in the late Upper Jurassic. Middle and Early Jurassic exclusively agglutinated groups of benthic larger foraminifera characterize the Early Mesozoic but do by far not cover the total timespan by a continuous sequence of evolving species.
This topic may be introduced by a general view of global maturation cycles and complemented by some round table discussion about the best way to introduce zone numbers in biostratigraphy.
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