biostratigraphy and paleoecology of cretaceous/tertiary boundary in ...

Chapter Four
Depositional Environmenment and Paleoecology
CHAPTER FOUR
DEPOSITIONAL ENVIRONMENT AND PALEOECOLOGY
4.1- Preface
Paleoecology is defined as the study of the interaction of organisms with one
another and with the environment in the geological past, and the study of the
causes of patterns of distribution and abundance of organisms. It is concerned
with interaction between individuals and their physical, chemical and biological
parameters of the environment, consequently through high resolution studies of
these important parameters with lithologic characters of lithofacies, textures, and
sedimentary structures.
The most important group of organisms used in this study is planktonic and
benthonic foraminifera, which play an important role in interpretation of
depositional environment and paleoecology of most of the sedimentary basin of
Mesozoic and Cenozoic Era in the world.
The paleontologists continuously faced the problem of how the fossil communities
reveal the paleoenvironment in which they lived. The worthy approach to solve such
problem has been answered through the quantitative evolution of the planktonic and
benthonic foraminiferal species and their abundance patterns. The variations in the
relative abundance of these assemblages are used to document the rate and nature
of the planktonic foraminiferal evolution and diversification through the Cretaceous/
Tertiary boundaries.
In the present studied area , the encountered parts of Maastrichtian, Early
Paleocene planktonic as well as benthonic foraminiferal assemblages developed
not only to construct the biostratigraphic zones but also their species communities
could reflect the nature of the biotope controlled by abiotic sedimentary
environments. Paleobathymetric and paleoecological factors are studied through
the distribution patterns of planktonic and benthonic foraminifera, where the total
numbers of foraminiferal species, the diversity and statistical analysis of planktonic,
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