الطباقية الحياتية لمكمن العصر الطباشيري الأعلى في حقل بطمة

Abstract

This study revealed the Bio-content component of the late Cretaceous sequences (Campanian- Maastrichtian), which has been used in distinguishing four Biozones, which are:

1 - Gansserina gansseri - Gublerina cuvilleri zone

2 - Globotruncanita subspinosa zone

3 - Globotruncanita calcarata zone

4 - Hartella inflatotriangularis zone

The upper three zones are related to Shiranish Formation, the Bio-content of this formation show rich in Planktonic Foraminifera in comparison with that of Mushorah Formation. The Zonal index forms clearly indicate Late - Campanian to Lower Late Maastrichtian age. While the fourth zone representing the Mushorah Formation, its Bio-facies characterized by rare Planktonic Foraminifera but more Benthonic Foraminifera and Calcispheres, the zonal form  indicate the  Early Campanian age.

A lateral distribution of Gansserina gansseri - Gublerina cuvilleri zone accompanied with thickness have been noticed along the Butmah structure. This variation might be attributed to post depositional differential erosion, which took place at the end of Cretaceous. Whereas the variation in thicknesses of the other Biozone of Shiranish Formation are most likely considered to represent a response to the tectonic activity prevailed at the time of deposition and manifested as a growthfaults