The Eocene-Oligocene foraminiferal boundary of Pakistan

Résumé En Fr

The Tertiary deposits of Pakistan are divided into three basins, the Baluchistan, the Lower and the Upper Indus basins. The Eocene-Oligocene deposits are exposed in all these basins with the exception of the Upper Indus basin, where both Late Eocene and Early Oligocene deposits are not exposed. In the Baluchistan and Lower Indus basins the Eocene and Oligocene deposits are well exposed and their boundary is well marked on the basis of the larger and planktic Foraminifera. The planktic Foraminifera of Late Eocene are : Globorotalia cerroazulensis, G. gnaucki, G. turritilina and Hantke-nina alabamensis , and among the larger Foraminifera the diagnostic species are : Nummulites pengaroensis, N. vredenburgi, Discocy-clina sella, D. omphalus and Pellatispira sp. The planktic foraminifera of Early Oligocene is characterized by Globigerina ampliaper-tura, G. angiporoides, G. pseudovenezuelana, G. officinalis and Globorotalia euaperture, and among the larger foraminifera the diagnostic species of Early Oligocene are : Nummulites ficbteli, N. intermedins, Cyciopeus communis and Heterosiegina invoiuta.

Les dépôts tertiaires du Pakistan sont divisés en trois bassins : le Baluchistan, l'Indus inférieur, l'Indus supérieur. Dans les deux premiers, les dépôts éocènes et oligocènes affleurent bien et leur limite est marquée par les Grands Foraminifères et les Foraminifères planctoniques.