Iraqi National Journal of Earth Sciences

Abstract

Recently a new lithology is found at the middle part of Tanjero Formation (Maastrichtian) and consists of a bluish marl succession about 100m thick in Sulaimayia area. This succession is lithologically similar to Shiranish Formation and has nearly same color and stacking pattern which didn’t described in the original description in the type section of Tanjero Formation. Geographically
it can be seen in Piramagroon and Sharazoor plains, Chaqchaq valley
(to the northwest of Sulaimani City) and Dokan area. The biostratigraphy of this succession indicates Early Maastrichtian to Early Late Maastrichtian which includes four interval zones of:
Racemiguembelina fructicosa Interval Zone (CF4) (Early late Maastrichtian), Pseudotextularia intermedia Interval Zone (CF5) (Early Maastrichtian)
Contusotruncana contusa Interval Zone (CF6) (Early Maastrichtian)
Gansserina gansseri Interval Zone (CF7) (Early Maastrichtian)
As concerned to the affinity of this succession two possibilities can be assigned:
1-Middle part of Tanjero Formation.
2-lentils of Shiranish Formation inside Tanjero Formation.
This study prefers the first assignation as the foraminiferal assemblages show that the marly succession is not belonging to Shiranish which has, in the studied area, the age of Campanian. Another reason for this assignation is that the environment and sequence stratigraphy, tectonics of Tanjero Formation is more understandable than the first assignation (If it is included in the Shiranish Formation). The record of this new lithology and submergence of the type section of the formation under the water of Darbandikhan (dam) impose selection of a new type section or a supplementary type section for the formation either in Dokan or Chwarta areas where there are representatives of the new lithology inside the Tanjero Formation and the sections are well exposed.