BIOSTRATIGRAPHY OF THE CRETACEOUS/ PALEOGENE BOUNDARY IN DOKAN AREA, SULAIMANIYAH, KURDISTAN REGION, NE IRAQ

Abstract

The studied area is located within the High Folded Zone in Dokan area, northeastern Iraq. The Cretaceous/ Paleogene boundary consists of flysch clastic beds of Tanjero and Kolosh formations, interbedded with marl. The study is achieved on the outcrops of the uppermost part of the Late Cretaceous successions (upper part of Tanjero Formation) and the Early Paleogene (lowermost part of Kolosh Formation). Based on identified planktonic foraminiferal assemblages, five biozones were recorded from the upper part of the Tanjero Formation, these zones are from bottom to top: Pseudotextularia intermedia Interval Zone (CF5), Racemiguembelina fructicosa Interval Zone (CF4), Pseudoguembelina hariaensis Interval Zone (CF3), Pseudoguembelina palpebra Interval Zone (CF2), Plummerita hantkeninoides Total Range Zone (CF1) and two biozones were recorded from the lower part of Kolosh Formation, which are: (P1a) Parvularugoglobigerina eugubina – Subbotina triloculinoides Interval Zone and (P1b) Subbotina triloculinoides – Globanomalina compressa/ Praemurica inconstans Interval Zone. The result of the present study (in contrast to previous studies) shows that the Early Danian is found for the first time in the sediments of the Kolosh Formation. It is possible that the other two zones: P0 (Guembelitria cretacea Zone), and Pα (Parvularugoglobigerina eugubina Zone) were not recorded completely or continuously in the studied area. The biostratigraphic correlations; based on planktonic foraminiferal zonations showed a comparison between the biostratigraphic zones, which were established in this study with other equivalents of the commonly used planktonic zonal scheme around the Cretaceous/ Paleogene boundary, in and outside Iraq.