Biostratigraphy and Paleoecology Study of the Coniacain, Santonian and Campanian Sediments by Using the Calcareous Nannofossils in the Southern Palmyridian Chain, Syria

Abstract

In the Southern Palmyriadian Chain, the sediments of the Coniacian- Santonian and Campanian are represented by Sawwn AL-Ramah (Coniacian – Early Campanian) and Al-Sawwneh (topmost part of the Early Campanian – Late Campanian) Formations. These sediments are represented by carbonate and clay facies with flint bands and phosphatic strata. To achieve the present study, three surface geological sections (Jabal Sawwanahet Al-Mahesa – Jabal El-Bardeh and Jabal Al-Roaq) were studied in the Southern Palmyridian Chain and collected about 114 samples. Based on the detailed study of the content of samples from calcareous nanofossils, the Coniacian- Santonian and Campanian are were divided into an eleven biozones, and these biozones were correlated with equivalent planktic foraminiferal biozones. The paleoecological study showed that the diversity in the numbers of the nanofossil increases from Coniacian into ending of Campanian with some changing in their numbers during that period which reflected changes in the sedimentary basin. During deposition of the lower part of Al-Sawwneh Formation, in the Palmyridean, especially the southern part, was characterized by phosphate sedimentation, which was reflected in decreasing diversity of calcareous nanofossils, at the border of the Sawwn AL-Ramah and Al-Sawwneh Formations, i.e. with the boundary between Aspidolithus parcus CC 18 and Calculites ovalis CC 19 Zones. The study also showed the dominance of warm surface waters in general during Coniacian, Santonian and Campanian, with some minor frequencies and fluctuations during that period. In addition, the relative abundance of some calcareous nanofossils which have paleoecological importance has been studied.