Biostratography and palaeoecology of the Late Cretaceous planktonic foraminifera in the Palmyride Region, Syria

Pecimotika, Gabrijela (2014) Biostratography and palaeoecology of the Late Cretaceous planktonic foraminifera in the Palmyride Region, Syria. Doctoral thesis, Faculty of Science > Department of Geology.

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Abstract

For detailed micropalaeontological investigation of planktonic foraminiferal assemblages from the Upper Turonian to Maastrichtian interval samples of deep exploration wells Al Mahr-1, Mustdaira-1, Mustadira-2 and Palmyra-1 in the Palmyride area of Syria were selected. The investigated strata are divided into three litostratigraphical units: 1) the upper part of the Judea Formation (upper Turonian–Coniacian); 2) the Soukhne Formation (Santonian–lower Campanian); and 3) the Shiranish Formation (upper Campanian– Maastrichtian). The presence of rich and highly diverse planktonic foraminiferal assemblages enabled biostratigraphical zonation of the upper Turonian to Maastrichtian deposits based on the presence of indextaxa and/or the entire microfossil assemblages. Nine biozones have been established: I) Dicarinella concavata Interval Zone; II) Dicarinella asymetrica Total-range Zone; III) Globotruncanita elevata Partialrange Zone; IV) Contusotruncana plummerae Interval Zone; V) Globotruncanita stuarti Interval Zone; VI) Globotruncana aegyptiaca Interval Zone; VII) Gansserina gansseri Interval Zone; VIII) Contusotruncana contusa–Racemiguembelina fructicosa Partial-range Zone and 9) Abathomphalus mayaroensis Interval Zone. The established biostratigraphic zonation is compared with the Tethys standard zonation. The late Turonian to early Campanian foraminiferal assemblages (biozones I–IV) are highly dominated by opportunistic taxa (r-strategists) and suggest a generally fluctuating subtropical climate and deposition in outer shelf environments. The well-preserved and highly diverse late Campanian to Maastrichtian foraminiferal assemblages (biozones V–IX) imply the presence of a well-stratified water column, tropical to subtropical climate, and deposition in outer shelf to upper bathyal environments. A decrease in the number of globotruncanids during the late Maastrichtian indicates less stratified water column and unfavourable palaeoceanographic conditions for K-selected species. Common occurrence of phosphate grains in the Soukhne Formation (Santonian–Lower Campanian) present an important indicator of specific geological and palaeoenvironmental conditions, such as oxygen deficiency, upwelling and transgression. These conditions support the interpretations of high domination of opportunistic planktonic foraminiferal taxa (heterohelicids and muricohedbergelids) in biozones II and III. This study provides insight into the nature of deposition along the northern passive margin of the Gondwana during the Late Cretaceous, while determination of the composition and diversity of foraminiferal assemblages allowed important new palaeoecological and palaeoclimatic interpretations.

Item Type: Thesis (Doctoral thesis)
Keywords: planktonic foraminifera, biostratigraphy, palaeoecology, Upper Turonian–Maastrichtian, Palmyride Region, Syria
Supervisor: Cvetko Tešović, Blanka and Premec Fućek, Vlasta
Date: 2014
Number of Pages: 150
Subjects: NATURAL SCIENCES > Geology
Divisions: Faculty of Science > Department of Geology
Depositing User: Sonja Borak
Date Deposited: 29 Apr 2014 10:26
Last Modified: 29 Apr 2014 10:27
URI: http://digre.pmf.unizg.hr/id/eprint/993

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