Naslov
Planktonic foraminiferal biostratigraphy and paleoecology of Upper Cretaceous deposits from the Palmyride Region, Syria

Autori
Pecimotika, Gabrijela ; Cvetko Tešović, Blanka ; Premec Fuček, Vlasta

Izvornik
Geologia Croatica : journal of the Croatian Geological Survey and the Croatian Geological Society (1330-030X) 67 (2014), 2; 87-110

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Planktonic foraminifera; Biostratigraphy; Phosphatic grains; Upper Turonian–Maastrichtian; Palmyride region; Syria

Sažetak
This study represents a detailed micropalaeontological investigation of the composition and diversity of planktonic foraminiferal assemblages from the upper Turonian to Maastrichtian interval of two deep exploration wells (Al Mahr-1 and Palmyra-1) in the Palmyride area of Syria. In combination with lithostratigraphic analysis, this detailed biostratigraphic study provided important new palaeoecological and palaeoclimatic interpretations and insights into the nature of deposition along the northern passive margin of Gondwana during the Late Cretaceous. The investigated strata belong to three lithostratigraphic units (from base to top): the upper part of the Judea Formation (upper Turonian–lowermost Santonian), the Soukhne Formation (Santonian–lower Campanian), and the Shiranish Formation (upper Campanian–Maastrichtian). The results represent the first detailed determination of planktonic foraminifera from the Palmyride region. The presence of rich and diverse foraminiferal associations enabled the establishment of the following nine late Turonian to Maastrichtian biostratigraphic zones, based on documented index-taxa and/or the entire microfossil assemblages: I) Biozone I ; II) Biozone II ; III) Biozone III ; IV) Contusotruncana plummerae Zone ; V) Biozone V ; VI) Globotruncanella havanensis Zone ; VII) Pseudoguembelina palpebra Zone ; VIII) Racemiguembelina fructicosa Zone ; and IX) Abathomphalus mayaroensis Zone. The late Turonian to early Campanian foraminiferal assemblages (biozones I–IV) are dominated by opportunistic taxa (r-strategists) and suggest a generally fluctuating subtropical climate and deposition an outer shelf environments. The well-preserved and highly diversified 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 globotruncanid species during the late Maastrichtian indicates a less stratified water column and unfavourable environmental conditions for K-strategists. The common occurrence of phosphate grains in the Soukhne Formation (Santonian–lower Campanian) represents an important indicator of specific geological and palaeoenvironmental conditions, such as oxygen deficiency, upwelling and transgression. These conditions support the interpretation of the domination by opportunistic planktonic foraminiferal taxa (heterohelicids and muricohedbergellids) in Biozone II.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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