Palaeoenvironmental Significance of Pithonellid Calcitarchs in SE Anatolia: a Discussion on the Use of the Term ‘Calcispheres

Date

2023-09-27

Author

Yılmaz, İsmail Ömer
Mülayim, Oğuz
Ferré, Bruno

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‘Pithonellid calcitarchs” (middle? Cenomanian) arefound in the organic-rich limestones of the DerdereFormation at SE Türkiye in the northern ArabianPlatform. Unfortunately, little is known about thepithonellid calcitarchs in the Cretaceous strata ofTürkiye. The diversity or occurrence of “pithonellidcalcitarchs’ is extremely low in the study area.Three morphogroups of “pithonellid calcitarchs’ aredistinguished in the study. In the literature, Pithonellasphaerica (Kaufmann, 1865) and P. ovalis (Kaufmann,1865), both dominant in the pithonellid assemblages, andBonetocardiella conoidea (Bonet, 1956), less abundant,are mentioned. The marked increase in pithonellids maybe related to an early transgressive phase due to sealevelchanges during the Cretaceous time, particularlyevident in the Cenomanian (Upper Cretaceous). Theyrepresent a potentially useful correlative biomarkerhorizon in the successions of SE Türkiye. ‘Pithonellidcalcitarchs’ have been interpreted as indicators ofincreased nutrient input and discussed in terms ofpaleoecology/paleoenvironment and their associationwith roveacrinid crinoids. In the base of the DerdereFormation, a carbonate succession deposited undereutrophic conditions, there is a positive relationshipbetween “pithonellid calcitarchs” and nutrient input, asindicated by the low diversity or abundance of benthicand planktonic foraminifera. Platform drowning orpossibly a mid–Cenomanian event (MCE1) and ananoxic bottom environment could be related to theabundance peak of “pithonellid calcitarchs’. In addition,the terminology of calcisphere is also discussed inthis study. Nowadays, the term calcispheres is usedinconsistently. To eliminate this confusion, the term“pithonellid calcitarchs” is proposed to be used in bothglobal and regional studies.

Subject Keywords

pithonellid calcitarcha, calcispheres

URI

https://hdl.handle.net/11511/107615

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Department of Geological Engineering, Conference / Seminar