Organic facies and paleo-depositional environments of the Aptian-Albian Kazhdumi source rock in the Zagros basin of Iran

The Kazhdumi Formation of SW Iran is considered as one of the main petroleum source rocks of the Cretaceous petroleum system. Despite an overwhelming body of research on the gross organic geochemistry of this for-mation, little is known about its organic facies and paleo-depositional environments. In this research, organic geochemical and sequence stratigraphic principals was used to throw light on the mechanisms controlling organic enrichment in the Kazhdumi Formation. Petrographic examinations revealed that the Kazhdumi organic -rich facies was deposited during times of relative sea-level rise and the related euxinia. In addition, the organic matter preserved in the Kazhdumi Formation varied strongly in type from SW to NE of the paleo-depositional settings. In contrast, organic-lean facies were accommodated within the Kazhdumi intra-shelf basin during pe-riods of sea-level fall. These results have practical implications for future geochemical studies including oil -source correlations and petroleum system analysis.

Automated summary

This research uses organic geochemical and sequence stratigraphic principles to reveal the mechanisms controlling organic enrichment in the Kazhdumi Formation. The petroleum source rocks are deposited during times of relative sea-level rise and euxinic conditions, and the organic matter types vary greatly in the paleo-depositional environments. These findings have practical implications for future geochemical studies and petroleum system analysis.