Microencrusters from the Upper Jurassic–Lower Cretaceous İnaltı Formation (Central Pontides, Turkey): remarks on the development of reefal/peri-reefal facies

A detailed taxonomical study was carried out for the identification of encrusting micro- organisms. Among these microencrusters, Perturbatacrusta leini, Iberopora bodeuri, Calcistella jachenhausenensis, and Pseudorothpletzella schmidi have been taxonomically revealed for the first time in Turkey. Within the biostratigraphic frame of the I. nalti Formation consisting of Mesoendothyra izjumiana zone ( Kimmeridgian), Calcistella jachenhausenensis zone ( Lower Tithonian- Upper Tithonian) and Protopeneroplis ultragranulata zone ( Upper Tithonian- Berriasian), carbonate sedimentation occurred in five depositional environments comprising slope, fore- reef, reef, back- reef and lagoonal environments. The majority of the reefal deposits of the I. nalti carbonates can be classified as coral- microbial- microencruster boundstones, which frequently occur in association with back- reef and fore- reef deposits within the Kimmeridgian- Berriasian interval. A shallowing and a subsequent deepening of water depth in the Berriasian have been revealed by the examination of stacking patterns and vertical evolution of the microfacies. Based on the observed microfacies and general features of micro- encrusting organisms, it is concluded that I. nalti carbonates share many similarities with the reefal carbonate deposits of Intra- Tethyan domain in terms of microfacies types and microencruster content

Age, microfacies and depositional environment of the Middle to Late Paleocene shallow-marine carbonates in the Sirt Basin of Libya (Upper Sabil Formation) : "Are Intisar domal structures pinnacle reefs?"

In the central-eastern Sirt Basin, enigmatic Intisar domal structures host significant hydrocarbon accumulations. These structures have been commonly interpreted as pinnacle reefs/bioherms occurring in the open-marine basinal environment. Generally, pinnacle reefs/bioherms are mainly characterized by in situ carbonates. The current study challenges the Intisar pinnacle reef/bioherm model by examining one of the domal structures in terms of biostratigraphy, microfacies and depositional environment. These structures were dated using larger benthic foraminifera, which yielded a Middle to Late Paleocene age (Selandian–Early Thanetian). Thirteen microfacies types representing different carbonate ramp environments ranging from outer ramp to inner ramp, were defined. Outer ramp deposits have been observed adjacent to the domal structure, represented mainly by wackestone with small benthic and planktonic foraminifera. The outer ramp deposits are most likely isochronous to the domal structures. The lower part of the domal structures is composed mainly of foraminiferal–algal–echinodermal packstones. The upper part is characterized by foraminiferal–algal–echinodermal packstones with intercalated microbialite–coral boundstones. The euphotic inner ramp deposits are preserved on the crest of the domal structure, consisting of grainstone and packstone rich in Glomalveolina. As a result of this study, the Intisar domal structures are seen as erosional relics of a carbonate ramp and no evidence for pinnacle reef/bioherm model was found