Sedimentology of the Baluti Formation (Late Triassic) in the Warte area, northeastern Iraqi Kurdistan region

Abstract

A detailed sedimentological investigation of the Baluti Formation (Late Triassic) in the Warte section, Imbricated Zone, northeastern Kurdistan region of Iraq has been undertaken for the first time. The formation is comprised of 34 m of dolomitic limestone, marly limestone, and marly dolomitic limestone which is partially brecciated and all interbedded with shale and several beds of marl in the lower part. Based on the field observations and petrographic inspections, four different lithostratigraphic units were identified in the studied section, which are, in ascending order: marly dolomitic limestone interbedded with marl and shale unit, brecciated marly dolomitic limestone interbedded with shale unit, fractured marly dolomitic limestone unit, and marly limestone interbedded with shale unit. The petrographic study of 19 thin sections of Baluti carbonates shows that the majority are composed of carbonate mud (micrite). The skeletal grains include ostracods, calcispheres, benthonic foraminifera, gastropods, bivalves, clasts, and bioclasts. While non‐skeletal grains include peloids, intraclasts, and extraclasts. The results of X‐ray diffraction (XRD) of five samples and scanning electron microscope (SEM) of three samples of the shale and marl of the studied formation show that the main clay mineral is illite, whereas non‐clay mineral is dolomite. The carbonate rocks of the Baluti Formation were subjected to different diagenetic processes, such as micritization, dolomitization, cementation, compaction, solution, pyritization, neomorphism, and fracturing. Three main microfacies were identified in the Baluti carbonates and according to their environmental interpretation, they are grouped into one basic type of facies association—subtidal‐semi restricted lagoon. Field observation, petrographic, microfacies, and textural analysis indicate that the Baluti Formation in the Warte section was deposited in a shallow marine, subtidal (lagoon) environment with semi‐restricted conditions.

Depositional Setting of Khurmala Formation (Paleocene-Early Eocene) in Nerwa section, Berat Anticline, Kurdistan Region, Northern Iraq

“…The dasycladacean green algae which is common in the middle part of the studied section indicates shallow water environment with less than 10m depth (Aguirre et al, 2000). The coexistence of gastropods and ostracods with benthonic foraminifera indicate lagoonal shallow marine environment (Asaad et al, 2021). Intraclast lime wackestone-packstone is occur in the backshoal/lagoonal setting (Asaad and Omer, 2020).The cortoid lime grainstone which form skeletal and non-skeletal grains with dark thin micritic envelope are formed in the high-energy area of backreef setting (Flügel, 2010).Intraformational conglomerate bearing intraclasts lime packstone supposed to be accumulated in the shallowest part of the basin below storm wave-base (Enos, 1983) and may be created from reworking of subtidal sediments by storms (Dravis, 1979).The extensive bioturbation of the beds at the middle and lower part of the studied section may interpret as the fine, organic-rich sediment in lagoons furnishes an excellent feeding places for organisms that can tolerate the reduced/enhanced salinity conditions and producing bioturbation (Nichols, 2009).…”

Unlocking the hydrocarbon potential: Formation evaluation and petrophysical properties of the upper Triassic Kurra Chine Formation in Sarta Oil Field, Kurdistan Region, Northern Iraq

“…1 ), located at coordinates 430 58′ 20.399″ E 360 31′ 39.228″ N. The Kurra Chine Formation underlies the Baluti Formation and overlies the Galikhana Formation. The lower contact of the Kurra Chine Formation is unconformable, while its upper contact is conformable [ 26 ].

Fig.

…”

Stratigraphic Correlation and Source Rock Characteristics of the Baluti Formation From Selected Wells in the Zagros Fold Belt, Kurdistan Region, Northern Iraq

“…The presence of oilprone kerogen was interpreted in the anoxic proximal shelf facies (Type II) and distal basin shales (Type II > I). Asaad et al (2021) provided a sedimentological evaluation of the Baluti in the Warte outcrop (location in Fig. 1), where the formation consists of 36 m of marly and dolomitic limestones with interbedded shales, interpreted to reflect shallow-marine, semi-restricted, lagoonal settings.…”