Depositional Pattern in the Lower to Middle Miocene Jal Az-Zor Formation from Subsurface of North Kuwait

Abstract The Jal Az-Zor Formation sediments in north Kuwait were deposited on the southwestern margin of the Zagros foreland basin. They are organized into 30–60 ft (9–18 m)–thick repeated fining upward high-frequency sequences. The sequences generally consist of conglomerate and pebbly sandstone, coarse- to fine-grained sandstone, muddy sandstone, siltstone, and mudstone lithofacies, ideally stacked in ascending order. In upper part of the sequences, burrowing and fossiliferous horizons are developed, which reflect marine influence during their deposition. Each sequence is interpreted to have been developed by infilling of an incised valley during base-level rise. Such valleys had been cut down into the underlying strata during base-level drop. The formation was sourced from west–southwest from the Arabian Massif. From the biostratigraphic analysis, late Burdigalian–early Langhian age is assigned to these sediments in north Kuwait. The uppermost mudstone interval (Cap Shale) contains Miogypsina remains considered early Langhian in age. Based on this, we suggest possible correlation of this zone to the Arabian Plate MFS Ng30. Considering the age limits for the studied section, there is another possibility of MFS Ng20 within the basal mudstone horizon.