The Timezgadiouine Formation, sometimes spelled as the Timesgadiouine Formation, is a Triassic geological formation in the Argana Basin of Morocco. It is a succession of red bed sediments spanning from the Olenekian to at least the Carnian, encompassing members T3 to T5 of the Argana Group. It is preceded by the Permian Ikakern Formation and succeeded by the Late Triassic Bigoudine Formation.

The formation is split into three members. The Early Triassic Tanamert Member (T3) is a relatively thin band of volcaniclastic conglomerate, likely emplaced by braided rivers. The Middle Triassic Aglegal Member (T4) is a thick sequence of muddy and silty cyclical deposits interspersed with wide sandstone lenses. It would have been deposited within a semi-arid playa, mudflat, and ephemeral lake system cut by meandering streams or sheet floods. The late Carnian (or possibly early Norian) Irohalene Member (T5) comprises bioturbated mudstone complemented by an increasing abundance of sandstone beds. This final member is likely equivalent to a more humid period with large permanent lakes or wide meandering rivers. The formation as a whole was deposited in a wide and tectonically stable basin, in contrast to the narrow rift basins which developed elsewhere along the present-day Central Atlantic margin during the Triassic.

The Timezgadiouine Formation is quite fossiliferous; footprints and other trace fossils are found throughout the entire strata, while skeletal material is common in the Irohalene Member. The fossil content of the Irohalene Member includes phytosaurs, aetosaurs, metoposauroid amphibians, stahleckeriid dicynodonts, early dinosauromorphs, and other typical Carnian to early Norian animals. Several animals are distinctive, such as the large herbivorous archosauromorph Azendohsaurus laaroussii, and massive three-toed footprints (Eubrontes sp.) emplaced by a Tyrannosaurus-sized archosaur.

The Timezgadiouine Formation is part of the Argana Group, a long succession of red bed sediments deposited in the Argana Basin. The Argana Basin is a northeast-to-southwest oriented valley extending for about 85 km (53 mi) in the western part of the High Atlas. The Argana Group, sometimes known as the Argana Formation, includes most of the geological layers within the basin, separated into eight members, often labelled T1 to T8. Argana Group sediments generally have a shallow dip towards the west or northwest, though faulting can strongly alter this dip in some areas.

The Timezgadiouine Formation corresponds to members T3 (the Tanamert Member) T4 (the Aglegal Member) and T5 (the Irohalene member) of the Argana Group. The base of the Timezgadiouine Formation is separated from the underlying Permian-age Ikakern Formation (members T1-T2) via an angular unconformity. This unconformity may be a result of tectonic instability and erosion related to crustal thinning or post-orogenic collapse of the Variscan mountains. The end of the Timezgadiouine Formation appears to smoothly transition to the succeeding Late Triassic Bigoudine Formation (members T6-T8).

The Argana Basin is divided by a series of steep faults striking in an east-to-west direction. Early studies suggested that normal faults developed during several phases of north–south rifting in the Late Triassic, splitting up the basin into a series of uneven fault blocks. This was partially driven by the assumption that the entire Timezgadiouine Formation was Late Triassic in age, equivalent to rift basins in eastern North America and elsewhere in Morocco. These neighboring rift basins are typically characterized as half-grabens, associated with asymmetrical faulting and the breakup of Pangea.

However, later work argued that the Timezgadiouine Formation was deposited in a broad and tectonically stable basin, with subsidence controlled by gradual sediment loading throughout the Triassic, rather than local faulting or rifting in the Late Triassic specifically. The major east–west faults only affect Permian sediments, so they were likely emplaced during the unconformity between the Ikakern and Timezgadiouine formations. The Timezgadiouine Formation is affected by a few northeast–southwest striking faults, but they appear to have been emplaced after deposition. These later faults were likely a result of tectonic activity related to the Central Atlantic Magmatic Province. Both the east–west and northeast–southwest faults have been reactivated by recent mountain building. Once faulting has been accounted for, the depth of the Timezgadiouine Formation can be reconstructed as fairly uniform and symmetrical during its time of deposition.

The Tanamert (or Tanameurt) Member, T3, is a quite thin section, only about 10 meters (33 feet) thick. This member consists of volcaniclastic conglomerate arranged into shallow, indistinct cross-beds. Rhyolite is the most common clast type, with smaller proportions of quartz, limestone, phyllite, and fine-grained sedimentary rocks. This conglomerate would have been deposited by braided rivers eroding older volcanic and sedimentary rocks from the Variscan orogeny. The only fossils known from the Tanamert Member are tetrapod footprints consistent with an Early Triassic (Olenekian?) age.