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Pre- and post-deposition stages of Messinian evaporites based on facies interpretations in the Hatay Graben and its sub-basins, southeastern Turkey

2019    Tekin, Erdogan; Varol, Baki; Herece, Erdal; Buyukmeric, Yesim; Akca, Nihal; Sozeri, Koray

The Hatay Graben (HG), divided into two sub-basins, Hatay-Samandag (HS) and Altinozu-Babatorun (AB) consists of very typical deposits of the pre- and post-evaporite stages spaning to the latest Tortonian/early Messinian to Zanclean time. In the graben center (HG/HS), pre-evaporite stage starts with an environmental shallowing episode following deeper sea turbidites (FN1) deposited during early-middle Tortonian time. The basinal shallowing episode trigerred by the late Tortonian tectonics, had involved a siliciclastic-dominated accumulation of coastal sands, small-size fan/Gilberttype deltas, braided rivers, and f uvial incices andilleianopsis-bearing mudstone (L1), and these kinds of deposition collectivelly reflec a deposition under the estuarine-brackish (oligohaline) conditions (FN2-4). However, in some places (e.g., Hancagiz), some pteripod-bearing sandy mudstones and grey mudstones are present within the shallow marine-estuarine/brackish (oligohaline) associations, indicating that relatively deeper environmental conditions, that were temporaly developed within the pre-evaporite succession. The pre-evaporitic environmental f uctutations from brackish to marine was ended by an evaporite-precipitated stage (Vakif 1 Formation), where the gypsum dominated evaporites (FV1) were deposited in the marginal basins as upper gypsum. They are fault-controlled isolated/mini basins represented by bedded-selenitic gypsum, mudstone-alternating laminated gysum and locally slumped gypsum. The evaporitic stage was terminated by gyrogonites-bearing mudstone (FV2), which is marked by L2 assigned to the establisment of the second stage estuarine/brackish (oligohaline) environment. In Kusalani district, some sandy mudstones that are time equivalent of the FV2, composed of a few Paratethyan mollusk species such as melanopsids, dreissenids and lymnocardiids that can be tentatively considered as Lago-Mare type deposits formed after the Messinian evaporite stage. Subsequently, Zanclean marine ref ooding was distinguished by different kinds of sediments (e.g., Samandag Fm), but it is generally onset of the coarse-grained delta, fan/Gilbert-types and followed upward by the wave-tidal-storm-dominated shallow water silisiciclastics (FS1-8), suggesting the graben/basin margin was subjected to a catastrophic or fast marine ref ooding after the MES. In the Graben center, there has not been any clear boundary between the Messinian/Zanclean succesions. In Hancagiz section, gypsum blocks (FN 5) beneath Zanclean deposits may be evidence of Messinian Erosion Surface (IVIES); however, there is no notable time gap between the Miocene and Pliocene units that can be attributed to conformity or low-grade disconformity. This sitution is contrasting to the graben-margin setting, represented by erosional unconformity, where Zanclean deposits sit directly on the Tortonian turbidite unit, lacking upper Tortonian shallow water siliciclastics and Messinian evaporite. This resulted in a late Tortonian tectonics phase (sensu lato: Tortonian erosion surface "TES"). At the same time this evolved a new basin, Altmorti-Babatorun (AB) which is differentiated from the neighboring subbasins by means of its own depositional character represented by alternations of Zanclean shallow water sandstones and pelagic limestone beds or pelagic sills and dykes within the sandy matrix.