Sedimentary Evidences for the Depositional and Environmental Changes Regarding to Regression during Mid to Late Miocene in the Neogene Adana Basin (Southern Turkey)

Abstract

In this study we investigate sedimentary and stratigraphic characteristics of the Mid to Late Miocene deposits to better understanding of the Tertiary evolution of the Adana Basin (Southern Turkey). For this purpose, detailed mapping, sedimentary survey and interpretations were made considering the stratigraphic relations in the Middle-Late Miocene units in the region. The depositional evolution of the Adana Basin starts during the Early Miocene as a foreland basin within the Çukurova region. An extensive marine transgression during the Early Miocene commenced the filling of the basin. The pre-Miocene deposition area was a large platform with an adjacent depression area. This depositional environment widely controlled the Miocene sedimentation after the Aquitanian-Burdigalian transgression. The Miocene sequences in the Adana Basin were deposited due to the northward transgression. The northerly sourced deltaic and littoral-brackish Kaplankaya Formation and a slightly deeper reefal Karaisalı Formation were deposited in the areas close to the shore. Documented by shallow to deeper marine sedimentation, the marine inundation of the region occurred during Aquitanian-Burdigalian and continued into the Serravallian causing the former coastline to migrate north. Synchronously tectonic subsidence further south cause southward progressive deepening. Therefore, various facies types, ranging from deep marine turbidites to terrestrial, deposited in the basin. The northern margin of the basin was experienced normal faulting in consequence of progressive tectonic and subsidence events during this marine transgression in the Langhian-Serravallian. Mapped and interpreted within three facies types, Güvenç Formation include; i) deep marine sediments, ii) offshore sediments and iii) shallow marine sediments. Deep sea deposits were accumulated in the early stages of the Early-Middle Serravalian period in the deeper part of the basin. During the Mid-to Late Serravallian offshore sediments were deposited in the southern parts of the basin. Further south, due to the continued regression, the shallow marine sediments were deposited in the basin during the Serravalian. Related to the neotectonic period of Anatolia, the transgressive sequences deposited within the basin were tilted during Late Serravallian to Early Tortonian period. The marine regression towards the south was accompanied by tectonic re-organisation in the Early Tortonian. Consequently, regressive sequences of the Tortonian age, the Kuzgun member of Kuzgun Formation, which involve shallow marine (beach) sediments and meandering river deposits are resting on the tilted Güvenç Formation with low angle unconformity.