Architecture and facies differentiation within a Middle Miocene carbonate platform, Ermenek, Mut Basin, southern Turkey

Abstract

In south-central Turkey, a carbonate platform system of early middle Miocene age is exposed in three-dimensional outcrops displaying a rich variety of carbonate facies associated with exceptionally well-preserved depositional geometries. This paper presents a detailed reconstruction of the geometries and facies organization across the prograding margin of one intra-platform carbonate bank that grew during the Langhian on the Ermenek Platform. The total thickness of the margin is approximately 250 m, and it has prograded over a distance of 1.2 km. The geometrical pattern shows an alternation between sigmoid, sigmoid-oblique, and oblique accretionary units at different scales.Based on the facies distribution and the geometrical framework two large-scale depositional sequences and eight medium-scale depositional sequences were defined. The general evolution from a low-angle shelf geometry to a prograding flat-topped platform was associated with an evolution from oligophotic-dominated carbonate producers, such as large benthic foraminifera, molluscs, echinoderms, red algae and bryozoans at the base, to mesophotic and euphotic carbonate producer organisms, such as corals, red algae and porcellaneous small benthic foraminifera at the top. The eight medium cycles were defined primarily using the depositional geometries, since facies changes were observed only locally within these cycles. Several mechanisms influenced the stratigraphic architecture of this margin: (1) eustatic sea-level controlled the overall transgressive-regressive Langhian sequence, and two superposed large-scale sequences. Medium cycles were probably also influenced by higher frequency sea-level fluctuations; (b) climate change probably influenced the overall evolution of the faunal assemblage; and (c) antecedent topography determined the overall architecture of a shelf bordering a deeper basin.

Middle-Upper Miocene paleogeography of southern Turkey: insights from stratigraphy and calcareous nannofossil biochronology of the Olukpınar and Başyayla sections (Mut-Ermenek Basin)

“…The Miocene deeper marine deposits of the MutErmenek Basin (Köselerli Formation) were dated upper Burdigalian-Serravallian by using ostracods, planktonic foraminifera, and calcareous nannofossils (Tanar & Gökçen 1990;Atabey et al 2000). More recently, referring to the calcareous nannofossil biostratigraphy of Martini and Müller (1986), Bassant et al (2005) identified the upper part of the marine succession on the east side of the Mut Basin to be part of the NN5 biozone, whereas Janson et al (2010) identified in the uppermost strata of the Ermenek platform calcareous nannofossil assemblages of the NN6 biozone, confirming a Serravallian age for the topmost part of the Miocene marine deposits in the MutErmenek Basin.…”

“…In the Ermenek area, above a subtropical flat platform of late Burdigalian age (NN4), a platform-basin system developed during the Langhian (Janson et al 2010). At that time, a composite platform system developed to the NE of the town of Ermenek, including an aggradational barrier at the platform edge and several platform-banks prograding into intraplatform depression deposits.…”

“…At that time, a composite platform system developed to the NE of the town of Ermenek, including an aggradational barrier at the platform edge and several platform-banks prograding into intraplatform depression deposits. In this paleogeographic framework, foreslope and basin deposits were deposited SW of the Langhian aggradational barrier that was developing in the vicinity of the present position of the town of Ermenek (Janson et al 2010).…”

“…Olukpınar section Başyayla section 1999; Bassant et al 2005;Janson et al 2010;Pomar et al 2012). Less attention was given to the deeper depositional environment at the slope-to-basin transition (Köselerli Formation), which in both the published maps (e.g., Gedik et al 1979;Şenel 2002;Ulu 2002) and in the derived paleogeographical schemes (e.g., Bassant et al 2005;Janson et al 2010;Pomar et al 2012) appears to be underestimated in terms of extent.…”

“…Less attention was given to the deeper depositional environment at the slope-to-basin transition (Köselerli Formation), which in both the published maps (e.g., Gedik et al 1979;Şenel 2002;Ulu 2002) and in the derived paleogeographical schemes (e.g., Bassant et al 2005;Janson et al 2010;Pomar et al 2012) appears to be underestimated in terms of extent. To the south and to the west of the town of Ermenek, in the Olukpınar and Başyayla areas, deeper marine marls (Köselerli Formation) extensively crop out, challenging the extent of the Miocene carbonate platform in those areas.…”