Location of the River Euphrates in the Late Miocene; Dating of Terrace Gravel at Shireen, Syria T

Location of the River Euphrates in the Late Miocene; dating of terrace gravel at Shireen, Syria T. Demir, M. Pringle, S. Yurtmen, R. Westaway, D. Bridgland, A. Beck, K. Challis, G. Rowbotham To cite this version: T. Demir, M. Pringle, S. Yurtmen, R. Westaway, D. Bridgland, et al.. Location of the River Euphrates in the Late Miocene; dating of terrace gravel at Shireen, Syria. eEarth Discussions, 2006, 1 (3), pp.167- 188. hal-00298248 HAL Id: hal-00298248 https://hal.archives-ouvertes.fr/hal-00298248 Submitted on 12 Dec 2006 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. eEarth Discuss., 1, 167–188, 2006 eEarth www.electronic-earth-discuss.net/1/167/2006/ Discussions eED © Author(s) 2006. This work is licensed 1, 167–188, 2006 under a Creative Commons License. eEarth Discussions is the access reviewed discussion forum of eEarth Late Miocene River Euphrates Location of the River Euphrates in the T. Demir et al. Late Miocene; dating of terrace gravel at Shireen, Syria Title Page Abstract Introduction T. Demir1, M. Pringle2, S. Yurtmen3, R. Westaway4,5, D. Bridgland6, A. Beck7, Conclusions References K. Challis8, and G. Rowbotham9 Tables Figures 1Department of Geography, Harran University, 63300 S¸anlıurfa, Turkey 2Isotope Geosciences Laboratory, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA ◭ ◮ 3 Department of Geology, Çukurova University, 01330 Adana, Turkey ◭ ◮ 4Faculty of Mathematics and Computing, The Open University, Eldon House, Gosforth, Newcastle-upon-Tyne NE3 3PW, UK Back Close 5School of Civil Engineering and Geosciences, Newcastle University, Newcastle-upon-Tyne NE1 7RU, UK Full Screen / Esc 6Department of Geography, Durham University, Durham DH1 3LE, UK 7 School of Computing, University of Leeds, Leeds LS2 9JT, UK Printer-friendly Version 8Birmingham Archaeology, University of Birmingham, Birmingham B15 2TT, UK 9School of Earth Sciences and Geography, Keele University, Staffordshire ST5 5BG, UK Interactive Discussion Received: 31 August 2006 – Accepted: 28 November 2006 – Published: 12 December 2006 EGU Correspondence to: R. Westaway ([email protected]) 167 Abstract eED We report gravel of the River Euphrates, capped by basalt that is Ar-Ar dated to ∼9 Ma, at Shireen in northern Syria. This gravel, preserved by the erosion-resistant basalt, 1, 167–188, 2006 allows us for the first time to reconstruct the history of this major river during the 5 Late Miocene. In response to progressive regional surface uplift, the Euphrates ex- Late Miocene River tended SE by ∼800 km between the early Middle Miocene, when the coast was near Euphrates Kahramanmaras¸in southern Turkey, and the Pliocene, when it lay in western Iraq, east of the Arabian Platform uplands. T. Demir et al. 1 Introduction Title Page 10 Due to their action of transporting the products of erosion, and thus facilitating the Abstract Introduction isostatic rebound that has contributed to the systematic growth of topography in the Conclusions References Late Cenozoic, large rivers have had a significant role in long-timescale global change. However, relatively few pre-Pleistocene upland localities are known with demonstrable Tables Figures evidence that a major river was present. Examples include: Australian rivers with 15 records back to the Palaeogene (Stevenson and Brown, 1989; Nott, 1992); rivers in ◭ ◮ eastern Europe that are documented back to the Late Miocene (e.g., Matoshko et al., 2004); and the Colorado in the SW USA that has been reconstructed back to the Middle ◭ ◮ Miocene (e.g., McKee and McKee, 1972; Lucchitta, 1979). However, in most other Back Close regions one can only infer roughly where rivers once flowed from the provenance of 20 sediment reaching lowland or offshore depocentres, with no direct supporting evidence. Full Screen / Esc With a length of ∼2800 km, the Euphrates is the longest river in SW Asia. From its source in NE Turkey it flows initially west and south, then SE across the Arabian Printer-friendly Version Platform in Syria and Iraq (Fig. 1) to the Persian Gulf. The Arabian Platform was a marine depocentre until the Middle-Late Miocene (e.g., Lovelock, 1984). Fluvial sand and Interactive Discussion 25 gravel are widespread near its northern margin around Kahramanmaras¸(e.g., Derman, 1999; Fig. 1), dated to the early Middle Miocene (Langhian; ∼16 Ma) using interbedded EGU 168 basalt (Arger et al., 2000) and shallow marine sediments (Karig and Kozlu, 1990). The diverse clast content, including metamorphic lithologies not found in situ in the Ara- eED bian Platform, indicates that a major river, draining at least part of the modern upper 1, 167–188, 2006 Euphrates catchment, reached the sea here at this time (1, Fig. 1). 5 A staircase of Late Cenozoic fluvial terraces records the evolution of the Euphrates along its present course, indicating net incision by ∼110 m at Birecik (Sanlaville, 2004; Late Miocene River Demir et al., 2004), near the Turkey-Syria border, and by ∼70 m at Khan al-Baghdadi Euphrates (Tyracek,´ 1987) at the eastern margin of the Arabian Platform uplands (Fig. 1). Across eastern Syria (around and below Raqqa, where much less incision has occurred since T. Demir et al. 10 both the Late Pliocene and the late Early Pleistocene; Westaway et al., 2005a) and western Iraq, the modern Euphrates valley is flanked by extensive older stacked fluvial Title Page gravels (attributed to the ancestral Euphrates from their diverse clast content), which indicate the course of the river in the Early Pliocene (e.g., Besançon and Geyer, 2003; Abstract Introduction 3, Fig. 1). However, its modern course farther upstream (4, Fig. 1) is no older than Conclusions References 15 ∼2 Ma, from the ratio of the offset of its gorge through the East Anatolian fault zone (EAFZ) to the total slip on this fault zone (e.g., Westaway, 2004). Tables Figures There is thus a significant information gap, spanning the Late Miocene and more, for which the geometry of the Euphrates has been obscure. One view (Arger et al., 2000) ◭ ◮ has been that it terminated in a large palaeo-lake north of the modern Ataturk¨ Dam 20 (Fig. 1). Another possibility, suggested by the modern drainage geometry (Fig. 1), is ◭ ◮ that it flowed SW into the Mediterranean Sea, along either the Karasu Valley or the line Back Close of the modern River Ceyhan (Fig. 1), before being diverted eastward, possibly due to the initiation at ∼4 Ma of the modern geometry of the northern Dead Sea Fault Zone Full Screen / Esc (DSFZ), which is strongly transpressive, with left-lateral slip accompanying localised 25 surface uplift (e.g., Westaway, 2004; Seyrek et al., 2006). The most recent estimate Printer-friendly Version of the initiation of this modern geometry of strike-slip faulting is 3.73±0.05 Ma (West- away et al., 2006a), based on evidence from the SW part of the EAFZ to the east Interactive Discussion of Kahramanmaras¸(Fig. 1). Previous work on reconstructing Plio-Pleistocene fluvial systems in Syria (Bridgland et al., 2003) and Turkey (Westaway et al., 2004, 2005b, EGU 169 2006b) has required the documentation of fragmentary sedimentary sections, often with dimensions of only a few square metres. We have identified one such site, at eED Shireen in northern Syria (Fig. 1), where fluvial gravel – attributed to the Euphrates 1, 167–188, 2006 and preserved due to capping by basalt – has been dated to ∼9 Ma by Ar-Ar dating of 5 the basalt, thus demonstrating the location of this major river in the Late Miocene. Late Miocene River Euphrates 2 Regional geology and tectonics T. Demir et al. Most outcrop in this part of northern Syria (Fig. 2) consists of Cenozoic marine car- bonates. Late Eocene chalky and clayey limestone is overlain by ∼70 m of Oligocene hard crystalline limestone and dolomitic limestone (Ponikarov et al., 1967). During de- Title Page 10 position of these sediments the northern Arabian Platform formed a seaway linking the Mediterranean Sea and Indian Ocean. Abstract Introduction Unconformable Miocene marine limestone was assigned by Ponikarov et al. (1967) Conclusions References to the Jeribe Formation. This stratigraphic unit has regional significance, extending from Syria to Iran, dated to the early Middle Miocene (Langhian; James and Wynd, Tables Figures 15 1965; Alsharhan and Nairn, 1995). Diverse carbonate facies are evident, suggest- ing rapidly-changing shallow-marine conditions. This limestone is overlain by deposits ◭ ◮ assigned by Ponikarov et al. (1967) to the Lower Fars Formation, another regionally ◭ ◮ significant unit, of late Middle Miocene (Burdigalian) age (James and Wynd, 1965; Al- sharhan and Nairn, 1995). Around Shireen this consists of interbedded green calcare- Back Close 20 ous clay and marl, red mudstone and white limestone with occasional gypsum layers, and is no more than a few tens of metres thick. Farther north near the Turkish bor- Full Screen / Esc der, conglomerate and cross-bedded sandstone are also assigned to this unit. These sediments indicate marginal marine conditions with input of clastic sediment from the Printer-friendly Version north. By this time a land bridge connected Arabia with Turkey (between Aleppo and Interactive Discussion 25 Kahramanmaras¸; Fig. 1), isolating the Mediterranean Sea from the Mesopotamian Basin of Syria, Iraq and Iran. EGU No younger stacked sediments are found in this area. However, east of Raqqa 170 (Fig. 1) there is extensive outcrop of the Upper Fars Formation, consisting of up to ∼250 m of clay, siltstone, fine-grained sandstone and gypsum.

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