Quaternary Science Reviews 222 (2019) 105895 Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev Magneto-biostratigraphic age constraints on the palaeoenvironmental evolution of the South Caspian basin during the Early-Middle Pleistocene (Kura basin, Azerbaijan) * Sergei Lazarev a, , Elisabeth L. Jorissen a, Sabrina van de Velde b, Lea Rausch c, Marius Stoica c, Frank P. Wesselingh b, Christiaan G.C. Van Baak d, Tamara A. Yanina e, Elmira Aliyeva f, Wout Krijgsman a a Paleomagnetic Laboratory «Fort Hoofddijk», Department of Earth Sciences, Utrecht University, Budapestlaan 17, 3584CD, Utrecht, the Netherlands b Naturalis Biodiversity Center, P.O. Box 9517, 2300RA, Leiden, the Netherlands c Department of Geology, Faculty of Geology and Geophysics, Bucharest University, Bǎlcescu Bd. 1, 010041, Bucharest, Romania d CASP, West Building, Madingley Rise, Madingley Road, CB3 0UD, Cambridge, United Kingdom e M.V. Lomonosov Moscow State University, Geographical Faculty, Leninskiye Gory, 119992, Moscow, Russia f Institute of Geology ANAS, H. Javid av., 29A, 1143, Baku, Azerbaijan article info abstract Article history: The sedimentary record of the Caspian Basin is an exceptional archive for the palaeoenvironmental, Received 21 January 2019 palaeoclimatic and biodiversity changes of continental Eurasia. During the Pliocene-Pleistocene, the Received in revised form Caspian Basin was mostly isolated but experienced large lake level fluctuations and short episodes of 19 August 2019 connection with the open ocean as well as the Black Sea Basin. A series of turnover events shaped a Accepted 21 August 2019 faunal record that forms the backbone of the Caspian geological time scale. The precise ages of these Available online 14 September 2019 events are still highly debated, mostly due to the lack of well-dated sections. Here, we provide an in- tegrated magneto-biostratigraphic age model for two sections from the Kura Basin e Goychay and Keywords: Early e Middle Pleistocene Hajigabul. Our results reveal several major intervals with elevated salinity, associated with mesohaline Caspian Sea faunas, and propose the following age constraints: 1) The Productive Series-Akchagylian boundary is Magnetostratigraphy marked by a marine transgression from the open ocean that occurred around the Gauss-Matuyama Biostratigraphy reversal (~2.7e2.6 Ma); 2) The Akchagylian-Apsheronian transition is characterized by a regression Akchagylian event and introduction of a new, “Pontocaspian” mollusc assemblage, dated within the Reunion sub- Apsheronian chron (~2.13 Ma). The ostracod assemblages of the two sections do not show a major faunal turnover Bakunian here; 3) The early Bakunian transgression occurs after the upper Apsheronian lowstand (0.85e0.83 Ma). Kura Basin We conclude that major transitions in the age-indicative mollusc groups sometimes occur at different Mollusc fauna time intervals (i.e. diachronic) and are highly depended on the local depositional environments. A high- Ostracods resolution interdisciplinary approach on sections outside the Kura Basin is required to better understand the potential diachroneity of these turnover events in the entire Caspian Basin. © 2019 Elsevier Ltd. All rights reserved. 1. Introduction (Popov et al., 2006; van Baak et al., 2017). Since that time, the Caspian Sea went through periods of dramatic lake-level drops and The Caspian Sea is an endorheic basin, located between Eastern spectacular expansions. The Caspian Sea was mostly isolated but Europe and Central Asia. Even though the Caspian Sea has marine periodically connected to the Black Sea Basin and global ocean aspects (salinity, particular faunas), it is technically a long-lived (Krijgsman et al., 2019). Consequently, a unique fauna evolved in lake and it is the largest lake in the world. The Caspian Basin the Caspian Basin through a series of strong turnover events. The became isolated from the Paratethys Sea during the latest Miocene sedimentary record of the Caspian Sea Basin provides a detailed geological archive to study these faunal changes and the coeval climatic and environmental history of Eurasia. * Corresponding author. The most complete geological successions crop out in the South E-mail address: [email protected] (S. Lazarev). https://doi.org/10.1016/j.quascirev.2019.105895 0277-3791/© 2019 Elsevier Ltd. All rights reserved. 2 S. Lazarev et al. / Quaternary Science Reviews 222 (2019) 105895 Caspian Basin (including the Kura Basin and the West Turkmenian Caucasus mountain ranges (Fig. 1B). Because of the extreme depth Depression). Here, active tectonic uplift of the basin margins and (up to 20 km) the composition of the basement of the Kura Basin is hinterlands, accompanied with high subsidence rates in the basin, poorly known. It may be a westward continuation of the South preconditioned accumulation of kilometres of sediments since the Caspian Basin basement (Zonenshain and Le Pichon, 1986), con- late Miocene (Allen et al., 2002; Morton et al., 2003; Forte et al., taining Early Palaeozoic crystalline rocks (Azizbekov, 1972) and/or 2015). A succession of endemic species (Trubikhin, 1977) that the remnant of a Mesozoic island arc (Nadirov et al., 1997). The late occupied the anomalohaline (“brackish”) lakes of the South Caspian Cenozoic history of the Kura Basin is closely linked to the amplifi- Basin has been used to erect regional stratigraphic schemes. The cation of the Arabian e Eurasian collision that caused progradation Pliocene e Middle Pleistocene succession of the South Caspian of the Kura thrust fold belt (Forte et al., 2010). This belt accom- Basin is subdivided into several regional stratigraphic stages: modated most of the post five Ma shortening, which is expressed in Akchagylian, Apsheronian, Bakunian and Khazarian (Muratov and a series of well-exposed sedimentary successions, located along the Nevesskaya, 1986; Jones and Simmons, 1997). These regional northern flank of the Kura Basin. This late Cenozoic sedimentary stages have been uniformly applied to the entire Caspian Basin sequence is about 5e7 km thick and is similar to that found in the (Nevesskaya et al., 2004; Zastrozhnov et al., 2013). Yet the tectono- South Caspian Basin (Mangino and Priestley, 1998; Allen et al., sedimentary histories of the North, Middle and South Caspian ba- 2002; Forte et al., 2010). sins have been very different and might have resulted in the dia- chronous evolution of depositional environments and associated 2.2. Caspian Sea: from Paratethys to an isolated basin faunas (e.g., Forte et al., 2015). Furthermore, preservation potential and lateral variability of The Caspian Sea became isolated during the fragmentation of habitats, which may affect the definition of regional biostrati- the Paratethys, a large epicontinental sea reaching in the Oligocene graphic stages, remain largely unexplored. Well-preserved deep from the Molasse Basin in France in the West to the Tien Shan water faunas are often lacking and in shallower settings faunas may mountains in western China in the East (Laskarev, 1924). The Par- respond to local paleoenvironmental change rather than represent atethys has been shrinking in size throughout its Neogene and basin-wide synchronous turnover events (Markova, 1962; Magyar Quaternary history due to the ongoing collision between the Afri- et al., 2013). In this paper we study two long sections in can, Arabian and Eurasian plates (Rogl,€ 1999; Schulz et al., 2005; Azerbaijan covering the Productive Series to the Khazarian regional Popov et al., 2006). Isolation of the Caspian Sea from other Para- stages, straddling the interval ~3e0.5 Ma. The Goychay and Haji- tethyan basins occurred during the latest Miocene, around gabul sections are located in proximal and distal settings in the 5.6e5.5 Ma (Allen et al., 2002, 2003; Jackson et al., 2002). At that Kura Basin, respectively. time, a complex combination of climatic and tectonic factors led to The aim of this study is to characterize major depositional units a major Paratethys sea-level drop (Krijgsman et al., 2010; van Baak, and combine magnetostratigraphic and biostratigraphic (molluscs 2015; van Baak et al., 2017). Consequently, intensification of the and ostracods) approaches to develop an integrated stratigraphic Caucasian orogeny provoked a permanent closure of the Ciscau- framework, which will facilitate the identification of major drivers casian Strait and thus, isolation of the Caspian Basin from the of regional paleoenvironmental changes. Euxinian (Black Sea) Basin (Popov et al., 2010). During the early Pliocene, both climatic and tectonic factors 2. Geological background contributed to a large lake-level drop in the Caspian Basin (Kroonenberg et al., 2005). The basin reduced in size to the South 2.1. The South Caspian Basin: setting and structure Caspian Depression and deep river canyons eroded into the desic- cated North and Central Caspian basins (Kroonenberg et al., 2005). The Caspian Sea is elongated in a meridional direction and The Palaeo-Volga, Palaeo-Kura and Palaeo-Amu-Darya deltas overlies several tectonic-structural zones, forming three sub- reached the South Caspian Basin and locally deposited about basins: North, Middle (Central) and South Caspian basins 7e8 km of sediments (Morton et al., 2003; Green et al., 2009; (Fig. 1A). The North Caspian Basin is a depression that was formed Abdullayev et al., 2017). This Pliocene lake-level lowstand was in the Late Proterozoic (Khain et al., 2004; Khain and Popkov,