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Global and Planetary Change 103 (2013) 119–134

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Global and Planetary Change

j ourna l homepage: www.e lsev ie r .com/ locate /g lop lacha

A magnetostratigraphic time frame for Plio-Pleistocene transgressions in the SouthCaspian Basin, Azerbaijan

C.G.C. Van Baak a,⁎, I. Vasiliev a, M. Stoica b, K.F. Kuiper c, A.M. Forte d, E. Aliyeva e, W. Krijgsman a

a Paleomagnetic Laboratory “Fort Hoofddijk”, Utrecht University, Budapestlaan 17, 3584 CD, Utrecht, The Netherlandsb Department of Geology, Faculty of Geology and Geophysics, University of Bucharest, Balcescu Bd. 1, 010041, Bucharest, Romaniac Faculty of Earth and Life Sciences, Institute of Earth Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlandsd Department of Geology, University of California, Davis, Davis, CA 95616, USAe Geological Institute of Azerbaijan (GIA), H. Javid Av. 29A, AZ1143, Baku, Azerbaijan

⁎ Corresponding author. Tel.: +31 30 253 5246; fax:E-mail address: [email protected] (C.G.C. Van BaaURL: http://www.geo.uu.nl/~forth/ (C.G.C. Van Baak

0921-8181/$ – see front matter © 2012 Elsevier B.V. Alldoi:10.1016/j.gloplacha.2012.05.004

a b s t r a c t
a r t i c l e i n f o
Article history:Received 30 April 2011Accepted 7 May 2012Available online 12 May 2012

Keywords:South Caspian BasinmagnetostratigraphyPlio-PleistoceneProductive SeriesAkchagylianApsheronian

The isolation of the Caspian Sea took place in the latestMiocene coincidingwith a significant lowering of sea leveland the deposition of a massive lowstand deltaic system. This so-called Productive Series is the main reservoirunit of the South Caspian oil-province. The Productive Series is overlain by marine clays from the Akchagylianand Apsheronian regional stages. During the Plio-Pleistocene, the Caspian basin experienced several short pe-riods of intermittent connectivity with other marine basins. This work aims to create integrated, high-resolution, bio-magnetostratigraphic dating of these regional transgressions in key sections of the South CaspianBasin in Azerbaijan. We sample two long sections, the Lokbatan section in the Palaeo-Volga delta and theXocashen section in the Kura Basin. Palaeoenvironmental reconstructions are derived from characteristic ostra-cod species. Rock magnetic analyses combined with thermal demagnetisation data indicate that the magneticsignal is carried dominantly by the iron oxide magnetite in the Productive Series of Lokbatan section and inthe Xocashen section. The marine Akchagylian and Apsheronian of Lokbatan are characterised by the iron sul-phide greigite, which appears to be of (near-) primary origin. Themost logical correlation of themagnetic polar-ity patterns to the Geomagnetic Polarity Time Scale dates the Akchagylian transgression at ~3.2 Ma, a majortransgression during the Apsheronian at ~2.0 Ma and the Bakunian transgression at 0.85–0.89 Ma. Ostracod as-semblages indicate increasing salinities during these transgressions, from fresh water lacustrine to brackish-marine species. This implies thatmarine connections have been createdwith an adjacent basin that has a highersalinity, most likely the Black Sea.

© 2012 Elsevier B.V. All rights reserved.

1. Introduction

During the Oligocene and Miocene, the Caspian region was part ofthe Paratethys domain, a large epicontinental sea, stretching fromWestern Europe to China. Paratethys retreat towards the present-dayremnants, the Black Sea and the Caspian Sea, had a major impact onEurasian geography, climate and environment (e.g. Ramstein et al.,1997). The continental collision associated with the rise of the Alpine–Himalayan mountain chain caused the Paratethys to evolve from openoceanic to restrictedmarine and, ultimately, into separate lacustrine en-vironments (Jones and Simmons, 1996; Popov et al., 2006). Major re-striction occurred during the latest Miocene resulting in the isolationof the Black Sea and the Caspian Sea and a significant lowering oftheir sea levels (Reynolds et al., 1998; Gillet et al., 2007; Krijgsman etal., 2010; Munteanu et al., 2012). This event is suggested to coincide

+31 30 253 1677.k).).

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with Mediterranean sea-level lowering during the Messinian SalinityCrisis.

Alternatively, the sea level lowering in the Caspian basin isexplained by large-scale plate tectonic processes, such as the initiationof high uplift rates in the Greater Caucasus Range (Avdeev and Niemi,2011) and the onset of subduction in the South Caspian Basin (Allenet al., 2002). Mio-Pliocene loading of the lithosphere, together with tec-tonic convergence, initiated compressional flexure of the South CaspianBasin (Brunet et al., 2003). In the resulting depression, three major riv-ers (Volga, Kura and Amu Darya, Fig. 1) deposited sediments that erod-ed from a vast drainage basin stretching as far east as the Himalayamountains and as far north as present-dayMoscow. In the basin centre,up to 7 km of Late Miocene and Pliocene fluvial and deltaic sedimentsare deposited (Allen et al., 2002). Thismassive lowstand-deltaic system,the so-called Productive Series, is the main reservoir unit of the SouthCaspian oil-province.

Despite this trend of progressive restriction, several short pe-riods of intermittent connectivity between the Caspian Sea andother Paratethys basins have been recorded in the Plio-Pleistocene, fol-lowing the restriction during the Productive Series (Popov et al., 2010).

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Fig. 1. Schematic map and overview of regional stages; a) Map of the greater Caspian and Eastern Paratethys region, stars indicate location of Lokbatan and Xocashen sections.;b) Geological map of the Lokbatan section area (based on Nalivkin, 1976); c) Geological map of the Xocashen section (modified from Forte et al., 2010); d) South Caspian Basinnomenclature, stages plotted vs. stratigraphic thickness in the South Caspian Basin (from Allen et al., 2002; Hinds et al., 2004), Abbreviations: NKG: Post-Kirmaky Clay Suite,NKP: Post-Kirmaky Sand Suite, PK: Pre-Kirmaky Sand Suite, KAS: Kalin Suite.

120 C.G.C. Van Baak et al. / Global and Planetary Change 103 (2013) 119–134

The oldest of these events is the Akchagylian transgression, whichmarks the end of the Productive Series. In Akchagylian times, the max-imum extent of the Caspian Sea reached far to the north, creating awater body stretching more than 2000 km (Popov et al., 2006)(Fig. 1). A second transgression took place during the ApsheronianStage. According to seismic data offshore the Apsheron peninsula, thistransgression postdates a regional tectonic phase in which folding ofthe Akchagylian occurs (Fowler et al., 2000). The youngest transgres-sion, marking the Apsheronian/Bakunian boundary, is a regionally ex-tensive event characterised by a brackish-marine incursion that canbe traced westward throughout the Kura Basin (Jones and Simmons,1996; Nevesskaya et al., 2002).

The large range of both climatic and tectonic forcing mechanismsacting at different time scales on the sea-level of the Caspian Basinmakes unambiguous time control essential when trying to interpret ob-served changes in the geological record. Here, we present a new bio-magnetostratigraphy for two long sections in Azerbaijan, to place thePliocene and Pleistocene transgressions of the Caspian Sea into a region-al and global timeframe. Palaeoenvironmental conditions will be de-rived using characteristic ostracod species to discern between marine,brackish-marine and fresh water conditions.

The Lokbatan section on the Apsheron Peninsula in Azerbaijan issampled as it is a key section for both the Productive Series and theoverlying Akchagylian and Apsheronian stages (Vincent et al., 2010).

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121C.G.C. Van Baak et al. / Global and Planetary Change 103 (2013) 119–134

The Apsheronian regional stage is better exposed further west in theKura basin. There, we sample the Xocashen section, which is long andcontinuous, comprising the shallow depositional environment of theApsheronian and Bakunian.

2. Existing timescales

Interpreting the Plio-Pleistocene sea-level and salinity variations inthe South Caspian Basin is difficult because of the large range of process-es controlling the Caspian sea-level. To interpret observed changes inthe geological record, unambiguous time control is essential.Many pub-lications discuss the age of the Pliocene and Pleistocene deposits of theCaspian Sea, and present highly variable and contrasting results, espe-cially for the marine Akchagylian regional stage overlying the Produc-tive Series (Fig. 2). Part of the problem arises from different boundarydefinitions. Original definitions of Paratethys regional stages are basedon (mollusc and/or ostracod) faunal zonations (e.g. Nevesskaya et al.,2002 and references therein). However, many recent publications, usethe same nomenclature in a lithostratigraphical (and seismic) sense(e.g. Abreu and Nummedal, 2007 or Green et al., 2009). Under this def-inition, the Akchagylian refers to a condensed clay succession of ~100 mthick (Abreu and Nummedal, 2007; Green et al., 2009). The lack of cleardefinitions leads to significant confusion since these two definitions donot need to describe formation-boundaries at similar levels.

A comprehensive review of proposed timescales in the EasternParatethys region and the Caspian Sea is given by Jones and Simmons

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(1996). Ages are derived by incorporating the regional stratigraphicstages in a global sea-level framework using biostratigraphic andmagnetostratigraphic correlations. However, they note the possibilityof refining the framework by incorporating more detailed magneto-stratigraphic subdivisions.

One of thefirstmagnetostratigraphic records ever constructed in theParatethys region was in the Plio-Pleistocene of Turkmenistan andAzerbaijan (Khramov, 1963). This early work focusesmainly on the rec-ognition and correlation of magnetozones between sections. Many fol-lowing contributions refine this work and allow for interregionalcorrelations and correlations to global timescales (Trubikhin, 1989;Molostovsky, 1997).

According toNevesskaya et al. (2002), the age of the lower boundaryof the Akchagylian in the Eastern Paratethys regional stratigraphy is3.4 Ma. In the lowermost Akchagylian of Azerbaijan a series of tuff inter-calations (5–15 cm thick) is found. Two different radiometric dates arefrequently given for this ash-layer. According to Devlin et al. (1999) andVincent et al. (2010) volcanic ashes in the lower Akchagylian have a fis-sion track age of 3.34±0.35 Ma (Chumakov et al., 1988). On the otherhand, Abdullayev (2000) and Fowler et al. (2000) claim an age of 2.4–2.6 Ma for the Akchagylian, based on isotopic dating by Groves et al.(1996). Mitchell andWestaway (1999) indicate that prior work by Rus-sian authors places the Akchagylian transgression at either ~2.5 Ma or~1.8 Ma. They propose a correlation of a paleomagnetic normal periodat the boundary of the Akchagylian and Apsheronian with the C1r.2n(CobbMt.) cryptochron (~1.18 Ma), favouring an Akchagylian between

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2 and 1.2 Ma. Further attempts have been made to assign absolute agesto the Productive Series based on a correlation to an oxygen-isotope re-cord (Abreu and Nummedal, 2007), assigning 5.9 Ma and 3.1 Ma for thelower and upper boundaries respectively.

3. Section descriptions

3.1. Lokbatan section

The Lokbatan section (base section: N 40°20′3.96″, E 49°44′58.28″)is located 12 km west of Baku (Fig. 1b). The section is located on topof an anticlinal structure, which, in terms of stratigraphy and geometry,is a good analogue for structures offshore Azerbaijan (Souque et al.,2010). The section is continuously exposed in the uppermost part ofthe Productive Series (Surakhany Suite) and into the overlyingAkchagyl and Apsheron. Part of our section has previously been de-scribed by Vincent et al. (2010), who interpret the Surakhany Suite ofthe Productive Series as ephemeral fluvial flood plain, overbank pondand saline lake facies.

The 520 mof the Productive Series is characterised by an alternationof predominantly grey, green and reddish-brown silty clays and (sub-)metre-scale friable sandstone layers. Overlying the Productive Series isan interval of 25 m of brown clays and silts with 5–15 cm thick volcanicash-layers, referred to here as the ash-interval (Fig. 3a). The lowerboundary of the Akchagylian is positioned at the first dark, homogenousclays, after which the section is characterised by 110 m of fine beddedblue and black clays, (light-) grey silty clays and thin ferruginous layers.These clays are frequently rich in molluscs (Dreissena rostriformis,Didacna sp.) and multiple levels are abundant in ostracods. At 605 m,a 10 m thick layer of fine-bedded blackish clays is found without ostra-cods and molluscs, indicating anoxic conditions. The section continueswith 45 m of grey clays and silty intercalations rich in molluscs, cappedby fine-grained pebbles and clays rich in mollusc shells. Based on ourmicropalaeontological work, we place the boundary of the Akchagylian

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Fig. 3. a) Transgressions in Plio-Pleistocene deposits. a) Lokbatan section overview, Prodb) Lokbatan section, blue clays overlying laminated brown clays, transgression in lower Ap(572 m).

and Apsheronian at 660 m. Finely laminated brown-grey silty clayswith thin ferruginous layers characterise the lowermost part of theApsheronian. At 700 m a 3 cm thin whitish tuff layer is interbedded.Just before the top of this part of the section, at 715 m, a sharp changein lithology marks a return to homogenous blue clay. Above this aretwo beds of slumped layers in which reworked tuff elements andshell-fragments are found. The sharp change to blue clays is alsofound 300 m further north (N 40°20′36.54″, E 49°44′20.54″), wherethe section continues (Fig. 3b). From here, the section consists of blue,dark-grey and brown clays with ferruginous layers and layers withiron concretions (up to 40 cm in diameter). Some levels are rich inmol-lusc shells. For the lower part of the section, the bedding dip of thelayers is relatively constant between 272/55W and 280/45W, at660 m this abruptly changes to 275/28W. From this point onwards,the bedding changes gradually to 264/20W at 695 m. In the uppermostsection, the bedding gradually changes from 158/15W to 145/12W.

3.2. Xocashen section

The Xocashen section is located inwestern Azerbaijan (base section:N 40°59′28.65″, E 46°48′33.92″), 38 km southwest of Shaki (Fig. 1c), onthe northern flank of an E–W-trending anticline north of the Min-gachevir Reservoir. Here Akchagylian, Apsheronian and Bakunian de-posits are exposed. The anticlinal structure on which the section islocated forms part of the Kura fold-thrust belt. This is the actively def-orming southern margin of the Greater Caucasus Range. It is thoughtto have accommodated in excess of 40% of the shortening between Ara-bia and Eurasia in the past 5 million years (Forte et al., 2010).

The base of the section is placed within the Apsheronian. TheAkchagylian is not exposed on this flank of the structure, but fossil-rich mudstones distinctly different from the Apsheronian are found inthe core and on the southern flank. Field conditions did not allow fora continuous sampling up to this point. The extent of the Akchagylian

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and exact location of the Akchagylian–Apsheronian boundary can onlybe traced on geological maps and is thus poorly constrained.

The section consists of grey and brown silts, with a section-upwardincrease of 1–5 m thick sandstone and conglomeratic layers (Fig. 3). Atlevel 460 m ametre-thick ash-layer is present. The base of a 20 m thickfinely laminated dark mudstone marks a short transgression and theend of the Apsheronian (Fig. 3c). This marker-bed can be traced overlarger distances in the Kura Basin. In the overlying Bakunian, a packageof fine and coarse sandstones is observed. In the uppermost part of thesection, the sedimentary rocks become more silty and more unconsoli-dated, making them unsuitable for paleomagnetic oriented sampling.The bedding dip changes gradually throughout the section from 300/60NE to 300/35NE.

4. Biostratigraphy

4.1. Methods

Both Lokbatan and Xocashen sections are investigated in detail formicropalaeontological analyses, primarily focusing on foraminiferaand ostracods. At every paleomagnetic sampling site a micro-palaeontological sample is taken. Samples are processed by standardmicropalaeontological methods, sieved over sieves of 63 μm andhand-picked under a microscope (e.g. Stoica et al. (2013)). Mac-ropalaeontological analyses on molluscs are performed in less detail.Taxonomic identifications and ecological inferences are based on previ-ous reports of Plio-Pleistocene sediments throughout the Eastern Para-tethys (Liventhal, 1929; Schneider, 1939; Schweyer, 1949; Agalarova,1956; Suzin, 1956; Agalarova et al., 1961; Mandelstam et al., 1962;Gofman, 1966; Vekua, 1975). Unfortunately, the huge amount of newspecies erected in these works is sometimes illustrated using styliseddrawings. Recently, some studies illustrate Pliocene and Late Pleisto-cene species from Aral Sea, Caspian Sea and Black Sea areas using SEMpictures (Boomer et al., 1996, 2005; Rostovtseva and Tesakov, 2009;Boomer et al., 2010; Schornikov, 2011).

4.2. Lokbatan — upper productive series (Surakhany Suite) ostracodfauna

Biostratigraphic sampling in the Surakhany Suite is mainly con-ducted on clay intercalations between cross laminated or wave rippledsandstones. Ostracod abundance is highly variable, with some levelsparticularly rich in ostracods. The ostracod fauna from these clay inter-calations is dominated by fresh water species (Fig. 4a): Limnocytherearalensis Schornikov, Pseudocandona sp., Ilyocypris bradyi Sars, Ilyocyprisgibba (Ramdohr), Ilyocypris aff. caspiensis (Negadaev), Candoniella sp.,Darwinula stevensoni (Brady and Robertson). They are associated withZonocypris membranae (Livental), Paracandona sp., Cyprinotus sp. Cyprissp, Pontocypris sp., and Eucypris sp. These lacustrine clays are also abun-dant in charophyta algae and fish teeth. Some clay levels rich in gypsumcrystals provide an ostracod fauna represented exclusively by largenumbers of Cyprideis torosa (Jones). In general, the ostracod faunafrom the upper part of Productive Series has been noticed in marginalfresh water bodies throughout the Eastern Paratethys during theKimmerian (Dacian)–Kuyalnikian (Romanian) time interval.

For the Surakhany Suite of the Productive Series, we infer a mainlydeltaic depositional environment. This alternates with lacustrine de-posits, with a rich freshwater ostracod fauna. In specific levels, ostracoddiversity diminishes and becomes dominated by Cyprideis torosa(smooth specimens), a species which is known to tolerate a wide salin-ity range of 0–60‰ (De Deckker, 1981), and is even found in hyper-saline athalassic lakes. They are also described in studies of recentfauna from theAral Sea (Boomer et al., 1996).We infer that highly evap-oritic conditions allow these lakes to becomemore saline in a relativelyshort time. The episodic flooding described here is similar to the modelfor the Productive Series proposed byHinds et al. (2004). They interpret

depositional conditions in the Lokbatan section as an episodic anddischarge-driven fluvial environment. Palynological assemblages areindicative of restricted lakes and salt marshes (Vincent et al., 2010). Inthe centre of the South Caspian Basin, 20–40 m thick evaporite bedsare found in the Surakhany Suite (Green et al., 2009).

4.3. Lokbatan — Akchagylian and Apsheronian ostracod fauna

The ostracod fauna present in the beds overlying the Productive Se-ries shows a significant change in composition (Fig. 4b). The dominantfresh water ostracod assemblage is replaced by a more brackish to sa-line one. The deltaic environment is replaced by shallow basinal condi-tions as a consequence of a rise in water level and a permanentconnection with another more saline water body.

The most common species is Eucythere ex. gr. naphtatscholana(Livental), which has been identified in recent sediments of the BlackSea. Some levels in the Lokbatan section are particularly rich in this spe-cies. The Leptocytheridae family iswell represented bynumerous species:Amnicythere cymbula (Livental), Amnicythere andrusovi (Livental),Amnicythere palimpsesta (Livental), Amnicythere gracilloides (Schornikov),Amnicythere multituberculata (Livental), Amnicythere ex. gr. pediformis(Schornikov), Euxinocythere praebosqueti (Suzin), and Euxinocytherebosqueti (Livental). Some levels from the basal part of the Akchagyl con-tain also species of the Limnocythere genus: Limnocythere ex. gr. alveolataSuzin and Limnocythere sp.

Cytherissa genus is represented by Cytherissa bogatchovi (Livental)with longer and less tuberculated morphotypes. The Loxoconchidae arerepresented by at least three species: Loxoconcha petasa Livental,Loxoconcha babazananica (Livental) and Loxoconcha sp. Some levels areparticularly rich in Candonidae. They are mostly represented byCaspiocypris sp. (large forms that possibly belong to Caspiocypris candida),Caspiolla acronasuta (Livental) and Caspiolla aff. karatengisaMandelstam.

Most of the Akchagylian species continue into the Apsheroniandeposits. In the top part of the Akchagylian the first occurrences ofTyrrhenocythere species are found: Tyrrhenocythere donetziensis(Dubowsky) and Tyrrhenocythere pontica (Livental). These two spe-cies become more abundant at 660 m, which is where we place theboundary between the Akchagylian and Apsheronian. They developfurther during the Apsheronian and they are also frequent in recentsediments of the Black Sea.

4.4. Xocashen — Apsheronian and Bakunian ostracod fauna

In the lower part of the Xocashen section (up to 572 m) a poorlypreserved fresh-water ostracod fauna is present (Fig. 5a). Species arecharacteristic for lacustrine environments. The most common ostra-cod taxa are represented by species of Ilyocypris genus, e.g. Ilyocyprisex. gr. gibba (Ramdohr) and Ilyocypris ex. gr. bradyi Sars, as well assome Candonidae, like Candoniella sp. (possible juveniles of Candonasp.) and Pseudocandona compressa (Koch). No age-specific speciesare found, because all species present are still alive in modern freshwater environments. Some lacustrine intercalations are very rich inCharophyta algae gyrogonites: Nitellopsis (T) merani merani Grambastand Soulié-Märche, Nitellopsis sp. and Chara group globularis.

In contrast, starting at 572 m more saline ostracod species be-come abundant. They are represented by brackish water species(Fig. 5b) dominated bymorphotypes of Eucythere ex.gr. naphtatscholana(Livental) associated with Leptocitheridae ostracods, Amnicytherepediformis (Schornikov), A. cymbula (Livental), Amnicythere sp. (possi-ble from the A. andrusovi group), Amnicythere quinquetuberculata(Schweyer) and Euxinocythere bacuana (Livental). From Loxoconchidae,the species we find most frequently is Loxoconcha babazananica(Livental), considered by some authors as Loxoconcha immodulata Step-anaitys. This ostracod assemblage is similar to assemblages of recentostracod fauna developing in sublittoral conditions from the Caspianand Black Seas.

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SURAKHANY SUITEPRODUCTIVE SERIES

AKCHAGYLIANa b

Fig. 4. a) Ostracod species from the upper part of Productive Series — Lokbatan Section (all adult valves, external lateral views, LV = left valve, RV = right valve,UA47=micropalaeontological sample): 1. Darwinula stevensoni (Brady and Robertson), LV (UA 47, 322.5 m); 2. “Candoniella” sp., RV (UA 12, 444.5 m); 3,4. Pseudocandonasp.(juveniles), LV(UA 80, 253 m); 5. Cyprinotus sp., RV (UA 12, 444.5 m); 6. Cypris sp., RV (UA47, 322.5 m); 7, 8. Ilyocypris ex.gr. gibba (Ramdohr); 7. LV; 8, RV (UA 47, 322.5 m);9, 10. Ilyocypris ex.gr. bradyi Sars; 9. LV; 10. RV (UA 52, 326 m); 11. Ilyocypris aff. caspiensis (Neg.), LV (UA 47, 322.5 m). 12. Zonocypris membranae (Livental), LV (UA 12,444.5 m). 13, 14. Limnocythere aralensis Schornikov; 13. RV, female; 14. RV., male (UA 40, 357 m); 15. Pontocypris sp., RV (UA 47, 322.5 m); 16, 17. Cyprideis torosa (Jones), smoothvariety; 16. RV, female; 17. RV, male (UA 4, 469.5 m); 18. Eucypris sp., LV, fragmented shell (UA 80, 253 m). b) Ostracod species from the Akchagylian — Lokbatan Section (all adultvalves, external lateral views, LV = left valve, RV = right valve, UP28=micropalaeontological sample): 1. Caspiocypris sp., LV (UP 28, 584 m); 2. Caspiolla acronasuta (Livental), LV(UP 28, 584 m); 3. Caspiolla aff. karatengisa Mandelstam, LV (UP 28, 584 m); 4. Cytherissa bogatchovi (Livental), RV, male (UP 25, 573.5 m); 5, 6. Eucythere ex. gr. naphtatscholana(Livental); 5. RV, female; 6. LV, male (UP 14, 546 m); 7, 8. Limnocythere ex. gr. alveolata Suzin; 7. RV, male; 8. RV, female (UP 28, 584 m); 9. Limnocythere sp., RV (UP 13, 543.5 m); 10,11. Amnicythere andrusovi (Livental); 10. RV, possible female; 11. RV, possible male; 12. Amnicythere palimpsesta (Livental), RV; 13. Euxinocythere praebosqueti (Suzin), RV (UP 28,584 m); 14, 15. Euxinocythere bosqueti (Livental); 14. RV, male; 15. RV, female (UP 38, 609 m); 16. Amnicythere multituberculata (Livental), RV (UP 28, 584 m); 17.Amnicytheregracilloides (Schornikov), LV(UP 28, 584 m); 18. Amnicythere ex. gr. pediformis (Schornikov), RV (UP 28, 584 m); 19. Amnicythere cymbula (Livental), LV (UP 28, 584 m); 20.Tyrrhenocythere donetziensis (Dubowsky), RV (UV 9, 633 m); 21. Tyrrhenocythere pontica (Livental), RV (UV 9, 633 m); 22. Loxoconcha petasa Livental, RV (UP 28, 584 m); 23.Loxoconcha sp., RV (UP 28, 584 m); 24. Loxoconcha babazananica (Livental), LV (UP 28, 584 m).


5. Magnetostratigraphy

5.1. Methods

In the 850 m long Lokbatan section, 285 levels are sampled; 143 in theProductive Series and 142 in the overlying Akchagylian and Apsheronian.TheXocashen section is ~900 m long and97 levels are sampled, using ori-ented hand samples and standard paleomagnetic cores. paleomagneticsamples from both sections are taken with an electrical drill and a gener-ator as power supply, taking two standard-oriented cores per stratigraph-ic level. In the laboratory, the hand-samples are embedded in plaster ofParis and subsequently drilled using compressed air.

Thermal demagnetisation (TH) of at least one sample per stratigraphiclevel is applied for magnetostratigraphic purposes. Demagnetisation is

performed with temperature increments of 10–50 °C, up to a maximumof 600 °C, in amagnetically shielded, laboratory-built, furnace. Thenaturalremanent magnetization (NRM) is measured on a horizontal 2G Enter-prises DC SQUID cryogenic magnetometer (noise level 3×10−12 Am2).Susceptibility measurements are performed on a Kappabridge KLY-2after multiple temperature steps, to check for newly formed magneticminerals. In case a significant increase of susceptibility is measured,additional demagnetisation steps are not performed. When thermaldemagnetisation is not conclusive a second sample is demagnetisedusing alternating fields (AF) with small increments up to a maximum of100 mT. First these samples are heated to a temperature of 150 °C follow-ing the procedure of Van Velzen and Zijderveld (1995). Samples aremea-sured on an in-house built robotized sample handler controller attachedto a horizontal 2 G Enterprises DC SQUID cryogenic magnetometer. To

image of Fig.�4

APSHERONIAN BAKUNIANa b

1

2 3

4

5

10

11

12

6

7

8

9

13

14

15

1

2

3

4

5

10

11

12

6

7

8

9

13

14

15

16

17

0.5 mm0 0.5 mm0

Fig. 5. a) Fresh water ostracods and Charophyta gyrogonites from Apsheronian — Xocashen Section (LV = left valve, RV = right valve, SX 11 =micropalaeontological sample): 1, 2.“Candoniella” sp.; 1. LV; 2. RV (SX 32, 231 m); 3. Pseudocandona compressa (Koch), carapace, lateral view from RV, adult (SX 11, 51 m); 4, 5. Pseudocandona sp., RV, juveniles (SX 45,312 m); 6, 7. Ilyocypris ex. gr. gibba (Ramdohr); 6. LV; 7; RV (SX 11, 51 m) 8, 9. Ilyocypris ex. gr. bradyi Sars; 8. LV; 9. RV (SX 11, 51 m); 10–15; Charophyta gyrogonites; 10,11.Nitellopsis (T) merani merani Grambast and Soulié-Märche, (SX 45, 312 m); 12, 13. Nitellopsis sp., (SX 11, 51 m);14, 15. Chara group globularis, elongated morph, (SX 11, 51 m).b) Brackish water ostracods from Bakunian - Xocashen Section (all adult valves, external lateral views, LV = left valve, RV = right valve, SX 87 = micropalaentological sample):1–4. Eucythere ex.gr. naphtatscholana (Livental); 1, 3. LV; 2, 4. RV; 1, 2 (SX 87, 578 m); 3, 4 (SX 96, 674.5 m); 5, 6. Loxoconcha babazananica (Livental); 5. LV; 6. RV, (SX 87, 578 m); 7,8. Amnicythere pediformis (Schornikov); 7. LV; 8. RV, (SX 96, 674.5 m) 9, 10. Amnicythere sp.; 9. LV; 10. RV, (SX 96, 674.5 m); 11, 12. Amnicythere cymbula (Livental); 11. LV; 12. RV,(SX 96, 674.5 m); 13–16. Euxinocythere bacuana (Livental); 13, 14. LV; 15, 16. RV, (SX 96, 674.5 m); 17. Amnicythere quinquetuberculata (Schweyer), RV, (SX 96, 674.5 m).


determine the magnetic carrier for representative samples, thermomag-netic measurements are performed in air on a modified horizontal trans-lation type Curie balance (noise level 5×10−9 Am2). An alternatinggradient magnetometer (Princeton Measurements Corporation, Micro-Mag Model 2900 with 2T magnet, noise level 2×10−9Am2) is used tosuccessively measure hysteresis loops, first order reversal curves (FORC)diagrams, IRM acquisition (after having used the demagnetisation optionof theMicroMag) andback-field demagnetisation curves, all at room tem-perature. Sample masses range from 20 to 40 mg. Hysteresis loops aremeasured for representative samples in order to determine the saturationmagnetization (Ms), the saturation remanent magnetization (Mrs) andthe coercive force (Bc). These parameters are determined after correctionfor the paramagnetic contribution on a mass-specific basis. Due to thepartial saturation of the pole shoes of the electromagnet, the responsewhen measuring in-field is not linear for fields above 1.6 T. Thereforewe use the values for amaximum field of 1.6 T. To further assess themag-netic domain state, the effects of magnetic interactions, and themagneticmineralogy, FORC diagrams are measured. Signal-to-noise ratios are

sufficient to enable the use of a maximum smoothing factor (SF) of 5(Pike et al., 1999); for most samples, we use SF=3.

5.2. Demagnetisation and rock magnetic behaviour

5.2.1. LokbatanDuring the thermal demagnetisation of Lokbatan samples a low-

temperature, low-field, secondary overprint is removed from mostsamples up to a maximum temperature of 300 °C (T3) or fields ofb20 mT. A high-temperature (HT) or high-coercivity (HC) compo-nent is, where present, identified above this temperature (fieldstrength). Fig. 6 shows orthogonal vector diagrams with tectoniccorrection (tc) and without tectonic correction (notc). Thermaldemagnetisation diagrams show different types of magnetic behaviourthat have a clear relationship with lithology. The first group (T1) repre-sents the demagnetisation of iron oxides around a temperature of580 °C, typically found in the deltaic Productive Series. The secondgroup (T2) represents iron sulphides with a demagnetisation ~400 °C,

image of Fig.�5


found only in the marine Akchagylian and Apsheronian. A thirdgroup (T3) is characterised by low intensities and low curie-temperatures (~300 °C). This is found in two distinct intervals, theash-interval (520–550 m) and in the laminated lowermost Apsheronian(660–715 m).

5.2.1.1. Iron oxides (T1). The iron-oxide group of samples is the dom-inant type for the Productive Series and for part of the Akchagyliansamples. Fig. 6a,b,d and e shows the typical behaviour for these sam-ples. Most of the samples collected from the Productive Series haverelatively high intensities, typically 10's of mAm−1 (Fig. 6a and d).The Akchagylian and Apsheronian samples tend to have intensitiesthree orders of magnitude lower than the Productive Series samples(Fig. 6b and e). Upon demagnetisation, no significant increase in sus-ceptibility is found. For temperatures up to 250–300 °C a secondary,most likely present-day, overprint can be isolated in most of the sam-ples. Some samples show a minor overprint to temperatures of 100 °C.After the removal of this first component, a linear decay of the NRM isfound up to temperatures of 540–600 °C. Unblocking temperatures(Tb) for the Productive Series samples always lie between 550°and

UP19.1A

N

up/Wth / tc

UA01.1Ath / tc

N

up/W

UA24.1Ath / tc

N

up/W

UP31.2Baf / tc

L: 591 m.

N

up/W

80°

200

400

520580

80°

300

500

150

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390

580

200

400

580

80°

520

300

0 mT10

20

30 40

5060

80100

0.24 mAm-1

16.1 mAm -1 L: 411.5 m. L: 560 m.1.19 mAm-1 0

23.0 mAm-1 L: 479.5 m.

0.

SX21.Ath / no tc

X: 130 m.

Nup/W

560520

400300

200

80°1.677 mAm

-1

0.

SX34.A

X: 252 m.

N

up/Wth / tc

600

520400

300

200

80°

4.253 mAm-1

a b

d e

h iT1: 580 (˚C)Alternating Field HandSample T1: 580 (˚C)Components:

Fig. 6. Thermal (th/red) and alternating field (af/blue) demagnetization diagrams of charactthose presented with (without) tectonic correction; upper right: sample name; lower left: mAll diagrams are presented up/W. Values along vectors are temperature steps in °C (th) or

600 °C, close to the Curie-temperature (Tc) of magnetite. The hysteresiscurves, up to 1.6 T are closed in fields of 300 mT, (Fig. 7g), the IRM ac-quisition curves are saturated in fields of 300 mT (Fig. 7h) confirmingthe presence of a lower coercivity mineral, most likely magnetite. TheFORC diagrams (Fig. 7i) infer an interacting multi-domain (MD) stateof the magnetic minerals suggesting detrital magnetite as the carrierof the magnetisation. A further subdivision can be made in sampleswith low intensity (typical in red levels, Fig. 6a) and high intensity(Fig. 6b). For the reddish levels the hysteresis curves, up to 1.6 T, werenot closed in fields of 300 mT, or even in 500 mT (Fig. 7j). They have a‘wasp-waisted’ shape indicating the presence of an extra high coercivitymineral next to the magnetite. The IRM acquisition curves are unsatu-rated in fields of 2 T. The FORC diagrams (Fig. 6l) indicate an interactingMD-state of the magnetic minerals. For low intensity Akchagylian sam-ples, Tb is hard to determine but measurements indicate a Tb around500–550 °C (Fig. 7d). AF-demagnetisation was performed on all lowerintensity Akchagylian and Apsheronian samples and isolates, wherepresent, a component at fields above 30 mT (Fig. 6e). Complete AF-demagnetisationwas not achieved inmost samples, indicating the pres-ence of an additional high-coercivity mineral.

UV70.2Aaf / tc

N

up/W

UV70.1Ath / tc

N

up/WUV21.1Ath / no tc

N

up/W

UV68.1A

N

up/Wth / tc

SX 96.A

N

up/WSX 96.A

N

up/Wth / tc th / no tc

80°

150

100

80°

330

210

180

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180330

0 mT

10

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3040

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60

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100L: 715 m.3.49 mAm-1

100

80°

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150320

230

-1

L: 654 m..13 mAm-1

X: 690 m.496 mAm-1

200

520

80°

300

200

400

520

80°

300

L: 713 m.53 mAm

c

f g

j

T3: 300 (˚C)T2: 400 (˚C)

eristic samples. Per sample: upper left: components found in key, tc (notc) samples areagnetic intensity at 250 °C and stratigraphic level in metres (L: Lokbatan; X: Xocashen).af field in mT.

image of Fig.�6


5.2.1.2. Iron sulphides (T2). For the iron sulphide group a low temper-ature overprint is removed at temperatures up to 200–250 °C(Fig. 6f), further demagnetisation reveals a second component witha rapid decay up to 300–400 °C. Curie-balance measurements show

a0.01

0.02

0.03

0 200 400 600

To

tal

Ma

gn

. (A

m² x

kg

-1) UA60.1RL: 311.5 m.

L: 311.5 m.

0

0.01

0.02

0.03

0.04

0 200 4

L: 298.5 m.

0.01

0.02

0.03

0 200TemperatTemperature ( C )

L: 715 m.

L: 715 m.

X: 154.5 m.

d

0.01

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0 200 400 600

To

tal

Ma

gn

. (A

m² x

kg

-1) UP16.1BL: 554.5 m.

SX23A

Hc = 13 mTMr/Ms = 0.12

0

-0.05

0.05

M (

Am

² x k

g-1)

0

-0.005

0.005

0

-0014

0.0014

M (

Am

² x k

g-1)

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-0.01

0.01

UA60.1R

Hc = 12 mTMr/Ms = 0.20

0-2000 -1000

B (

0

-0.0015

0.0015

0-500 500

B (mT)

M (

Am

² x k

g-1)

0

-0.003

0.003UV70.2B

Hc = 37 mTMr/Ms = 0.42

g

j

m

Fig. 7. Rock magnetic experiments. Panels a–f are representative thermo-magnetic runs forrates of 10 °C/min. Total magnetisation is plotted in a series of runs to increasingly higher tbetween 150 and 300 mT. The sample codes are indicated in the upper left corner. Hysteresamples. Hysteresis curves were measured for 2 T≤B≤2 T. The hysteresis figures show theare with applied paramagnetic contribution and mass contribution. Also displayed: saturatioand remanent coercive force (Bcr). The FORC diagrams have indicated smoothing factors (SFposition at 10 to 15 mT.

a Tb around 400 °C (Fig. 7e), typical for an iron sulphide. However,for some of the samples the expected alteration of pyrite (commonlyassociated with magnetic iron sulphides) to a magnetic phase is notobserved. This indicates the presence of exclusively a magnetic iron

00 600

UA65.1B

b c

f400 600ure ( C ) Temperature ( C )

UV70.2B

0

0.02

0.04

0.06

0 200 400 600

SX81BX: 534 m.

0

0.02

0.04

0 200 400 600

SC87.1RX: 584 m.

e

SX23A

Hcr = 48 mT

50

40

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SX23A, SF = 3

Hu (

mT

)

1006020 40 80 140120

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-20

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UA60.1R, SF = 5

1006020 40 80 140120

Hu (

mT

)

Hcr = 48 mT

UA60.1R

20001000

mT)

UV70.2B

Hcr = 61 mT

Hc (mT)

UV70.2B, SF = 5

Hu (

mT

)

50

40

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-40

-20

-30

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1006020 40 80 140120

hi

kl

n

o

selected samples. Heating (thinner lines) and cooling (thicker lines) were performed atemperatures. Individual data points have been omitted for clarity. Cycling field variedsis curves (g,j,m), IRM and back-field curves (h,k,n) and FORC (i,l,o) for characteristicresults up to ±500 mT (the important part of the loop); the IRM and back-field curvesn magnetisation (Ms), the remanent saturation magnetisation (Mrs), coercive force (Bc)) presented at 10 contours levels. The samples have a MD with low coercivity and peak

image of Fig.�7


sulphide. Iron sulphide-bearing samples are typically found in theAkchagylian and Apsheronian, with generally low intensities. The ac-quisition of gyroremanence during AF-demagnetisation further sug-gests the magnetic carrier to be the mineral greigite (Fig. 6g). Thehysteresis loops for this group have a squared shape (Fig. 7m) typicalof single domain magnetic mineralogy. The FORC diagrams indicatethe presence of a highly interactive (pseudo) single domain compo-nent with a Hc peak at ~60 mT (Fig. 7o). This type of FORC diagramis very similar to the ones produced from other greigite bearingrocks of the Paratethys (Vasiliev et al., 2007, 2008, 2010).

5.2.1.3. Low-temperature component (T3). A group of low-temperaturesamples is completely demagnetised at temperatures between 200and 250 °C. No primary component of the NRM can be identified forthese samples. Fig. 6c shows a demagnetisation diagram for thermaldemagnetisation of a representative sample, plotted without tectoniccorrection (notc).

The mean direction of the T3 group samples plots close to theexpected direction for the geocentric axial dipole (GAD) field nearBaku (inc: 59°17′) (Fig. 10). This is similar to the direction of thelow-T overprint component of the Productive Series samples. Thesesamples are considered to represent a later, secondary overprintand are thus not used for the magnetostratigraphic interpretation.

5.2.2. XocashenSamples from the Xocashen section are typified by one dominant

type of magnetic carrier. A low-T component is removed at tempera-tures below 250 °C. In half of the samples this accounts for a large partof the NRM (as much as 75%). Samples are completely demagnetisedat temperatures between 500 °C and 600 °C (Fig. 6h, i and j). Due tothe relatively steep dip of the bedding (60–70°), a clear distinctioncan be made between primary normal directions and a present dayfield overprint of the samples (Fig. 6j). Initial intensities range be-tween 2 and 100 mA m−1 and show a generally decreasing trendsection-upwards (Fig. 9). Unblocking temperatures are between550° and 580 °C (Fig. 7c and f), which also points to magnetite asthe main magnetic carrier. As in the Lokbatan section, the hysteresiscurves, up to 1.6 T, are closed in fields of 300 mT and the IRM acqui-sition curves are saturated in fields of 300 mT (Fig. 7h) confirmingthe presence of a lower coercivity mineral, most likely magnetite(Fig. 7g). The FORC diagrams (Fig. 6i) suggest an interacting MDstate of the magnetic minerals, suggesting detrital magnetite as thecarrier of the magnetisation.

5.3. Magnetic polarity pattern

5.3.1. Lokbatan sectionThree polarity zones are found in the Productive Series part of the

Lokbatan section, a lower reversed part (0–253 m), followed by normalpolarities (253–457 m) and again reversed polarities (457–500 m)(Fig. 8). In the uppermost part of the Productive Series and in the ash-interval the polarity does not show a consistent behaviour. This coin-cides with a dramatic decrease in specific susceptibility and NRM-intensity (Fig. 8). The Akchagylian shows mostly reversed polarity. At580 m a short interval of near-horizontal direction is found. Samplesin the lowermost Apsheronian do not show reliable, consistent behav-iour. The NRM-intensity is generally low and directions are interpretedas secondary present-day overprint. At 710 m a clearly reversed polari-ty interval starts, followed at 715 m by normal polarities. After a strati-graphic gap in the record, 40 mof reversed polarity is found at the top ofthe section.

5.3.2. Xocashen sectionIn the 900 m long Xocashen section five polarity zones are inter-

preted, two long reverse intervals, with three short normal intervals(Fig. 9). Both oriented hand-samples (squares) and drilled cores (circles)

show identical polarities and can be used for the magnetostratigraphy.Completely overprinted samples, found in both hand-samples and drilledcores, are equally spaced throughout the section and represent around20%of the samples. The exact position of the upper reversal is lesswell de-fined since it is located in 40 m of section that was not suitable for sam-pling. This results in an additional uncertainty on the age of theBakunian transgression.

The reversal test of McFadden and McElhinny (1988) is performedand is negative for both sections (Fig. 10). In Lokbatan, this can beexplained by the bad preservation of the original signal in the low in-tensity Apsheronian samples and the incomplete removal of the low-T component. In the Xocashen section, this is probably due to the lownumber of normal oriented samples and the incomplete removal ofthe large low-T component.

6. Correlation to the GPTS

The obtained magnetostratigraphy for the Lokbatan and Xocashensections is correlated to the astronomically dated Geomagnetic Polar-ity Time Scale (GPTS) of Lourens et al. (2004). Fig. 11 shows the mostlikely correlation of the sections polarity patterns with the GPTS andthe oxygen isotope record of Lisiecki and Raymo (2005).

The magnetostratigraphy of the Lokbatan section does not allowfor a straightforward correlation to the GPTS and calls for an uncon-formity somewhere in the section. An unconformity at the base ofthe Akchagylian is known from works by Azizbekov (1972), indicat-ing the transgressive nature of the basal Akchagylian. A conformablecontact between the Productive Series and the overlying Akchagylianis assumed by Vincent et al. (2010) and in the field we find no indica-tions to suggest otherwise (Fig. 3a). With this reasoning, we followVincent et al. (2010) here and assume a continuous succession acrossthe Productive Series, ash-interval and Akchagylian at Lokbatan.

The age of the ash-interval is a key part of the correlation of theLokbatan section. Two different radiometric ages have been proposedfor these ashes, a fission track age of 3.34±0.35 Ma (Chumakov et al.,1988) or 2.4–2.6 Ma (Groves et al., 1996). The 3.34±0.35 Ma age allowsfor a straightforward downward correlation of the polarity patterns to theGPTS. The reversed interval (465–500 m) underlying the ashes correlatesto C2An.2r (Mammoth subchron), the normal (250–465 m) to C2An.3n(Lower Gauss) and the lowermost reversed interval (0–250 m) withC2Ar (top Gilbert chron). The reversed oriented Akchagylian correlatesto C2An.1r (Kaena) and/or C2An.2r (Mammoth). The brown clays in theash-interval are distinctly different from the Productive Series sand andsilt/clay alternations (b520 m). The onset ofmarine clays and the first oc-currence of more saline ostracods occur after this interval (550 m)whichdates the Akchagylian transgression at ~3.2 Ma.

An important tectonic event occurs at the boundary between theAkchagylian and Apsheronian (at 660 m) in Lokbatan. The abruptchange in bedding orientation above the boundary indicates active for-mation of the anticlinal structure. This agreeswith seismic data offshorefrom the Apsheron Peninsula, where folding is shown to start at the topof the Akchagylian (Fowler et al., 2000). Furthermore, ourfield observa-tions at the boundary show thinly layered reworked layers of pebblesand shell-material. The angular contact between the upper Akchagylianand lowermost Apsheronian thus probably represents an unconformityof significant duration. In addition, normal magnetozones attributed tothe Akchagylian which are not found in Lokbatan are known from theJeirankechmez River section of SE Gobustan (Trubikhin, 1989) and theKvabebi mammal site in Georgia (Agusti et al., 2009). The normal inter-val in the Apsheronian (715–780 m) must then represent a youngernormal zone, most likely C2n (Olduvai). The age of the transgressionin the Apsheronian according to this magnetostratigraphic correlationis ~2.0 Ma.

An alternative option is a correlation of the normal Apsheronianmagnetozone to C2An.1n (Gauss), followed by C1r.3r (Matuyama).However, this results in highly variable sedimentation rates, with

Lokbatan (Azerbaijan)Productive Series / Akchagylian / Apsheronian

Str

atig

rap

hic

leve

l (m

)

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Specific susceptibility(k/gram) Intensity 250°C

(mAm ) -2

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90 180 270 360 450

Declination

0

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-90 0 90

Inclination

Pro

du

ctiv

e S

erie

s / S

ura

khan

y S

uit

e A

kch

agyl

ian

Ap

sher

on

ian

1000100000

ab c

Fig. 8.Magnetostratigraphy for the Lokbatan section, from left to right: stratigraphic level (m); stage names and lithostratigraphy, in grey (yellowish) silts and clays (sands), in redare ashes, a) clay, b) silt and clay, c) sand; measured declination; interpreted polarity (black: normal, white: reverse); measured inclination; specific magnetic susceptibility atroom temperature, thick line 3-point moving average; magnetic intensity at 250 °C. Solid dots (diamonds) are reliable th (af) directions, open dots (diamonds) overprinted th(af) directions.


~200 cm/kyr in the reversed (550–715 m) and 14 cm/kyr in the over-lying normal magnetozone.

The Apsheronian fauna found in both Xocashen and the upperLokbatan sections, shows that the Xocashen section should be youngerthan or (partially) overlap the Lokbatan section. Three possible correla-tionswhich result in a roughly constant sedimentation rate exist for theXocashen section. In the oldest correlation, the normal chrons correlateto (from old to young) C2An.1n (Gauss), C2r.1n (Reunion) and C2n(Olduvai). In the second correlation these correlate to C2n (Olduvai),C1r.2n (CobbMt.) and C1r.1n (Jaramillo). The third and youngest optioncorrelates them to C2n (Olduvai), C1r.1n (Jaramillo) and C1n (Brunhes).

Previous studies place the base of the Bakunian close to theMatuyama/Brunhes (M/B) reversal at 0.780 Ma (Jones and Simmons,1996), which supports the youngest correlation for the Xocashensection between the Olduvai and the Brunhes. Mitchell and Westaway(1999) favour a correlation of the lower Apsheronian with the CobbMt. subchron. Correlating the Xocashen section in this way results in acorrelation of the normal polarities to C1r.2n (Cobb Mt.), C1r.1n(Jaramillo) and C1n (Brunhes). This would imply a dramatically highersedimentation rate for the lower part of the section, which we find noevidence of in the field. Therefore, we consider the correlation between

C2n (Olduvai) and C1n (Brunhes) the most likely option (Fig. 11). Inthis case the Xocashen section spansmore than amillion years. Assum-ing constant sedimentation rate between reversals, the transgression at572 m has an age between 0.89 Ma and 0.85 Ma. Since the base of thesampled section is not yet the base of the Apsheronian, its lower bound-ary should be older than ~1.9 Ma, which is in agreement with our pre-ferred correlation of Lokbatan.

7. Discussion

7.1. Transgressions/sea level variations

Interpreting the Plio-Pleistocene sea-level and salinity variations inthe Caspian Sea is difficult because of the large range of processes con-trolling the Caspian Sea level. The present-day Caspian Sea level isforcedmainly by Volga discharge, which is highly dependent on precip-itation in the vast Volga-drainage area (Kroonenberg et al., 2000; Leroyet al., 2007). The evaporation rate over the Caspian Sea is another im-portant process, since this is the only hydrological flux out of the pres-ently landlocked Caspian Sea (Arpe and Leroy, 2007). Furthermore,the inflow from the Amu Darya river is highly variable. In the past, it

image of Fig.�8

Xocashen (Azerbaijan)

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Fig. 9. Xocashen magnetostratigraphy, columns and symbols similar to Fig. 8. Lithostratigraphy: a) mud, b) silt, c) fine sand, d) coarse sand, e) granule gravel, and f) cobble gravel.


has switched regularly between draining into the Aral and Caspian Seas(Boomer et al., 2000).

One explanation for the transgressions is based on marine faunaentering the Caspian Sea. This links the Akchagylian transgression toa eustatic highstand that caused overflow of marine waters into theCaspian Sea (Nevesskaya et al., 2002). The exact location of this con-nection to the Indian Ocean or to the Black Sea remains unclear(Popov et al., 2006).

Alternatively, the Late Pleistocene transgressions in the CaspianSea are proposed to coincide with a freshening of the water, strongerriver inflow and regionally cooler climate (Leroy et al., 2007). Majortransgressions in this time-period are interpreted as an overflow ofpro-glacial lakes during extensive Northern Hemisphere Glaciations(Grosswald, 1980; Mangerud et al., 2004). This would cause increasedfresh-water discharge into the Black Sea and Caspian Sea, which thenfill until they spill into adjacent basins, creating a pathway for faunato migrate from and into the Caspian Sea (Badertscher et al., 2011).Further, a moment of connection with the Arctic basin is necessaryto explain present-day species with an Arctic marine origin, such ascrustaceans (Audzijonyte et al., 2006; Väinölä et al., 2008), fish andthe Caspian seal (Palo and Väinölä, 2006). Different hypothesesexist for when this pathway was open, varying in age from Plioceneto (Late) Pleistocene (Palo and Väinölä, 2006).

Alongside climatic changes to the hydrological budget, tectonicopening and closure of gateways must be taken into account. Activeplate-tectonic processes causing uplift of the Greater Caucasus and

subsidence of the South Caspian Basin strongly intensify during thePlio-Pleistocene (Brunet et al., 2003). This results in a wide range ofclimatic and tectonic forcing mechanisms potentially acting on thesea-level of the Caspian Sea at different time scales.

Our newmagnetostratigraphic results allow the validity of the dif-ferent forcing mechanisms to be tested. The Akchagylian transgres-sion is dated at ~3.2 Ma in the interval straddling the C2An.2r(Mammoth) and C2An.1r (Kaena) subchrons. This time intervaldoes not correspond to a major eustatic highstand, nor to a periodof extreme glacial cooling. The tectonic opening of a marine gatewayis the most likely cause. Whether this opening occurred between theBlack Sea and Caspian Sea regions, or between the Eastern Paratethysregion and the Mediterranean Sea is beyond the scope of thispaper. Alternatively, a gradual climatic change may have altered thelocal hydrological budget, causing the observed transgressions. TheLate Pliocene intensification of the Northern Hemisphere glaciationsmay have triggered such a climatic change (Mudelsee and Raymo,2005).

The Apsheronian transgression is magnetostratigraphically datedat ~2.0 Ma, close to the base of the C2n (Olduvai) subchron. Giventhis age, there is no direct correlation to a eustatic highstand, butthe time span comprises several glacial peaks including Marine Iso-tope Stages (MIS) 78 and 82.

The Middle Pleistocene transgressive event in the Xocashen sec-tion may also have a climatic origin. The transgression is dated be-tween 0.89 and 0.85 Ma, which coincides to MIS 22 and the Mid-

image of Fig.�9

Reversal test: γ = 14.9 ≤ γc = 12.1 Reversal test: γ = 26.3 ≤ γc = 13.9

Reversal test: γ = 77.8 ≤ γc = 9.4 Reversal test: γ = 26.1 ≤ γc = 15.7

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Fig. 10. Top row: equal area plots of the low temperature component of the Productive Series and the Akchagylian and Apsheronian (T3) samples with a complete overprint. Redstars indicate the GAD-direction for Azerbaijan. Middle and bottom row: Equal area plots of the groups of ChRM-components of samples from the Lokbatan and Xocashen sections.T3 directions are the not completely overprinted low-T samples. Solid (open) dots: downward (upward) projections, small red dots are directions that lie outside the Vandammecut-off (Vandamme, 1994). Per stereographic projection: Dec.: declination, Inc.: inclination, N, number of samples, κ: precision parameter of Fischer (1953), α95: 95% cone of con-fidence. N (R) is separated Normal (Reversed) directions.


Pleistocene Transition (Mudelsee and Schulz, 1997). A marked North-ern Hemisphere ice-volume increase occurred at this time. This is as-sociated with the onset of large glacial-interglacial temperature and

ice-volume variability of the Middle Pleistocene. Younger MiddlePleistocene transgressions in the Black Sea region have also shownthis strong climatic link (Badertscher et al., 2011).

image of Fig.�10

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Fig. 11. Magnetostratigraphy correlation to GPTS. From left to right: Global stratigraphic stages, South Caspian Basin regional stages, δ18O curve of Lisiecki and Raymo (2005), cor-relation to GPTS.


7.2. Towards a high-resolution timescale for the South Caspian Basin

The timescale for the Neogene South Caspian Basin suffers from alack of well-dated sections and unclear nomenclature. As a result, nounambiguous timescale for this economically important region exists,which makes (1) correlation to global climatic records highly specu-lative and (2) high-resolution stratigraphical correlations throughoutthe region very difficult.

The boundary between the non-marine clastic Productive Seriesand the marine Akchagylian is a good example of the general confu-sion. Due to a lack of macro-fauna, the Productive Series is not definedas a biostratigraphic stage. Based on the underlying Pontian and over-lying Akchagylian, it is correlated to the Kimmerian regional stage(Jones and Simmons, 1996). Definitions of the Productive Series arebased on lithostratigraphic subdivisions, which allow for regional cor-relations using flooding surfaces and sequence boundaries (Reynoldset al., 1998).

The Akchagylian is originally defined as a biostratigraphic zone,recognized throughout the Eastern Paratethys region, subdividedinto a fresh-water lower part, marine middle and quasi-marineupper part (Jones and Simmons, 1996). Lithostratigraphically, theterm Akchagylian is also used to describe a regionally extensive con-densed clay section overlying the Productive Series at the ApsheronPeninsula (Green et al., 2009). The upper boundary is defined in seis-mic records as a maximum flooding surface over which downlappinggeometries are observed (Torres, 2007), or as the moment of onset ofstructural growth (Fowler et al., 2000). Across the Caspian Sea region,the specific stacking pattern of this interval can be remarkably differ-ent (Abreu and Nummedal, 2007).

We find in the Lokbatan section that the Akchagylian consists of asequence of roughly 100 m. Ostracod-fauna indicate higher salinities(19–20 ppt) at the moment of transgression (550 m in the Lokbatansection) and records the first introduction of typical Apsheronian spe-cies at 645 m. A gradual faunal change is observed and faunas typical

image of Fig.�11


for the Apsheronian become abundant at 660 m, which coincideswith the 20° change in dip. It appears both biostratigraphic andlithostratigraphic nomenclature would describe roughly the same in-terval in this section. However, significant thickness variations areknown in the Akchagylian (Azizbekov, 1972; Forte et al., 2010). Inthese cases boundaries may be defined at different levels.

Distinguishing geodynamic from climatic causes is one of themost challenging, but complex issues in modern Earth sciences.The reconstruction of the Plio-Pleistocene transgressions in theCaspian basin requires not only a dramatic improvement in its chro-nology but also detailed studies on its evolving environment. Wehave shown here that Caspian basin sediments are suitable to estab-lish magnetostratigraphic time constraints and to reconstruct pal-aeoenvironmental conditions marking periods of interbasinalconnectivity. Additional geochronological constraints by radioisoto-pic dating methods and detailed palaeoenvironmental proxy recordswill be needed to help further solve ongoing controversies about theorigin of the Plio-Pleistocene transgressions of the South CaspianBasin.

8. Conclusions

We sample two long Plio-Pleistocene sections in the South CaspianBasin and Kura Basin of Azerbaijan for magnetostratigraphic datingand for palaeoenvironmental reconstruction based on ostracods. TheLokbatan section, close to Baku, comprises the uppermost part of theProductive Series, the overlying marine Akchagylian and the basalpart of the Apsheronian. The Xocashen section is located in westernAzerbaijan, starts in the Apsheronian and extends upwards into theBakunian. Our new bio-magnetostratigraphic time frame allows us todate important facies changes and marine transgressions:

(1) The uppermost part of the Productive Series is characterised bymainly deltaic and lacustrine sediments. Directly overlying theProductive Series is an interval of brown clays and siltswithmul-tiple volcanic ash layers, followed by the first marine clays of theAkchagylian. Ostracod assemblages in the Productive series arehighly variable and are dominated by fresh water species. Rockmagnetic analyses and thermal demagnetisation diagrams indi-cate that the magnetic signal in the Productive Series is carriedby magnetite. Our preferred magnetostratigraphic correlationdates the upper boundary of the Productive Series, and theAkchagylian transgression in Lokbatan at ~3.2 Ma.

(2) The Akchagylian is mainly composed of blue-grey clays rich inmolluscs and ostracods. The ostracod assemblages indicatebrackish and saline environments resulting from a sudden riseof the water level. Thermal demagnetisation shows that the en-tire Akchagylian section is of reversed polarity, and rockmagnet-ic experiments indicate that magnetite and greigite are themaincomponents. The upper boundary with the Apsheronian is mar-ked by an angular unconformity, probably related to a regionaltectonic folding phase.

(3) The Apsheronian is sampled at both Lokbatan and Xocashen. InLokbatan the main lithologies are homogenous clays and finely-bedded silts, with some levels rich in molluscs. Ostracod assem-blages indicate brackish conditions, similar to the Akchagylian. InXocashen grey and brown silts dominate, with interbeddedsands and conglomerates. A fresh-water fauna is found in theApsheronian. The magnetic signal in Lokbatan is mainly based ongreigite, in Xocashen on magnetite, probably caused by the dif-ferent palaeoenvironmental conditions. The transgression inLokbatan during the Apsheronian is dated to occur just beforethe C2n (Olduvai) subchron at an age of ~2.0 Ma.

(4) In Xocashen the base of the Bakunian is represented by 20 mof blue clays. Above this homogenous clay the section consistsof relatively coarse grained deposits like sands and silts. The

ostracod species at the base of the Bakunian indicate a returnto more saline (brackish) conditions. This transgression ismagnetostratigraphically dated between C1r.1n (Jaramillo)and C1n (Brunhes) at an age of 0.88–0.85 Ma.

Acknowledgements

This work is carried out in the frame of activities sponsored by theNetherlands Research Centre for Integrated Solid Earth Sciences(ISES). We are grateful to the DARIUS programme and its sponsors forfunding ofmultiple fieldworks in Azerbaijan.We thank Eldar Huseynov,Hagi Ibrahimov and Arjen Mascini for their help in the field. Thoroughreviews ofMiguel Garces and an anonymous reviewer helped to signifi-cantly improve the manuscript.

References

Abdullayev, N.R., 2000. Seismic stratigraphy of the Upper Pliocene and Quaternary de-posits in the South Caspian Basin. Journal of Petroleum Science and Engineering 28,207–226.

Abreu, V., Nummedal, D., 2007. Miocene to Quaternary sequence stratigraphy of theSouth and Central Caspian basins. In: Yilmaz, P.O., Isaksen, G.H. (Eds.), Oil andGas in the Greater Caspian Area: AAPG Studies in Geology, 55, pp. 65–86.

Agalarova, D.A., 1956. Microfauna of the productive beds of Azerbaijan and the red-beds of Turkmenistan. Izvestiya Akademia Nauk Turkmenistan SSR (pls 5–16),pp. 88–125.

Agalarova, D.A., Kadyrova, Z.K., Kulieva, S.A., 1961. Ostracoda from Pliocene and Post-Pliocene Deposits of Azerbaijan (in Russian). Azerbaijan State Publisher, Baku.420 pp.

Agusti, J., Vekua, A., Oms, O., Lordkipanidze, D., Bukhsianidze, M., Kiladze, G., Rook, L.,2009. The Pliocene–Pleistocene succession of Kvabebi (Georgia) and the back-ground to the early human occupation of Southern Caucasus. Quaternary ScienceReviews 28, 3275–3280.

Allen, M.B., Jones, S., Ismail-Zadeh, A.D., Simmons, M.D., Anderson, L., 2002. Onset ofsubduction as the cause of rapid Pliocene–Quaternary subsidence in the SouthCaspian basin. Geology 30, 775–778.

Arpe, K., Leroy, S.A.G., 2007. The Caspian Sea level forced by the atmospheric circula-tion, as observed and modelled. Quaternary International 173–174, 144–152.

Audzijonyte, A., Daneliya, M.E., Väinölä, R., 2006. Comparative phylogeography ofPonto-Caspian mysid crustaceans: isolation and exchange among dynamic inlandsea basins. Molecular Ecology 15, 2969–2984.

Avdeev, B., Niemi, N.A., 2011. Rapid Pliocene exhumation of the central Greater Cauca-sus constrained by low-temperature thermochronometry. Tectonics 30 (TC2009),1–16.

Azizbekov, S.A., 1972. Geology of the USSR, Azerbaijan SSR (in Russian). Nauka, Mos-cow, p. 433.

Badertscher, S., Fleitmann, D., Cheng, H., Edwards, R.L., Göktürk, O.M., Zumbühl, A.,Leuenberger, M., Tüysüz, O., 2011. Pleistocene water intrusions from the Mediter-ranean and Caspian Seas into the Black Sea. Nature Geoscience 4, 236–239.

Boomer, I., Whatley, R., Aladin, N., 1996. Aral Sea Ostracoda as environmental indica-tors. Lethaia 29, 77–85.

Boomer, I., Aladin, N., Plotnikov, I., Whatley, R., 2000. The palaeolimnology of the AralSea: a review. Quaternary Science Reviews 19, 1259–1278.

Boomer, I., von Grafenstein, U., Guichard, F., Bieda, S., 2005. Modern and Holocene sub-littoral ostracod assemblage (Crustacea) from the Caspian Sea: a unique brackish,deep-water environment. Palaeogeography, Palaeoclimatology, Palaeoecology225, 173–186.

Boomer, I., Guischard, F., Lericolais, G., 2010. Late Pleistocene ostracod assemblagesfrom the western Black Sea. Journal of Micropaleontology 29, 119–133.

Brunet, M., Korotaev, M.V., Ershov, A.V., Nikishin, A.M., 2003. The South Caspian Basin:a review of its evolution from subsidence modelling. Sedimentary Geology 156,119–148.

Chumakov, I.S., Byzova, S.L., Ganzey, S.S., Mamedov, A.V., Alekserov, B.D., 1988. Radio-metric scale of the late Cenozoic of Azerbaijan (in Russian). Geologiya, Razvedka YRazrabotka Neftegazovykh Mestorozhdeniy, N2, pp. 4–7.

De Deckker, P., 1981. Ostracods from athalassic saline lakes. Hydrobiologia 81,131–144.

Devlin, W.J., Cogswell, J.M., Gaskins, G.M., Isaksen, G.H., Pitcher, D.M., Puls, D.P., Stanley,K.O., Wall, G.R.T., 1999. South Caspian Basin: young, cool and full of promise. GSAToday 9 (7), 1–9.

Fischer, R.A., 1953. Dispersion on a sphere. Proceedings of the Royal Society of London,Series A 217, 295–305.

Forte, A.M., Cowgill, E., Bernardin, T., Kreylos, O., Hamann, B., 2010. Late Cenozoic de-formation of the Kura fold-thrust belt, southern Greater Caucasus. GSA Bulletin122 (3/4), 465–486.

Fowler, S.R., Mildenhall, J., Zalova, S., Riley, G., Elsley, G., Desplanques, A., Guliyev, F.,2000. Mud volcanoes and structural development on Shah Deniz. Journal of Petro-leum Science and Engineering 28, 189–206.

Gillet, H., Lericolais, G., Réhault, J.-P., 2007. Messinian event in the black sea: evidenceof a Messinian erosional surface. Marine Geology 244, 142–165.


Gofman, E.A., 1966. Ecology of Modern and Novocaspian Ostracods of the Caspian Sea.Akademie NAUK SSSR, Moscow. (183 pp.).

Green, T., Abdullayev, N.R., Hossack, J., Riley, G., Roberts, A.M., 2009. Sedimentation andsubsidence in the South Caspian Basin, Azerbaijan. Geological Society, London,Special Publications 312, 241–260.

Grosswald, M.G., 1980. Late Weichselian ice sheet of Northern Eurasia. Quaternary Re-search 13, 1–32.

Groves, J.R., Stein, J.A., Babazade, A., Koshkarly, R.O., Mamedova, D.N., 1996. Biostrati-graphic and isotopic evidence for determining rates of rock accumulation withinthe productive series of eastern Azerbaijan. Symposium on Rapidly Subsiding Ba-sins (Abstract), Baku, Azerbaijan Republic. American Association of PetroleumGeologists.

Hinds, D.J., Aliyeva, E., Allen, M.B., Davies, C.E., Kroonenberg, S.B., Simmons, M.D.,Vincent, S.J., 2004. Sedimentation in a discharge dominated fluvial/lacustrine sys-tem: the Neogene productive series of the South Caspian Basin, Azerbaijan. Marineand Petroleum Geology 21, 613–638.

Jones, R.W., Simmons, M.D., 1996. A review of the stratigraphy of eastern Paratethys(Oligocene–Holocene). Bulletin of the Natural History Museum (Geology Supple-ment) 52, 25–49.

Khramov, A.N., 1963. Pliocene and PostPliocene paleomagnetic results of outcrops fromApsheron-Caspian region and their correlation (In Russian). Gostoptechizdat,Leningrad, pp. 220–263.

Krijgsman, W., Stoica, M., Vasiliev, I., Popov, V.V., 2010. Rise and fall of the ParatethysSea during the Messinian Salinity Crisis. Earth and Planetary Science Letters 290(1–2), 183–191.

Kroonenberg, S.B., Badyukova, E.N., Storms, J.E.A., Ignatov, E.I., Kasimov, N.S., 2000. Afull sea-level cycle in 65 years: barrier dynamics along Caspian shores. Sedimenta-ry Geology 134, 257–274.

Leroy, S.A.G., Marret, F., Gibert, E., Chalié, F., Reyss, J.-L., Arpe, K., 2007. River inflow andsalinity changes in the Caspian Sea during the last 5500 years. Quaternary ScienceReviews 26, 3359–3383.

Lisiecki, L.E., Raymo, M.E., 2005. A Pliocene–Pleistocene stack of 57 globally distributedbenthic D18O records. Paleoceanography 20, PA1003.

Liventhal, V.E., 1929. Ostracoda of Akchagilian and Apsheronian beds of the Babazansection (in Russian). Izvestiya Azerbajdzahnskogo Politekhnischeskogo Instituta,Baku, 1, pp. 1–58.

Lourens, L.J., Hilgen, F.J., Laskar, J., Shackleton, N.J., Wilson, D., 2004. The Neogene peri-od. In: Smith, A.G. (Ed.), A Geological Time Scale 2004. Cambridge University Press,Cambridge.

Mandelstam, M.I., Markova, L., Rosyeva, T., Stepanaitys, N., 1962. Ostracoda of the Plio-cene and Post-Pliocene Deposits of Turkmenistan. Turkmenistan Geological Insti-tute, Ashkhabat. (288 pp.).

Mangerud, J., Jakobsson, M., Alexanderson, H., Astakhov, V., Clarke, G.K.C., Henriksen,M., Hjort, C., Krinner, G., Lunkka, J.-P., Möller, P., Murray, A., Nikolskaya, O.,Saarnisto, M., Svendsen, J.I., 2004. Ice-dammed lakes and rerouting of the drainageof northern Eurasia during the Last Glaciation. Quaternary Science Reviews 23,1313–1332.

McFadden, P.L., McElhinny, M.W., 1988. The combined analysis of remagnetization cir-cles and direct observations in paleomagnetism. Earth and Planetary Science Let-ters 87, 161–172.

Mitchell, J., Westaway, R., 1999. Chronology of Neogene and Quaternary uplift andmagmatism in the Caucasus: constraints from K–Ar dating of volcanism in Armenia.Tectonophysics 304, 157–186.

Molostovsky, E.A., 1997. Magnetostratigraphy of the Pliocene deposits in Black Sea,Caspian regions and adjacent areas. Geodiversitas 19 (2), 471–495.

Mudelsee, M., Raymo, M.E., 2005. Slow dynamics of the Northern Hemisphere glacia-tion. Paleoceanography 20, PA4022. http://dx.doi.org/10.1029/2005PA001153.

Mudelsee, M., Schulz, M., 1997. The Mid-Pleistocene climate transition: onset of 100 kacycle lags ice volume build-up by 280 ka. Earth and Planetary Science Letters 151,117–123.

Munteanu, I., Matenco, L., Dinu, C., Cloetingh, S., 2012. Effects of large sea-level varia-tions in connected basins: the Dacian–Black Sea system of the Eastern Paratethys.Basin Research 1–15.

Nalivkin, D.V., 1976. Geological map of the Caucasus (in Russian). Union of Soviet So-cialist Republics, scale 1:500,000.

Nevesskaya, L.A., Goncharova, I.A., Ilyina, L.B., Paramonova, N.P., Khondkarian, S.O.,2002. The Neogene Stratigraphic Scale of the Eastern Paratethys. Stratigraphyand Geological Correlation 11 (2), 105–127.

Palo, J.U., Väinölä, R., 2006. The enigma of the landlocked Baikal and Caspian sealsaddressed through phylogeny of phocine mitochondrial sequences. Biological Jour-nal of the Linnean Society 88 (1), 61–72.

Pike, C.R., Roberts, A.P., Verosub, K.L., 1999. Characterizing interactions in fine magneticparticle systems using first-order reversal curves. Journal of Applied Physics 85,6660–6667.

Popov, S.V., Shcherba, I.G., Ilyina, L.B., Nevesskaya, L.A., Paramonova, N.P., Khondkarian,S.O., Magyar, I., 2006. Late Miocene to Pliocene palaeogeography of the Paratethys

and its relation to the Mediterranean. Palaeogeography, Palaeoclimatology, Palaeo-ecology 238, 91–106.

Popov, S.V., Antipov, M.P., Zastrozhnov, A.S., Kurina, E.E., Pinchuk, T.N., 2010. Sea-levelFluctuations on the Northern Shelf of the Eastern Paratethys in the Oligocene–Neogene. Stratigraphy and Geological Correlation 18 (2), 200–224.

Ramstein, G., Fluteau, F., Besse, J., Joussaume, S., 1997. Effect of orogeny, plate motionand land-sea distribution on Eurasian limate change over the past 30 millionyears. Nature 386, 788–795.

Reynolds, A.D., Simmons, M.D., Bowman, B.J., Henton, J., Brayshaw, A.C., Ali-Zade, A.A.,Guliyev, I.S., Suleymanova, S.F., Ateava, E.Z., Mamedova, D.N., Koshkarly, R.O., 1998.Implications of outcrop geology for reservoirs in the Neogene Productive Series:Apsheron Peninsula, Azerbaijan. AAPG Bulletin 82 (1), 25–49.

Rostovtseva, Y.V., Tesakov, E.M., 2009. Late Miocene ostracodes (Ostracoda, Crustacea)from the Enikal Strait (Eastern Paratethys) as indicators of salinity changes. Pale-ontological Journal 43 (2), 170–177.

Schneider, G.F., 1939. Miocene ostracod fauna of the Caucasus and Crimea (in Russian).Problemi paleontologhi, Leningrad — Moskva, 34, pp. 177–208.

Schornikov, E.I., 2011. Ostracoda of the Caspian origin in the Azov–Black Seas basin.Joannea Geol. Palaont., 11.

Schweyer, A.V., 1949. On the Pliocene Ostracoda of the Northern Caucases and LowerVolga Region. With some new data on the systematics of fossil ostracods. TrudyVesoyuznogo Neftyanogo Nauchno-Isseldovatelskogo Geologo-RazvedochnogoInstituta (VNIGRI), New Series, 30, pp. 9–68.

Souque, C., Fisher, Q.J., Casey, M., Bentham, P., 2010. Structural controls on mechanicalcompactionwithin sandstones: an example from the Apsheron Peninsula, Azerbaijan.Marine and Petroleum Geology 27, 1713–1724.

Steiniger, F.F., Rögl, F., 1984. Paleogeography and palinspastic reconstruction of theNeogene of the Mediterranean and Paratethys. Geological Society, London, SpecialPublications 17, 659–668.

Steiniger, F.F., Berggren, W.A., Kent, D.V., Bernor, R.L., Sen, S., Agustí, J., 1996. Circum-Mediterranean Neogene (Miocene and Pliocene) marine-continental chronologiccorrelations of European mammal units. In: Mittmann, H.-W. (Ed.), The Evolutionof Western Eurasian Neogene Mammal Faunas. Columbia Univ Press, New York.

Stoica,M., Lazar, I., Krijgsman,W., Vasiliev, I., Jipa, D.C., Floroiu, A., 2013. Palaeoenvironmentalevolution of the East Carpathian foredeep during the lateMiocene - early Pliocene(Dacian Basin; Romania). Global and Planetary Change 103, 135–148.

Suzin, A.V., 1956. Ostracoda from Tertiary deposits of the North Caucasus (in Russian).Gostoptekhizdat, Moscow. (191 pp.).

Torres, M.A., 2007. The petroleum geology of Western Turkmenistan: the Gograndag-Okarem Province. In: Yilmaz, P.O., Isaksen, G.H. (Eds.), Oil and Gas of the GreaterCaspian Area: AAPG Studies in Geology, pp. 109–132.

Trubikhin, V.M., 1989. Paleomagnetic data for Pontian. In: Stevanovic, P., Nevesskaya, L.A.,Marinescu, F., Sokac, A., Jambor, A. (Eds.), Chronostratigraphie und Neostratotypen-Pontien. Chronostratigraphie und Neostratotypen, Zagreb-Beograd, pp. 76–79.

Väinölä, R., Witt, J.D.S., Grabowski, M., Bradbury, J.H., Jadzewski, K., Sket, B., 2008. Glob-al diversity of amphipods (Amphipoda; Crustacea) in freshwater. Hydrobiologia595, 241–255.

Van Velzen, A.J., Zijderveld, J.D.A., 1995. Effects of weathering on single domain magne-tite in early Pliocene marls. Geophysical Journal International 121, 267–278.

Vandamme, D., 1994. A new method to determine paleosecular variation. Physics ofthe Earth and Planetary Interiors 85, 131–142.

Vasiliev, I., Krijgsman, W., Langereis, C.G., Panaiotu, C.E., Matenco, L., Bertotti, G., 2004.Towards an astrochronological framework for the eastern Paratethys Mio-Pliocenesedimentary sequences of the Focsani basin (Romania). Earth and Planetary Sci-ence Letters 227, 231–247.

Vasiliev, I., Dekkers, M.J., Krijgsman, W., Franke, C., Langereis, C.G., Mullender, T.A.T.,2007. Early diagenetic greigite as a recorder of the paleomagnetic signal in Mio-cene–Pliocene sedimentary rocks of the Carpathian foredeep (Romania). Geophys-ical Journal International 171, 613–629.

Vasiliev, I., Franke, C., Meeldijk, J.D., Dekkers, M.J., Langereis, C.G., Krijgsman, W., 2008.Putative greigite magnetofossils from the Pliocene epoch. Nature Geoscience 11,782–786.

Vasiliev, I., De Leeuw, A., Filipescu, S., Krijgsman, W., Kuiper, K.F., Stoica, M., Briceag, A.,2010. The age of the Sarmatian–Pannonian transition in the Transylvanian Basin(Central Paratethys). Palaeogeography, Palaeoclimatology, Palaeoecology 297 (1),54–69.

Vekua, M.L., 1975. The ostracods of the Kimmerian and Kujalinikian deposits of Abkha-zia and their stratigraphic significance (in Russian). Academia Nauc Gruzinskoi SSREd. Metzniereba, Tibilisi, 137 pp.

Vincent, S.J., Davies, C.E., Richards, K., Aliyeva, E., 2010. Contrasting Pliocene fluvial de-positional systems within the rapidly subsiding South Caspian Basin; a case studyof the palaeo-Volga and palaeo-Kura river systems in the Surakhany Suite, UpperProductive Series, onshore Azerbaijan. Marine and Petroleum Geology 27 (10),2079–2106.

Zubakov, V.A., 2001. History and causes of variations in the Caspian Sea level: theMiopliocene, 7.1–1.95 million years ago. Water Resources 28 (3), 249–256.

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