The Role of Neo-Tectonics in the Variation of the Relative Mean Sea Level Throughout the Last 6000 Years on the Taman Peninsula (Black Sea, Azov Sea, Russia)
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Polish Geological Institute Special Papers, 11 (2004): 47–58 Proceedings of the Conference “Rapid transgressions into semi-enclosed basins” THE ROLE OF NEO-TECTONICS IN THE VARIATION OF THE RELATIVE MEAN SEA LEVEL THROUGHOUT THE LAST 6000 YEARS ON THE TAMAN PENINSULA (BLACK SEA, AZOV SEA, RUSSIA) Eric FOUACHE1, Alexei POROTOV2, Christel MÜLLER3, Youri GORLOV4 Abstract. Sediments, carbon-datings on seashells, allow us to reconstruct the evolution of the average sea level for some 6000 years on the Taman Peninsula. The current sea level, regionally, appears to be the highest level ever reached on the pen- insula. It seems that for the Anapa area and Tchouchtchka Spit area it is possible to propose a sea level curve characterised by a slow, continuous rising during the past 6000 years. On the Taman Peninsula itself, the sedimentary record of this slow ascent has been distorted by a heavy tectonic subsidence. We have identified this neo-tectonic subsidence effect on at least two areas on the peninsula. The south of the peninsula, Burgaz Spit and Vityazevos Lagoon, is the most affected area. The Taman Gulf is an intermediate area. The tectonic subsidence is particularly noticeable from 1500 to 500 BC, which we believe to have been misinterpreted until now, and to be at the origin of the notion of “Phanagorian Regression”. Key words: sea level, geo-archaeology, neo-tectonics, Holocene, Black Sea, Russia. INTRODUCTION According to the results of studies over the last thirty years, Peninsula was composed of one main island and four islets it seems that the Holocene transgression in the Black Sea, during the time of Grecian colonisation in the 6th century BC which starts later than the global ocean evolution around 7500 (Fouache et al., 2000a). With the deposit of its alluvium, its BP (Ryan, Pitman, 1998), was characterised by a succession of successive changes of course and the progradation of its delta, rapid sea level fluctuations (Pirazzoli, 1991; Ismailov et al., the Kuban River is at the origin of the attachment of the is- 1989). Those fluctuations (Fig. 1) have been related mostly to lands to dry land. But this attachment came late, during climatic changes during the Holocene and the possible distor- the Late Antiquity or the Early Middle Ages. Greek colonis- tion due to the neo-tectonic factor has been neglected. The new ation founded settlements such as Hermonassa, Phanagoria, data we obtained on the Taman Peninsula (Fig. 2) confirm the Kepoi and Patrasys, to name but the most important ones, and importance of the neo-tectonic effect. these cities were still in activity until the 4th century AD and The results presented here have been obtained within the war against the Scythians. Our reconstruction confirms the frame of the Franco/Russian archaeological survey of the models proposed by Nevesky (1958) (Fig. 3). One ques- the Taman Peninsula, directed by Christel Müller and Youri tion remains in this reconstruction: what about the extension Gorlov. This survey is the result of a partnership between the of beach-barriers and spits all along this period? We decided Russian Academy of Sciences, the French School of Archae- to carry out a core programme on different beaches of the pen- ology in Athens, the “Black Sea” GDR and the French Minis- insula to identify palaeobeaches facies and to obtain radiocar- try of Foreign Affairs. The first objective of our palaeogeo- bon datings. Our objective was also to obtain sea level curves graphical study was to prove that the extremity of the Taman with these data. 1 Université de Paris XII, IUF, EA 435, 61 avenue du Général de Gaulle, 94010 Créteil, France; e-mail: [email protected] 2 Geography Faculty, Moscow State University 3 Université de Paris I, École Française d’AthÀnes 4 Institute of Archaeology, Russian Academy of Sciences 48 Eric Fouache et al. Fig. 1. Reconstruction of Holocene sea level fluctuations in Black Sea (adapted after Pirazzoli, 1991) N historical and Holocene sand barrier and spit -10 -10 historical and Holocene alluvial filling T historical and Holocene I -11 -9 P Azov Sea limans S A 89 K 60 historical and Holocene H 40 63 C lagoons T -8 H 20 -11 C S3 Pliocene rock (mainly sand U O -0,2 20 and clay) H 40 C -2 -7 T -0,2 70 113 Miocene rock (mainly sand The role of neo-tectonics in the variation of the relative mean sea level... 49 -0,8 99 Ty ra m b e and clay) Kerch 10 12 5,2 -4 5 3,4 colluvial glacis and lower 5 2,9 p 50 o slope spreading Gulf -2 1,9 107 114 Pa tra sys s -0,6 Artanizovski t -4,6 of -5 Ke p o• 40 14 1 -3 8 height spot -1,8 Phanagoria lim a n S8 76 6,2 7 72 S7 S9 20 0 Ta m a n -1,8 -5 -5,4 actual or former channel -5,2 29 69 of the Kouban river -5,4 15,2 5 3,6 He rm o n a ssa -0,2 5 Temrjuk -3 20 6,6 1,3 a 20 active cliff, 40 nte more than 20 m high 5 164 113 20 1 9,5 870 121 active cliff, 40 14,8 14 less than 20 m high 5,2 5,2 S1 historical and Holocene 9,9 10,3 135 4,2 coastal marshes 4,2 14,2 1 20 184 130 dead mud volcano 20 40 88 Kizilta sc h 106 148 lagoon 141 active mud volcano S2 B UR G AZ flexure SPI T 20 supposed fault UKRAINA RUSSIA S4 40 anticlinal axes Azov Sea A 162 CRIMEA NA 177 Ko P C u A 2 longshore drift A b S U P C a I T A n S Bla c k Se a U S S6 archaeological site Bla k Se a S5 S2 location of the cores Gorgippia TURKEY 0 10 km (equidistance: 20 m) Anapa Conception : E.FOUACHE Realisation : F. BONNAUD - Paris -Sorbonne - 1997 Fig. 2. Geomorphological map of the Taman Peninsula 50 Eric Fouache et al. Fig. 3. Possible reconstruction of sea-shore IX to V century BC (adapted from Nevesky, 1958) GEOLOGICAL SETTING The Taman Peninsula (Fig. 2), situated to the south of Rus- the largest of which are over 100 m high and occupy the highest sia, is located at the end of the Western part of Caucasus. point of the topography. The formations of which it is made are to be found on the other The general features of the geological structure of the Taman side of the Kerch Strait in the Crimea. These formations are Peninsula are defined by its disposition in the area of contact be- made up of Miocene and Pliocene rocks, essentially clay, sands tween the folded structure of the Caucasus and mountainous Cri- and very occasionally chalk (Touzla Cape or Achileion Cape). mea. According to the recent geological data (Chniukov et al., These rocks were deposited on the bottom of a sea, in the posi- 1981; Andreev et al., 1981; Peklo et al., 1974; Naumenko, tion of a retro-arc basin which stretched from the north of the 1977), this area includes several tectonic zones (Fig. 4). The Viennese Carpathians to the present Black Sea. The Alpine northern Taman zone (IIa, Fig. 4) is linked with the uplifting orogenesis, through its compressive tectonics originated the movement of Crimea’s mega-anticlinorium. The Anapa promi- emergence of these rocks, of their folding along the anticlinal nence (III, Fig. 4) is in the same type of uplifting context due to and synclinal WSW/ENE axes and the group of NNE/SSW the proximity of the Caucasus. Between these two areas, the faults (Chnioukov et al., 1981). The current relief of the Taman Kerch–Taman inter-periclinal trough is located (II, Fig. 4). Peninsula is the result of the evolution in the open air of folded Tectonic faults are superimposed on this general feature ridges since the end of Pliocene. The folded ridges have been (Plachotny et al., 1989). On the base of geophysical, geological levelled (Blagovolin, 1962; Blagovolin, Pobedonostsev, and geomorphological data, the Taman area comprises several 1973), which explains the extension of plateaux eroded into blocks limited by a number of local and regional faults (Fig. 5) cliffs. Along the anticlinal axes diapirism has caused, since as of sublatitudinal and submeridional directions. Three principal early as the end of the Pliocene, alignments of mud volcanoes blocks are observed from west to east: the Kertch/Gdanovsky, (Chnioukov et al., 1981), giving birth to eruptive cones, the Vishestebleevsky and the Djiginsky areas. The role of neo-tectonics in the variation of the relative mean sea level... 51 Fig. 4. General features of geological Azov Sea structure of Kerch–Taman region V II IIa Taman Peninsula Crimea III I IV Black Sea The boundary of principle tectonic features I Mega-anticlinorium of Crimea local anticline structures II Kerch periclinorium IIa Northern Taman Raising location of Indol-Kouban foredeep trough Ill Kerch–Taman inter-periclinal trough IV Anapa prominence present shoreline V Indol–Kouban foredeep trough Fig. 5. Regional pattern of tectonic structure Kerch–Taman region 52 Eric Fouache et al. METHOD For this study we have drilled six boreholes (Fig. 2) on S9). Due to practical reasons, we were obliged to collect sam- the peninsula down to 12 metres deep: one in the Kouban delta ples on the field and to determine the stratigraphy and lithology (S1), one on the Burgaz Spit (S2), one on the Tchouchtchka on the spot.