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7. Sediment distribution pattern of the South Caspian Sea: possible hydroclimatic implications

Author

Lahijani, H.A.K., Abbasian, H., Beni, A. Naderi, Leroy, S.A.G., Haghani, S., Habibi, P., Hosseindust, M., Shahkarami, S., Yeganeh, S., Zandinasab, Z., Tavakoli, V., Vahabi-Asil, F., Azizpour, J., Sayed-Valizadeh, M., Pourkerman, M., and Shah-Hosseini, M.

Subjects
Basins (Geology) -- Analysis -- Natural history, Terrigenous sediments -- Analysis -- Distribution, Geomorphology -- Analysis, Company distribution practices, Earth sciences
Abstract

The south Caspian subbasin extends from the foot of the Alborz Mountains to the deepest part of Caspian Sea. The lithological background and tectonic setting of the study area primarily control the deposition of thick sedimentary sequences of the basin, while hydroclimatic processes exert secondary impacts on the sediment distribution pattern. To evaluate past hydroclimatic changes, short sediment cores were retrieved from the continental shelf and upper slope of the south Caspian Sea and were treated for basic sedimentological properties and mineralogy. The results show that the sediments are composed of terrigenous, biogenic, and chemical components. The chemical component has a significant signature in the internal structure of the sediment, which reflects degradation of organic material due to a succession of aerobic and anaerobic conditions. Aerobic conditions reflect the extreme climatic conditions that lead to formation of well-oxygenated deep water in lowstands and extremely cold winters, when dense oxygenated water is allowed to touch the bottom sediments. The sediment distribution pattern demonstrates three distinctive areas in the southern continental margin with different organic matter and carbonate content. Fluvial inputs and wave hydrodynamics control the sediment properties and their distribution pattern in the upper shelf, while in deeper parts, the dynamics of water stratification and its temporal and long-term variations, relating to climate and water level changes, determine sediment composition. Overall, the sedimentary distribution pattern is a result of their sources in the catchment basin and the hydroclimate of the Caspian Sea. Key words: Caspian Sea, climate change, continental margin, deep-sea ventilation, sea level. Le sous-bassin Caspien meridional s'etend du pied des montagnes Alborz jusqu'a la partie la plus profonde de la mer Caspienne. Le contexte lithologique et le milieu tectonique de la region a l'etude sont les principaux contrôles du depôt d'epaisses sequences sedimentaires du bassin, des processus hydroclimatiques exerçant des influences secondaires sur la repartition des sediments. Afin d'evaluer les changements hydroclimatiques passes, de courtes carottes de sediments ont ete prelevees de la plateforme continentale et de la pente superieure de la mer Caspienne meridionale et ont fait l'objet d'analyses pour en determiner les proprietes sedimentologiques et la mineralogie. Les resultats montrent que les sediments sont composes de fractions terrigenes, biogenes et chimiques. La composante chimique est importante dans la structure interne des sediments, refletant une degradation de la matiere organique causee par une succession de conditions aerobies et anaerobies. Les conditions anaerobies refletent des conditions climatiques extrêmes qui menent a la formation d'eau profonde bien oxygenee durant des niveaux bas et des hivers extrêmement froids, quand l'eau oxygenee dense peut atteindre les sediments du fond marin. La repartition des sediments indique trois zones distinctes dans la marge continentale meridionale caracterisees par differents contenus en matiere organique et en carbonates. Les apports fluviaux et l'hydrodynamique des vagues contrôlent les proprietes des sediments et leur repartition sur la plateforme superieure, alors que, dans les zones plus profondes, la dynamique de la stratification de l'eau et ses variations temporelles a plus ou moins long terme reliees aux changements climatiques et du niveau de l'eau determinent la composition des sediments. Globalement, le motif de repartition des sediments est le resultat de leurs sources dans le bassin versant et de l'hydroclimat de la mer Caspienne. [Traduit par la Redaction] Mots-cles: mer Caspienne, changement climatique, marge continentale, ventilation du fond marin, niveau de la mer, [gamma]-globine., Introduction The Caspian Sea (CS) as a remnant basin of the Paratethys ancient ocean is the largest landlocked water body in the world (Lerche et al. 1997; Kosarev 2005). Its [...]

Published
2019
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22. Role of substrate on the dendroclimatic response of Scots pine from varying elevations in northern Scotland

Author

Moir, A.K., Leroy, S.A.G., and Helama, S.

Subjects
Pine -- Environmental aspects -- Physiological aspects, Climate -- Environmental aspects, Growth (Plants) -- Research, Earth sciences
Abstract

The influence of substrate was evaluated by comparing annual ring widths of Scots pine (Pinus sylvestris L.) with climate data at 13 new sites (five bog, three peat, and five soil), together with 17 previously studied soil sites in northern Scotland. Radial growth rates < 1.0 and > 1.5 mm x [year.sup.-1] differentiate well between pine growing on bog and peat, respectively, highlighting the role of pine as a indicator of water levels in these environments. Scots pine chronologies from bog are shown to have a weak temperature-growth response and so limit potential in dendroclimatic reconstructions. How-ever, correlation analysis shows temperature in January-February and July-August to be important determinants of the radial growth of Scots pine on soil. Moving correlation analysis indicates that the relationship between the radial growth of pine on soil near the altitudinal tree line and summer temperature (July-August) is time stable, despite an increase of temperature in northern Scotland. However, winter (January-February) temperature has become less limiting since the 1920s. Scots pine at some soil, bog, and peat sites have increased or developed correlation with October temperature since the 1940s, suggesting an extension of the growth season, particularly on the western coast of Scotland. Resume: L'influence du substrat a ete evaluee en comparant la largeur des cernes annuels du pin sylvestre (Pinus sylves-tris L.) aux donnees climatiques provenant de 13 nouvelles stations (cinq tourbieres, trois tourbes et cinq sols) et de 17 stations precedemment etudiees au nord de l'Ecosse. Des taux de croissance radiale inferieurs a 1,0 mm x [an.sup.-1] et superieurs a 1,5 mm x [an.sup.-1] distinguent adequatement les pins croissant respectivement dans les tourbieres et les tourbes, ce qui met en evidence le role du pin comme indicateur de la hauteur de la nappe phreatique dans ces milieux. Les series chronologiques du pin sylvestre etabli dans les tourbieres revelent une faible reaction de croissance en fonction de la temperature et ont, par consequent, un potentiel limite pour les reconstitutions dendroclimatiques. Cependant, une analyse de correlation montre que la croissance radiale du pin sylvestre etabli sur des sols est fortement liee aux temperatures de janvier a fevrier et de juillet a aout. Une analyse de correlation mobile indique que la relation entre la croissance radiale du pin etabli sur des sols pres de la limite altitudinale des arbres et la temperature estivale (juillet et aout) est stable dans le temps malgre une hausse de la temperature dans le nord de l'Ecosse. Toutefois, la temperature hivernale (janvier et fevrier) est devenue moins limitative depuis les annees 1920. La correlation entre la croissance du pin sylvestre etabli sur certains sols, dans des tourbieres et des tourbes et la temperature d'octobre s'est accrue ou s'est developpee depuis les annees 1940, ce qui indique un allonge-ment de la saison de croissance, particulierement sur la cote ouest de l'Ecosse. [Traduit par la Redaction], Introduction The peatlands of northern Scotland are one of the largest and most intact areas of blanket bog in the world. Pinus pollen (Birks 1975) and widespread occurrence of subfossil [...]

Published
2011
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30. Pollen-derived biomes in the Eastern Mediterranean–Black Sea–Caspian-Corridor

Author

Marinova, E. Harrison, S.P. Bragg, F. Connor, S. de Laet, V. Leroy, S.A.G. Mudie, P. Atanassova, J. Bozilova, E. Caner, H. Cordova, C. Djamali, M. Filipova-Marinova, M. Gerasimenko, N. Jahns, S. Kouli, K. Kotthoff, U. Kvavadze, E. Lazarova, M. Novenko, E. Ramezani, E. Röpke, A. Shumilovskikh, L. Tanţǎu, I. Tonkov, S.

Abstract

Aim: To evaluate the biomization technique for reconstructing past vegetation in the Eastern Mediterranean–Black Sea–Caspian-Corridor using an extensive modern pollen data set and comparing reconstructions to potential vegetation and observed land cover data. Location: The region between 28–48°N and 22–62°E. Methods: We apply the biomization technique to 1,387 modern pollen samples, representing 1,107 entities, to reconstruct the distribution of 13 broad vegetation categories (biomes). We assess the results using estimates of potential natural vegetation from the European Vegetation Map and the Physico-Geographic Atlas of the World. We test whether anthropogenic disturbance affects reconstruction quality using land use information from the Global Land Cover data set. Results: The biomization scheme successfully predicts the broadscale patterns of vegetation across the region, including changes with elevation. The technique discriminates deserts from shrublands, the prevalence of woodlands in moister lowland sites, and the presence of temperate and mixed forests at higher elevations. Quantitative assessment of the reconstructions is less satisfactory: the biome is predicted correctly at 44% of the sites in Europe and 33% of the sites overall. The low success rate is not a reflection of anthropogenic impacts: only 33% of the samples are correctly assigned after the removal of sites in anthropogenically altered environments. Open vegetation is less successfully predicted (33%) than forest types (73%), reflecting the under-representation of herbaceous taxa in pollen assemblages and the impact of long-distance pollen transport into open environments. Samples from small basins (

Published
2018

31. Realising consilience: How better communication between archaeologists, historians and natural scientists can transform the study of past climate change in the Mediterranean

Author

Izdebski, A. Holmgren, K. Weiberg, E. Stocker, S.R. Büntgen, U. Florenzano, A. Gogou, A. Leroy, S.A.G. Luterbacher, J. Martrat, B. Masi, A. Mercuri, A.M. Montagna, P. Sadori, L. Schneider, A. Sicre, M.-A. Triantaphyllou, M. Xoplaki, E.

Abstract

This paper reviews the methodological and practical issues relevant to the ways in which natural scientists, historians and archaeologists may collaborate in the study of past climatic changes in the Mediterranean basin. We begin by discussing the methodologies of these three disciplines in the context of the consilience debate, that is, attempts to unify different research methodologies that address similar problems. We demonstrate that there are a number of similarities in the fundamental methodology between history, archaeology, and the natural sciences that deal with the past ("palaeoenvironmental sciences"), due to their common interest in studying societal and environmental phenomena that no longer exist. The three research traditions, for instance, employ specific narrative structures as a means of communicating research results. We thus present and compare the narratives characteristic of each discipline; in order to engage in fruitful interdisciplinary exchange, we must first understand how each deals with the societal impacts of climatic change. In the second part of the paper, we focus our discussion on the four major practical issues that hinder communication between the three disciplines. These include terminological misunderstandings, problems relevant to project design, divergences in publication cultures, and differing views on the impact of research. Among other recommendations, we suggest that scholars from the three disciplines should aim to create a joint publication culture, which should also appeal to a wider public, both inside and outside of academia. © 2015 The Authors.

Published
2016

33. Realising consilience: How better communication between archaeologists, historians and natural scientists can transform the study of past climate change in the Mediterranean

Author

Izdebski, A., Holmgren, K., Weiberg, E., Stocker, S.R., Büntgen, U., Florenzano, Assunta, Gogou, A., Leroy, S.A.G., Luterbacher, J., Martrat, Belen, Masi, A., Mercuri, A.M., Montagna, P., Sadori, L., Schneider, A., Sicre, M.A., Triantaphyllou, M., Xoplaki, E., Izdebski, A., Holmgren, K., Weiberg, E., Stocker, S.R., Büntgen, U., Florenzano, Assunta, Gogou, A., Leroy, S.A.G., Luterbacher, J., Martrat, Belen, Masi, A., Mercuri, A.M., Montagna, P., Sadori, L., Schneider, A., Sicre, M.A., Triantaphyllou, M., and Xoplaki, E.

Abstract

This paper reviews the methodological and practical issues relevant to the ways in which natural scientists, historians and archaeologists may collaborate in the study of past climatic changes in the Mediterranean basin. We begin by discussing the methodologies of these three disciplines in the context of the consilience debate, that is, attempts to unify different research methodologies that address similar problems. We demonstrate that there are a number of similarities in the fundamental methodology between history, archaeology, and the natural sciences that deal with the past ("palaeoenvironmental sciences"), due to their common interest in studying societal and environmental phenomena that no longer exist. The three research traditions, for instance, employ specific narrative structures as a means of communicating research results. We thus present and compare the narratives characteristic of each discipline; in order to engage in fruitful interdisciplinary exchange, we must first understand how each deals with the societal impacts of climatic change. In the second part of the paper, we focus our discussion on the four major practical issues that hinder communication between the three disciplines. These include terminological misunderstandings, problems relevant to project design, divergences in publication cultures, and differing views on the impact of research. Among other recommendations, we suggest that scholars from the three disciplines should aim to create a joint publication culture, which should also appeal to a wider public, both inside and outside of academia.

Published
2016

36. A comparison of climate simulations for the last glacial maximum with three different versions of the ECHAM model and implications for summer-green tree refugia

Author

Arpe, K., Leroy, S.a.g., and Mikolajewicz, U.

Subjects
lcsh:GE1-350, lcsh:Environmental pollution, lcsh:Environmental protection, lcsh:TD172-193.5, lcsh:TD169-171.8, lcsh:Environmental sciences
Abstract

Model simulations of the last glacial maximum (21 ± 2 ka) with the ECHAM3 T42 atmosphere-only, ECHAM5-MPIOM T31 atmosphere-ocean coupled and ECHAM5 T106 atmosphere-only models are compared. The topography, land-sea mask and glacier distribution for the ECHAM5 simulations were taken from the Paleoclimate Modelling Intercomparison Project Phase II (PMIP2) data set while for ECHAM3 they were taken from PMIP1. The ECHAM5-MPIOM T31 model produced its own sea surface temperatures (SST) while the ECHAM5 T106 simulations were forced at the boundaries by this coupled model SSTs corrected from their present-day biases and the ECHAM3 T42 model was forced with prescribed SSTs provided by Climate/Long-Range Investigation, Mapping, and Prediction project (CLIMAP). The SSTs in the ECHAM5-MPIOM simulation for the last glacial maximum (LGM) were much warmer in the northern Atlantic than those suggested by CLIMAP or Overview of Glacial Atlantic Ocean Mapping (GLAMAP) while the SSTs were cooler everywhere else. This had a clear effect on the temperatures over Europe, warmer for winters in western Europe and cooler for eastern Europe than the simulation with CLIMAP SSTs. Considerable differences in the general circulation patterns were found in the different simulations. A ridge over western Europe for the present climate during winter in the 500 hPa height field remains in both ECHAM5 simulations for the LGM, more so in the T106 version, while the ECHAM3 CLIMAP-SST simulation provided a trough which is consistent with cooler temperatures over western Europe. The zonal wind between 30° W and 10° E shows a southward shift of the polar and subtropical jets in the simulations for the LGM, least obvious in the ECHAM5 T31 one, and an extremely strong polar jet for the ECHAM3 CLIMAP-SST run. The latter can probably be assigned to the much stronger north-south gradient in the CLIMAP SSTs. The southward shift of the polar jet during the LGM is supported by palaeo-data. Cyclone tracks in winter represented by high precipitation are characterised over Europe for the present by a main branch from the British Isles to Norway and a secondary branch towards the Mediterranean Sea, observed and simulated. For the LGM the different models show very different solutions: the ECHAM3 CLIMAP-SST simulation shows just one track going eastward from the British Isles into central Europe, while the ECHAM5 T106 simulation still has two branches but during the LGM the main one goes to the Mediterranean Sea, with enhanced precipitation in the Levant. This agrees with an observed high stand of the Dead Sea during the LGM. For summer the ECHAM5 T106 simulation provides much more precipitation for the present over Europe than the other simulations, thus agreeing with estimates by the Global Precipitation Climatology Project (GPCP). Also during the LGM this model makes Europe less arid than the other simulations. In many respects the ECHAM5 T106 simulation for the present is more realistic than the ECHAM5 T31 coupled simulation and the older ECHAM3 T42 simulation, when comparing them with the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis or the GPCP precipitation data. For validating the model data for the LGM, pollen, wood and charcoal analyses were compared with possible summer-green tree growth from model estimates using summer precipitation, minimum winter temperatures and growing degree days (above 5 °C). The ECHAM5 T106 simulation suggests for more sites with findings of palaeo-data, likely tree growth during the LGM than the other simulations, especially over western Europe. The clear message especially from the ECHAM5 T106 simulation is that warm-loving summer-green trees could have survived mainly in Spain but also in Greece in agreement with findings of pollen or charcoal. Southern Italy is also suggested but this could not be validated because of absence of palaeo-data. Previous climate simulations of the LGM have suggested less cold and more humid climate than that reconstructed from pollen findings. Our model results do agree more or less with those of other models but we do not find a contradiction with palaeo-data because we use the pollen data directly without an intermediate reconstruction of temperatures and precipitation from the pollen spectra.

Published
2011

37. Late Pleistocene and Holocene sea-level change and coastal paleoenvironment evolution along the Iranian Caspian shore

Author

Kakroodi, A.A. (author), Leroy, S.A.G. (author), Kroonenberg, S.B. (author), Lahijani, H.A.K. (author), Alimohammadian, H. (author), Boomer, I. (author), Goorabi, A. (author), Kakroodi, A.A. (author), Leroy, S.A.G. (author), Kroonenberg, S.B. (author), Lahijani, H.A.K. (author), Alimohammadian, H. (author), Boomer, I. (author), and Goorabi, A. (author)

Abstract

The level of the Caspian Sea is influenced by rivers mostly from the high latitudes of the Northern hemisphere and therefore any change of its catchments including temperature and precipitation directly reflects on Caspian Sea-level. We reconstructed Late Pleistocene to Holocene Caspian Sea-level by a multi-disciplinary approach from a 27.7 m long core in the SE corner of the Iranian Caspian coast in the Gomishan Lagoon. Late Pleistocene deposits containing typical Pleistocene fauna and dated around 20,120 cal yr BP bordered with a major hiatus indicating sea-level fall. Lagoonal deposits with shells dated at around 10,590 cal yr BP suggest that, after this deep lowstand, an initial transgression started, leading to landward advance of barrier–lagoon systems which still continued without any lowstand until 8400 cal yr BP. This corresponded to a biofacies change from lagoonal to the deeper biofacies including diatom and Gastropoda species. Around 8400 cal yr BP sea-level started to fall again, and reddish oxidized sediments with abundant foraminifera (Ammonia beccarii) record a regressive phase around 7700 cal yr BP. The mid-Holocene between 15.7 and 4.9 depths is characterized by a shallow marine environment mostly with high carbonate and gypsum contents, and lagoonal and highstand tract with no subaerial facies. The upper part of the core above a 4.9 m depth reflects at least five Late Holocene Caspian Sea-level cycles from 3260 cal yr BP onward. The Caspian Sea-levels are influenced both by global and regional events., Geoscience & Engineering, Civil Engineering and Geosciences

Published
2015
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38. Dinocyst assemblages and water surface conditions in the Sea of Marmara during MIS 6 and 5 from two long cores.

Author

Leroy, S.A.G., Henry, P., Marret, F., Pailles, C., Licari, L., Kende, J., Rostek, F., and Bard, E.

Subjects
*SAPROPEL, *FOSSIL microorganisms, *SEAWATER, *DINOFLAGELLATE cysts, *WATER levels, *PALYNOLOGY, *WATER depth
Abstract

The Sea of Marmara is the connection between the vast Black Sea-Caspian Sea basin (Pontocaspian) and the Global Ocean via the Mediterranean Sea. Its water levels and water conditions has widely varied over times. Combining two cores in the Sea of Marmara (Turkey) and using organic-walled dinoflagellate cyst assemblages as the main proxy (combined with alkenones, diatoms and benthic foraminifera), allow qualitatively reconstructing water conditions during Marine Isotopic Stage (MIS) 6 and 5, such as salinity and oxygen level. A clear main marine phase is illustrated in MIS 5e. A minor marine incursion occurred during MIS 5c, mostly supported by alkenone data. The rest of the record indicates brackish Pontocaspian conditions, with more Spiniferites inaequalis in MIS 6 and more S. cruciformis in the non-marine parts of MIS 5. At the MIS 6/MIS 5 transition, an earlier initial marine flooding in the Sea of Marmara (dinocyst assemblages) in comparison to the Black Sea was highlighted. The marine reconnection occurred at different moments as seen in the terrestrial vegetation reconstructed from pollen analysis linking the two seas. The sapropels of the Sea of Marmara form when marine water penetrates at depth from the Aegean Sea beneath a layer of lower salinity water. Variations of the residence time of the marine deep water in a stratified Sea of Marmara are potentially an important factor underlying hypoxia/anoxia and sapropel deposition. When combining surface water proxies with benthic foraminifera (test assemblages and presence of inner organic lining), it appears that the successive MIS 5 sapropels formed under decreasing salinity and oxygen availability conditions as the marine inflow was increasingly restricted. Understanding the hydrologic evolution of the Sea of Marmara during MIS 5 implies taking into account that the Bosphorus and Dardanelle straits are hydrodynamically coupled and may not be simplified as on/off switches based on present day sill depths. • Dinocyst analyses of last interglacial and previous glacial in the Sea of Marmara on two long cores. • Marine phase in MIS5e (dinocysts, benthic foraminifera, alkenones) minor in MIS5c • BrackishPontocaspian conditions for rest of sequence although different in MIS6 & 5. • Earlier marine flooding at beginning of MIS5e in Sea of Marmara than in Black Sea. • Three sapropels highlight decreasing anoxic conditions over time. [ABSTRACT FROM AUTHOR]

Published
2023
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39. Holocene vegetation history and sea level changes in the SE corner of the Caspian Sea: Relevance to SW Asia climate

Author

Leroy, S.A.G. (author), Kakroodi, A.A. (author), Kroonenberg, S. (author), Lahijani, H.K. (author), Alimohammadian, H. (author), Nigarov, A. (author), Leroy, S.A.G. (author), Kakroodi, A.A. (author), Kroonenberg, S. (author), Lahijani, H.K. (author), Alimohammadian, H. (author), and Nigarov, A. (author)

Abstract

The palynological investigation of core TM (27.7 m long) taken in a dried out lagoon reveals both Holocene vegetation history in the north-eastern foothills of the Alborz Mountains and past water level changes of the Caspian Sea (CS). The delay in woodland expansion at the beginning of the Holocene, which is typical of eastern Turkey, the Iranian plateau and recorded in the CS south basin, is only weakly felt as the region is close to glacial refugia of trees. The succession of the main trees out of their refugia has been established as deciduous Quercus, Carpinus betulus, Parrotia persica, and Fagus orientalis-Pterocarya fraxinifolia, presenting therefore close affinities to south European interglacials of the Early Pleistocene. This suggests a similarity in climate. A Pterocarya decline is observed after AD 495. The studied region is close to the easternmost tree distribution; this could explain why it has been affected earlier than elsewhere in the northern Alborz and the Caucasus. In addition human activities during the Sasanian Empire and the subsequent drying of the climate contributed to weakening the spread of this tree. A maximal sea level occurs in the first part of the Holocene from 10.6 to 7.2 cal. ka. It is suggested that the CS levels were significantly influenced by the monsoon precipitations over the western Himalayas (via the Uzboy inflow). This is followed by low levels from 7.2 to 3.5 cal. ka with a minimum at 3.9 cal. ka. The Neocaspian period should be considered a biozone rather than a chronozone, as the environmental conditions reconstructed from dinocyst assemblages are different in shallow shelf waters and in the deep basins., Geoscience & Engineering, Civil Engineering and Geosciences

Published
2013
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41. Dark Nature

Author

Leroy, S.A.G., primary, Michetti, A.M., additional, and Pasquaré, F.A., additional

Published
2007
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42. Boron content of Lake Ulubat sediment: a key to interpret the morphological history of NW Anatolia, Turkey.

Author

Kazanci N., Costa P., Emre O., Erturac K., Ileri O., Leroy S.A.G., McGee E., Oncel S., Toprak O., Kazanci N., Costa P., Emre O., Erturac K., Ileri O., Leroy S.A.G., McGee E., Oncel S., and Toprak O.

Abstract

The lake receives sediment from a 10 414 km2 area in the seismically active Susurluk drainage basin. Radionuclide data indicate that deposition has been 1.60 cm/a for the last 50 years, but C-14 dating suggests a sedimentation rate over the last millennium of 0.37 cm/a. The B content of the lacustrine infill displays a slight increase at 0.50 m and a drastic increase at 4 m depth, occurring about 31 and 1 070 years ago respectively. The topmost change probably corresponded to the start of open-cast mining in the basin and the second one to the natural trenching of borate ores, which are easily dissolved in fresh water, from the 0-100 m thick borate zone with its layers of colemanite, colemanite nodules or colemanite and hydroborasite interspersed with clays, marls and tuffs. The dates also show indirectly a 1.4 cm/a erosion rate during the last millennium as the borate beds were trenched to depths of up to 15 m. Extrapolation of the data indicates that river incision in the southern Marmara region began in the late Pleistocene and developed particularly over the last 75 ka., The lake receives sediment from a 10 414 km2 area in the seismically active Susurluk drainage basin. Radionuclide data indicate that deposition has been 1.60 cm/a for the last 50 years, but C-14 dating suggests a sedimentation rate over the last millennium of 0.37 cm/a. The B content of the lacustrine infill displays a slight increase at 0.50 m and a drastic increase at 4 m depth, occurring about 31 and 1 070 years ago respectively. The topmost change probably corresponded to the start of open-cast mining in the basin and the second one to the natural trenching of borate ores, which are easily dissolved in fresh water, from the 0-100 m thick borate zone with its layers of colemanite, colemanite nodules or colemanite and hydroborasite interspersed with clays, marls and tuffs. The dates also show indirectly a 1.4 cm/a erosion rate during the last millennium as the borate beds were trenched to depths of up to 15 m. Extrapolation of the data indicates that river incision in the southern Marmara region began in the late Pleistocene and developed particularly over the last 75 ka.

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