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Lower–Middle Miocene successions from Kütahya province (Seyitömer and Tunçbilek sub-basins) were analyzed to reconstruct the palaeoclimate and vegetation of the period. A rich coniferous forest formed the dominant components among sporomorphs and consisted mainly of undeterminable Pinaceae, Pinus haploxylon type, Pinus diploxylon type, Picea, Cedrus, Cathaya, Keteleeria and Podocarpus.
Turkish Journal of Earth Sciences (Turkish J Earth Sci.),M.Vol 21, 2012, pp Copyright ©TÜBİTAK S AKKİRAZ ET213–235 AL doi:10.3906/yer-1007-45 First published online 15 February 2011 Palaeoflora and Climate of Lignite-bearing LowerMiddle Miocene Sediments in the Seyitửmer and Tunỗbilek Sub-basins, Kỹtahya Province, Northwest Turkey MEHMET SERKAN AKKİRAZ1, FUNDA AKGÜN2, TORSTEN UTESCHER3, VOLKER WILDE4, ANGELA ANNELIESE BRUCH4, VOLKER MOSBRUGGER4 & SARİYE DUYGU ÜÇBAŞ1 Dumlupınar University, Department of Geological Engineering, TR−43270 Kütahya, Turkey (E mail: serkanakkiraz@dpu.edu.tr) Dokuz Eylül University, Department of Geological Engineering, Buca, Tınaztepe Campus, TR−35160 İzmir, Turkey Institute für Geologie, Nusalle 8, 53115 Bonn, FRG, Germany Senckenberg Research Institute and Natural Museum, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany Received 11 August 2011; revised typescripts received 13 November 2010 & 14 January 2011; accepted 15 February 2011 Abstract: LowerMiddle Miocene successions from Kỹtahya province (Seyitửmer and Tunỗbilek sub-basins) were analyzed to reconstruct the palaeoclimate and vegetation of the period A rich coniferous forest formed the dominant components among sporomorphs and consisted mainly of undeterminable Pinaceae, Pinus haploxylon type, Pinus diploxylon type, Picea, Cedrus, Cathaya, Keteleeria and Podocarpus Pollen data also indicate the presence of some fern taxa (Osmunda, Polypodiaceae, Schizeaceae) Selaginella and Lycopodium Cupressaceae frequently occur in all samples from both subbasins, and form part of the mixed forest assemblage Two woody plants Castanea-Castanopsis and evergreen Quercus predominate in the assemblages as well The reconstruction of palaeoclimate is based on the Coexistence Approach (CA) method and documents subtropical climate with cyclic variation in the sediment sequence The vegetation does not show a clear change through the sequences studied Small changes in the quantity of pollen taxa (e.g., thermophilous and arctotertiary) indicate small-scale cyclic temperature and precipitation oscillations during the deposition of the sediments Using CA, seven palaeoclimate parameters were estimated Quantitative palaeoclimate data indicate mean annual temperatures of 17−18°C, with winter temperatures of 8−10°C and summer temperatures of 27−28°C Mean annual precipitation exceeded 1200 mm The driest month precipitation was between 20 and 25 mm, the wettest month precipitation most frequently ranged between 200 and 250 mm and the summer precipitation was 100−150 mm These values imply that the Kütahya area was warm and received more precipitation during the Early−Middle Miocene than in modern times Key Words: LowerMiddle Miocene, Seyitửmer, Tunỗbilek, Kỹtahya, palaeoecology, palynology, sub-basin Seyitửmer ve Tunỗbilek Ast-Havzalarnda Linyit ỗerikli AltOrta Miyosen Tortullarnn Paleofloras ve klimi, Kütahya Alanı, Kuzeybatı Türkiye Özet: Paleoiklim ve vejetasyonu yeniden kurmak iỗin, Kỹtahya alannn (Seyitửmer ve Tunỗbilek ast-havzalar) AltOrta Miyosen istifleri incelenmiştir Sporomorfların arasında, zengin bir konifer ormanı baskın bileşenleri oluşturmaktadır ve başlıca ayırtlanmamış Pinaceae, Pinus haploxylon tip, Pinus diploxylon tip, Picea, Cedrus, Cathaya, Keteleeria ve Podocarpus’tan meydana gelmektedir Polen verileri, bazı eğreltilerin (Osmunda, Polypodiaceae, Schizeaceae) Selaginella ve Lycopodium’ların varlığını da belirtir Cupressaceae her iki ast-havzanın tüm örneklerinde sıklıkla bulunur ve karışık orman topluluğuna katılırlar İki odunsu bitki, Castanea-Castanopsis ve her daim yeşil Quercus da topluluklarda baskındır Paleoiklimi yeniden kurma Birarada Olma Yaklaşımı (KA) yöntemine dayalıdır ve istifte devirsel değişimli ılık-sıcak olduğunu belgelemektedir Çalışılan istifler boyunca bitki ưrtüsü belirgin bir değişim gửstermemektedir Polenlerin (ửrnek, termofil ve aktotersiyer) miktarndaki kỹỗỹk deiimler, tortullarn çökelimi süresince, küçük ölçekli devirsel sıcaklık ve yağış miktarlarındaki dalgalanmaları belirtmektedir KA yöntemine göre, yedi iklimsel değişken elde edilmiştir Sayısal paleoiklimsel veriler, yıllık ortlama sıcaklığın 17−18°C, kış sıcaklıklarının 8−10°C ve yaz sıcaklıklarının 27−28°C olduğunu belirtir Yıllık yağış miktarı 1200 mm’yi aşmaktadır En kurak ay yağış miktarı 213 MIOCENE PALYNOLOGY OF KÜTAHYA PROVINCE 20 ve 25 mm arasındadır Nemli ay yağış miktar bỹyỹk ỗounlukla 200 ve 250 mm ve yaz ya miktarı 100−150 mm arasındadır Bu veriler, Kütahya alanının Erken−Orta Miyosen süresince sıcak ve günümüzdeki iklimsel kayıtlardan daha fazla yağış aldığını gửstermektedir Anahtar Sửzcỹkler: AltOrta Miyosen, Seyitửmer, Tunỗbilek, Kỹtahya, paleoekoloji, palinoloji, ast-havza Introduction Western Turkey is dominated by large E–Wtrending grabens and a number of approximately N–S-trending grabens In the Kütahya area, lignitebearing sediments crop out in two locations, namely the Seyitửmer and Tunỗbilek basins that were filled with continental sediments (Figures & 2) Neogene lignite-bearing lacustrine deposits are also widespread in western Turkey (e.g., Soma, Çanakkale-Çan, Konya-Ilgın, and Uşak) Most of the studies in these areas have been made in order to solve their tectonic, stratigraphical and sedimentological problems Initial studies were to establish palynostratigraphic aspects of these lignites (Akyol 1963, 1964, 1968; Nakoman 1965; Benda 1971; Arslan 1979; Benda & Meulenkamp 1979) but later these were extended to characterize clastic sequences, especially the Miocene deposits in western Turkey, improving knowledge of vegetation and climate during this time (e.g., Ediger 1990; Akyol & Akgün 1990, 1992; Yavuz et al 1995; Ediger et al 1996; Akgün et al 2007; Yavuz-Işık 2007; Kayseri & Akgỹn 2008) The Seyitửmer and Tunỗbilek open pit mines are in one of the biggest lignite-producing areas Initial studies to shed light on the geological divisions around Kütahya were made by Nebert (1960) and Baş (1983) The first palynological studies were carried out by Nakoman (1968) and Özcan (1987) in the Seyitömer sub-basin, but it is difficult to determine the botanical affinity of their pollen since they used morphological classification for most of the pollen and spores The first comprehensive palaeoecological study in the Seyitömer sub-basin was made by Yavuz-Işık (2007) who recognized two different pollen zones indicating two different periods: late Early Miocene (Zone 1) and Middle Miocene (Zone 2) Zone is represented by a high percentage of Pinus and Cedrus Deciduous Quercus and evergreen Quercus occur abundantly in Zone The percentage of Taxodiaceae decreases from Zone to Zone The author also indicated that discrepancies between Zone and Zone may 214 reflect the global Middle Miocene cooling In this study we enlarge the palynological data by analysis of new samples from the whole Lower–Middle Miocene sequence of the Seyitömer sub-basin and lower lignite seam of the Tunỗbilek sub-basin within a stratigraphic framework since the palaeoflora has already been investigated by other researchers The present paper provides an analysis of the Early– Middle Miocene vegetation evolution on the basis of pollen and leaves The palynological data have also been analyzed using the Coexistence Approach (CA) in order to obtain quantitative palaeoclimatic data, and to understand the link between the climate changes and vegetation (Mosbrugger & Utescher 1997) Geological Setting The study areas are located in the northwest of Seyitömer County (39° 34ʹ 14ʹʹN, 29° 51ʹ 04ʹʹE and 1160 m above sea level) and north of Tunỗbilek County (39 39 14N, 29 26ʹ 30ʹʹE and 1035 m above sea level) in Kütahya Province (Northwestern Turkey) Pre-Miocene metamorphic and ophiolitic rocks and granites form the basement of the basin (Okay 1981) These locations are here termed subbasins belonging to the Kütahya Graben, as they are not isolated and are underlain by basement rocks consisting of metamorphic rocks of various grades and ophiolitic melanges (Okay 1981; Türkmenoğlu & Yavuz-Işık 2008) which were unconformably overlain by Neogene lacustrine deposits In the Seyitömer sub-basin, the Miocene sequence includes, in ascending order: a lower clastic unit, a claystone-mudstone unit, a lower lignite seam, an organic shale unit, an upper lignite seam, a silicified limestone unit, and a clayey limestone unit: all these units belong to the Seyitömer Formation (Sarıyıldız 1987) that is unconformably overlain by an upper clastic unit named the Kocayatak Tepe Formation (Sarıyıldız 1987) (Figure 1a) The lower clastic unit mainly comprises greenish unconsolidated M S AKKİRAZ ET AL O O O 36E 30E N 42E Black Sea 40E Seyitömer Thick.(m) Fm Mediterranean Sea Koca Age O 35E O ANKARA KÜTAHYA Lithology 200 km Explanation Investigated sediments lower lignite seam alluvium 76 upper lignite seam organic shale SW Figure 3a organic shale NE clayey limestone 20< siliceous limestone lower lignite seam Middle Miocene Seyitömer b upper lignite seam 12 organic shale with leaf and ostracod fossils 10 us lim siliceo ye e, cla eston stone y lime seam lignite uppe r organic shale organic shale lower lignite seam 15 20 greyish mudstone - claystone 99 lower clastics v v v v v v v v v v v v v v v v v v v v v v v v MESO NW ultramafics, metamorphics, olistostroms Figure 3b SE lower lignite seam c a Figure (a) Generalized stratigraphic column of the Seyitömer sub-basin (Sarıyıldız 1987) (b) Field photograph showing the Aslanlı section (c) Field photograph showing the Tumulus section Open circles show beginning of the sections conglomerates and yellowish planar and cross-bedded sandstones that are overlain by a greenish medium to poorly bedded claystone-mudstone unit, up to 50 to 60 m thick, over lignite seam, ranging from to 15 m thick, is medium to thick bedded with claystone and silicified interlayers The organic shale unit generally consists of grey shale and siltstone, containing leaves, mammals and ostracoda The upper lignite seam, which is non-commercial, is made up of an alternation of lignite, silicified limestone and clayey lignite (Figure 1) The clayey limestone unit consists of consolidated tuffite and clayey limestone 215 MIOCENE PALYNOLOGY OF KĩTAHYA PROVINCE In the Tunỗbilek sub-basin, terrestrial and lacustrine sediments contain half-cemented conglomerates, claystones of fluviatile origin showing a fining-upward sequence, marls, siltstones, sandstones, lacustrine limestones, and lignite, located in the lower and upper parts of the sequence (Figure 2a, d) The main lignite seam, from to 15 m thick, includes claystone interlayers as well The overlying claystone-marl alternations, over 300 m in total thickness (Figure 2c), are generally horizontal bedded but locally folded, and include poorly preserved leaves The sequence ends with lacustrine limestones containing chert nodules and thin lignite seams (Figure 2a) All these lithologies belong to the Tunỗbilek Formation described by Ba (1983) Upper Miocene to Pliocene volcanic rocks, lava, tuff and agglomerate of the Domaniỗ Series (Nebert 1960) unconformably overlie the Tunỗbilek Formation (Figure 2b) Özcan (1987) studied the palynology of lignitebearing sediments exposed in the Seyitömer sub-basin, and also identified a vertebrate fossil, Aceratherium tetradactylum (Lartert) Hooijer which suggested a Vallesian age (Late Miocene) Later Kaya (1993) described mammalian fauna including Begertherium grimmi (Heissig) (RhinocerotidaePerissodactyla) and Moropus elatus (Marsh) (Chalicotheriidae-Perissodactyla) in the lower lignite seam, and suggested a late Middle Miocene age of the Seyitömer sub-basin In contrast, a late Early Miocene–Middle Miocene (MN 4-8) age was suggested by Saraỗ (2003) based on mammalian data Recent observations indicate that sediments in the Seyitömer sub-basin were deposited during the early Langhian (Middle Miocene) based on the mammal data (T Kaya, personal communication) But although comprehensive mammal data have been obtained from the Seyitömer sub-basin to date, the age is still debated Also, as no age data are available for the Tunỗbilek sub-basin, better age control of the sedimentary sequences in the basin is needed Material and Methods The study was carried out at three sections in two different lignite open pit mines Two stratigraphic sections were measured from the Seyitömer subbasin (Figure 1a, b) One, north of Aslanlı village, 216 located on the northern side of the mine, is named here the Aslanlı section, up to 33 m in total thickness (Figures 1b & 3a) The other, measured east of the archaeological excavation area, is named here the Tumulus section (total thickness around 37.40 m) (Figures 1c & 3b) During the field studies, palynological samples of the Tumulus section were collected from the lower and upper lignite seams, since the organic shale includes sandy and coarsegrained clastics which are not suitable lithologies for palynological analysis (Figures 3b & 4b) Additionally, a section from the lower lignite seam, approximately 17 m thick, was sampled in the Tunỗbilek sub-basin (Figure 3c) A total of 171 samples were collected from the outcrop sections, where palynologically productive fine-grained sediments and lignites are well exposed 139 samples were collected from the Seyitömer sub-basin (Figure 3a, b) 32 samples were taken from the lower lignite seam of the Tunỗbilek sub-basin (Figure 3c) Samples which were barren or contained very few pollen grains were not included in the analysis Quantitative data are thus confined to 73 productive samples, of which 59 came from the Seyitömer sub-basin (Figure 4) and 14 samples from the Tunỗbilek sub-basin (Figure 5) Distinguishable genera and families were identified In most cases, the spore and pollen sums were based on more than 200 grains (Figure 5) TILIA software was used to calculate the sporomorphs, and TILIAGRAPH was used to plot the sporomorph diagrams (Grimm 1994) Selected palynomorphs are illustrated on Plates 1–4 For the recovery of palynofossils, mineral components were first removed with specific acids: the silicates were removed with 40–60% HF; carbonates, commonly found as calcite, were dissolved in HCl; sulphates, sulphides and carbon contents are soluble in concentrated HNO3 Slides prepared from the productive samples were investigated under the microscope for qualitative and quantitative assessment of palynofossils The CA method has been used to reconstruct the palaeoclimate (Mosbrugger & Utescher 1997) The application of the CA was facilitated by the computer program ClimStat and the database Palaeoflora that includes nearest living relatives of more than 3000 Tertiary plant taxa, together with their climatic requirements, which are derived from meteorological stations located within the distribution areas of the M S AKKİRAZ ET AL O O O 36E 30E N 42E Tunỗbilek ANKARA KĩTAHYA basalt O 35E O 40E Black Sea Age Series Mediterranean Sea 200 km Explanations Lithology tuff Investigated sediments SE NW Domaniỗ Pliocene cherty limestone reddish - brownish basalt flows b tuff limestone agglomerate whitish clayey limestone, limestone basalt clayey limestone, limestone tuff NW marl, claystone SE Tunỗbilek Middle Miocene whitish marl with horizontal bedding, folded and leaf fossils c marl lower lignite seam including claystone interlayers v v v v v v v v v v v v v v v v v v v v v v v v MESO ultramafics, metamorphics, olistostroms SE NW mudstone lower lignite seam greyish poorly sorted conglomerates a d Figure (a) Generalized stratigraphic column of the Tunỗbilek sub-basin (Nebert 1960) (b) Field photograph showing the boundary between the tuff and basalt (c) Field photograph showing marl-dominated lithologies and volcanics (d) Field photograph showing lower lignite seam including claystone interlayers and also syn-sedimentary fault 217 10 15 20 Explanations lignite claystone unconsolidated organic shale laminated unconsolidated organic shale organic shale with leaf and ostracod fossils yellowish sandstone with ostracod marl with plant debris lignite with ostracod consolidated organic shale consolidated organic shale with ostracod organic shale with ostracod yellowish marl organic shale marl consolidated organic shale yellowish marl greenish - black, consolidated organic shale with lignite lense greyish organic shale organic shale with ostracod unconsolidated marl organic shale with lignite lense unconsolidated marl greenish unconsolidated organic shale with lignite lense organic shale yellowish marl marl organic shale claystone unconsolidated organic shale with iron marl marl with iron lignite whitish marl with ostracod silicified limestone lignite marl lignite with iron claystone marl lignite claystone tuff claystone lignite claystone marl silicified limestone laminated marl claystone - lignite alternation 08/103-110 08/112 08/111 08/120-121 08/119 08/118 08/117 08/122-125 08/126-128 08/135-139 08/135 08/132-134 08/129-131 08/141-143 08/140 08/144-146 08/147-148 08/149 08/150 08/154 08/153 08/155 08/161 08/160 08/168 08/176 08/169 08/177 08/182 08/183 08/192 08/194 08/193 08/195 08/198-200 08/197 08/196 08/201205 08/206 08/208 08/207 08/209 Fm Age b Seyitömer Formation Lower - Middle Miocene Samples 08/218 08/215 08/214 08/210 10 15 20 25 30 35 Thick (m) Lithology Explanations claystone lignite alternation brownish claystone, lignite with plant debris lignite sandy lignite lignite brownish shale with plant debris lignite sandy lignite organic shale including plant debris, leaves and ostracoda marl lignite alternation marl lignite with marl lense marl marl and lignite lignite with marl lense lignite with gastropod greyish marl with plant debris and ostracod marl with thin lignite interlevel yellowish silicified limestone tuff lignite marl silificied limestone lignite marl marl and lignite alternation marl and silified limestone tuff mp les 08/14 08/13 08/12 08/11 08/10 08/09 08/08 08/07 08/06 08/15 08/18 08/17 08/16 08/19 08/21 08/20 08/22 08/24 08/23 08/26 08/25 08/28 08/27 08/29 08/30 08/31 08/32 08/33 Sa ? ? Fm c 10 15 Thick (m) Lithology Explanations lignite wth clay intercalations brownish claystone, lignite with plant debris lignite with brownish shale and sandy lignite organic shale including plant debris, leaves and ostracoda clayey limestone, claystone alternation Lower lignite seam 08/263 08/262 08/261 08/260 08259 08/266 08/265 08/264 08/268 08/267 08/278 08/277 08/276 08/275 08/274 08/273 08/272 08/271 08/270 08/269 08/281 08/280 08/279 08/288 08/287 08/286 08/285 08/284 08/283 08/282 08/289 Samples Figure Logs showing the stratigraphic positions of samples used for sporomorphs, (a, b) Aslanlı and Tumulus sections of the Seyitömer sub-basin, (c) lower lignite seam of the Tunỗbilek sub-basin a Age Lower - Middle Miocene Fm Seyitömer Formation 25 Meters Upper lignite seam Organic shale Lower lignite seam 30 Lithology metre Upper lignite seam Organic shale Lower lignite seam Age Tunỗbilek Formation Lower - Middle Miocene 218 metre Thick (m) MIOCENE PALYNOLOGY OF KÜTAHYA PROVINCE Organic shale Lower lignite seam Fe 5.00m 20.00m 25.00m 29.80m Fe 08/06 08/09 08/07 08/20 08/17a 08/17 08/16 08/13-14 08/10-11 08/23 08/24 di 20 po