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The study area is situated in the Araplı-Erdemli (Kayseri) area in the north-eastern part of the Cappadocian Volcanic Province (CVP), central Anatolia. The Late Miocene series comprises lacustrine and fluvial deposits interbedded with ignimbrites and lava flows. The Late Miocene Mustafapaşa member of the Ürgüp Formation comprises yellow to red mudstone that alternates with thin sandstone beds in the north-eastern part of the CVP.
Turkish Journal of Earth Sciences Turkish J Earth Sci (2013) 22: 427-443 © TÜBİTAK doi:10.3906/yer-1112-1 http://journals.tubitak.gov.tr/earth/ Research Article Geology of Late Miocene clayey sediments and distribution of palaeosol clay minerals in the north-eastern part of the Cappadocian Volcanic Province (Araplı-Erdemli), central Anatolia, Turkey 1, 2 Selahattin KADİR *, Ali GÜREL , Hülya SENEM , Tacit KÜLAH Department of Geological Engineering, Eskişehir Osmangazi University, TR-26480 Eskişehir, Turkey Department of Geological Engineering, Niğde University, TR-51200 Niğde, Turkey Received: 05.12.2011 Accepted: 19.06.2012 Published Online: 06.05.2013 Printed: 06.06.2013 Abstract: The study area is situated in the Araplı-Erdemli (Kayseri) area in the north-eastern part of the Cappadocian Volcanic Province (CVP), central Anatolia The Late Miocene series comprises lacustrine and fluvial deposits interbedded with ignimbrites and lava flows The Late Miocene Mustafapaşa member of the Ürgüp Formation comprises yellow to red mudstone that alternates with thin sandstone beds in the north-eastern part of the CVP This unit continues upward through the Cemilköy ignimbrite palaeosol layers (comprising altered Cemilköy ignimbrite, vertisol and well-developed palaeosol layers), the Gördeles ignimbrite and red palaeosol layers, and includes two fallout levels; it is overlain by the Kızılkaya ignimbrite The Mustafapaşa member is dominated by smectite±illite±chlorite, whereas the altered Cemilköy ignimbrite is predominantly kaolinite±smectite±chlorite The underlying lower level of the Gördeles ignimbrite contains palaeosol layers, and continues upward through smectite-dominated layers Alteration of feldspars and glass shards in the Cemilköy and Gördeles ignimbrites resulted in the depletion of soluble alkaline elements (such as Ca, Na and K) from these ignimbrites downward to the Mustafapaşa member, and palaeosol levels (Bayramhacılı member) in the Araplı area favoured precipitation of smectite in an alkaline environment However, the absence of these elements in these ignimbrites may have resulted in the enhancement of Al+Fe/Si-favoured precipitation of kaolinite in an acidic environment Conversely, palaeosol of the Erdemli area consists of smectite±illite±chlorite Micromorphologically, flaky smectite rims illite in both the Araplı and Erdemli areas and this can be explained by the release of K and Al during desorption of feldspar Additionally, higher Ni, Co and Cr2O3 values in the mudstone samples of the Mustafapaşa member and palaeosol levels, the presence of iron oxide and partially chloritised pyroxene and hornblende, together with ophiolitic and metamorphic grains, indicate that the basin also accumulated ophiolitic and metamorphic rock fragments in its sediment supply This suggests that the Araplı area in the southern part of the CVP has undergone erosion, and that the present-day Erdemli area was close to the shallow-lake depositional environment of the northern part of CVP Key Words: Palaeosol, ignimbrite, smectite, kaolinite, central Anatolia Introduction Since the last quarter of the 20th century, palaeoclimatological changes have been studied using sedimentary-petrographic data from marine (Thiry 2000; Ehrmann et al 2005; Berrocoso et al 2008) and non-marine sediments (Singer 1984; Bellanca et al 1992; Prudêncio et al 2002) This study area covers 100 km2 in the north-eastern part of the Cappadocia region of central Anatolia (Turkey) The occurrence of a large clay deposit in the Late Miocene Mustafapaşa member of the Ürgüp Formation, the altered Cemilköy ignimbrite, and the palaeosols between the Gördeles and Kızılkaya ignimbrites are first described in the area in this work The Mustafapaşa member consists of alternating conglomerate, sandstone, and mudstone * Correspondence: skadir_esogu@yahoo.com The altered Cemilköy ignimbrite, red palaeosols, vertisols and mature, white palaeosol layers developed between the Cemilköy and Gördeles ignimbrites Red palaeosols, mature brown and red palaeosol levels occur between the Gördeles and Kızılkaya ignimbrites The Cappadocian Volcanic Province in central Anatolia has been previously studied in order to elucidate the stratigraphy (Pasquaré 1968; Schumacher & MuesSchumacher 1997; Le Pennec et al 2005; Viereck-Goette et al 2010), the relationship between magmatism and tectonism (Innocenti et al 1975; Pasquaré et al 1988; Göncüoğlu & Toprak 1992; Temel et al 1998; Toprak 1998), the mineralogy and origin of clay minerals (Gürel & Kadir 2006; Gürel & Kadir 2008; Ertek & Öner 2008), and ecosystem changes (Lepetit & Viereck-Goette 2007) 427 KADİR et al / Turkish J Earth Sci Prior to the present study, no information about the clay sedimentology and mineralogy of the Late Miocene units between the Araplı and Erdemli areas was available Therefore, the aim of this paper is to describe the geology, mineralogy, and geochemistry of the north-eastern section of the CVP sediments, and to discuss the genesis of the clay deposits and their depositional environment Local geological setting Basement rocks of the Araplı area comprise Palaeozoic mica schists and marbles and Late Cretaceous ophiolitic rocks which tectonically overlie the older units (Figure 1) The Oligocene Yeşilhisar conglomerate contains metamorphic and ophiolitic rock fragments, and the Palaeogene-Neogene series discordantly overlies basement rocks This unit is discordantly overlain by the Neogene Ürgüp Formation (Figure 2) The Mustafapaşa member (Late Miocene) is the earliest unit of the Ürgüp Formation in the Araplı area, comprising alternating conglomerate, sandstone and mudstone laid down in a lacustrine environment The Late Miocene Cemilköy ignimbrite overlies the Mustafapaşa member and separates it from the overlying Bayramhacılı member (Pasquaré 1968) The Bayramhacılı member is split into two sub-members (the Lower and Upper Bayramhacılı) by the Gördeles ignimbrite The Upper Bayramhacılı unit is overlain by the Kızılkaya ignimbrite (Gürel & Kadir 2006) These volcaniclastic units are discordantly overlain by Quaternary white travertine (outside the study area) and alluvium Description of stratigraphic sections Five north–south stratigraphic sections have been studied, in the study area between the villages of Araplı and Erdemli (Kayseri)(Figure 3) 3.1 Araplı - Section I This section begins with palaeosol layers Each palaeosol is mud containing pumice and plant rootlets These palaeosol horizons are overlain by a white fallout-I unit, containing more than 80% pumice After 3-4 m of covered section, the section continues upward with similar palaeosol layers, and the fallout-II layer contains lithic clasts and pumice (A1-3) This horizon is overlain by more palaeosol layers which begin with white, pumicebearing palaeosol, and continue upward with palaeosols containing brown to light brown, fine-grained lithic clasts, plant rootlets and pumice These units are overlain by the pale grey Gördeles ignimbrite, comprising mainly lithic pumice This ignimbritic unit is overlain by fine-grained and coarse-grained palaeosol levels, respectively Finally, the massive and columnar-jointed Kızılkaya ignimbrite sits at the top of this section 428 3.2 Araplı – Section II This section has a basal fine-grained, clayey palaeosol layer, then a fine-grained and lithic-clast-bearing palaeosol layer, deposited above the Yeşilhisar conglomerate or ophiolitic rocks These units are overlain by the pale grey Cemilköy ignimbrite (Figure 4a), comprising mainly lithic pumice and altered Cemilköy ignimbrite (Figure 4b,c) layers These layers are overlain by palaeosol layers, beginning with a massive, clayey, fine-grained palaeosol and continuing with a red, fine-grained palaeosol layer and a grey vertisol layer (Figure 4d) These units are overlain by fallout-II deposits with lithic-pumice and lithic clasts and a red, fine-grained, clayey palaeosol horizon (Figure 4e) These are overlain by the pale grey Gördeles ignimbrite, which is in turn overlain by two palaeosol layers: a lightbrown, fine-grained palaeosol and a red, fine-grained palaeosol Finally, the Kızılkaya ignimbrite sits at the top of this section 3.3 Yeşilhisar Section At the base of this section is the Yeşilhisar conglomerate, which contains ophiolitic and metamorphic rock fragments within a silty to sandy matrix This unit is overlain by lacustrine sediments, beginning with greenish-grey, medium-grained sandstone and continuing sequentially upward with grey siltstone, greenish-grey sandstone, siltstone, pinkish-grey mudstone and grey sandstone horizons Up to this level, the lacustrine sediments are mainly greenish-grey and grey They continue upward with a level of pinkish-brown conglomerate, with a finegrained matrix, then ignimbritic sandstone, mudstone, fine-grained conglomerate, sandstone (Figure 4f-g) and siltstone layers The Cemilköy ignimbrite sits at the top of this section 3.4 Akköy Section This section has ophiolitic rocks (Figure 4h) at its base These are overlain by the Erdemisin agglomerate, and the Kavak ignimbrite, which comprises volcanic agglomerates, and pumiceous and vitric tuffites This unit is overlain by lacustrine sediments, comprising pumiceous claystone and sandstone beds (AK-2, AK-3, AK-4) and these sediments are overlain by the pale grey Cemilköy ignimbrite which contains lithic pumice This unit is overlain by palaeosol beds intercalated with conglomerate and fluvial sandstone beds The Kızılkaya ignimbrite sits at the top of this section 3.5 Erdemli Section The Erdemisin agglomerate at the base of this section (Figure 4i), comprises abundant basaltic rock fragments and marl-rich sediments, and is overlain by lacustrine claystone beds and the pale grey Cemilköy ignimbrite This unit is in turn overlain by palaeosol (E-1, E-2) and white tuffite beds, and the section continues upward with more palaeosol layers, which are overlain by fluvial channel KADİR et al / Turkish J Earth Sci Black Sea Erdemli Erdemli section T U R K E Y Kayseri Study area 100 km Mediterranean Sea Kurt Mt Kỹỗỹkkurt H N Keşlik YEŞİLHİSAR Early Pliocene Quaternary EXPLANATION scree slopes alluvium unconformity Kızılkaya ignimbrite Çataltepe basalt Akkưy section Akkưy Gưrdeles ignimbrite Bükkale H Tahar ignimbrite Kaleköy L ate Miocene Cemilköy ignimbrite Bayramhacılı member Mustafapaşa member Kavak ignimbrite Büyükkale tepe andesite Olig oMiocene Erdemisin agglomerate unconformity Yeşilhisar conglomerate unconformity L ate Cretaceous Yeşilhisar section ophiolitic complex fault Araplı Araplı I Ar a plı I I settlement km Figure Simplified geological map of the Araplı-Erdemli area of the Ürgüp Basin (modified from Pasquaré 1968) 429 KADİR et al / Turkish J Earth Sci İncesu ignimbrite (2.8 My) P, L, D, F Seksenveren lavas Kızılkaya ignimbrite (4.3 My) P, L, D, F P, L, D, F Catal tepe lavas double mass flow Gördeles ignimbrite (5.7 My) P, L, D, F P, L, D, F Tahar ignimbrite (5.8 My) double pumice fallout P, L, D, F mass flow Cemilköy ignimbrite (6.6 My) L, F Topuz dağı lavas Salur conglomerate Damsa valley lavas P, L, D, F Sarımaden ignimbrite (8.2 My) Mustafapaşa member Zelve ignimbrite (8.8 My) P, F P, F 40 m P, F Kavak ignimbrite (9.0 My) (11.2 My) Güvercinlik ignimbrite (10 My) P, F En Yaşlı [oldest] ignimbrite (11 My) Figure Generalised stratigraphic section of the study area (modified after Viereck et al 2010) P: palaeosol, L: carbonate, D: diatomite, F: fluvial sediments sediments (Figure 4j), sandstones and conglomeratic units These are overlain by palaeosol horizons, and the Tahar ignimbrite overlies the former units as three flow units The Tahar ignimbrite is overlain by a brown, massive palaeosol horizon which is intercalated with two layers of fine-grained, brown, red-clay-pellet-bearing palaeosols This unit is in turn overlain by a massive, white limestone horizon and pale grey, coarse-grained pumice and lithicfragment-bearing lahar deposits This series is overlain by the Kızılkaya ignimbrite, and a basaltic flow unit at the top of this section Lithofacies Distribution Eight lithofacies have been distinguished within the Late Miocene sediments of the Araplı-Erdemli area; these 430 lithofacies are adapted from Miall (1996; Figure 3) Basement rocks in the study area are metamorphic and ophiolitic rocks 4.1 Erdemisin Agglomerate (EA) The Erdemisin agglomerate is the first product of Neogene volcanic activity in the study area It comprises volcanic agglomerates, pumiceous and vitric tuffites, and marl-rich sediments The cobbles in the unit are set in a greenish-grey or violet tuffaceous matrix containing clayey arenaceous components consisting of grey andesitic and ophiolitic rock fragments (Pasquaré 1968) 4.2 Yeşilhisar Conglomerate (YC) The Yeşilhisar conglomerate consists of thick-bedded fluvial sediments It almost entirely comprises more-orless cemented conglomerates Pebbles of metamorphic and ophiolitic rock are rounded and vary in diameter from a few mm to 20-30 cm 4.3 Conglomerate (C) This facies is characterised by massive, grey, unsorted and sub-rounded conglomerates The conglomerate is mainly matrix-supported The average clast size is 10 cm, and measured profiles range from 20 – 50 cm thick Palaeoflow direction is generally from south to north 4.4 Sandstone (St) This facies comprises greenish-grey, medium- to finegrained, medium-bedded sandstone with plant rootlets This unit also encloses gypsiferous claystone intercalations 4.5 Mudstone (Mt) This facies occurs at two levels: the lower unit is generally greenish-grey claystone, and the upper unit is generally brownish red It also encloses plant rootlets and desiccation cracks 4.6 Ignimbrite (I) Four different ignimbrite members of the Ürgüp Formation have been examined in the study area: The Cemilköy ignimbrite consists of white, massive or thick-bedded lahar deposits with lithic, vitric and pumiceous fragments of ignimbritic origin (Pasquaré 1968) The Tahar ignimbrite is represented by thick-bedded pinkish tuffite and fine lahar deposits of ignimbritic derivation (Pasquaré 1968) The Gördeles ignimbrite consists of thick-bedded pink to white ignimbrite, which passes laterally into a tuffite of similar composition (Pasquaré 1968) The Kızılkaya ignimbrite is a single pinkish, wellwelded columnar flow unit (Temel 1992) 4.7 Fallout (FO) This facies is represented by two white fallout levels, comprising more than 80% pumice 4.8 Palaeosol (P) The palaeosol can be considered to be aridisol (Soil Survey Staff 1975) Based on the system outlined by Retallack S a nd fallout I fallout II Gördeles ignimbrite Gra ve l Mud S ilt A1-1 A1-2 A1-3 A1-4 A1-5 A1-6 S a nd Cemilköy ignimbrite Gördeles ignimbrite Mud S ilt A1-7 Gra ve l A2-1 A2-2 A2-3 A2-4 A2-5 A2-6 S a nd Cemilköy ignimbrite YH-12 YH-13 YH-14 YT-2 YT-1 YH-11 YH-10 YH-8 YH-9 YH-7-6 YH-5 YH-2 YH-3 YH-4 YH-1 Yeşilhisar Section Mud S ilt A1-8 Gra ve l Kızılkaya ignimbrite S a nd Kavak ignimbrite Cemilköy ignimbrite Kızılkaya ignimbrite Akköy Section Mud S ilt Kızılkaya ignimbrite Gra ve l Araplı II Section AK-1 AK-4 AK-3 AK-2 AK-5 AK-6 AK-7 AK-8 S a nd Cemilköy ignimbrite Tahar ignimbrite Kızılkaya ignimbrite Mud S ilt Araplı I Section 2m E-2 E-1 E-3 E-4 E-5 ignimbrite E-6 ophiolitic complex Erdemisin agglomerate conglomerate clay palaeosol / pumice and rock fragments vertisol lahar sandstone basalt covered limestone EXPLANATION E-7 E-8 N Erdemli Section Gra ve l S KADİR et al / Turkish J Earth Sci Figure Distribution of the principal lithologies of the Araplı-Erdemli areas (see Figure for section locations, and Table for mineralogical compositions of the samples) 431 2m 2m 2m 2m KADİR et al / Turkish J Earth Sci ignimbrite altered ignimbrite a b ignimbrite mudstone vertisol c d sandstone palaeosol e f ophiolite conglomerate g h fluvial sediments basalt palaeosol agglomerate i j Figure Field view of: (a) Cemilköy ignimbrite, (b) altered Cemilköy ignimbrite, (c) contact relationship between the Mustafapaşa member and Cemilköy ignimbrite, (d) vertisol levels, (e) mature-type developed palaeosols, (f) sandstone levels of the Mustafapaşa member, (g) conglomerate level of the Mustafapaşa member, (h) ophiolitic rocks, (i) Erdemisin agglomerate, (j) fluvial-channel deposits and mature developed palaeosol level 432 KADİR et al / Turkish J Earth Sci serpentinised olivine serpentinised olivine a 0.1 mm b 0.2 mm chloritised pyroxene volcanic glass plagioclase pyroxene c 0.1 mm d 0.2 mm organic organic clay clay e 0.1 mm f 0.2 mm oxypyroxene organic sesquioxides clay + calcite organic g plagioclase clay 0.2 mm h oxyhornblende 0.2 mm Figure Photomicrographs of (a) serpentinized olivine crystal (AK-1, plane polarised light), (b) serpentinized olivine crystal (AK-1, plane polarised light), (c) alteration and chloritization of pyroxene crystal (AK-1, YH-1 and YH-2, in-plane polarised light), (d) plagioclase (andesine) and amphibole phenocrysts in volcanic-glass matrix (AK-1, YT-1 and YT-2, crossed nicols), (e-g) palaeosol samples, sesquioxide and organic material bearing and resembling highly altered volcanic units with irregular clay materials, plane polarised light, (h) ultramafic and volcanic rock fragments, feldspar, pyroxene, amphibole, cemented by clay, sesquioxides and microsparitic calcite in sandstone (AK-8, crossed nicols) 433 KADİR et al / Turkish J Earth Sci (1988), these palaeosols can be roughly classified as poorly to moderately developed, mature-type palaeosols The palaeosol layers also enclose scattered pumice pebbles, in contrast to the root zones in near-surface mature palaeosols, and subsurface clayey, sesquioxide-rich areas have developed The most mature soils are associated with fluvial overbank deposits at some distance from the main channels, which were the source of incremental additions of fine-grained sediments Overbank deposits proximal to palaeochannels have better-preserved bedding and less mature palaeosols, and pedogenic disruption of bedding and palaeosol maturity increase away from the channels toward more distal floodplain settings Methods In the field, typical stratigraphic sections were measured in order to study lateral and vertical variations within the Late Cretaceous ophiolitic complex, the Oligo-Miocene Yeşilhisar conglomerate and the Late Miocene fluvial and lacustrine deposits interbedded with ignimbrites and lava flows Forty-six characteristic samples of Oligo-Miocene Yeşilhisar conglomerate, Late Miocene fluvio-lacustrine sediments and associated palaeosols were collected from the study area (Figure 3) Lithofacies definitions are based on those of Miall (1996) Thin sections were prepared from them to describe their petrographic properties The mineralogical characteristics of the samples were determined by X-ray powder diffractometry (XRD) (Rigaku Geigerflex) and scanning electron microscopy (SEM-EDX) (JEOL JSM 84A-EDX) Representative palaeosol samples were prepared for clay-mineral analysis (size fraction