Mehmet Özkul

Neotectonic development of the Çameli Basin, southwestern Anatolia, Turkey

Abstract This study of the Çameli Basin presents a detailed basin evolution combined with structural analysis and provides the first detailed time-stratigraphic framework for the neotectonic development of Neogene grabens along the Fethiye-Burdur Fault Zone in southwestern Anatolia. During the Early Tortonian, the Çameli Basin was established as a broad fault-bounded fluviolacustrine basin that experienced NW-SE extension. By Mid-Pliocene time, continued NW-SE extension resulted in the formation of a new intrabasinal fault zone that split the basin longitudinally into two compartments. The development of a new generation of normal faults further split the basin into four narrow half-graben compartments at the end of the Late Pliocene. Structural analysis of basin-bounding and intrabasinal faults related to this three-stage basin development shows that NW-SE extension apparently persisted from Late Miocene to early Quaternary time. The youngest (i.e. Holocene), deformation is characterized by dextral shear along NE-SW-trending strikeslip faults and continuing NW-SE extension. The Late Miocene foundering of the basin was related to extension in the northerly hinterland zone of the still-emplacing Lycian nappes, whereas outward growth of the Hellenic Arc in response to the westward Anatolian extrusion is the main cause for NW-SE extension from the Pliocene onward. Dextral strike-slip faulting is localized and is associated with the activity of NW-SE-trending faults that accommodated NE-SW extension. The simultaneous activity of these faults suggests the existence of biaxial extensional tectonics, as initially proposed for the Burdur-Dinar area. Sinistral strike-slip faulting, continuing along the eastern Hellenic Arc, penetrated the southernmost part of Turkey but has not yet reached the Çameli Basin area. Our biostratigraphically well-constrained tectonosedimentary model for the evolution of the Çameli Basin provides a reliable time-stratigraphic framework for NE-SW extension in the ‘Fethiye-Burdur Fault Zone’ of SW Anatolia. We believe that this fault zone represents a broad zone of isolated or interconnected NE-SW-trending basins that formed under prevailing NW-SE extension, rather than being a significant strike-slip fault zone.

Growth of fissure ridge travertines from geothermal springs of Denizli Basin, western Turkey

Fissure ridge travertines grown from geothermal springs of Denizli Basin, southwestern Turkey, are investigated through stratigraphic, structural, geochemical, and geochronological methods, with the aim of understanding the growth of these elongate mound-shaped structures. Two main types of travertine deposits are recognized: (1) bedded travertines, which grew as flowstone on sloping surfaces and form the bulk of fissure ridges, and (2) banded travertines, which grew as veins within the bedded travertine chiefly along its central feeding conduit. Stratigraphic and structural observations shed light on the bedded-banded travertine relationships, where the banded features grew through successive accretion phases, crosscutting the bedded travertine or forming sill-like structures. The bedded and banded travertines alternated their growth, as demonstrated by complicated crosscutting relationships and by the upward suture, in places, of banded travertine by bedded travertine that was, in turn, crosscut by younger banded travertine. The bedded travertine is often tilted away from the central axis of the fissure ridge, thus leaving more room for the central banded travertine to form. U-series ages confirm the bedded-banded travertine temporal relationships and show that the growth of the studied fissure ridges lasted up to several tens of thousands of years during Quaternary time. The banded travertine was deposited mainly during cold events, possibly in coincidence with seismic events that might have triggered the outflow of deep geothermal fluids. C and O stable isotope and rare earth element data indicate a shallow feeding circuit for the studied structures with a fluid component deriving from a deeper geothermal circuit. A crack-and-seal mechanism of fissure ridge growth is proposed, modulated by the interplay of local and regional influencing factors and mechanisms such as geothermal fluid discharge, paleoclimate, tectonics, and the progressive tilting of bedded travertine limbs over a soft substratum creating the necessary space for the central veins to grow.

Depositional Properties and Geochemistry of Holocene Perched Springline Tufa Deposits and Associated Spring Waters: A Case Study from the Denizli Province, Western Turkey

Abstract The Güney waterfall area is a perched springline tufa site developed on the southeast slope of the Büyük Menderes River near Güney town, in the Denizli province, Western Turkey. The site is 12 km away from Güney and 72 km from the city centre of Denizli. The spring waters emerge from the boundary between Palaeozoic marble and micaschist and precipitated tufa deposits downslope at the altitudes ranging from 220 to 400 metres. The tufa deposits cover an area of about 20 hectares. Flat upper surfaces of the deposits are indicative of mature stage. The waters are of the Ca–HCO3 type and supersaturated with respect to CaCO3. The stable isotope values of the spring waters are −49.94 for δ2H and −7.15 for δ18O. The δ13C and δ18O values of active and passive tufa samples are in the range from −9.13 to −6.0‰, and from −8.44 to −7.40‰, respectively. These isotopic values are typical for fresh water tufa. The passive tufas give the 14C age in the range from 2000 to 5800 yr BP. According to the 14C age data, passive tufas are not older than Holocene. The stable isotope composition is similar south European examples.

Natural and anthropogenic factors affecting the nest-site selection of Loggerhead Turtles, Caretta caretta, on Dalaman-Sarıgerme beach in South-west Turkey.

Abstract The nesting activities of Loggerhead Turtles (Caretta caretta Stejneger, 1902) and anthropogenic factors affecting them were monitored over 7 years (2002–2008) on Dalaman-Sarıgerme beach, one of the main nesting grounds in Turkey. Out of the 2620 nesting emergences recorded during the entire study period, only 645 (24.6%) resulted in successful nesting, giving an annual mean number of nests of 92. The collective number of eggs in these nests numbered 50239, with 40079 (79.8%) of them producing hatchlings. Out of the total number of eggs laid, 8128 (16.2%) resulted in dead embryos and 2032 (4.0%) in unfertilized eggs. The mean incubation period averaged 49 days (range 40–67 days) and the mean clutch size was 79.0 (range 18–150 eggs). Turtle nests were more concentrated on the undeveloped parts of the beach than on developed parts. In the other sections, few emergences occurred and either no or few nests were recorded. In Section I, which contained hotels and water sports facilities, only a few non-nesting emergences were observed. Of the number of nests that were observed, 32% were laid in Section II, which contained recently built hotels, 60% were in Section III and 8% were in Section IV, the undeveloped portion containing beach rocks. There is very clear evidence that the Loggerhead Turtles are shifting their nesting sites to the undisturbed sites along the beach. The negative factors that seem to be affecting them include water sports, hotel lights and beach rocks. In order to protect sea turtles, there needs to be a better understanding of how effective beach protection can be established.

Multiscale approach to (micro)porosity quantification in continental spring carbonate facies: Case study from the Cakmak quarry (Denizli, Turkey)

Carbonate spring deposits gained renewed interest as potential contributors to subsurface reservoirs and as continental archives of environmental changes. In contrast to their fabrics, petrophysical characteristics - and especially the importance of microporosity (< 1 mu m) - are less understood. This study presents the combination of advanced petrophysical and imaging techniques to investigate the pore network characteristics of three, common and widespread spring carbonate facies, as exposed in the Pleistocene Cakmak quarry (Denizli, Turkey): the extended Pond, the dipping crystalline Proximal Slope Facies and the draping Apron and Channel Facies deposits formed by encrustation of biological substrate. Integrating mercury injection capillary pressure, bulk and diffusion Nuclear Magnetic Resonance (NMR), NMR profiling and Brunauer-Emmett-Teller (BET) measurements with microscopy and micro-computer tomography (mu-CT), shows that NMR T-2 distributions systematically display a single group of micro-sized pore bodies, making up between 6 and 33% of the pore space (average NMR T-2 cut-off value: 62 ms). Micropore bodies are systematically located within cloudy crystal cores of granular and dendritic crystal textures in all facies. The investigated properties therefore do not reveal differences in micropore size or shape with respect to more or less biology-associated facies. The pore network of the travertine facies is distinctive in terms of (i) the percentage of microporosity, (ii) the connectivity of micropores with meso- to macropores, and (ii) the degree of heterogeneity at micro- and macroscale. Results show that an approach involving different NMR experiments provided the most complete view on the 3-D pore network especially when microporosity and connectivity are of interest.

ESR dating of stalagmite from Keloğlan cave in the southwestern part of Turkey

The determination of the geological age of two stalagmites (designated as A and B) found in Keloğlan cave (Denizli, Acıpayam, Turkey) was investigated using an electron spin resonance (ESR) technique. The natural ESR spectra had the signals of Mn2+ in addition to the signal at g=2.0006. In the ESR spectra of the γ-irradiated samples, three additional signals appear at g=2.0030, g=20016 and g=1.9972. The radicals produced by irradiation in stalagmites were attributed to orthorhombic and isotropic CO ion radicals. The signal intensity of the CO was used as a dating signal. Stalagmites were irradiated with a 60Co gamma source and measured with an ESR spectrometer (X-band) to obtain the signal intensity vs. dose curve, and fitted with the sum of two single exponential saturation functions. Based on this model, accumulated geological dose (DE) values for dating are obtained by using an additive dose method. The DE values of A and B stalagmites for each section range from 15±1 to 83±4 and 25±1 to 100±6 Gy, respectively. As the 238U, 232Th and 40K concentrations of the stalagmites are very low, the measured in situ value of the external gamma dose rate was used for dating calculations. Because some parts of the stalagmites show secondary calcite recrystallization in the pore spaces, the calculated age values of these parts do not agree with the model of stalagmite growth. Except these porous parts, the ESR ages of other sections between A.5–A.8 and B.3–B.6 range from 14±2 to 86±18 and 24±5 to 92±19 kyr, respectively, which is consistent with the model of stalagmite growth.

Sedimentology and evaporite genesis of neogene continental sabkha playa complex, Karakeçili basin, central Anatolia, Turkey

The Karakeçili basin is an intermontane basin located about 60 km SE of Ankara in central Turkey and covers an area of approximately 200 km2. This Neogene basin is bordered by granite and gabbro of the Kirsehir massif to the north-northeast and east, and massive gypsum of the Mezgit Formation (Oligocene) to the west and southwest.Facies associations characterizing a playa complex crop out in this Neogene basin. These facies associations include, from the basin margin to the center, 1-Red massive conglomerate and pebbly mudstone (alluvial fan), 2-Organically rich mudstone, bearing sparse gypsum crystals (marsh), 3-Cross-laminated-bedded gypsarenite (eolian), 4-Brown-gray mudstone bearing gypsum-roses and discoidal and radial gypsum crystals (saline mudflat), and 5-Bedded-laminated gypsum (ephemeral salt lake).Evaporites occur commonly as discoidal crystals, sigmoidal crystals, rosettes, and nodular forms. These were formed displacively within mudstone from calcium sulphate-rich groundwater during the arid conditions. Stratified gypsum represented by macrocrystalline aspects is generally restricted laterally and is precipitated by the evaporation of brine sheets on mudflats.The source of evaporites in the Karakeçili basin is the gypsum of the Oligocene Mezgit Formation.

Travertine occurrences along major strike-slip fault zones: structural, depositional and geochemical constraints from the Eastern Anatolian Fault System (EAFS), Turkey

The Eastern Anatolian Fault System (EAFS) is a left-lateral strike-slip fault zone, 30 km wide and 700 km long, that is the second most important neotectonic structure of Turkey. In this study, relationship between travertine precipitation and tectonic activity of some segments along this major strike-slip fault zone has been investigated by a multidisciplinary research. Structural, sedimentological, geochemical and geochronological studies were conducted on several travertine occurrences along the Karlıova-Bingöl segment (KBS) and the Adıyaman Fault Zone (AFZ) of the EAFS. The Baltaşı travertine mass on the AFZ was cross-cut by many extensional fractures that were filled by calcite veins. Geochemical analyses of the calcite veins indicate that some are hydrothermal in origin, whereas others are non-hydrothermal. Hydrothermal circulation in the crust was caused intermittently by the left-lateral strike-slip movements that have oblique- to normal-slip components in both the (KBS) and the (BYS) segments. Our results suggest that, from at least 325 ka until present, tectonic activity was consistently accompanied by travertine deposition. Based on dating of the travertine occurrences in the valley of the Göynük Stream around Hacılar and Elmalı, it is concluded that the NE-trending KBS is currently still active.