BRIEFLY OVERVIEW OF THE MAJOR ELEMENT ANALYSIS AND THE CLASSIFICATION OF THE ERCİYES STRATOVOLCANO AND SOUTHWESTERN CAPPADOCIA SAMPLES

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Mineralogy and Petrograph

Polarized microscope

Samples collected from the studied area were cut and left for drying. Later on these samples were carefully studied under the daylight and parts considered as altered were then rasped in cutting machine in “Magmas et Volcans” laboratory, Blaise Pascal University (Clermont-Ferrand/France). After this process, thin sections were prepared. Thin sections were polished at 3 different processes with 10 minute periods each in Mecatech 334 brand machine.

Electron Probe Micro Analyses (EPMA)

In order to determine the chemical compositions of minerals, a Cameca SX-100 brand electron microscope was used at “Magmas et Volcans” laboratory, Blaise Pascal University (Clermont-Ferrand/ France). Analyses were made at 15 kv, 10-12 nA and 10 s for phenocrysts, microphenocrysts and microlites, and at 15 kv, 4 nA and 5µm, 10 s for glass analyses. Na and K elements were analyzed first, in order to prevent to the migration of these mobile alkaline elements.

Geochemical Analyses

Major and trace elements analytical methods

For the accuracy of the analyses, fresh and unaltered samples were selected. Selected samples were cut and made into small chips in jaw crusher. Afterwards, small chips milled in agate mortar. The trace and rare earth element analyses have been made at the Center of Petrographic and Geochemical Research (Centre de Recherches Pétrographiques et Géochimiques) (Nancy/ France). Main element dissolutions were expressed in oxide %. Trace and rare earth element analyses were expressed in ppm (parts per million).

ICP-AES (Inductively Coupled Plasma – Atomic Emission Spectrometry)

Major element (Si, Al, Fe, Mn, Mg, Ca, Na, K, P, and Ti) analyses have been performed at Service d’Analyse des Roches et des Minéraux, CRPG – CNRS (Nancy/France) using Jobin-Yvon JY 70. Powdered samples (200 mg) were molten by LiBO2 (Lithium metaborate) and dissolved by HNO3. Prepared solutions were analyzed by the automatic procedure installed in the system. Detection limits and uncertainties at given intervals for major elements were given in Table1.1 (http://helium.crpg.cnrs-nancy.fr/SARM/pages/roches.html).
Trace element analyses have been conducted in Service d’Analyse des Roches et des Minéraux, CRPG – CNRS (Nancy, France) using Perkin Elmer 5000 Mass Spectrometer. The detection limits and uncertainties at given intervals, for trace elements, are given in Table 1.2 (http://helium.crpg.cnrs-nancy.fr/SARM/pages/roches.html).
During the selection of the sample for isotope analysis, hand specimen and thin section observations, major and trace element results, LOI contents and previous wrokers studies were taken into consideration. The Sr, Nd and Pb isotope analyses were performed by C.Deniel, both at UMR 6524 Clermont-Ferrand (Sr and Nd) and ENS Lyon (Pb).
Isotopic analyses for Sr and Nd were made using Thermo-Finnigan Triton (TI) brand mass spectrometer at the “Magmas et Volcans” laboratory, Blaise Pascal University (Clermont-Ferrand/France).
Samples selected for isotope analyses were prepared in 4 different data sets and measurements have been completed at different periods. Selected samples were first crushing by jaw crusher at the laboratory “Magmas et Volcans”, quartered then approximately 50 mg of it was separated (hand picked selection of unaltered chips). A part of 0.5 mg was selected from unaltered crushed small chips that have no sign of cutting or alteration. Then, 0.2 mg of the selected 0.5 mg grains were weighed then put into teflon beakers. These separated samples were first washed for 10 minutes by 2N HCl, then was cleaned by distilled water. Later, 1 ml HNO3+4 ml HF was added and placed on a hot plate at 90°C. During 2 days, three times a day (morning, noon and night) ultrasonic bath were applied then they were again put onto the hot plate. After dissolution process had been completed, Pb, Sr and Nd elements were separated by the method of ion exchange chromatography.
Solutions obtained were taken into a solution by 0.05M HNO3 and loaded into single Re (Rhenium) filaments with 2 µl Ta2O5 activator and 3 drop of 3M H3PO4 for Sr isotope measurements. However, for Nd isotope measurements solutions obtained were taken into a solution by 0.05M HNO3 then loaded into dual W (Tungsten) filament (except the 4th series onto double Re filament) with a drop of 1M H3PO4. For the isotopic measurements of Sr and Nd, National Bureau of Standards NBS 987 and JNDi standards have been used, respectively to evaluate the accuracy and reproducibility of the mass spectrometer. Over the period of measurements, replicate analyses of standards gave for the NBS 987, 87Sr/86Sr=0.710238 ± 5.5.10-6 (2σ) (N=19) and for JNDi, 143Nd/144Nd=0.512102 ± 7.2.10-6 (2σ) (N=24). The 87Sr/86Sr ratios were normalized to 87Sr/86Sr =0.1194, and 143Nd/144Nd ratios were normalized to143Nd/144Nd =0.7219. Total blanks were 0.05-0.1 ng for Sr and 0.09-0.4 ng for Nd. The samples HA15 and ER27 were duplicated to check the reproducibility of the chemical preparation.
Pb isotope analyses were carried out at Ecole Normale Supérieure de Lyon (France) using MC-ICP-MS (Multicollector mass spectrometer) (Nu instrument 041). In order to follow the mass fractionation in Pb isotope measurements Tl (thallium) spike has been added (White et al., 2000). The Pb isotopic ratios were corrected for instrumental fractionation using average measured values of the NBS981 standard. Total blank levels were less than 50 pg.
Based on the handspecimen, thin section, major and trace element results of the samples, low LOI contents and unaltered samples were selected for stable isotope analysis. 0.7 mg of powder samples, which milled in agate mortar were manupulated for oxygen isotope analyses.
Oxygen isotope analyses have been performed at the Stable Isotope Laboratory of Jean-Monnet University by Marie-Christine Gerbe, Laboratory of Lithospheric Transfers (LTL) (Saint-Etienne, France).
The extraction of oxygen from the whole rocks and minerals is performed on a conventional extraction line type by reaction at high temperature with BrF5 (Bromine pentafluoride) and oxygen is converted to CO2 (Clayton and Mayeda, 1963). The performance of each analysis was calculated by systematically measuring the volume of CO2 obtained during the conversion reaction. For oxygen isotope measurement of each series, MQ laboratory standard (Université de Capedown, South Africa, Murchinson Quartz) used regularly. MQ results calibrated according to the suggested international quartz standard NBS-28 10.1±0.2 (Vennemann et Smith, 1990). The average of the repetitive measurements (N=16) of MQ value was determined as (10.01±0.10). This value is very close to the recommended value. The accuracy and preciseness of analyses were 0.3‰ (2 sigma) during the separation of oxygen from silicates in LTL.
Oxygen isotope analyses were performed on a micromass isoprime triple collector-dual inlet mass spectrometer. In order to correlate the oxygen gas of samples in measurements, the references NBS19 and CO8 carbonate gases were used. The measurement results were normalized as δ18O‰=(R sample/R standard-1)×103, R=(18O/16O) according to the Standard Mean Ocean Water (VSMOW) (Coplen, 1993). Duplicates were made for 12 whole rock samples to determine the average reproducibility of analyzes of our samples. It is ± 0.3 ‰ for whole rock (2 sigma).

K-Ar Dating Method

The selection of the samples for the analysis of K-Ar dating; major and trace elements results, LOI values, macroscopic (hand specimen)-microscopic (thin section) observations and the previous studies were taken into account.
The dating of selected samples has been performed in Laboratoire des Sciences du Climat et de l’Environnement by Hervé Guillou, Unité Mixte de Recherche CEA-CNRS (LSCE) in Gif-sur-Yvette, France.
Samples were crushed (nearly 500 g) and sieved to 0.25 – 0.125 mm size fraction. Approximately, 60 g of fractioned samples were washed in ultrasonic bath with HC2H3O2. Groundmass of the rocks was separated following the procedure detailed in Guillou et al. (1998). Initially, magnetic separation was made and later phenocrysts and microphenocrysts were removed by means of heavy liquids (diodomethane). K analyses have been made in the “Centre de Recherches Pétrographiques et Géochimiques” at Nancy, France. Ar extraction and the method of analysis are presented in Carbit et al. (1998). The Isotopic composition of Ar and total Ar content were determined applying the unspiked K-Ar technique, (see Cassignol et al. (1982) and Carbit et al. (1998)). For calibration reference materials, analytical procedure and the settings of the mass spectrometers used refer to Guillou et al. (1998) and references therein.

GENERAL GEOLOGY

General Setting of the Studied Areas in Cappadocia

The tectonic regime changed as a result of the collision of the Eurasian and Arabian plates in the Middle (Early) Miocene, marking the beginning of neotectonic times (Şengör, 1980; Şengör and Yılmaz, 1981). Due to the effects of this collision in Eastern Anatolia, deformations started on the continental crust along the Bitlis Suture Belt. The shortening and thickening of the crust with time was not able to compensate for the deformations, and the Anatolian block started to move westward along the NAF (North Anatolian Fault) and EAF (East Anatolian Fault), which are strike-slip faults (McKenzie, 1972; Şengör et al., 1985; Dewey et al., 1986). Intraplate deformations developed in the Anatolian Block during this period as well as pull apart basins and thrust faults (Şengör, 1980; Dhont et al., 1998; Seyitoğlu et al., 2009).
The Anatolian Plate was the scene of intense volcanic activity, mainly concentrated in three regions: West, Central and East Anatolia. This thesis considers the Quaternary Erciyes and Hasandağ stratovolcanoes and the dispersed volcanism of Obruk-Zengen and Karapınar, from Central Anatolia, Cappadocia. However, easy to make comparison for regions, Hasandağ stratovolcano, Obruk-Zengen and the Karapınar dispersed volcanisms are collected under the Southwestern Cappadocia volcanism title.
A geological map of the studied area was prepared by reference to Pasquare et al. (1988), Le Pennec et al. (1994) and Temel et al. (1998) (Figure 2.1). However, in order to investigate volcanic units in more detail, the geological maps that former investigators prepared for the Erciyes and Hasandağ stratovolcanoes were used, and also the 1/500 000 scaled geological maps of Turkey of MTA (The General Directorate of Mineral Research and Exploration) for the Karapınar and Obruk-Zengen dispersed volcanism. Geological maps related to the studied areas were superposed with SRTM (Shuttle Radar Topography Mission) images. Sampling locations were noted in Figure 2.2 for Erciyes stratovolcano, in Figure 2.3 for Hasandağ stratovolcano, in Figure 2.4 for Obruk-Zengen dispersed volcanism and in Figure 2.5 for Karapınar dispersed volcanism.
The first detailed stratigraphic studies for the Erciyes and Hasandağ stratovolcanoes were made by Şen (1997) and Aydar (1992), respectively.
UTM coordinates of 29 samples, and of other samples belonging to the four regions for which the ages had been determined using K/Ar dating, are given in Table 2.1. Colors representing the four different regions in Table 2.1 will always be used to indicate the same regions throughout the thesis. Purple represents Erciyes stratovolcano, green represents Hasandağ stratovolcano, red for the Obruk-Zengen volcanism and blue for the Karapınar area. Some modifications were made to the stratigraphical sections prepared by former investigators using the new geochronological data obtained in this study.

Table of contents :

1 INTRODUCTION
1.1. PURPOSE AND SCOPE
1.2. STUDIED AREAS
1.3. PREVIOUS STDUDIES IN CAPPADOCIA
1.4. LABORATORY STUDIES AND ANALYTICAL METHODS
1.4.1. Mineraology and Petrography
1.4.2. Geochemical Analyses
1.4.3. K-Ar Dating Method
2 GENERAL GEOLOGY
2.1. GENERAL SETTING OF THE STUDIED AREAS IN CAPPADOCIA
2.2. OVERVIEW ON POST-COLLISIONAL MAGMATISM
2.3. THE BASEMENT ROCKS OF CAPPADOCIA
2.4. BRIEFLY OVERVIEW OF THE MAJOR ELEMENT ANALYSIS AND THE CLASSIFICATION OF THE ERCİYES STRATOVOLCANO AND SOUTHWESTERN CAPPADOCIA SAMPLES
2.5. THE ERCİYES STRATOVOLCANO
2.6. THE SOUTHWESTERN CAPPADOCIA VOLCANISM
2.6.1. Hasandağ Basaltic Volcanism
2.6.2. The Obruk-Zengen Dispersed Volcanism
2.6.3. The Karapınar Dispersed Volcanism
2.7. CONCLUSION
3 MINERALOGY AND PETROGRPHY
3.1. THE BASALTS S.L. OF ERCİYES STROTOVOLCANO
3.2. THE BASALTS S.L. OF SOUTHWESTERN CAPPADOCIA
3.2.1. The Basalts s.l. of Hasandağ Stratovolcano
3.2.2. The Basalts s.l. of the Obruk-Zengen Dispersed Volcanism
3.2.3. Basalts s.l. of the Karapınar Dispersed Volcanism
3.3. CONCLUSION
4 MINERAL CHEMISTRY
4.1. MINERAL CHEMISTRY OF THE BASALTS S.L. OF THE ERCİYES STROTOVOLCANO
4.2. MINERAL CHEMISTRY OF THE BASALTS S.L OF THE SOUTHWESTERN CAPPADOCIA VOLCANISM
4.2.1. The Hasandağ Stratovolcano
4.2.2. The Obruk-Zengen Dispersed Volcanism
4.2.3. The Karapınar Dispersed Volcanism
4.3. CRYSTAL-LIQUID EQUILIBRIUM
4.3.1. Erciyes Stratovolcano
4.3.1.1. Olivine-Liquid Equilibrium
4.3.1.2. Clinopyroxene-Liquid Equilibrium
4.3.1.3. Feldispar-Liquid Equilibrium
4.3.2. Southwestern Cappadocia Volcanism
4.3.2.1. Olivine-Liquid Equilibrium
4.3.2.2. Clinopyroxene-Liquid Equilibrium
4.3.2.3. Feldspar-Liquid Equilibrium
4.4. GEOTHERMOMETER AND GEOBAROMETER CALCULATION
4.4.1. Erciyes Stratovolcano
4.4.1.1. Olivine-Liquid Geothermometer
4.4.1.2. Clinopyroxene-Liquid Geothermometer
4.4.1.3. Clinopyroxene-Orthopyroxene Geothermometer
4.4.1.4. Plagioclase-Liquid Geothermometer
4.4.2. The Soutwestern Cappadocia
4.4.2.1. Olivine-Liquid Geothermometer
4.4.2.2. Clinopyroxene-Liquid Geothermometer
4.4.2.3. Plagioclase-Liquid Geothermometer
4.4.3. Conclusion
5 GEOCHEMISTRY
5.1. MAJOR, TRACE AND RARE EARTH ELEMENT (REE) ANALYSIS
5.1.1. Erciyes Strotovolcano
5.1.2. Southwestern Cappadocia Volcanism
5.2. ISOTOPE GEOCHEMISTRY
5.2.1. Sr-Nd-Pb-O Isotope Geochemistry
5.2.1.1. Erciyes Stratovolcano
5.2.1.2. Southwestern Cappadocia Volcanism
5.3. CONCLUSION
6 DISCUSSION and CONCLUSION
6.1. ERCİYES STRATOVOLCANO
6.1.1. Partial Melting
6.1.2. Fractional Crystallization
6.1.3. Crustal Contamination and AFC (Assimilation Fractional Crystallization)
6.1.3.1. Potential Contaminants and AFC modeling
6.1.4. Mixing Sources
6.2. SOUTHWESTERN CAPPADOCİA VOLCANISM
6.2.1. Partial Melting
6.2.2. Fractional Crystallization
6.2.3. Crustal Contamination-AFC
6.2.3.1. Potential Contaminants and AFC modeling
6.2.4. Mixing Souces
6.3. TECTONICS
6.4. POSSIBLE MAGMA SOURCES
6.5. COMPARISON OF ES, HS, OZ AND K
6.6. TEMPORAL AND SPATIAL EVOLUTION OF MAGMA

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