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Ozyurt, N. N.
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- PublicationOpen AccessThe origin of the fluids circulating over the Amik Basin (Turkey) and their relationships with the Dead Sea Fault(University of Patras, Greece, 2013-09-01)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Yuce, G.; Eskisehir Osmangazi University, Turkey ;Italiano, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;D'Alessandro, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Yalcin, T.H.; Istanbul Technical University, Turkey ;Yasin, D.U.; Eskisehir Osmangazi University, Turkey ;Gulbay, A.H.; Eskisehir Osmangazi University, Turkey ;Ozyurt, N.N.; Hacettepe University, Ankara, Turkey ;Rojay, B.; 5Middle East Technical University, Ankara, Turkey ;Karabacak, V.; Eskisehir Osmangazi University, Turkey ;Bellomo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Brusca, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Yang, T.F.; National Taiwan University, Taiwan ;Fu, C.C.; National Taiwan University, Taiwan ;Lai, C.W.; National Taiwan University, Taiwan; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Papatheodorou, G.; University of Patras, Dept. of Geology, Greece ;Iatrou, M.; University of Patras, Dept. of Geology, Greece ;Christodoulou, D.; University of Patras, Dept. of Geology, Greece ;Kordella, S.; University of Patras, Dept. of Geology, Greece ;Geraga, M.; University of Patras, Dept. of Geology, Greece; ; ; ; The Amik Basin is an asymmetrical composite transtensional basin developed between the seismically active left-lateral Dead Sea Fault (DSF) splays and the left-lateral oblique-slip Karasu Fault segment during neotectonic period. The relationship between the DSF and the East Anatolian Fault Zone is important as it represents a triple junction between Arabian Plate, African Plate and Anatolian Block in which the Amik Basin developed. The basin was formed on a pre-Miocene basement consisting of two rock series: Paleozoic crustal units with a Mesozoic allochthonous ophiolitic complex and ~1300 m thick Upper Miocene-Lower Pliocene sedimentary sequence. Plio-Quaternary sediments and Quaternary volcanics unconformably overlie the deformed and folded Miocene beds. Quaternary alkali-basaltic volcanism, derived from a metasomatized asthenospheric or lithospheric mantle, is most probably related to the syn-collisional transtensional strike-slip deformation in the area. Active faults in the region have the potential to generate catastrophic earthquakes (M>7). Nineteen samples of cold and thermal groundwaters have been collected over the Amik Basin area for dissolved gas analyses as well as two samples from the gas seeps, and one bubbling gas from a thermal spring Samples were analysed for their chemical and isotopic (He, C) composition. On the basis of their chemical composition, three main groups can be recognized. Most of the dissolved gases (16; Group I) collected from springs or shallow wells (< 150 m depth), contain mainly atmospheric gasses with very limited H2 (< 80 ppm) and CH4 (1– 2700 ppm) contents and minor concentrations of CO2 (0.5–11.2 %). The isotopic composition of Total Dissolved Carbon evidences a prevailing organic contribution with possible dissolution of carbonate rocks. However the CO2-richest sample shows a small but significant deep (probably mantle) contribution which is also evidenced by its He isotopic composition. Further three samples, taken from the northern part of the basin close to Quaternary volcanic outcrops and main tectonic structures, also exhibit a small mantle He contribution (Fig. 1). The two dissolved gases (Group II) collected from deep boreholes (> 1200 m depth) are typical of hydrocarbon reservoirs being very rich in CH4 (> 78 %) and N2 (> 13%). The water composition of these samples is also distinctive of saline connate waters (Cl- and B-rich, SO4-poor). Isotopic composition of methane (δ13C ~ -65‰) indicates a biogenic origin while He-isotopic composition points to a prevailing crustal signature for one (R/Ra 0.16) of the sites and a small mantle contribution for the other (R/Ra 0.98) (Fig. 1). The three free gas samples (Group III), taken at two sites within the ophiolitic basement west of the basin, have the typical composition of gas generated by low temperature serpentinisation processes with high hydrogen (37–50 %) and methane (10–61 %) concentrations. While all three gases show an almost identical δD-H2 of ~ -750‰, two of them display an isotopic composition of methane (δ13C ~ -5‰; δD ~ -105‰) and a C1/[C2+C3] ratio (~100) typical of abiogenic hydrocarbons and a significant contribution of mantle-type helium (R/Ra: 1.33). The composition of these two gasses is comparable to that of the gasses issuing in similar geologic conditions (Chimera-Turkey, Zambales-Philippine and Oman ophiolites). The gas composition of the other site evidences a contribution of a crustal (thermogenic) component (δ13C-CH4 ~ -30‰; δD-CH4 ~ -325‰; C1/[C2+C3] ~ 3000). Such crustal contribution is also supported by higher N2 contents (40% instead of 2%) and lower He-isotopic composition (R/Ra 0.07) (Fig. 1). These first results highlight contributions of mantle-derived volatiles possibly drained towards shallow levels by the DSF and other parallel structures crossing the basin showing a tectonic control of the fluids circulating within the Basin .247 108 - PublicationRestrictedOrigin and interactions of fluids circulating over the Amik Basin (Hatay, Turkey) and relationships with the hydrologic, geologic and tectonic settings(2014-09)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Yuce, G.; Hacettepe University, Ankara, Turkey ;Italiano, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;D'Alessandro, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Yalcin, T. H.; Istanbul Technical University, Turkey ;Yasin, D. U.; Eskisehir Osmangazi University, Turkey ;Gulbay, A. H.; Eskisehir Osmangazi University, Turkey ;Ozyurt, N. N.; Hacettepe University, Ankara, Turkey ;Rojay, B.; Middle East Technical University, Ankara, Turkey ;Karabacak, V.; Eskisehir Osmangazi University, Turkey ;Bellomo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Brusca, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia ;Yang, T. F.; National Taiwan University, Taiwan ;Fu, C. C.; Institute of Earth Sciences of Academia Sinica, Taiwan ;Lai, C. W.; National Taiwan University, Taiwan ;Ozacar, A.; Middle East Technical University, Ankara, Turkey ;Walia, V.; National Center for Research on Earthquake Engineering, Taipei, Taiwan; ; ; ; ; ; ; ; ; ; ; ; ; ; ; We investigated the geochemical features of the fluids circulating over the Amik Basin (SE Turkey–Syria border), which is crossed by the Northern extension of theDSF (Dead Sea Fault) and represents the boundary area of three tectonic plates (Anatolian, Arabian and African plates). We collected 34 water samples (thermal and cold from natural springs and boreholes) as well as 8 gas samples (bubbling and gas seepage) besides the gases dissolved in the sampled waters. The results show that the dissolved gas phase is a mixture of shallow (atmospheric) and deep components either of mantle and crustal origin. Coherently the sampled waters are variable mixtures of shallow and deep ground waters, the latter being characterised by higher salinity and longer residence times. The deep groundwaters (fromboreholes deeper than 1000 m)have a CH4-dominated dissolved gas phase related to the presence of hydrocarbon reservoirs. The very unique tectonic setting of the area includes the presence of an ophiolitic block outcropping in the westernmost area on the African Plate, as well as basalts located to the North and East on the Arabic Plate. The diffuse presence of CO2-enriched gases, although diluted by the huge groundwater circulation, testifies a regional degassing activity. Fluids circulating over the ophiolitic block are marked by H2-dominated gases with abiogenic methane and high-pH waters. The measured 3He/4He isotopic ratios display contributions from both crustal and mantle-derived sources over both sides of the DSF. Although the serpentinization process is generally independent from mantle-type contribution, the recorded helium isotopic ratios highlight variable contents of mantle-derived fluids. Due to the absence of recent volcanism over the western side of the basin (African Plate), we argue that CO2-rich volatiles carrying mantle-type helium and enriched in heavy carbon, are degassed by deep-rooted regional faults rather than from volcanic sources.465 105