Helium isotope variations in Turkey: relationship to tectonics, volcanism and recent seismic activities

The distribution of helium isotope ratios in the various tectonic provinces of Turkey is examined through a synthesis of previously published data and the results of a recent survey along the North Anatolian Fault Zone (NAFZ) following the catastrophic 1999 earthquakes. The R/R-A values (where R = sample He-3/He-4 and RA = air He-3/He-4) cover a wide range from 0.05 to 7.87, and the mantle-derived helium is clearly identified in most locations, The mantle-derived component is high (> 50% of total He) in (a) regions of central and eastern Anatolia, both of which are associated with historically active volcanoes, and (b) the seismically active west-to-central segment of NAFZ. While the mantle contribution reaches a maximum at Nemrut volcano in eastern Anatolia-a region of dominantly compressional tectonics and with moderate enthalpy geothermal fields, it is relatively low (< 50%) in the western Anatolian extensional province even though this region has the highest geothermal potential. The average He-3/enthalpy ratios estimated for the different provinces suggest lithospheric stretching and rise of the geotherm as the major mechanism of high heat flow, yet limited intrusive activity in western Anatolia is suggested as the reason for the comparatively low He additions and consequently low (1.7 x 10(6) atoms/J) He-3/enthalpy ratios. A more extensive magmatic activity appears to be responsible for the greater input of both heat and helium in eastern and central Anatolia, with intra-province He-3/enthalpy variations (from 3.1 x 10(6) atoms/J in eastern to 0.25 x 10(6) atoms/J in central Anatolia) reflecting the ageing of hydro-magmatic systems. The relatively high He-3 concentrations in low enthalpy waters of northern Anatolia (2.8 x 10(6) atoms/J) are particularly significant since there is no evidence of volcanic activity associated with the strike-slip motion along the seismically active segment of NAFZ. Continuous monitoring of He-isotope compositions along NAFZ should lead to a better understanding of this apparent anomaly, as well as the relationship (if any) between He-isotope variations and seismic activities in this region.


Identification of morphometric properties of basins located on western part of NAFZ
Sarp, Gülcan; Toprak, Vedat; Düzgün, H. Şebnem; Department of Geodetic and Geographical Information Technologies (2012)
This study aims to investigate tectonic activity levels and development stages of the tectonic and hydrologic basin areas located on western part of the main trace of the North Anatolian Fault Zone (NAFZ) using quantitative measurement techniques. The basins investigated are Bolu, Yeniçağa, Dörtdivan, Çerkes, Ilgaz and Tosya. The methodology includes application of six morphometric indices (Basin Shape, Hypsometric curve and Hypsometric Integral, Sinuosity of Mountain Fronts, Stream Length Gradient Index, V...
Late Miocene transcurrent tectonics in NW Turkey: evidence from palaeomagnetism and 40Ar–39Ar dating of alkaline volcanic rocks
KAYMAKCI, N.; Kaymakcı, Nuretdin; LANGEREIS, C.; SPELL, T. L.; GURER, O. F.; ZANETTI, K. A. (Cambridge University Press (CUP), 2007-2-9)
<jats:p>A number of intra-continental alkaline volcanic sequences in NW Turkey were emplaced along localized extensional gaps within dextral strike-slip fault zones prior to the initiation of the North Anatolian Fault Zone. This study presents new palaeomagnetic and <jats:sup>40</jats:sup>Ar–<jats:sup>39</jats:sup>Ar geochronological results from the lava flows of NW Turkey as a contribution towards understanding the Neogene–Quaternary tectonic evolution of the region and possible roles of block rotations i...
Helium-carbon relationships in geothermal fluids of western Anatolia, Turkey
Mutlu, Halim; Güleç, Nilgün Türkan; Hilton, David R. (Elsevier BV, 2008-01-15)
We investigate the helium, carbon and oxygen-hydrogen isotopic systematics and CO(2)/(3)He ratios of 8 water and 6 gas samples collected from 12 geothermal fields in western Anatolia (Turkey). (3)He/(4)He ratios of the samples (R) normalized to the atmospheric (3)He/(4)He ratio (R(A) = 1.39 x 10(-6)) range from 0.27 to 1.67 and are significantly higher than the crustal production value of 0.05. Fluids with relatively high R/R(A) values are generally found in areas of significant heat potential (Kizildere an...
Source components and magmatic processes in the genesis of Miocene to Quaternary lavas in western Turkey: constraints from HSE distribution and Hf-Pb-Os isotopes
Aldanmaz, Ercan; Pickard, Megan; Meisel, Thomas; Altunkaynak, Şafak; Sayıt, Kaan; Sen, Pinar; Hanan, Barry B.; Furman, Tanya (Springer Science and Business Media LLC, 2015-08-01)
Hf-Pb-Os isotope compositions and highly siderophile element (HSE) abundance variations are used to evaluate the mantle source characteristics and possible effects of differentiation processes in lavas from western Turkey, where the eruption of Late Miocene to Quaternary OIB-type intraplate mafic alkaline lavas followed pre-Middle Miocene convergent margin-type volcanism. Concentrations of Os, Ir, and Ru (IPGE) in the OIB-type intraplate lavas decrease with fractionation for primitive melts (MgO > 10 wt%), ...
Cross-sectional anatomy and geodynamic evolution of the Central Pontide orogenic belt (northern Turkey)
Hippolyte, JC; Espurt, Nikolas; Kaymakcı, Nuretdin; SANĞU, ERCAN; Mueller, C. (2016-01-01)
Geophysical data allowed the construction of a similar to 250-km-long lithospheric-scale balanced cross section of the southern Black Sea margin (Espurt et al. in Lithosphere 6:26-34, 2014). In this paper, we combine structural field data, stratigraphic data, and fault kinematics analyses with the 70-km-long onshore part of the section to reconstruct the geodynamic evolution of the Central Pontide orogen. These data reveal new aspects of the structural evolution of the Pontides since the Early Cretaceous. T...
Citation Formats
N. T. Güleç and H. Mutlu, “Helium isotope variations in Turkey: relationship to tectonics, volcanism and recent seismic activities,” CHEMICAL GEOLOGY, pp. 129–142, 2002, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/49292.