Combined U-series dating and high-resolution geochemical analyses of co-seismic carbonate veins o... more Combined U-series dating and high-resolution geochemical analyses of co-seismic carbonate veins offer an invaluable opportunity to document young (<1 Ma) earthquake activity and for tracing origins of associated fluids. In this study, we analysed a total of 23 samples of fault-related carbonate veins and slickenfibered calcites collected from two separate SW– S-trending fault zones developed near Anamur and Gazipaşa areas in Southern Turkey. Microtexturally the carbonate veins mainly comprise medium- to coarse-grained, columnar calcite crystals elongated along growth direction. U-series dating indicated episodic fault-related carbonate mineralization between 132 ± 2 and 5.6 ± 0.4 ka and between 530 ± 63 and 30.0 ± 2.1 ka in Anamur and Gazipaşa areas, respectively. Carbon and oxygen isotope compositions of carbonates from both Anamur (δ13C = -12 to -6‰, δ18O = -7 to -4‰; relative to V-PDB) and Gazipaşa (δ13C = -12 to -7‰, δ18O = -7 to -3‰) areas are almost identical, whereas Anamu...
<p>Turkey lies along the transition zone between northerly and southerly climate regimes su... more <p>Turkey lies along the transition zone between northerly and southerly climate regimes such that it provides opportunity for a good understanding of Holocene climate that impacted ancient Eastern Mediterranean civilizations. Within the scope of the EU-funded SPELEOTOLIA project, 7 caves from western and southwestern Anatolia were visited and several stalagmite samples were collected. Detailed mineralogical and geochemical analyses performed on samples from one of the target caves, the S&#305;rtlanini Cave (Karacasu, Ayd&#305;n), helps to reconstruct the regional Holocene climate and gives insights on living conditions of Anatolian civilizations, mainly including Roman and Ottoman Empires. &#160;&#160;</p><p>The 450 m-long S&#305;rtlanini Cave (max. depth of ~40 m; ~1060 m a.s.l.) developed within the Mesozoic marbles of the Menderes Massif. We focus on the first set of U-series age, stable and radiogenic isotope (C, O, and Sr) and mineralogical data performed on the stalagmite (SRT-5) from this cave. The drip water isotope data (&#948;<sup>18</sup>O<sub>VSMOW</sub> = -7.8&#8240;, &#948;D<sub>VSMOW</sub> = -41.6&#8240;) indicated depletions in O and H isotopes compared to other cave waters in the region. The U-series age results of SRT-5 show that the 423 mm-long stalagmite was deposited fast (0.25 mm/y) between 0.111&#177;0.034 kyr and 1.825&#177;0.421 kyr (BP) spanning the Roman, Byzantine and Ottoman periods. SRT-5 seems to have grown intermittently with at least two possible hiatuses (at around 291 and 401 years BP) based on mineralogical studies. It is mainly composed of fine- to medium-grained columnar calcite, with occasional dendritic fabric and visible annual layering, particularly at the older bottom section of the stalagmite. Stable isotope profiles (&#948;<sup>13</sup>C: -10.5 to -8&#8240; VPDB, &#948;<sup>18</sup>O: -7 to -5.5&#8240; VPDB) constructed using 423 sub-sample analyses along the stalagmite demonstrate significant hydroclimatic variability through the Little Ice Age and Medieval Warm Period between 195 and 1909 CE. This variation correlates well with previously documented drought and related famine and migration events in western Anatolia primarily in the 19<sup>th</sup> century. Further investigations (e.g., high-resolution LA-ICPMS trace element analyses) will be performed specifically to constrain the anthropogenic sources and distinguish these from recent Aegean or possible global (e.g., southeast Asian) volcanogenic signals.&#160;</p><p>This project has received funding from the European Union&#8217;s Horizon 2020 research and innovation programme under the Marie Sk&#322;odowska-Curie grant agreement No: 842403.</p>
Microscope (microfabrics) and geochemical (stable isotope, trace element, Sr isotope) data derive... more Microscope (microfabrics) and geochemical (stable isotope, trace element, Sr isotope) data derived from the stalagmite BUI collected from Bucak (Burdur Province, SW Turkey) provide detailed insight into paleoclimatic conditions during MIS 5d–b for the first time. MC-ICP-MS U-series dating of the speleothem revealed a two-step growth pattern that spans between ∼118 and ∼89 kyr BP in the late Pleistocene and builds on previously published high-resolution stable isotope time series (10–90 kyr BP) from Dim Cave in S-SW Turkey (Ünal-İmer et al., 2015; 2016). In the microstratigraphic sequence of the BUI stalagmite, carbonate (mostly as calcite and aragonite) fabrics are characterized dominantly by columnar (elongated and microcrystalline) and dendritic forms of calcite, with lesser acicular aragonite and also by diagenetic mosaic calcite and lateral overgrowths. Stalagmite growth rates were determined to be dramatically higher during interstadials, displaying strong links with the summer...
The socle stones of the Great Temple in the Lower City of the Hittite capital city, Hattusha (Çor... more The socle stones of the Great Temple in the Lower City of the Hittite capital city, Hattusha (Çorum Province) have been studied for the first time by petrographic and geochemical analysis (Sr isotope, stable isotope, and trace element geochemistry). Study objectives were to determine the carbonate facies of the stone samples used in the Great Temple and investigate their possible sources. Petrographic analysis of 10 limestone samples presents five clusters of different microfacies. Stable isotope (δ 13 C and δ 18 O) analysis displayed the presence of 5 groups in parallel with petrographic analysis. Trace element analysis of the same groups displayed considerable difference among the stone samples and 87 Sr/ 86 Sr isotope ratios change between 0.70697 and 0.706867. Based on the results, it can be stated that the building using stones are from probably five different sources. This is of great importance to better understand the construction process and the acquisition of the building materials. Download at: https://journals.tubitak.gov.tr/earth/vol31/iss3/4
This study presents new U-Th age data from co-seismic carbonate vein deposition along the 1939 Er... more This study presents new U-Th age data from co-seismic carbonate vein deposition along the 1939 Erzincan earthquake-rupture segment of the North Anatolian Fault Zone (NAFZ). Our statistical evaluations on age correlations indicate that the carbonate vein deposition is concentrated at least in eight different periods during the last 7000 years along the NAFZ. The periods are well correlated with the historical earthquake records and with the previous dating results of the surrounding trench studies. At least six of the periods correspond to the 1200 BC, 499 AD, 1045 AD, 1166/1168 AD, 1419/22 AD, and 1783/84 AD earthquakes reported in the historical catalogues. The age correlations of carbonate precipitation interval for the last millennium show a recurrence along the eastern NAFZ with a mode at 130–330 years that is consistent with the previously proposed paleoseismic recurrence interval of the fault. Our results suggest that co-seismic carbonate veins could be used to determine paleo...
Abstract Central Anatolia represents one of the most outstanding examples of intraplate deformati... more Abstract Central Anatolia represents one of the most outstanding examples of intraplate deformation related to both continental collision and back-arc extension generating non-uniformly distributed stress fields. In this study, we provide direct field evidence of various stress directions and investigate carbonate-filled fracture systems in the Central Anatolian Volcanic Province using U/Th geochronology and isotope geochemistry for evaluating the episodes of latest volcanic activity under regional stress. Field data reveal two independent fracture systems in the region. Successive fracture development has been controlled by two different volcanic eruption centers (Hasandag Composite Volcano and Acigol Caldera). Trace element, and stable (C and O) and radiogenic (Sr) isotope compositions of carbonate veins indicate different fluid migration pathways for two different fracture systems. The U/Th age data for carbonate veins of two independent fracture systems indicate that the crustal deformation intensified during 7 episodic periods in the last 150 ka. The NNE-trending first fracture system was formed as a result of strain cycles in a period from 149 ± 2.5, through 91 ± 1.5 to 83 ± 2.5 ka BP. Subsequent deformation events represented by the ENE-trending second fracture zone have been triggered during the period of 53 ± 3.5, 44 ± 0.6 and 34 ± 1 ka BP before the first fracture zone resumed the activity at about 4.7 ± 0.15 ka BP. Although further studies are needed to evaluate statistical significance of age correlations, the periods of carbonate precipitation inferred from U-Th age distributions in this study are comparable with the previous dating results of surrounding volcanic eruption events.
Abstract Multiple climate-sensitive trace element/Ca and stable isotope (O and C) profiles derive... more Abstract Multiple climate-sensitive trace element/Ca and stable isotope (O and C) profiles derived from Dim Cave speleothems (S-SW Turkey) provide evidence of climatic changes and define a series of palaeohydrological conditions for the period ~10–90 kyr. Dim Cave speleothem Mg/Ca, Sr/Ca, U/Ca, Ba/Ca, and Y/Ca ratios demonstrate similar patterns over glacial–interglacial scales, in agreement with δ18O and δ13C records. Three episodes of more positive moisture balance (71–63 kyr, 51–40 kyr, and 18–10 kyr) were observed based on Y/Ca (and to a lesser extent Zr/Ca), 87Sr/86Sr ratios, calcite micromorphology, and growth rates. Increasing concentrations of Y, Zr (and U) and elevated 87Sr/86Sr ratios are attributed to enhanced levels of terrestrial input during these periods. Correlations between δ13C, δ18O and Mg/Ca during 40–18 kyr (corresponding with the lowest growth rate of ~ 0.8 mm/kyr), 63–51, and 80–71 kyr (relatively low growth rates), as well as co-varying and enhanced Mg/Ca, Sr/Ca, and to a lesser extent Ba/Ca, ratios point to the prior calcite precipitation, wall rock interaction, and preferential dolomite dissolution over calcite in the host dolomitic limestone during these periods. This relationship suggests that water–rock interactions are maximised during episodes of slower drip rates of water through the karst under drier conditions. Chondrite-normalised rare earth element and yttrium (REY) patterns of the stalagmites reveal seawater signatures closely linked to the dolomitic limestone. Excluding the aragonite formation during ~80–75 kyr, which is an autogenic effect, trace element/Ca ratios appear to respond to millennial scale global cooling periods such as Heinrich events.
Abstract Vein and breccia carbonates precipitated in a highly fractured/faulted carbonate bedrock... more Abstract Vein and breccia carbonates precipitated in a highly fractured/faulted carbonate bedrock in SW Turkey were investigated through high-resolution U-series geochronology, microstructural and geochemical studies including C–O–Sr isotope and rare-earth element and yttrium (REY) analyses. Petrographical observations and geochronological data are interpreted as evidence that the calcite veins formed through a crack-seal mechanism, mostly accompanied/initiated by intensive hydraulic fracturing of the host limestone in response to high-pressure fluids, which is manifested by multi-stage breccia deposits. Microscale U-series dates (272.6–20.5 kyr) and geochemical compositions of the vein/breccia samples provide information on the timing and mechanism of the vein formation and identify the source of CO 2 -bearing fluids responsible for the carbonate precipitation. δ 18 O VPDB and δ 13 C VPDB values of the calcite veins range between −5.9 and −1.7‰, and −10.6 and −4.6‰, respectively. The isotopic compositions of the veins show highly fluctuating values as calcite grew successively perpendicular to vein walls, which, in combination with microstructural and geochronological constraints, are interpreted to reflect episodic CO 2 degassing events associated with seismic and aseismic deformation. Oxygen and Sr isotope compositions (δ 18 O VPDB : −5.9 to −1.7‰; 87 Sr/ 86 Sr: 0.7082 to 0.7085) together with REY concentrations indicate deep infiltration of meteoric waters with various degrees of interactions mostly with the host limestone and siliciclastic parts of the basement rocks. Oxygen and carbon isotope compositions suggest CO 2 degassing through intensive limestone dissolution. While majority of the veins display similar Post-Archaean Australian Shale (PAAS)-normalised REY variations, some of the veins show positive Eu PAAS anomalies, which could be indicative of contributions from a deeply derived, heated, and reduced fluid component, giving rise to multiple fluid sources for the calcite veins. Vein calcite formed in fault-induced fractures offers insights into structural features, genetic characterisation of the parental fluids, and late Quaternary degassing of subsurface CO 2 accumulations.
Combined U-series dating and high-resolution geochemical analyses of co-seismic carbonate veins o... more Combined U-series dating and high-resolution geochemical analyses of co-seismic carbonate veins offer an invaluable opportunity to document young (<1 Ma) earthquake activity and for tracing origins of associated fluids. In this study, we analysed a total of 23 samples of fault-related carbonate veins and slickenfibered calcites collected from two separate SW– S-trending fault zones developed near Anamur and Gazipaşa areas in Southern Turkey. Microtexturally the carbonate veins mainly comprise medium- to coarse-grained, columnar calcite crystals elongated along growth direction. U-series dating indicated episodic fault-related carbonate mineralization between 132 ± 2 and 5.6 ± 0.4 ka and between 530 ± 63 and 30.0 ± 2.1 ka in Anamur and Gazipaşa areas, respectively. Carbon and oxygen isotope compositions of carbonates from both Anamur (δ13C = -12 to -6‰, δ18O = -7 to -4‰; relative to V-PDB) and Gazipaşa (δ13C = -12 to -7‰, δ18O = -7 to -3‰) areas are almost identical, whereas Anamu...
<p>Turkey lies along the transition zone between northerly and southerly climate regimes su... more <p>Turkey lies along the transition zone between northerly and southerly climate regimes such that it provides opportunity for a good understanding of Holocene climate that impacted ancient Eastern Mediterranean civilizations. Within the scope of the EU-funded SPELEOTOLIA project, 7 caves from western and southwestern Anatolia were visited and several stalagmite samples were collected. Detailed mineralogical and geochemical analyses performed on samples from one of the target caves, the S&#305;rtlanini Cave (Karacasu, Ayd&#305;n), helps to reconstruct the regional Holocene climate and gives insights on living conditions of Anatolian civilizations, mainly including Roman and Ottoman Empires. &#160;&#160;</p><p>The 450 m-long S&#305;rtlanini Cave (max. depth of ~40 m; ~1060 m a.s.l.) developed within the Mesozoic marbles of the Menderes Massif. We focus on the first set of U-series age, stable and radiogenic isotope (C, O, and Sr) and mineralogical data performed on the stalagmite (SRT-5) from this cave. The drip water isotope data (&#948;<sup>18</sup>O<sub>VSMOW</sub> = -7.8&#8240;, &#948;D<sub>VSMOW</sub> = -41.6&#8240;) indicated depletions in O and H isotopes compared to other cave waters in the region. The U-series age results of SRT-5 show that the 423 mm-long stalagmite was deposited fast (0.25 mm/y) between 0.111&#177;0.034 kyr and 1.825&#177;0.421 kyr (BP) spanning the Roman, Byzantine and Ottoman periods. SRT-5 seems to have grown intermittently with at least two possible hiatuses (at around 291 and 401 years BP) based on mineralogical studies. It is mainly composed of fine- to medium-grained columnar calcite, with occasional dendritic fabric and visible annual layering, particularly at the older bottom section of the stalagmite. Stable isotope profiles (&#948;<sup>13</sup>C: -10.5 to -8&#8240; VPDB, &#948;<sup>18</sup>O: -7 to -5.5&#8240; VPDB) constructed using 423 sub-sample analyses along the stalagmite demonstrate significant hydroclimatic variability through the Little Ice Age and Medieval Warm Period between 195 and 1909 CE. This variation correlates well with previously documented drought and related famine and migration events in western Anatolia primarily in the 19<sup>th</sup> century. Further investigations (e.g., high-resolution LA-ICPMS trace element analyses) will be performed specifically to constrain the anthropogenic sources and distinguish these from recent Aegean or possible global (e.g., southeast Asian) volcanogenic signals.&#160;</p><p>This project has received funding from the European Union&#8217;s Horizon 2020 research and innovation programme under the Marie Sk&#322;odowska-Curie grant agreement No: 842403.</p>
Microscope (microfabrics) and geochemical (stable isotope, trace element, Sr isotope) data derive... more Microscope (microfabrics) and geochemical (stable isotope, trace element, Sr isotope) data derived from the stalagmite BUI collected from Bucak (Burdur Province, SW Turkey) provide detailed insight into paleoclimatic conditions during MIS 5d–b for the first time. MC-ICP-MS U-series dating of the speleothem revealed a two-step growth pattern that spans between ∼118 and ∼89 kyr BP in the late Pleistocene and builds on previously published high-resolution stable isotope time series (10–90 kyr BP) from Dim Cave in S-SW Turkey (Ünal-İmer et al., 2015; 2016). In the microstratigraphic sequence of the BUI stalagmite, carbonate (mostly as calcite and aragonite) fabrics are characterized dominantly by columnar (elongated and microcrystalline) and dendritic forms of calcite, with lesser acicular aragonite and also by diagenetic mosaic calcite and lateral overgrowths. Stalagmite growth rates were determined to be dramatically higher during interstadials, displaying strong links with the summer...
The socle stones of the Great Temple in the Lower City of the Hittite capital city, Hattusha (Çor... more The socle stones of the Great Temple in the Lower City of the Hittite capital city, Hattusha (Çorum Province) have been studied for the first time by petrographic and geochemical analysis (Sr isotope, stable isotope, and trace element geochemistry). Study objectives were to determine the carbonate facies of the stone samples used in the Great Temple and investigate their possible sources. Petrographic analysis of 10 limestone samples presents five clusters of different microfacies. Stable isotope (δ 13 C and δ 18 O) analysis displayed the presence of 5 groups in parallel with petrographic analysis. Trace element analysis of the same groups displayed considerable difference among the stone samples and 87 Sr/ 86 Sr isotope ratios change between 0.70697 and 0.706867. Based on the results, it can be stated that the building using stones are from probably five different sources. This is of great importance to better understand the construction process and the acquisition of the building materials. Download at: https://journals.tubitak.gov.tr/earth/vol31/iss3/4
This study presents new U-Th age data from co-seismic carbonate vein deposition along the 1939 Er... more This study presents new U-Th age data from co-seismic carbonate vein deposition along the 1939 Erzincan earthquake-rupture segment of the North Anatolian Fault Zone (NAFZ). Our statistical evaluations on age correlations indicate that the carbonate vein deposition is concentrated at least in eight different periods during the last 7000 years along the NAFZ. The periods are well correlated with the historical earthquake records and with the previous dating results of the surrounding trench studies. At least six of the periods correspond to the 1200 BC, 499 AD, 1045 AD, 1166/1168 AD, 1419/22 AD, and 1783/84 AD earthquakes reported in the historical catalogues. The age correlations of carbonate precipitation interval for the last millennium show a recurrence along the eastern NAFZ with a mode at 130–330 years that is consistent with the previously proposed paleoseismic recurrence interval of the fault. Our results suggest that co-seismic carbonate veins could be used to determine paleo...
Abstract Central Anatolia represents one of the most outstanding examples of intraplate deformati... more Abstract Central Anatolia represents one of the most outstanding examples of intraplate deformation related to both continental collision and back-arc extension generating non-uniformly distributed stress fields. In this study, we provide direct field evidence of various stress directions and investigate carbonate-filled fracture systems in the Central Anatolian Volcanic Province using U/Th geochronology and isotope geochemistry for evaluating the episodes of latest volcanic activity under regional stress. Field data reveal two independent fracture systems in the region. Successive fracture development has been controlled by two different volcanic eruption centers (Hasandag Composite Volcano and Acigol Caldera). Trace element, and stable (C and O) and radiogenic (Sr) isotope compositions of carbonate veins indicate different fluid migration pathways for two different fracture systems. The U/Th age data for carbonate veins of two independent fracture systems indicate that the crustal deformation intensified during 7 episodic periods in the last 150 ka. The NNE-trending first fracture system was formed as a result of strain cycles in a period from 149 ± 2.5, through 91 ± 1.5 to 83 ± 2.5 ka BP. Subsequent deformation events represented by the ENE-trending second fracture zone have been triggered during the period of 53 ± 3.5, 44 ± 0.6 and 34 ± 1 ka BP before the first fracture zone resumed the activity at about 4.7 ± 0.15 ka BP. Although further studies are needed to evaluate statistical significance of age correlations, the periods of carbonate precipitation inferred from U-Th age distributions in this study are comparable with the previous dating results of surrounding volcanic eruption events.
Abstract Multiple climate-sensitive trace element/Ca and stable isotope (O and C) profiles derive... more Abstract Multiple climate-sensitive trace element/Ca and stable isotope (O and C) profiles derived from Dim Cave speleothems (S-SW Turkey) provide evidence of climatic changes and define a series of palaeohydrological conditions for the period ~10–90 kyr. Dim Cave speleothem Mg/Ca, Sr/Ca, U/Ca, Ba/Ca, and Y/Ca ratios demonstrate similar patterns over glacial–interglacial scales, in agreement with δ18O and δ13C records. Three episodes of more positive moisture balance (71–63 kyr, 51–40 kyr, and 18–10 kyr) were observed based on Y/Ca (and to a lesser extent Zr/Ca), 87Sr/86Sr ratios, calcite micromorphology, and growth rates. Increasing concentrations of Y, Zr (and U) and elevated 87Sr/86Sr ratios are attributed to enhanced levels of terrestrial input during these periods. Correlations between δ13C, δ18O and Mg/Ca during 40–18 kyr (corresponding with the lowest growth rate of ~ 0.8 mm/kyr), 63–51, and 80–71 kyr (relatively low growth rates), as well as co-varying and enhanced Mg/Ca, Sr/Ca, and to a lesser extent Ba/Ca, ratios point to the prior calcite precipitation, wall rock interaction, and preferential dolomite dissolution over calcite in the host dolomitic limestone during these periods. This relationship suggests that water–rock interactions are maximised during episodes of slower drip rates of water through the karst under drier conditions. Chondrite-normalised rare earth element and yttrium (REY) patterns of the stalagmites reveal seawater signatures closely linked to the dolomitic limestone. Excluding the aragonite formation during ~80–75 kyr, which is an autogenic effect, trace element/Ca ratios appear to respond to millennial scale global cooling periods such as Heinrich events.
Abstract Vein and breccia carbonates precipitated in a highly fractured/faulted carbonate bedrock... more Abstract Vein and breccia carbonates precipitated in a highly fractured/faulted carbonate bedrock in SW Turkey were investigated through high-resolution U-series geochronology, microstructural and geochemical studies including C–O–Sr isotope and rare-earth element and yttrium (REY) analyses. Petrographical observations and geochronological data are interpreted as evidence that the calcite veins formed through a crack-seal mechanism, mostly accompanied/initiated by intensive hydraulic fracturing of the host limestone in response to high-pressure fluids, which is manifested by multi-stage breccia deposits. Microscale U-series dates (272.6–20.5 kyr) and geochemical compositions of the vein/breccia samples provide information on the timing and mechanism of the vein formation and identify the source of CO 2 -bearing fluids responsible for the carbonate precipitation. δ 18 O VPDB and δ 13 C VPDB values of the calcite veins range between −5.9 and −1.7‰, and −10.6 and −4.6‰, respectively. The isotopic compositions of the veins show highly fluctuating values as calcite grew successively perpendicular to vein walls, which, in combination with microstructural and geochronological constraints, are interpreted to reflect episodic CO 2 degassing events associated with seismic and aseismic deformation. Oxygen and Sr isotope compositions (δ 18 O VPDB : −5.9 to −1.7‰; 87 Sr/ 86 Sr: 0.7082 to 0.7085) together with REY concentrations indicate deep infiltration of meteoric waters with various degrees of interactions mostly with the host limestone and siliciclastic parts of the basement rocks. Oxygen and carbon isotope compositions suggest CO 2 degassing through intensive limestone dissolution. While majority of the veins display similar Post-Archaean Australian Shale (PAAS)-normalised REY variations, some of the veins show positive Eu PAAS anomalies, which could be indicative of contributions from a deeply derived, heated, and reduced fluid component, giving rise to multiple fluid sources for the calcite veins. Vein calcite formed in fault-induced fractures offers insights into structural features, genetic characterisation of the parental fluids, and late Quaternary degassing of subsurface CO 2 accumulations.
Uploads
Papers by Ezgi Ünal İmer