... Damien DHONT Jean CHOROWICZ Tekin YÜRÜR Department de Géotectonique, ESA-CNRS 7072, case 129 ... more ... Damien DHONT Jean CHOROWICZ Tekin YÜRÜR Department de Géotectonique, ESA-CNRS 7072, case 129 Université Paris 6, 4 place Jussieu ... The authors are grateful to Onur Kose for providing the DEM images and to two anonymous reviewers for valuable comments and ...
In Turkey, extensive and fast housing works put in danger large surfaces of geological outcrops. ... more In Turkey, extensive and fast housing works put in danger large surfaces of geological outcrops. These activities provide housing to citizens, but the lack of sensibility to the geological heritage notion among construction-related institutions and the very high speed of the process result in the lost or degradation of geological exposures in a few months. In a hopeful case when a geologist comes to understand the situation and is able to work, we propose a simple method, based both on a classical approach such as lithological and structural observations in such places, and a new approach, that of taking high-resolution photographs, by hand cameras but also if possible by drones in order to enable tridimensional (3D) reconstructions of the site for geological discussions, after surface modifications. We present a case from Miocene andesitic rocks near the Yapracık town, a new district of Ankara having recently experienced extensive housing with approximately new 9000 houses and 40,000 residents. Since the Ankara city expands outside, areas nearby to housing locations may be candidates to new modifications for recreational areas or even new housing sites. In our method, we propose to save high-resolution pictures and associated 3D reconstructions with their geological interpretation together with classical field notes in a directory to be used in case where geological exposures may suffer modifications. With new technologies in data storage, geologists are able to save considerable data that may serve to transfer to future generations some characteristics of the geological heritage.
International Journal of Remote Sensing, Mar 20, 2006
A long (,15 km) and narrow (,4 km) offshore positive temperature anomaly (,1.7u C) is observed in... more A long (,15 km) and narrow (,4 km) offshore positive temperature anomaly (,1.7u C) is observed in the Landsat Thematic Mapper (TM) thermal infrared (TIR) image acquired the day following the large İzmit earthquake (Mw 7.4) of 17 August 1999, in eastern Marmara Sea, Turkey. The earthquake was generated along the North Anatolian Fault, which ruptured for about 150 km, and the anomaly formed at the western termination of this rupture. Discussions of this anomaly may develop by processes different than the seismic activity and considerations on fault geometry and sea bathymetry characteristics suggest that the anomaly may result from aftershock activity near the western end of the earthquake fault. The formation of the anomaly requires the addition of a large quantity of hot waters to the sea. The ascent to the sea bottom of fault-driven hot fluids (seismic pumping) and formation of thermal plumes may be the processes by which the sea surface temperature increased. Recent works and the present study suggest that TIR data analysis may be used as a tool in seismological studies.
To determine the shear sense on a fault surface, Turkish earthscientists widely use and teach a m... more To determine the shear sense on a fault surface, Turkish earthscientists widely use and teach a method that consists to rub the surface and to decide for the sense that presents the least resistance to the touch in the direction of the slickenlines. With examples of fault surfaces observed in the field, it is shown that this method induces errors and that more reliable methods based on the observation of minor fractures like Riedel shears and other structures should be used to better determine the shear sense of a fault surface in the field.
Yerbilimleri/Hacettepe Üniversitesi Yerbilimleri Uygulama ve Araştırma Merkezi Dergisi, 2018
Gold exploration works in central Anatolia, Turkey, were intensified during the last decade, and ... more Gold exploration works in central Anatolia, Turkey, were intensified during the last decade, and potentially important gold mineralizations were discovered. In the region, important gold discoveries hosted by metamorphic and granitic rocks are, in the west, Savcılıebeyit and Terziali (Kırşehir), in the middle part, Himmetdede and Mahmatlar (Kayseri), Akçataş (Nevşehir), and at the southeast, Gümüşler (Niğde) mineralizations. The Savcılı gold mineralization consists mainly of gold-quartz veins, and is the first discovered gold enrichment hosted by metamorphic rocks of west-central Anatolia. These veins are situated at the southeastern margin of the Cefalıkdağ-Baranadağ granite-migmatite dome, at 60 km west of the city of Kırşehir. In this study, preliminary results of geological and structural investigations of the gold-quartz veins are presented. The study area is part of the Palaeozoic-Mesozoic Kırşehir Massif that comprises mainly high-grade metamorphic and plutonic rocks covered by Cenozoic sediments. The gold-quartz veins are hosted by migmatite, migmatitic gneiss, gneiss-schist-marble intercalations, calc-silicate gneiss and marble. Quartz veins are discordant with respect to the foliation and major lithologic boundaries, and have sharp contacts with the enclosing metamorphic wall rocks. Veins occur as single or composite, relatively continuous veins that are up to about 2 km long and extend for at least 200 m down dip. Their thickness ranges from a few millimetres to two metres. The gold-quartz veins consist mainly of quartz, arsenopyrite, pyrite and secondary haematite and limonite. Other common minerals in the veins are calcite, muscovite, biotite, chlorite and epidote. The distribution of gold is erratic, and only weathered, haematite-and limonite-rich parts of the veins near the surface consistently display higher gold contents. Homogenisation temperatures obtained from fluid inclusions in the quartz vein have a wide range, from 160˚C to well above 400˚C. The fluid inclusions are generally rich in carbon dioxide and also have high salinities (20-33 % NaCl equivalent). The gold-quartz veins have many similarities to orogenic gold deposits in terms of metal associations, wall-rock alteration assemblages, mineralogy, formation conditions and structural control. The spatial association of the veins with migmatites, high-grade metamorphic rocks and granitoids suggests an origin related to metamorphism, uplift and/or migmatite doming and granitoid emplacement in central Anatolia.
A large earthquake (M=7.2 according to the records of the Kandilli observatory) occurred along th... more A large earthquake (M=7.2 according to the records of the Kandilli observatory) occurred along the N79¡E-trending dextral transcurrent North Anatolian Fault (NAF) zone, near the Gerede town, in NW Anatolia, on 1 February 1944. Its epicenter is determined at three different areas. One of the epicenters corresponds to the Gerede macroseismic epicenter where N75¡E-trending dextral surface ruptures are observed. The third aftershock (M=5.3) occurred near one of the other two epicenters located about 80 km far from the Gerede epicenter. The focal mechanism of the earthquake suggests a dextral transpressional fault plane with a direction (N52¡E) and kinematics not compatible with the transcurrent NAF. This data set suggest that the Gerede earthquake may be triggered by a first movement on a fault zone associated with one or two of the epicenters other than the Gerede epicenter, followed by the immediately release of the elastic energy stored along the Gerede segment of the NAF. Topographic, geologic and seismic data indicated that the KarabŸk fault zone located at the north of the NAF zone may have played this role. The data of BartÝn earthquake of 1968 confirm that the crust of the Pontide block, which is located between the NAF and the northern Black Sea and includes the KarabŸk zone deforms by shortening. This shortening is accommodated by simple shear deformation along the NAF and pure shear deformation at the Black Sea margin, and possibly by oblique faulting in the internal parts of the Pontide block.
Crustal extension directions trending NNE-SSW and NW-SE to NNW-SSE are documented at the southeas... more Crustal extension directions trending NNE-SSW and NW-SE to NNW-SSE are documented at the southeastern boundary of the Galatean Volcanic Province (GVP), located at the NW central Anatolia, and at the north of the Aegean Region, in Turkey. Extension affects a continental volcano-sedimentary sequence deposited between the Early Miocene to Pliocene (?) time. Field observations suggest syntectonic volcanism and sedimentation, and extension may begin in the Early-Middle Miocene time. Similar Miocene crustal extension directions are known from the Aegean Region. Both zones have also comparable Miocene magmatic evolutions, characterized by production of Lower-Middle Miocene calc-alkalic and Upper Miocene alkalic magmas. The GVP is presently bounded at the north by the North Anatolian fault (NAF), the most important active fracture zone of the Anatolian block. The stress fields associated with the GVP extensions and the NAF movements clearly are different. This implies that the GVP extension...
A long (,15 km) and narrow (,4 km) offshore positive temperature anomaly (,1.7u C) is observed in... more A long (,15 km) and narrow (,4 km) offshore positive temperature anomaly (,1.7u C) is observed in the Landsat Thematic Mapper (TM) thermal infrared (TIR) image acquired the day following the large İzmit earthquake (Mw 7.4) of 17 August 1999, in eastern Marmara Sea, Turkey. The earthquake was generated along the North Anatolian Fault, which ruptured for about 150 km, and the anomaly formed at the western termination of this rupture. Discussions of this anomaly may develop by processes different than the seismic activity and considerations on fault geometry and sea bathymetry characteristics suggest that the anomaly may result from aftershock activity near the western end of the earthquake fault. The formation of the anomaly requires the addition of a large quantity of hot waters to the sea. The ascent to the sea bottom of fault-driven hot fluids (seismic pumping) and formation of thermal plumes may be the processes by which the sea surface temperature increased. Recent works and the present study suggest that TIR data analysis may be used as a tool in seismological studies.
Journal of Volcanology and Geothermal Research, 1998
In the Eastern Mediterranean, plate convergence occurs between Africa-Arabia and Anatolia. The Af... more In the Eastern Mediterranean, plate convergence occurs between Africa-Arabia and Anatolia. The AfricarArabia motion is a strike-slip displacement along the Dead Sea fault. The AfricarAnatolia motion is taken up by subduction south of Cyprus. The convergence between Arabia and Anatolia is taken up along the East Anatolian fault. The analysis of the regional fault surfaces reveals the presence of two major tectonic phases that affected southeastern Turkey near the junction of these three plates. The older deformations are related to a N-S compression. The more recent movements are directed mainly westward and associated with strike-slip and extension tectonics. Near the triple junction since 2 Ma, a fissure volcanism produced tholeiite followed by alkali basalt along the Amanos fault, the northern end segment of the Dead Sea Fault. In addition, reconstruction of rigid-plate kinematics between Arabia, Africa and Anatolia using recent plate motion parameters and space geodesy data suggest for the East Anatolian fault a slip rate of 7.8-9 mmryear. The maximum finite displacement recognised for this structure being around 15 km, we have obtained 1.9 Ma as the maximum age for the fault formation. The volcanic, tectonic and kinematic data converge to propose a ca. 2 Ma age for the change of local tectonic regime in the junction area. The structural mapping, the geometry of the fractures used by the magma to reach the surface and the presence of alkali basalt of mantle source suggest that the deformation along the northern end of the Dead Sea transform, i.e., the Amanos fault, was modified by the formation of the East Anatolian fault zone. In this region, apparition of the East Anatolian fault accommodating westward motion of the Anatolian plate resulted in oblique-slip tension along the Amanos segment of the Dead Sea transform, giving rise to a fissure-fed, mantle-derived alkaline volcanism at ca. 2 Ma, Ž. which lasted until recent times 0.4 Ma .
The 17 August 1999 Kocaeli earthquake in Turkey produced a majorsurface rupture. We traced this s... more The 17 August 1999 Kocaeli earthquake in Turkey produced a majorsurface rupture. We traced this surface rupture from Gölcük toDüzce and located it accurately by using GPS. The closest distancefrom the surface rupture to the strong motion observation sites weredetermined. Then the attenuation characteristics of the observed peakground acceleration were compared with the attenuation relation given byFukushima and Tanaka (1992),
The Tosya basin is located in the bending segment of the North Anatolian Fault (NAF) in Turkey. W... more The Tosya basin is located in the bending segment of the North Anatolian Fault (NAF) in Turkey. We have obtained original observations on the neotectonics from SAR ERS images, Digital Elevation Model (DEM) and field structural analysis. Regional Neogene deformation is characterised by the occurrence of several basins that are superimposed in time and space. They result from differently oriented movements since 12 Ma, including southwestward motion along a fault subparallel to the NAF. We propose a model of polyphased tectonics related to the displacement of several individualised blocks. In the first stage (Tortonian), the North Tosya block has moved toward the N250º azimuth, parallel to the dextral N70º-striking segment of the NAF. As a consequence, a triple-junction-related compatibility basin was opened at the intersection with a N60º to N30º-striking fault. This pattern is similar to the Karliova corner where the NAF and the East Anatolian Fault meet. In the second stage (Early Pliocene-Middle Pleistocene), a segment of the former N70º-NAF was abandoned and the NAF propagated eastward to form a N90º-striking segment (N90º-NAF), cutting the former Tosya block and basin into two parts. The North Tosya block has moved again and this new geometry has permitted a South Tosya block to move parallel to the NAF but with a higher rate which has induced compression in the Tosya basin. In the third stage (Holocene), the South Tosya block moved toward N240º, obliquely to any of the NAF segments. This has resulted in the formation of two Holocene pull-apart type basins along the previous N60º to N30º-striking fault while extensional faults were formed in the South Tosya block. Estimated dextral displacement along the NAF is 5.9 to 8.5 km at this stage. This model of blocks moving in different directions, including Holocene local movements toward N240º, means that the NAF can be considered not to be a simple transform fault. Our model implies that the N90º-NAF was non-existent before the Early Pliocene.
Journal of Volcanology and Geothermal Research, 1998
Ž. Ž. Observations on Synthetic Aperture Radar SAR scenes of the European Remote Sensing ERS sate... more Ž. Ž. Observations on Synthetic Aperture Radar SAR scenes of the European Remote Sensing ERS satellite and Digital Ž. Elevation Models DEMs , complemented by field structural analysis permit a new understanding of relationships between Ž. tectonics and volcanism since the late Miocene 10 Ma in Central Anatolia. Volcanic edifices form elongate stratovolcanoes, linear clusters and volcanic ridges. They indicate emplacement on tension fractures and tail-crack or horsetail features. For instance, the Kara Dag volcano is rooted on a tail-crack which accommodates a horizontal left-lateral throw component at a fault termination. Caldera complexes of Cappadocia are associated with horsetail fault patterns. The emplacement of volcanoes also benefits from larger-scale tectonic structures: the Erciyes Dag volcano is localized by the Sultan Saz releasing bend which opens along the sinistral strike-slip Ecemis fault. Deformation has been analysed from tension fractures-which are perpendicular to the direction of extension-and from field structural analysis. On a regional scale, the tectonic regime responsible for the distribution of volcanic vents in this area of convergence and lateral extrusion, is not compression but extension. The Central Taurus range is the thermally uplifted shoulder of the Adana-Cilicia basin, which is related to lithosphere thinning. Westward movements in the northwestern part of the studied area are influenced by the active back-arc Aegean extension situated to the west. Farther to the south, the direction of motion turns southwest and south, under the influence of the opening of the Adana-Cilicia basin. We interpreted that extension in the Central Anatolian plateau is related to crustal blocks moving above sub-horizontal detachment surfaces located in the lower crust. This is based on several facts: the Tuz Golu fault zone is a within-crust detachment; the Tuz Golu basin does not affect the whole lithosphere becaus먨¨Ž. otherwise it would have been bordered by thermally uplifted shoulders; movements change trend within a small 50 km region.
<p>Extensive magmatic activities were developed in &#160;Central and Western Anatolia,&... more <p>Extensive magmatic activities were developed in &#160;Central and Western Anatolia,&#160; since middle miocene to quaternary times,&#160;&#160; the most primitive lavas are situated in eastern end of Central (Sivas) and also western (Kula) Anatolia, besides Kula basalts are&#160; one of the most recent basaltic rocks together with&#160; basalts&#160; from south-central Anatolia.&#160; &#160;Although the magmatism is generally&#160;&#160; observed at several different&#160; locations, the recent&#160;&#160; basaltic rocks in both of the regions &#160;&#160;seem to be derived from&#160; the melting&#160; of the peridotite and pyroxenite &#160;source &#160;domains and the latter one&#160; was ignored in previous studies as source component.</p><p>&#160;The previous studies indicate that many of the basaltic rocks from Central and Western Anatolia&#160; are related with spinel-garnet transition, but typical Tb/Yb(N) (>1.8; [1]) and Zn/Fe&#160; &#160;(separates peridotite-derived (Zn/Fe <12; [2]) and pyroxenite-derived (Zn/Fe 13-20); [2] melts)&#160; Co/Fe&#160; ratios of the basaltic rocks from&#160; several volcanic centers from Central and Western Anatolia&#160; reveal that&#160;&#160; melting from the single&#160; source component&#160; are not solely capable of&#160; the producing&#160; basaltic &#160;rocks.&#160;</p><p>&#160;Sr-Nd and Pb isotopic &#160;compositions &#160;clearly display the distinction &#160;of samples which are&#160; linked to&#160; &#160;&#160;asthenospheric source. The lead isotopic systematic &#160;shows&#160; no siginificant differences&#160; among the Central and Western Anatolian basalts,&#160; of all the samples are above the NHRL line and close to EM II&#160; mantle component, &#160;Sr- Nd&#160; isotopes&#160; also display similar compositions as well, the majority of the samples are in and close to mantle array,&#160;&#160; but the &#160;Sr isotopic composition &#160;&#160;of&#160; Miocene aged &#160;Gediz and Simav lavas have high radiogenic values.&#160;</p><p>Tb/Yb(N),&#160; Zn/Fe ratios&#160; and &#160;&#160;as well as the Pb isotopic&#160; compositions and REE-based melting model reveal &#160;that Sivas, Erciyes Hasanda&#287;, and Develida&#287; samples in central Anatolia,&#160; and Kula, Gediz basalt in western Anatolia&#160; seem to be&#160; derived from the amalgamated melting of&#160; pyroxenite and peridotite sources, &#160;&#160;besides, &#160;the sources melting is capable of &#160;the producing&#160; &#160; &#160;elemental variations in &#160;basaltic rocks related with either lithospheric delamination or lithospheric&#160; unstability</p><ul><li>1.Wang et al., 2002, J.Geophys.Res.vol:107,ECV 5 1-21</li> <li>2 .Le Roux, et al.,2011,EPSL, vol:307, 395-408</li> </ul><p>This study is financially supported by Hacettepe University, BAB project no: FHD-2018-17283</p><p>&#160;</p>
We present new Sr-Nd-Pb-Hf isotopic data on mafic lavas from the Sivas, Develidağ, Erciyes, and E... more We present new Sr-Nd-Pb-Hf isotopic data on mafic lavas from the Sivas, Develidağ, Erciyes, and Erkilet volcanic complexes in central Turkey and Tendürek in eastern Turkey to evaluate the mantle sources for volcanism in the context of the geodynamic evolution of the Anatolian microplate. Early Miocene through Quaternary volcanism in Western Anatolia and latest Miocene through Quaternary activity in Central Anatolia were dominated by contributions from two distinct source regions: heterogeneous metasomatized or subduction-modified lithosphere, and roughly homogeneous sublithospheric ambient upper mantle; we model the source contributions through mixing between three end members. The sublithospheric mantle source plots close to the Northern Hemisphere reference line (NHRL) with radiogenic 206Pb/204Pb of ~19.15, while the other contributions plot substantially above the NHRL in Pb isotope space. The lithospheric source is heterogeneous, resulting from variable pollution by subduction-r...
... Damien DHONT Jean CHOROWICZ Tekin YÜRÜR Department de Géotectonique, ESA-CNRS 7072, case 129 ... more ... Damien DHONT Jean CHOROWICZ Tekin YÜRÜR Department de Géotectonique, ESA-CNRS 7072, case 129 Université Paris 6, 4 place Jussieu ... The authors are grateful to Onur Kose for providing the DEM images and to two anonymous reviewers for valuable comments and ...
In Turkey, extensive and fast housing works put in danger large surfaces of geological outcrops. ... more In Turkey, extensive and fast housing works put in danger large surfaces of geological outcrops. These activities provide housing to citizens, but the lack of sensibility to the geological heritage notion among construction-related institutions and the very high speed of the process result in the lost or degradation of geological exposures in a few months. In a hopeful case when a geologist comes to understand the situation and is able to work, we propose a simple method, based both on a classical approach such as lithological and structural observations in such places, and a new approach, that of taking high-resolution photographs, by hand cameras but also if possible by drones in order to enable tridimensional (3D) reconstructions of the site for geological discussions, after surface modifications. We present a case from Miocene andesitic rocks near the Yapracık town, a new district of Ankara having recently experienced extensive housing with approximately new 9000 houses and 40,000 residents. Since the Ankara city expands outside, areas nearby to housing locations may be candidates to new modifications for recreational areas or even new housing sites. In our method, we propose to save high-resolution pictures and associated 3D reconstructions with their geological interpretation together with classical field notes in a directory to be used in case where geological exposures may suffer modifications. With new technologies in data storage, geologists are able to save considerable data that may serve to transfer to future generations some characteristics of the geological heritage.
International Journal of Remote Sensing, Mar 20, 2006
A long (,15 km) and narrow (,4 km) offshore positive temperature anomaly (,1.7u C) is observed in... more A long (,15 km) and narrow (,4 km) offshore positive temperature anomaly (,1.7u C) is observed in the Landsat Thematic Mapper (TM) thermal infrared (TIR) image acquired the day following the large İzmit earthquake (Mw 7.4) of 17 August 1999, in eastern Marmara Sea, Turkey. The earthquake was generated along the North Anatolian Fault, which ruptured for about 150 km, and the anomaly formed at the western termination of this rupture. Discussions of this anomaly may develop by processes different than the seismic activity and considerations on fault geometry and sea bathymetry characteristics suggest that the anomaly may result from aftershock activity near the western end of the earthquake fault. The formation of the anomaly requires the addition of a large quantity of hot waters to the sea. The ascent to the sea bottom of fault-driven hot fluids (seismic pumping) and formation of thermal plumes may be the processes by which the sea surface temperature increased. Recent works and the present study suggest that TIR data analysis may be used as a tool in seismological studies.
To determine the shear sense on a fault surface, Turkish earthscientists widely use and teach a m... more To determine the shear sense on a fault surface, Turkish earthscientists widely use and teach a method that consists to rub the surface and to decide for the sense that presents the least resistance to the touch in the direction of the slickenlines. With examples of fault surfaces observed in the field, it is shown that this method induces errors and that more reliable methods based on the observation of minor fractures like Riedel shears and other structures should be used to better determine the shear sense of a fault surface in the field.
Yerbilimleri/Hacettepe Üniversitesi Yerbilimleri Uygulama ve Araştırma Merkezi Dergisi, 2018
Gold exploration works in central Anatolia, Turkey, were intensified during the last decade, and ... more Gold exploration works in central Anatolia, Turkey, were intensified during the last decade, and potentially important gold mineralizations were discovered. In the region, important gold discoveries hosted by metamorphic and granitic rocks are, in the west, Savcılıebeyit and Terziali (Kırşehir), in the middle part, Himmetdede and Mahmatlar (Kayseri), Akçataş (Nevşehir), and at the southeast, Gümüşler (Niğde) mineralizations. The Savcılı gold mineralization consists mainly of gold-quartz veins, and is the first discovered gold enrichment hosted by metamorphic rocks of west-central Anatolia. These veins are situated at the southeastern margin of the Cefalıkdağ-Baranadağ granite-migmatite dome, at 60 km west of the city of Kırşehir. In this study, preliminary results of geological and structural investigations of the gold-quartz veins are presented. The study area is part of the Palaeozoic-Mesozoic Kırşehir Massif that comprises mainly high-grade metamorphic and plutonic rocks covered by Cenozoic sediments. The gold-quartz veins are hosted by migmatite, migmatitic gneiss, gneiss-schist-marble intercalations, calc-silicate gneiss and marble. Quartz veins are discordant with respect to the foliation and major lithologic boundaries, and have sharp contacts with the enclosing metamorphic wall rocks. Veins occur as single or composite, relatively continuous veins that are up to about 2 km long and extend for at least 200 m down dip. Their thickness ranges from a few millimetres to two metres. The gold-quartz veins consist mainly of quartz, arsenopyrite, pyrite and secondary haematite and limonite. Other common minerals in the veins are calcite, muscovite, biotite, chlorite and epidote. The distribution of gold is erratic, and only weathered, haematite-and limonite-rich parts of the veins near the surface consistently display higher gold contents. Homogenisation temperatures obtained from fluid inclusions in the quartz vein have a wide range, from 160˚C to well above 400˚C. The fluid inclusions are generally rich in carbon dioxide and also have high salinities (20-33 % NaCl equivalent). The gold-quartz veins have many similarities to orogenic gold deposits in terms of metal associations, wall-rock alteration assemblages, mineralogy, formation conditions and structural control. The spatial association of the veins with migmatites, high-grade metamorphic rocks and granitoids suggests an origin related to metamorphism, uplift and/or migmatite doming and granitoid emplacement in central Anatolia.
A large earthquake (M=7.2 according to the records of the Kandilli observatory) occurred along th... more A large earthquake (M=7.2 according to the records of the Kandilli observatory) occurred along the N79¡E-trending dextral transcurrent North Anatolian Fault (NAF) zone, near the Gerede town, in NW Anatolia, on 1 February 1944. Its epicenter is determined at three different areas. One of the epicenters corresponds to the Gerede macroseismic epicenter where N75¡E-trending dextral surface ruptures are observed. The third aftershock (M=5.3) occurred near one of the other two epicenters located about 80 km far from the Gerede epicenter. The focal mechanism of the earthquake suggests a dextral transpressional fault plane with a direction (N52¡E) and kinematics not compatible with the transcurrent NAF. This data set suggest that the Gerede earthquake may be triggered by a first movement on a fault zone associated with one or two of the epicenters other than the Gerede epicenter, followed by the immediately release of the elastic energy stored along the Gerede segment of the NAF. Topographic, geologic and seismic data indicated that the KarabŸk fault zone located at the north of the NAF zone may have played this role. The data of BartÝn earthquake of 1968 confirm that the crust of the Pontide block, which is located between the NAF and the northern Black Sea and includes the KarabŸk zone deforms by shortening. This shortening is accommodated by simple shear deformation along the NAF and pure shear deformation at the Black Sea margin, and possibly by oblique faulting in the internal parts of the Pontide block.
Crustal extension directions trending NNE-SSW and NW-SE to NNW-SSE are documented at the southeas... more Crustal extension directions trending NNE-SSW and NW-SE to NNW-SSE are documented at the southeastern boundary of the Galatean Volcanic Province (GVP), located at the NW central Anatolia, and at the north of the Aegean Region, in Turkey. Extension affects a continental volcano-sedimentary sequence deposited between the Early Miocene to Pliocene (?) time. Field observations suggest syntectonic volcanism and sedimentation, and extension may begin in the Early-Middle Miocene time. Similar Miocene crustal extension directions are known from the Aegean Region. Both zones have also comparable Miocene magmatic evolutions, characterized by production of Lower-Middle Miocene calc-alkalic and Upper Miocene alkalic magmas. The GVP is presently bounded at the north by the North Anatolian fault (NAF), the most important active fracture zone of the Anatolian block. The stress fields associated with the GVP extensions and the NAF movements clearly are different. This implies that the GVP extension...
A long (,15 km) and narrow (,4 km) offshore positive temperature anomaly (,1.7u C) is observed in... more A long (,15 km) and narrow (,4 km) offshore positive temperature anomaly (,1.7u C) is observed in the Landsat Thematic Mapper (TM) thermal infrared (TIR) image acquired the day following the large İzmit earthquake (Mw 7.4) of 17 August 1999, in eastern Marmara Sea, Turkey. The earthquake was generated along the North Anatolian Fault, which ruptured for about 150 km, and the anomaly formed at the western termination of this rupture. Discussions of this anomaly may develop by processes different than the seismic activity and considerations on fault geometry and sea bathymetry characteristics suggest that the anomaly may result from aftershock activity near the western end of the earthquake fault. The formation of the anomaly requires the addition of a large quantity of hot waters to the sea. The ascent to the sea bottom of fault-driven hot fluids (seismic pumping) and formation of thermal plumes may be the processes by which the sea surface temperature increased. Recent works and the present study suggest that TIR data analysis may be used as a tool in seismological studies.
Journal of Volcanology and Geothermal Research, 1998
In the Eastern Mediterranean, plate convergence occurs between Africa-Arabia and Anatolia. The Af... more In the Eastern Mediterranean, plate convergence occurs between Africa-Arabia and Anatolia. The AfricarArabia motion is a strike-slip displacement along the Dead Sea fault. The AfricarAnatolia motion is taken up by subduction south of Cyprus. The convergence between Arabia and Anatolia is taken up along the East Anatolian fault. The analysis of the regional fault surfaces reveals the presence of two major tectonic phases that affected southeastern Turkey near the junction of these three plates. The older deformations are related to a N-S compression. The more recent movements are directed mainly westward and associated with strike-slip and extension tectonics. Near the triple junction since 2 Ma, a fissure volcanism produced tholeiite followed by alkali basalt along the Amanos fault, the northern end segment of the Dead Sea Fault. In addition, reconstruction of rigid-plate kinematics between Arabia, Africa and Anatolia using recent plate motion parameters and space geodesy data suggest for the East Anatolian fault a slip rate of 7.8-9 mmryear. The maximum finite displacement recognised for this structure being around 15 km, we have obtained 1.9 Ma as the maximum age for the fault formation. The volcanic, tectonic and kinematic data converge to propose a ca. 2 Ma age for the change of local tectonic regime in the junction area. The structural mapping, the geometry of the fractures used by the magma to reach the surface and the presence of alkali basalt of mantle source suggest that the deformation along the northern end of the Dead Sea transform, i.e., the Amanos fault, was modified by the formation of the East Anatolian fault zone. In this region, apparition of the East Anatolian fault accommodating westward motion of the Anatolian plate resulted in oblique-slip tension along the Amanos segment of the Dead Sea transform, giving rise to a fissure-fed, mantle-derived alkaline volcanism at ca. 2 Ma, Ž. which lasted until recent times 0.4 Ma .
The 17 August 1999 Kocaeli earthquake in Turkey produced a majorsurface rupture. We traced this s... more The 17 August 1999 Kocaeli earthquake in Turkey produced a majorsurface rupture. We traced this surface rupture from Gölcük toDüzce and located it accurately by using GPS. The closest distancefrom the surface rupture to the strong motion observation sites weredetermined. Then the attenuation characteristics of the observed peakground acceleration were compared with the attenuation relation given byFukushima and Tanaka (1992),
The Tosya basin is located in the bending segment of the North Anatolian Fault (NAF) in Turkey. W... more The Tosya basin is located in the bending segment of the North Anatolian Fault (NAF) in Turkey. We have obtained original observations on the neotectonics from SAR ERS images, Digital Elevation Model (DEM) and field structural analysis. Regional Neogene deformation is characterised by the occurrence of several basins that are superimposed in time and space. They result from differently oriented movements since 12 Ma, including southwestward motion along a fault subparallel to the NAF. We propose a model of polyphased tectonics related to the displacement of several individualised blocks. In the first stage (Tortonian), the North Tosya block has moved toward the N250º azimuth, parallel to the dextral N70º-striking segment of the NAF. As a consequence, a triple-junction-related compatibility basin was opened at the intersection with a N60º to N30º-striking fault. This pattern is similar to the Karliova corner where the NAF and the East Anatolian Fault meet. In the second stage (Early Pliocene-Middle Pleistocene), a segment of the former N70º-NAF was abandoned and the NAF propagated eastward to form a N90º-striking segment (N90º-NAF), cutting the former Tosya block and basin into two parts. The North Tosya block has moved again and this new geometry has permitted a South Tosya block to move parallel to the NAF but with a higher rate which has induced compression in the Tosya basin. In the third stage (Holocene), the South Tosya block moved toward N240º, obliquely to any of the NAF segments. This has resulted in the formation of two Holocene pull-apart type basins along the previous N60º to N30º-striking fault while extensional faults were formed in the South Tosya block. Estimated dextral displacement along the NAF is 5.9 to 8.5 km at this stage. This model of blocks moving in different directions, including Holocene local movements toward N240º, means that the NAF can be considered not to be a simple transform fault. Our model implies that the N90º-NAF was non-existent before the Early Pliocene.
Journal of Volcanology and Geothermal Research, 1998
Ž. Ž. Observations on Synthetic Aperture Radar SAR scenes of the European Remote Sensing ERS sate... more Ž. Ž. Observations on Synthetic Aperture Radar SAR scenes of the European Remote Sensing ERS satellite and Digital Ž. Elevation Models DEMs , complemented by field structural analysis permit a new understanding of relationships between Ž. tectonics and volcanism since the late Miocene 10 Ma in Central Anatolia. Volcanic edifices form elongate stratovolcanoes, linear clusters and volcanic ridges. They indicate emplacement on tension fractures and tail-crack or horsetail features. For instance, the Kara Dag volcano is rooted on a tail-crack which accommodates a horizontal left-lateral throw component at a fault termination. Caldera complexes of Cappadocia are associated with horsetail fault patterns. The emplacement of volcanoes also benefits from larger-scale tectonic structures: the Erciyes Dag volcano is localized by the Sultan Saz releasing bend which opens along the sinistral strike-slip Ecemis fault. Deformation has been analysed from tension fractures-which are perpendicular to the direction of extension-and from field structural analysis. On a regional scale, the tectonic regime responsible for the distribution of volcanic vents in this area of convergence and lateral extrusion, is not compression but extension. The Central Taurus range is the thermally uplifted shoulder of the Adana-Cilicia basin, which is related to lithosphere thinning. Westward movements in the northwestern part of the studied area are influenced by the active back-arc Aegean extension situated to the west. Farther to the south, the direction of motion turns southwest and south, under the influence of the opening of the Adana-Cilicia basin. We interpreted that extension in the Central Anatolian plateau is related to crustal blocks moving above sub-horizontal detachment surfaces located in the lower crust. This is based on several facts: the Tuz Golu fault zone is a within-crust detachment; the Tuz Golu basin does not affect the whole lithosphere becaus먨¨Ž. otherwise it would have been bordered by thermally uplifted shoulders; movements change trend within a small 50 km region.
<p>Extensive magmatic activities were developed in &#160;Central and Western Anatolia,&... more <p>Extensive magmatic activities were developed in &#160;Central and Western Anatolia,&#160; since middle miocene to quaternary times,&#160;&#160; the most primitive lavas are situated in eastern end of Central (Sivas) and also western (Kula) Anatolia, besides Kula basalts are&#160; one of the most recent basaltic rocks together with&#160; basalts&#160; from south-central Anatolia.&#160; &#160;Although the magmatism is generally&#160;&#160; observed at several different&#160; locations, the recent&#160;&#160; basaltic rocks in both of the regions &#160;&#160;seem to be derived from&#160; the melting&#160; of the peridotite and pyroxenite &#160;source &#160;domains and the latter one&#160; was ignored in previous studies as source component.</p><p>&#160;The previous studies indicate that many of the basaltic rocks from Central and Western Anatolia&#160; are related with spinel-garnet transition, but typical Tb/Yb(N) (>1.8; [1]) and Zn/Fe&#160; &#160;(separates peridotite-derived (Zn/Fe <12; [2]) and pyroxenite-derived (Zn/Fe 13-20); [2] melts)&#160; Co/Fe&#160; ratios of the basaltic rocks from&#160; several volcanic centers from Central and Western Anatolia&#160; reveal that&#160;&#160; melting from the single&#160; source component&#160; are not solely capable of&#160; the producing&#160; basaltic &#160;rocks.&#160;</p><p>&#160;Sr-Nd and Pb isotopic &#160;compositions &#160;clearly display the distinction &#160;of samples which are&#160; linked to&#160; &#160;&#160;asthenospheric source. The lead isotopic systematic &#160;shows&#160; no siginificant differences&#160; among the Central and Western Anatolian basalts,&#160; of all the samples are above the NHRL line and close to EM II&#160; mantle component, &#160;Sr- Nd&#160; isotopes&#160; also display similar compositions as well, the majority of the samples are in and close to mantle array,&#160;&#160; but the &#160;Sr isotopic composition &#160;&#160;of&#160; Miocene aged &#160;Gediz and Simav lavas have high radiogenic values.&#160;</p><p>Tb/Yb(N),&#160; Zn/Fe ratios&#160; and &#160;&#160;as well as the Pb isotopic&#160; compositions and REE-based melting model reveal &#160;that Sivas, Erciyes Hasanda&#287;, and Develida&#287; samples in central Anatolia,&#160; and Kula, Gediz basalt in western Anatolia&#160; seem to be&#160; derived from the amalgamated melting of&#160; pyroxenite and peridotite sources, &#160;&#160;besides, &#160;the sources melting is capable of &#160;the producing&#160; &#160; &#160;elemental variations in &#160;basaltic rocks related with either lithospheric delamination or lithospheric&#160; unstability</p><ul><li>1.Wang et al., 2002, J.Geophys.Res.vol:107,ECV 5 1-21</li> <li>2 .Le Roux, et al.,2011,EPSL, vol:307, 395-408</li> </ul><p>This study is financially supported by Hacettepe University, BAB project no: FHD-2018-17283</p><p>&#160;</p>
We present new Sr-Nd-Pb-Hf isotopic data on mafic lavas from the Sivas, Develidağ, Erciyes, and E... more We present new Sr-Nd-Pb-Hf isotopic data on mafic lavas from the Sivas, Develidağ, Erciyes, and Erkilet volcanic complexes in central Turkey and Tendürek in eastern Turkey to evaluate the mantle sources for volcanism in the context of the geodynamic evolution of the Anatolian microplate. Early Miocene through Quaternary volcanism in Western Anatolia and latest Miocene through Quaternary activity in Central Anatolia were dominated by contributions from two distinct source regions: heterogeneous metasomatized or subduction-modified lithosphere, and roughly homogeneous sublithospheric ambient upper mantle; we model the source contributions through mixing between three end members. The sublithospheric mantle source plots close to the Northern Hemisphere reference line (NHRL) with radiogenic 206Pb/204Pb of ~19.15, while the other contributions plot substantially above the NHRL in Pb isotope space. The lithospheric source is heterogeneous, resulting from variable pollution by subduction-r...
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