Zafer Akpınar - Academia.edu (original) (raw)

Papers by Zafer Akpınar

Journal of Geodynamics, 2013

Journal of Asian Earth Sciences, 2015

Ülkemizin en aktif faylarindan Kuzey Anadolu Fay Kuşaği (KAFK) kontrolünde gelişmiş Kelkit Çayi v... more Ülkemizin en aktif faylarindan Kuzey Anadolu Fay Kuşaği (KAFK) kontrolünde gelişmiş Kelkit Çayi vadisinin kuzey kenari üzerinde, 17 Mart 2005 tarihinde meydana gelen Kuzulu Mahallesi (Sugözü köyü-Koyulhisar, Sivas) Heyelaninda 15 kişi yaşamini yitirmiş ve 50 dolayinda ev heyelanla zarar görmüştür. Kuzulu Mahallesi heyelan bölgesi çevresinde, yaşlari Geç Kretase-Eosen, Miyosen, Pliyosen ve Kuvaterner arasinda değişik fasiyeste kireçtaşi, volkanik/volkanotortul ve kirintili tortul

Tectonophysics, 2012

The North Anatolian Fault Zone (NAFZ) is a 1200km long dextral strike-slip fault zone forming the... more The North Anatolian Fault Zone (NAFZ) is a 1200km long dextral strike-slip fault zone forming the boundary between the Eurasian and Anatolian plates. It extends from the Gulf of Saros (North Aegean) in the west to the town of Karlıova in eastern Turkey. Although there ...

Journal of Volcanology and Geothermal Research, 2013

ABSTRACT The Central Anatolian Volcanic Province in Cappadocia includes 13 high volume calc-alkal... more ABSTRACT The Central Anatolian Volcanic Province in Cappadocia includes 13 high volume calc-alkaline ignimbrite sheets emplaced by plinian eruptions within a succession (the Ürgüp Formation) after ~ 10 Ma recording the last phase of Neotethyan subduction and accompanying emplacement of the Tauride orogen in southern Turkey. To evaluate magnetostratigraphy in the context of recent revisions of the chronostratigraphy we have extended palaeomagnetic investigation to 32 new sites yielding significant ChRM directions. Integrated rock magnetic and palaeomagnetic investigations identify magnetic remanence residing predominantly in Ti-poor titanomagnetites although secondary processes within the ignimbrite sheets, notably post-emplacement oxidation, have locally produced hematisation expressed by composite IRM spectra and variable reduction in intensity of magnetisation. The ignimbrite sheets possess weak anisotropies of magnetic susceptibility (AMS, mostly < 5%) describing tensors with axial distributions close to bedding and minimum axes predominantly perpendicular to this plane; collectively directions show weak imbrication correlating with palaeoflow during emplacement predominantly towards the north and east away from the Erdas Dağ, an inferred topographic palaeohigh at the southern margin of the basin. The precise control provided by magnetostratigraphy and radiometric age dating now shows that the bulk of Cappadocian ignimbrite magmatism was concentrated into two short episodes. An older Cardak Centre (Kavak Group and Zelve ignimbrites) produced in excess of 200 km3 of pyroclastic deposits during polarity chron C4r.1n between 9.31 and 9.43 Ma. Subsequent activity from the Acıgöl Centre further to the south west (Cemilköy, Gelveri, Gördeles, and Kızılkaya) produced in excess of 620 km3 of pyroclastic deposits during polarity chrons between 5.3 and 7.1 Ma. The younger İncesu ignimbrite was sourced in the Sultansazlığı pull-apart basin to the east during the Gauss Chron (2.58-3.60 Ma). All pre-İncesu ignimbrites are rotated uniformly anticlockwise and the overall (reversed) group mean direction of magnetisation is D/I = 170.8/- 52.4° (N = 9, R = 8.91, α95 = 5.4°, k = 91). The implied tectonic rotation in this sector of central Anatolia (16 ± 4° relative to Eurasia) is young and postdates the 5.3-7.1 Ma Acıgöl Centre whilst largely predating emplacement of the İncesu ignimbrite. Whilst rotational deformation within Anatolia is young, it proves to be distributed with a temporal variation from block to block. It is embraced by a complex post-Miocene tectonic regime of strike slip and extension during tectonic escape and suction towards the Hellenic Arc to the west.

Journal of Geodynamics, 2011

The Anatolian accretionary collage between Afro-Arabia and Eurasia is currently subject to two te... more The Anatolian accretionary collage between Afro-Arabia and Eurasia is currently subject to two tectonic regimes. Ongoing slip of Arabia relative to Africa along the Dead Sea Fault Zone in the east is extruding crustal blocks away from the indenter by a combination of strike-slip and rotation. This zone of compression gives way to an extensional province in western Turkey, which also includes the eastern sector of Aegean Province. Although it is now well established that rotational deformation throughout Anatolia is distributed and differential, the sizes of the blocks involved are poorly understood. As a contribution towards evaluating this issue in central-east Turkey, we report palaeomagnetic study of the mid-Miocene Kepezdag and Yamadag volcanic complexes in central-south Anatolia (38-39.5 • N, 37.5-39 • E). A distributed sample through the Yamadag complex identifies eruption during an interval of multiple geomagnetic field reversals (40 normal, 36 reversed, 8 intermediate sites) with a selected mean defined by 63 sites of D/I = 335.4/51.1 • (˛9 5 = 4.4 •). The smaller Kepezdag complex (8 reversed, 4 normal and 1 intermediate site) yields a comparable mean direction from 12 sites of 338.7/49.8 • (˛9 5 = 14.1 •). In the context of a range of radiometric age evidence, two thick normal polarity zones within the Yamadag succession probably correlate with zones C5ACn and C5ADn of the Geomagnetic Polarity Time Scale and imply that the bulk of the volcanic activity took place between ∼15 and 13.5 Ma. Comparison of the palaeomagnetic results with the adjoining major plate indenters shows that the Yamadag complex has rotated CCW by 29.3 ± 5.2 • relative to Eurasia; the much smaller dataset from the Kepezdag complex indicates a comparable CCW rotation of 26.0 ± 11.8 • with respect to Eurasia. The Arabian Indenter has also been rotating CCW since mid Miocene times, and the block incorporating these two volcanic complexes north of the East Anatolian Fault Zone (EAFZ) is determined to have rotated 18.2 ± 6.0 • CCW relative to the northern perimeter of Arabia. Comparison with data to the north identifies quasi-uniform rotation across a ∼200 km wide block extending from the Central Anatolian Fault Zone in the northwest to close to the East Anatolian transform fault zone in the south east. Although absence of suitable younger rocks does not permit the timing of this rotation to be determined in the study area, analogies with results from the Sivas Basin suggest that it is young, and followed establishment of the major transform faults. Rotation has evidently taken place around bounding arcuate faults and accompanied westward expulsion as the accretionary collage north of Arabia has been subject to ongoing post-collisional indentation.

Journal of Geodynamics, 2013

ABSTRACT Ongoing motion of Anatolia towards the west is caused by convergence of the Arabian and ... more ABSTRACT Ongoing motion of Anatolia towards the west is caused by convergence of the Arabian and Eurasian plates coupled with suction towards the retreating Hellenic Arc. This regime is controlling the development of neotectonic structures in Turkey with the resulting distributed deformation accommodated primarily between the East and North Anatolian Intracontinental Transform Faults. The Erzincan Basin is developed along the eastern part of the latter fault and although it incorporates one of the largest Quaternary basins in Turkey, the duration and tectonic evolution are disputed. Tectonic models proposed to explain the basin range from simple rhomboidal pull-apart to a complex multi-phase evolution. To help constrain the age and tectonic regime(s) forming the basin we have conducted a palaeomagnetic and geochronologic study of volcanic domes which occur mainly in proximity to strike-slip faulting along the northern margin of the basin. The investigated sample comprises 27 lava sites located within 14 cones, 13 to the north and one in the south. Although difficult propositions for palaeomagnetic investigation because the young predominantly-pyroclastic constructive topography is susceptible to collapse, all sites show positive inclinations and mainly northerly declinations showing that they are the consequence of a tectonic regime confined to the Brunhes Chron. Whilst the limitation of directional data from these young constructive features is stressed, ten cones are found to show clockwise rotations ranging from 12° to 195° with three cones showing no significant rotation. Geochronological studies from 13 samples yield a range of ages with 6 providing meaningful results <0.3 Myr in age and consistent with young ages evident from morphology and paleomagnetism. AMS (Anisotropy of Magnetic Susceptibility) studies identify a fabric related to downslope flow at most sites with the majority moving away from conduits controlled by fractures paralleling the dominant NW-SE trend of the master fault. The palaeomagnetic and geochronologic results show that the history of the Erzincan Basin has involved at least two phases with the later phase incoporating an extensional component permitting access to mantle melts and confined to the last ˜300,000 years. The earlier phase commenced in Late Miocene or Early Pliocene times and initiated the rift infill which currently attains a maximum thickness in excess of 2.7 km. We propose that the Erzincan Basin is now segmented as a mature basin by strike-slip cross faults although these cannot explain the consistent clockwise rotations observed within the small blocks incorporating the volcanic cones because these are confined to a narrow zone between two master faults and appear to be subject to ball-bearing style rotation.

Study area is situated at Boğazkaya village (Mecitözü-Çorum) and its surroundings. In this area, ... more Study area is situated at Boğazkaya village (Mecitözü-Çorum) and its surroundings. In this area, Tozanli complex represents the basement unit that consist of shists, fillites, metaophiolites, metavolcanites, metasedimentary units and marbles are in high pressure-lower temperature meatamorphism. The basement units are overlain by an angular disconformity with Upper Berriasian massive and fosilliferous micritic limestones; named as Ferhatkaya formation. Lower Eocene?-Lutetian

The 1939 Erzincan Earthquake (M = 7.8), occurred on the North Anatolian Fault Zone (NAFZ), was on... more The 1939 Erzincan Earthquake (M = 7.8), occurred on the North Anatolian Fault Zone (NAFZ), was one of the most active strike-slip faults in the world, and created a 360-km-long surface rupture. Traces of this surface rupture are still prominently observed. In the absence of detailed mapping to resolve the fault characteristics, detailed observations have been conducted at 20 different points on the 70-kmlong Kelkit Valley Segment (KVS) of the NAFZ's between Niksar and Koyulhisar. Field data defining fault character and slip amounts were found at eight points and show right-lateral slip varying between 1.8 and 4.25 m and the vertical slip varying between 0.5 and 2.0 m.

Journal of Geodynamics, 2013

Journal of Asian Earth Sciences, 2015

Ülkemizin en aktif faylarindan Kuzey Anadolu Fay Kuşaği (KAFK) kontrolünde gelişmiş Kelkit Çayi v... more Ülkemizin en aktif faylarindan Kuzey Anadolu Fay Kuşaği (KAFK) kontrolünde gelişmiş Kelkit Çayi vadisinin kuzey kenari üzerinde, 17 Mart 2005 tarihinde meydana gelen Kuzulu Mahallesi (Sugözü köyü-Koyulhisar, Sivas) Heyelaninda 15 kişi yaşamini yitirmiş ve 50 dolayinda ev heyelanla zarar görmüştür. Kuzulu Mahallesi heyelan bölgesi çevresinde, yaşlari Geç Kretase-Eosen, Miyosen, Pliyosen ve Kuvaterner arasinda değişik fasiyeste kireçtaşi, volkanik/volkanotortul ve kirintili tortul

Tectonophysics, 2012

The North Anatolian Fault Zone (NAFZ) is a 1200km long dextral strike-slip fault zone forming the... more The North Anatolian Fault Zone (NAFZ) is a 1200km long dextral strike-slip fault zone forming the boundary between the Eurasian and Anatolian plates. It extends from the Gulf of Saros (North Aegean) in the west to the town of Karlıova in eastern Turkey. Although there ...

Journal of Volcanology and Geothermal Research, 2013

ABSTRACT The Central Anatolian Volcanic Province in Cappadocia includes 13 high volume calc-alkal... more ABSTRACT The Central Anatolian Volcanic Province in Cappadocia includes 13 high volume calc-alkaline ignimbrite sheets emplaced by plinian eruptions within a succession (the Ürgüp Formation) after ~ 10 Ma recording the last phase of Neotethyan subduction and accompanying emplacement of the Tauride orogen in southern Turkey. To evaluate magnetostratigraphy in the context of recent revisions of the chronostratigraphy we have extended palaeomagnetic investigation to 32 new sites yielding significant ChRM directions. Integrated rock magnetic and palaeomagnetic investigations identify magnetic remanence residing predominantly in Ti-poor titanomagnetites although secondary processes within the ignimbrite sheets, notably post-emplacement oxidation, have locally produced hematisation expressed by composite IRM spectra and variable reduction in intensity of magnetisation. The ignimbrite sheets possess weak anisotropies of magnetic susceptibility (AMS, mostly < 5%) describing tensors with axial distributions close to bedding and minimum axes predominantly perpendicular to this plane; collectively directions show weak imbrication correlating with palaeoflow during emplacement predominantly towards the north and east away from the Erdas Dağ, an inferred topographic palaeohigh at the southern margin of the basin. The precise control provided by magnetostratigraphy and radiometric age dating now shows that the bulk of Cappadocian ignimbrite magmatism was concentrated into two short episodes. An older Cardak Centre (Kavak Group and Zelve ignimbrites) produced in excess of 200 km3 of pyroclastic deposits during polarity chron C4r.1n between 9.31 and 9.43 Ma. Subsequent activity from the Acıgöl Centre further to the south west (Cemilköy, Gelveri, Gördeles, and Kızılkaya) produced in excess of 620 km3 of pyroclastic deposits during polarity chrons between 5.3 and 7.1 Ma. The younger İncesu ignimbrite was sourced in the Sultansazlığı pull-apart basin to the east during the Gauss Chron (2.58-3.60 Ma). All pre-İncesu ignimbrites are rotated uniformly anticlockwise and the overall (reversed) group mean direction of magnetisation is D/I = 170.8/- 52.4° (N = 9, R = 8.91, α95 = 5.4°, k = 91). The implied tectonic rotation in this sector of central Anatolia (16 ± 4° relative to Eurasia) is young and postdates the 5.3-7.1 Ma Acıgöl Centre whilst largely predating emplacement of the İncesu ignimbrite. Whilst rotational deformation within Anatolia is young, it proves to be distributed with a temporal variation from block to block. It is embraced by a complex post-Miocene tectonic regime of strike slip and extension during tectonic escape and suction towards the Hellenic Arc to the west.

Journal of Geodynamics, 2011

The Anatolian accretionary collage between Afro-Arabia and Eurasia is currently subject to two te... more The Anatolian accretionary collage between Afro-Arabia and Eurasia is currently subject to two tectonic regimes. Ongoing slip of Arabia relative to Africa along the Dead Sea Fault Zone in the east is extruding crustal blocks away from the indenter by a combination of strike-slip and rotation. This zone of compression gives way to an extensional province in western Turkey, which also includes the eastern sector of Aegean Province. Although it is now well established that rotational deformation throughout Anatolia is distributed and differential, the sizes of the blocks involved are poorly understood. As a contribution towards evaluating this issue in central-east Turkey, we report palaeomagnetic study of the mid-Miocene Kepezdag and Yamadag volcanic complexes in central-south Anatolia (38-39.5 • N, 37.5-39 • E). A distributed sample through the Yamadag complex identifies eruption during an interval of multiple geomagnetic field reversals (40 normal, 36 reversed, 8 intermediate sites) with a selected mean defined by 63 sites of D/I = 335.4/51.1 • (˛9 5 = 4.4 •). The smaller Kepezdag complex (8 reversed, 4 normal and 1 intermediate site) yields a comparable mean direction from 12 sites of 338.7/49.8 • (˛9 5 = 14.1 •). In the context of a range of radiometric age evidence, two thick normal polarity zones within the Yamadag succession probably correlate with zones C5ACn and C5ADn of the Geomagnetic Polarity Time Scale and imply that the bulk of the volcanic activity took place between ∼15 and 13.5 Ma. Comparison of the palaeomagnetic results with the adjoining major plate indenters shows that the Yamadag complex has rotated CCW by 29.3 ± 5.2 • relative to Eurasia; the much smaller dataset from the Kepezdag complex indicates a comparable CCW rotation of 26.0 ± 11.8 • with respect to Eurasia. The Arabian Indenter has also been rotating CCW since mid Miocene times, and the block incorporating these two volcanic complexes north of the East Anatolian Fault Zone (EAFZ) is determined to have rotated 18.2 ± 6.0 • CCW relative to the northern perimeter of Arabia. Comparison with data to the north identifies quasi-uniform rotation across a ∼200 km wide block extending from the Central Anatolian Fault Zone in the northwest to close to the East Anatolian transform fault zone in the south east. Although absence of suitable younger rocks does not permit the timing of this rotation to be determined in the study area, analogies with results from the Sivas Basin suggest that it is young, and followed establishment of the major transform faults. Rotation has evidently taken place around bounding arcuate faults and accompanied westward expulsion as the accretionary collage north of Arabia has been subject to ongoing post-collisional indentation.

Journal of Geodynamics, 2013

ABSTRACT Ongoing motion of Anatolia towards the west is caused by convergence of the Arabian and ... more ABSTRACT Ongoing motion of Anatolia towards the west is caused by convergence of the Arabian and Eurasian plates coupled with suction towards the retreating Hellenic Arc. This regime is controlling the development of neotectonic structures in Turkey with the resulting distributed deformation accommodated primarily between the East and North Anatolian Intracontinental Transform Faults. The Erzincan Basin is developed along the eastern part of the latter fault and although it incorporates one of the largest Quaternary basins in Turkey, the duration and tectonic evolution are disputed. Tectonic models proposed to explain the basin range from simple rhomboidal pull-apart to a complex multi-phase evolution. To help constrain the age and tectonic regime(s) forming the basin we have conducted a palaeomagnetic and geochronologic study of volcanic domes which occur mainly in proximity to strike-slip faulting along the northern margin of the basin. The investigated sample comprises 27 lava sites located within 14 cones, 13 to the north and one in the south. Although difficult propositions for palaeomagnetic investigation because the young predominantly-pyroclastic constructive topography is susceptible to collapse, all sites show positive inclinations and mainly northerly declinations showing that they are the consequence of a tectonic regime confined to the Brunhes Chron. Whilst the limitation of directional data from these young constructive features is stressed, ten cones are found to show clockwise rotations ranging from 12° to 195° with three cones showing no significant rotation. Geochronological studies from 13 samples yield a range of ages with 6 providing meaningful results <0.3 Myr in age and consistent with young ages evident from morphology and paleomagnetism. AMS (Anisotropy of Magnetic Susceptibility) studies identify a fabric related to downslope flow at most sites with the majority moving away from conduits controlled by fractures paralleling the dominant NW-SE trend of the master fault. The palaeomagnetic and geochronologic results show that the history of the Erzincan Basin has involved at least two phases with the later phase incoporating an extensional component permitting access to mantle melts and confined to the last ˜300,000 years. The earlier phase commenced in Late Miocene or Early Pliocene times and initiated the rift infill which currently attains a maximum thickness in excess of 2.7 km. We propose that the Erzincan Basin is now segmented as a mature basin by strike-slip cross faults although these cannot explain the consistent clockwise rotations observed within the small blocks incorporating the volcanic cones because these are confined to a narrow zone between two master faults and appear to be subject to ball-bearing style rotation.

Study area is situated at Boğazkaya village (Mecitözü-Çorum) and its surroundings. In this area, ... more Study area is situated at Boğazkaya village (Mecitözü-Çorum) and its surroundings. In this area, Tozanli complex represents the basement unit that consist of shists, fillites, metaophiolites, metavolcanites, metasedimentary units and marbles are in high pressure-lower temperature meatamorphism. The basement units are overlain by an angular disconformity with Upper Berriasian massive and fosilliferous micritic limestones; named as Ferhatkaya formation. Lower Eocene?-Lutetian

The 1939 Erzincan Earthquake (M = 7.8), occurred on the North Anatolian Fault Zone (NAFZ), was on... more The 1939 Erzincan Earthquake (M = 7.8), occurred on the North Anatolian Fault Zone (NAFZ), was one of the most active strike-slip faults in the world, and created a 360-km-long surface rupture. Traces of this surface rupture are still prominently observed. In the absence of detailed mapping to resolve the fault characteristics, detailed observations have been conducted at 20 different points on the 70-kmlong Kelkit Valley Segment (KVS) of the NAFZ's between Niksar and Koyulhisar. Field data defining fault character and slip amounts were found at eight points and show right-lateral slip varying between 1.8 and 4.25 m and the vertical slip varying between 0.5 and 2.0 m.