: The sinistral East Anatolian Fault Zone (EAFZ) and the dextral North Anatolian Fault Zone (NAFZ) are two important strike-slip faults that delimit the boundaries of the Anatolian plate. The north-south directed compressional forces in eastern Türkiye trigger the westward escape of the Anatolian plate along these prominent structures. This study aims to reveal the earthquake history of the Sürgü and Çardak faults, which are important fault segments that splay from the EAFZ. In this context, overall, four paleoseismologic trenches were dug, two trenches on the Sürgü Fault and two trenches on the Çardak Fault. Along the Sürgü Fault, at least two paleoearthquake events have been determined on the trench walls, one event occurred around 3400 BCE and the second event happened between 2085 ± 65 BCE and 790 ± 20 BCE. Moreover, trenching results from the Çardak Fault indicate two surface rupturing paleoearthquakes between 10520 ± 95 BCE and 5780 ± 65 BCE, and between 3215 ± 125 BCE and 825 ± 55 CE, respectively. The focal mechanisms of important instrumental earthquakes around the Sürgü and Çardak faults on the EAFZ show that NNE-SSW trending compressional forces are actively dominating the tectonic setting of the region in the contemporary era. Paleoseismological investigations suggested that the Sürgü and Çardak faults have the potential to produce surface-rupturing earthquakes with an estimated magnitude of 7 or larger.
{"title":"Paleoseismology of the Sürgü and Çardak faults - splays of the Eastern Anatolian Fault Zone, Türkiye","authors":"Musa Balkaya, H. Akyüz, Süha Özden","doi":"10.55730/1300-0985.1851","DOIUrl":"https://doi.org/10.55730/1300-0985.1851","url":null,"abstract":": The sinistral East Anatolian Fault Zone (EAFZ) and the dextral North Anatolian Fault Zone (NAFZ) are two important strike-slip faults that delimit the boundaries of the Anatolian plate. The north-south directed compressional forces in eastern Türkiye trigger the westward escape of the Anatolian plate along these prominent structures. This study aims to reveal the earthquake history of the Sürgü and Çardak faults, which are important fault segments that splay from the EAFZ. In this context, overall, four paleoseismologic trenches were dug, two trenches on the Sürgü Fault and two trenches on the Çardak Fault. Along the Sürgü Fault, at least two paleoearthquake events have been determined on the trench walls, one event occurred around 3400 BCE and the second event happened between 2085 ± 65 BCE and 790 ± 20 BCE. Moreover, trenching results from the Çardak Fault indicate two surface rupturing paleoearthquakes between 10520 ± 95 BCE and 5780 ± 65 BCE, and between 3215 ± 125 BCE and 825 ± 55 CE, respectively. The focal mechanisms of important instrumental earthquakes around the Sürgü and Çardak faults on the EAFZ show that NNE-SSW trending compressional forces are actively dominating the tectonic setting of the region in the contemporary era. Paleoseismological investigations suggested that the Sürgü and Çardak faults have the potential to produce surface-rupturing earthquakes with an estimated magnitude of 7 or larger.","PeriodicalId":49411,"journal":{"name":"Turkish Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41350233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: This study was carried out on granitic rocks from the Biga Peninsula in order to investigate petrographic, and mineralogical properties in comparison with mechanical strength properties. This study was conducted in four different locations where granitic rocks outcrop from north to south in the Biga Peninsula: Lapseki (Şevketiye granite), Ezine (Kestanbol granite), Bayramiç (Yassıbağ granite), and Edremit (Eybek granite). Field observations and detailed petrographic studies of representative samples indicate that they are quartz monzodiorite (Şevketiye and Yassıbağ), quartz monzonite (Kestanbol), and granodiorite (Eybek) in composition. All the rocks have similar mineral composition, comprising mainly feldspar (plagioclase–alkali feldspar), quartz, mafic minerals (biotite and amphibole), accessory minerals (sphene, zircon, opaque minerals), and secondary minerals (sericite, epidote, chlorite) with differences in the percentage of modal mineralogy, textural details, and weathering. Physical and mechanical properties were also defined in this study, these include water absorption, porosity, uniaxial compressive strength (UCS), tensile strength (TS), Schmidt hardness tests (SHT), Los Angeles test (LA), and frost resistance test (FRT) with sodium sulfate (Na 2 SO 4 ). The results of strength tests show that the Şevketiye granite had the lowest strength values with the highest values for Los Angeles abrasion, frost resistance, water absorption, and porosity. The Eybek granite exhibited the highest value for strength, with the lowest values for Los Angeles abrasion, frost resistance, water absorption, and porosity. A comparison of the petrographic properties of all studied rocks with their respective strengths show that modal mineralogy, degree of alteration, and texture influence the strength of the rocks. Additionally, an increasing propensity for UCS and TS values was found with increasing SHT values. The LA abrasion values and the FRT values were found to increase with decreasing Schmidt hardness test values for the tested samples. The found results of this study could help in the application of these rocks as row material.
{"title":"Relationship of petrographic and mineralogical characteristics with mechanical strength properties of granitic rocks: a case study from the Biga Peninsula, NW Turkey","authors":"Güven Eroğlu, Ayten Çalık","doi":"10.55730/1300-0985.1831","DOIUrl":"https://doi.org/10.55730/1300-0985.1831","url":null,"abstract":": This study was carried out on granitic rocks from the Biga Peninsula in order to investigate petrographic, and mineralogical properties in comparison with mechanical strength properties. This study was conducted in four different locations where granitic rocks outcrop from north to south in the Biga Peninsula: Lapseki (Şevketiye granite), Ezine (Kestanbol granite), Bayramiç (Yassıbağ granite), and Edremit (Eybek granite). Field observations and detailed petrographic studies of representative samples indicate that they are quartz monzodiorite (Şevketiye and Yassıbağ), quartz monzonite (Kestanbol), and granodiorite (Eybek) in composition. All the rocks have similar mineral composition, comprising mainly feldspar (plagioclase–alkali feldspar), quartz, mafic minerals (biotite and amphibole), accessory minerals (sphene, zircon, opaque minerals), and secondary minerals (sericite, epidote, chlorite) with differences in the percentage of modal mineralogy, textural details, and weathering. Physical and mechanical properties were also defined in this study, these include water absorption, porosity, uniaxial compressive strength (UCS), tensile strength (TS), Schmidt hardness tests (SHT), Los Angeles test (LA), and frost resistance test (FRT) with sodium sulfate (Na 2 SO 4 ). The results of strength tests show that the Şevketiye granite had the lowest strength values with the highest values for Los Angeles abrasion, frost resistance, water absorption, and porosity. The Eybek granite exhibited the highest value for strength, with the lowest values for Los Angeles abrasion, frost resistance, water absorption, and porosity. A comparison of the petrographic properties of all studied rocks with their respective strengths show that modal mineralogy, degree of alteration, and texture influence the strength of the rocks. Additionally, an increasing propensity for UCS and TS values was found with increasing SHT values. The LA abrasion values and the FRT values were found to increase with decreasing Schmidt hardness test values for the tested samples. The found results of this study could help in the application of these rocks as row material.","PeriodicalId":49411,"journal":{"name":"Turkish Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44518205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: The East Anatolian Fault Zone (EAFZ) is a left-lateral transform fault zone located between the Anatolian and Arabian plates. In this study, in order to image the upper crustal structure beneath the eastern segments of EAFZ, 3D seismic velocity variations are computed using local earthquake tomography. The initial catalog for the tomography process consists of 2200 well-located earthquakes recorded at 49 seismic stations around the study region between 2007 and 2020. 1D initial velocity model is constructed based on previous studies in the region. The maximum number of iterations and the velocity perturbations which sustain the linearity of the inversion are determined based on the detailed tests. Reliable zones of the final model are decided based on the Derivative Weighted Sum and Hit Count distribution. The resulting velocity model displays a clear velocity contrast across the surface trace of the EAFZ down to a depth of 12 km. While the Anatolian side of the fault displays higher velocities associated with the ophiolitic units in the region, the south of the fault zone is represented by lower velocities due to sedimentary deposits. The vertical cross-sections of tomographic models show a north dipping fault between Palu and Çelikhan. The complete earthquake catalog is relocated using the 3D velocity model. Together with the obtained velocity model, the relocated hypocenters indicate that the dip of the EAFZ is not uniform, the Palu segment dips to the north with an angle of ~80°, while the Pütürge and Erkenek segments dip to the north with a lower angle of ~60–70°.
{"title":"A local earthquake tomography on the EAF shows dipping fault structure","authors":"S. E. Güvercin","doi":"10.55730/1300-0985.1845","DOIUrl":"https://doi.org/10.55730/1300-0985.1845","url":null,"abstract":": The East Anatolian Fault Zone (EAFZ) is a left-lateral transform fault zone located between the Anatolian and Arabian plates. In this study, in order to image the upper crustal structure beneath the eastern segments of EAFZ, 3D seismic velocity variations are computed using local earthquake tomography. The initial catalog for the tomography process consists of 2200 well-located earthquakes recorded at 49 seismic stations around the study region between 2007 and 2020. 1D initial velocity model is constructed based on previous studies in the region. The maximum number of iterations and the velocity perturbations which sustain the linearity of the inversion are determined based on the detailed tests. Reliable zones of the final model are decided based on the Derivative Weighted Sum and Hit Count distribution. The resulting velocity model displays a clear velocity contrast across the surface trace of the EAFZ down to a depth of 12 km. While the Anatolian side of the fault displays higher velocities associated with the ophiolitic units in the region, the south of the fault zone is represented by lower velocities due to sedimentary deposits. The vertical cross-sections of tomographic models show a north dipping fault between Palu and Çelikhan. The complete earthquake catalog is relocated using the 3D velocity model. Together with the obtained velocity model, the relocated hypocenters indicate that the dip of the EAFZ is not uniform, the Palu segment dips to the north with an angle of ~80°, while the Pütürge and Erkenek segments dip to the north with a lower angle of ~60–70°.","PeriodicalId":49411,"journal":{"name":"Turkish Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44444799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstrac t: This study aims to review the geology of the Andız Peninsula and compare the pre-Neogene Andız succession with the middle part of the Karaburun Peninsula to discuss the nature of the Paleozoic-Mesozoic boundary in the Karaburun Peninsula. The pre-Neogene units of the Andız Peninsula are represented by the Paleozoic Dikendağı, Triassic Güvercinlik, and Jurassic Nohutalan Formations. In this study, the Triassic carbonate rocks in the Andız Peninsula are paleontologically defined for the first time. The Megalodont-bearing Güvercinlik Formation contains a late Norian-Rhaetian characteristic foraminiferal assemblage consisting of Aulotortus gr. sinuosus , A. tenuis , A. friedli , A. impressus , and Triasina hantkeni . The Thaumatoporella- bearing Nohutalan Formation conformably overlies the Güvercinlik Formation and yields a typical Liassic fossil assemblage of Orbitopsella praecursor, Siphovalvulina gibralterensis, S. colomi, Meandrovoluta asiagoensis , and Palaeodasycladus mediterraneus . In the Andız Peninsula, the Mesozoic Güvercinlik and Nohutalan Formations tectonically overlie the Paleozoic Dikendağı Formation along a displacement contact . In the middle Karaburun Peninsula, the Triassic Gerence Formation lies directly on the Dikendağı Formation along a displacement contact. Lateral continuation of this displacement contact is discovered between the Triassic Gerence and Camiboğazı Formations at the top and Paleozoic Dikendağı Formation at the bottom. Further north, the same displacement contact extends into the Paleozoic sequence where the Carboniferous Alandere Formation tectonically overlies the Dikendağı Formation. These observations suggest that the succession in the Karaburun Peninsula ranging from Bashkirian to Cretaceous, is a tectonic slice or a package of slices over the Dikendağı Formation
{"title":"New Triassic finding in Andız Peninsula (İzmir, Western Turkey) and comparison of pre-Neogene sequences of Andız and Karaburun Peninsulas: Stratigraphic and tectonic implications","authors":"I. Işintek","doi":"10.55730/1300-0985.1858","DOIUrl":"https://doi.org/10.55730/1300-0985.1858","url":null,"abstract":"Abstrac t: This study aims to review the geology of the Andız Peninsula and compare the pre-Neogene Andız succession with the middle part of the Karaburun Peninsula to discuss the nature of the Paleozoic-Mesozoic boundary in the Karaburun Peninsula. The pre-Neogene units of the Andız Peninsula are represented by the Paleozoic Dikendağı, Triassic Güvercinlik, and Jurassic Nohutalan Formations. In this study, the Triassic carbonate rocks in the Andız Peninsula are paleontologically defined for the first time. The Megalodont-bearing Güvercinlik Formation contains a late Norian-Rhaetian characteristic foraminiferal assemblage consisting of Aulotortus gr. sinuosus , A. tenuis , A. friedli , A. impressus , and Triasina hantkeni . The Thaumatoporella- bearing Nohutalan Formation conformably overlies the Güvercinlik Formation and yields a typical Liassic fossil assemblage of Orbitopsella praecursor, Siphovalvulina gibralterensis, S. colomi, Meandrovoluta asiagoensis , and Palaeodasycladus mediterraneus . In the Andız Peninsula, the Mesozoic Güvercinlik and Nohutalan Formations tectonically overlie the Paleozoic Dikendağı Formation along a displacement contact . In the middle Karaburun Peninsula, the Triassic Gerence Formation lies directly on the Dikendağı Formation along a displacement contact. Lateral continuation of this displacement contact is discovered between the Triassic Gerence and Camiboğazı Formations at the top and Paleozoic Dikendağı Formation at the bottom. Further north, the same displacement contact extends into the Paleozoic sequence where the Carboniferous Alandere Formation tectonically overlies the Dikendağı Formation. These observations suggest that the succession in the Karaburun Peninsula ranging from Bashkirian to Cretaceous, is a tectonic slice or a package of slices over the Dikendağı Formation","PeriodicalId":49411,"journal":{"name":"Turkish Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48459066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: Magnetotelluric (MT) and audio-magnetotelluric (AMT) studies are sensitive to the geothermal fluids filling the faults and/ or fracture zones of the geothermal system. In India, MT/AMT studies have been carried out in NW Himalayas, central, eastern, and western India. In other areas, detailed MT/AMT studies need to be expedited. This review paper presents the art of geothermal exploration in India by using MT/AMT techniques and identifies potential zones that can be exploited for power generation and direct application. Reservoir characteristics, carbon emissions reduction methods, and levelised cost factor are also discussed.
{"title":"Magnetotelluric investigations over geothermal provinces of India: an overview","authors":"Prabhala Bhakhara Venkata Subbarao, Pachigolla Venkata Vijaya Kumar, D. Chandrasekharam, Vasu Deshmukh, Ashutosh Kumar Singh","doi":"10.55730/1300-0985.1835","DOIUrl":"https://doi.org/10.55730/1300-0985.1835","url":null,"abstract":": Magnetotelluric (MT) and audio-magnetotelluric (AMT) studies are sensitive to the geothermal fluids filling the faults and/ or fracture zones of the geothermal system. In India, MT/AMT studies have been carried out in NW Himalayas, central, eastern, and western India. In other areas, detailed MT/AMT studies need to be expedited. This review paper presents the art of geothermal exploration in India by using MT/AMT techniques and identifies potential zones that can be exploited for power generation and direct application. Reservoir characteristics, carbon emissions reduction methods, and levelised cost factor are also discussed.","PeriodicalId":49411,"journal":{"name":"Turkish Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46764389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: We investigate the multiphase deformation, fluid flow, and mineralization processes in epithermal systems by presenting a detailed study of vein textures and breccias of the Kestanelik epithermal Au-Ag deposit, NW Turkey. The mineralization in the deposit is associated with several quartz veins. Fault-hosted veins and mode I veins share many textural and breccia characteristics owing to (i) overprinting of tectonic breccias formed during coseismic rupturing by subsequent coseismic hydrothermal brecciation and (ii) reworking of earlier vein breccia phases by repeated rupturing and hydraulic fracturing events. The spatial distribution of breccias at fault-hosted veins proposes that power of coseismic hydrothermal brecciation is controlled by the distance to the level of boiling within a vein. The brecciation affects the entire vein proximal to the level of boiling; however, it is limited to the footwall contact of the vein more distally at the upper levels of a vein. Varying number of mineralization events for the veins suggests that any individual earthquake event reopened only one or more sealed vein, but not all at once. Fewer mineralization events in fault-hosted veins compared to the mode I veins is either linked to (i) focusing of high fluid flux into the conduits of mode I veins that accommodate more dilation or (ii) reopening of mode I veins owing to the driven of extensional failure under low differential stress. Although fault-hosted veins record fewer mineralization events, they have higher average Au grade (4.106 g/t) compared to that of mode I veins (2.736 g/t). On the other hand, fewer mineralization events in wall rock structures compared to the adjacent faults is attributed to (i) absence or poor development of the damage zone structures in earlier seismic events or (ii) deactivation of them after clogging due to the rotation of the optimum stress field or (iii) their formation as hydraulic extension fractures. This study emphasizes the importance of detailed studies of vein infill for understanding the internal structural evolution of the veins in epithermal deposits that is interest to the geologists within both industry and academic fields.
{"title":"Multiphase deformation, fluid flow and mineralization in epithermal systems: Inferences from structures, vein textures and breccias of the Kestanelik epithermal Au-Ag deposit, NW Turkey","authors":"Nilay Gülyüz, Z. Shipton, İ. Kuşçu","doi":"10.55730/1300-0985.1828","DOIUrl":"https://doi.org/10.55730/1300-0985.1828","url":null,"abstract":": We investigate the multiphase deformation, fluid flow, and mineralization processes in epithermal systems by presenting a detailed study of vein textures and breccias of the Kestanelik epithermal Au-Ag deposit, NW Turkey. The mineralization in the deposit is associated with several quartz veins. Fault-hosted veins and mode I veins share many textural and breccia characteristics owing to (i) overprinting of tectonic breccias formed during coseismic rupturing by subsequent coseismic hydrothermal brecciation and (ii) reworking of earlier vein breccia phases by repeated rupturing and hydraulic fracturing events. The spatial distribution of breccias at fault-hosted veins proposes that power of coseismic hydrothermal brecciation is controlled by the distance to the level of boiling within a vein. The brecciation affects the entire vein proximal to the level of boiling; however, it is limited to the footwall contact of the vein more distally at the upper levels of a vein. Varying number of mineralization events for the veins suggests that any individual earthquake event reopened only one or more sealed vein, but not all at once. Fewer mineralization events in fault-hosted veins compared to the mode I veins is either linked to (i) focusing of high fluid flux into the conduits of mode I veins that accommodate more dilation or (ii) reopening of mode I veins owing to the driven of extensional failure under low differential stress. Although fault-hosted veins record fewer mineralization events, they have higher average Au grade (4.106 g/t) compared to that of mode I veins (2.736 g/t). On the other hand, fewer mineralization events in wall rock structures compared to the adjacent faults is attributed to (i) absence or poor development of the damage zone structures in earlier seismic events or (ii) deactivation of them after clogging due to the rotation of the optimum stress field or (iii) their formation as hydraulic extension fractures. This study emphasizes the importance of detailed studies of vein infill for understanding the internal structural evolution of the veins in epithermal deposits that is interest to the geologists within both industry and academic fields.","PeriodicalId":49411,"journal":{"name":"Turkish Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47112526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: The east-west extended Sivas Basin in central-eastern Anatolia is a foreland basin that formed after the obduction of the Tethyan ophiolite during the late Cretaceous and is also a north-verging fold-and-thrust belt. The basement rocks of the basin represent mainly sedimentary (Mesozoic platform-type carbonates) and late Cretaceous Divriği ophiolitic complex. As the ophiolitic rocks are affected by intense tectonic processes, field-based mapping studies require long processes and costs. The study tests to reveal the lithological features of the ophiolitic complex outcropping around the Ulaş district of the Sivas Province using remote sensing methods and techniques. Due to arid climatic conditions and rare vegetation cover in the region, almost all outcrops of the basin rocks can be separated by spectral enhancement methods easily. Band ratio (BR), spectral indices (SI), decorrelation stretch (DS), principal component analysis (PCA), and support vector machine (SVM) on Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were used in this research. BR, PCA, DC, and SI techniques clearly distinguish the Divriği Ophiolitic Complex from the basement and cover sedimentary rocks. SVM distinguishes the chromite-bearing dunites from the other ophiolite-related rock units. According to image analysis performances, it has been observed that the rocks of the Divriği ophiolitic complex can be differentiated in more detail compared to a 1/100.000 scaled geological map of the region.
{"title":"Lithological mapping of ophiolitic rocks from southern part of the Sivas Basin (Turkey) using ASTER imagery","authors":"Taner Ekici","doi":"10.55730/1300-0985.1838","DOIUrl":"https://doi.org/10.55730/1300-0985.1838","url":null,"abstract":": The east-west extended Sivas Basin in central-eastern Anatolia is a foreland basin that formed after the obduction of the Tethyan ophiolite during the late Cretaceous and is also a north-verging fold-and-thrust belt. The basement rocks of the basin represent mainly sedimentary (Mesozoic platform-type carbonates) and late Cretaceous Divriği ophiolitic complex. As the ophiolitic rocks are affected by intense tectonic processes, field-based mapping studies require long processes and costs. The study tests to reveal the lithological features of the ophiolitic complex outcropping around the Ulaş district of the Sivas Province using remote sensing methods and techniques. Due to arid climatic conditions and rare vegetation cover in the region, almost all outcrops of the basin rocks can be separated by spectral enhancement methods easily. Band ratio (BR), spectral indices (SI), decorrelation stretch (DS), principal component analysis (PCA), and support vector machine (SVM) on Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data were used in this research. BR, PCA, DC, and SI techniques clearly distinguish the Divriği Ophiolitic Complex from the basement and cover sedimentary rocks. SVM distinguishes the chromite-bearing dunites from the other ophiolite-related rock units. According to image analysis performances, it has been observed that the rocks of the Divriği ophiolitic complex can be differentiated in more detail compared to a 1/100.000 scaled geological map of the region.","PeriodicalId":49411,"journal":{"name":"Turkish Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44880154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zahra Najafi, H. Ahmadipour, A. Moradian, F. Sarjoughian, K. Nakashima
: At the south of the Bardsir, Kerman province, Iran, the southeastern part of the Urmia-Dokhtar magmatic arc (UDMA), a large number of gabbroic intrusions are intruded into the Eocene lava flows and pyroclastic rocks with the form of small stocks and dykes. In this paper, geochemical variations, magmatic evolutions, and the origin of these intrusions are investigated. The studied intrusions are characterized by fine-grained margins resulting from rapid cooling and flow differentiation. They display porphyritic texture and include coarse-grained clinopyroxene with diopside compositions (Wo = 46.89, En = 40.78, Fs = 12.32), plagioclase with labradorite composition (An = 54.14), and olivine in an intergranular crystalline groundmass. Their whole-rock chemistry proves that the rocks belong to the calc-alkaline series. The abundances of trace elements and REE, depletion of Nb, Ta, Zr, Ti, and Hf, and enrichment of LILE relative to HFSE indicate that these rocks belong to a subduction zone setting. Geochemical characteristics (Sm/Yb and La/Sm ratios) show that the source rock of these intrusions was the lithospheric mantle with spinel lherzolite composition, which initially underwent partial melting (10% to 20%) events and then was metasomatized by fluids derived from the subducting Neo-Tethys lithosphere.
{"title":"Petrological characteristics of gabbroic intrusions in southeastern Urmia-Dokhtar magmatic belt, Kerman province, Iran: Evidence for post-Eocene mafic magmatism","authors":"Zahra Najafi, H. Ahmadipour, A. Moradian, F. Sarjoughian, K. Nakashima","doi":"10.55730/1300-0985.1856","DOIUrl":"https://doi.org/10.55730/1300-0985.1856","url":null,"abstract":": At the south of the Bardsir, Kerman province, Iran, the southeastern part of the Urmia-Dokhtar magmatic arc (UDMA), a large number of gabbroic intrusions are intruded into the Eocene lava flows and pyroclastic rocks with the form of small stocks and dykes. In this paper, geochemical variations, magmatic evolutions, and the origin of these intrusions are investigated. The studied intrusions are characterized by fine-grained margins resulting from rapid cooling and flow differentiation. They display porphyritic texture and include coarse-grained clinopyroxene with diopside compositions (Wo = 46.89, En = 40.78, Fs = 12.32), plagioclase with labradorite composition (An = 54.14), and olivine in an intergranular crystalline groundmass. Their whole-rock chemistry proves that the rocks belong to the calc-alkaline series. The abundances of trace elements and REE, depletion of Nb, Ta, Zr, Ti, and Hf, and enrichment of LILE relative to HFSE indicate that these rocks belong to a subduction zone setting. Geochemical characteristics (Sm/Yb and La/Sm ratios) show that the source rock of these intrusions was the lithospheric mantle with spinel lherzolite composition, which initially underwent partial melting (10% to 20%) events and then was metasomatized by fluids derived from the subducting Neo-Tethys lithosphere.","PeriodicalId":49411,"journal":{"name":"Turkish Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44768085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Floyd, R. King, D. Paradissis, H. Karabulut, S. Ergintav, Kostas Raptakis, R. Reilinger
: GNSS observations in and around the Aegean Sea, Peloponnese
：全球导航卫星系统在爱琴海及其周围的观测，伯罗奔尼撒
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S. Ergintav, M. Floyd, D. Paradissis, H. Karabulut, P. Vernant, F. Masson, I. Georgiev, A. Konca, U. Doğan, Robert W. King, R. Reilinger
: We present a broad view of present-day motions and deformations derived from uniform processing of GNSS observations within the Nubia-Arabia-Eurasia zone of plate interaction. The new observations we present provide a ~29% increase in the number of velocity determinations, a reduction in average station spacing from ~76 km to ~39 km, and an improvement in velocity uncertainties (for <1 mm/year), from 180 to 578 sites compared to our prior published solution (Reilinger et al., 2006). We use these new constraints to better evaluate the role of faults and blocks in controlling the character of continental deformation within the zone of plate interactions. Simple elastic block models show that internal deformation of the region occurs in large part on mapped, seismically active fault systems, indicating elastic behavior of the seismogenic crust (above ~15 km). For example, eastern central Anatolia, an area of > ~126,000 km 2 , bounded by the North and East Anatolian Faults exhibits internal velocity differences of <0.5 mm/year, indicating strain rates of < ~1.5 nanostrain/year. Geodetically constrained fault slip rates obtained from this simplified approach are comparable to geologic rates, indicating that major faults have controlled the recent geologic evolution of the region (i.e. 5–10 Myr). The pattern of present-day deformation, including increasingly fast motions towards the Hellenic trench, and the roughly simultaneous opening of all the major Mediterranean basins in the early Miocene with the slowing of the Nubia-Eurasia convergence, support conceptual models that foundering and rollback of the subducted Nubian slab beneath the Aegean is the primary mechanism responsible for present-day motion and internal deformation of the Anatolian-Aegean region.
我们对努比亚-阿拉伯-欧亚板块相互作用区域内GNSS观测数据的统一处理得出的现今运动和变形进行了广泛的观察。我们提出的新观测提供了~29%的速度测定数量增加，平均站间距从~76 km减少到~39 km，并且速度不确定性有所改善(在~126,000 km 2中，以北安纳托利亚断层和东安纳托利亚断层为边界，内部速度差<0.5 mm/年，表明应变率< ~1.5纳米应变/年)。这种简化方法得到的受大地测量约束的断层滑动速率与地质速率相当，表明主要断层控制了该地区最近的地质演化(即5-10迈拉)。现今的变形模式，包括越来越快的向希腊海沟移动，以及中新世早期所有主要地中海盆地几乎同时开放，努比亚-欧亚大陆辐合速度减慢，支持了爱琴海下俯冲的努比亚板块的沉没和回滚是造成安纳托利亚-爱琴海地区现今运动和内部变形的主要机制的概念模型。
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