Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.685387
B. Rahimzadeh, Zheira Ghosoun, F. Masoudi
This study is aimed to determine the Fe content in natural epidote from Varan area (Urumieh-Dokhtar Magmatic Arc, Iran) by using vibrational FTIR and Raman spectroscopy and EPMA analyses. Fe3+ concentration calculated from FTIR spectroscopic data is in the range of 0.96 to 1 apfu. The results are in complete agreement with EPMA data. The comparison between obtained Raman spectra of studied epidote grains and those from the RRUFF database suggest that epidote from Varan area is rich in Fe3+. High Fe3+ content might reflect moderate to high oxygen fugacity during the crystallization of epidote. This short paper demonstrates that the quantification of the Fe content in epidote via FTIR method is as good as EPMA, whereas the utilization of a low-cost Raman spectrometer helps in quickly distinguishing between Fe-rich and Fe-poor epidote, which even could be useful in the case of field studies.spectrometer helps in quickly distinguishing between Fe-rich and Fe-poor epidote, which even could be useful in the case of field studies.Key-words: Epidote, FTIR, Raman spectroscopy, Iron content, Urumieh-Dokhtar Magmatic Arc, Iran.
采用振动傅里叶变换红外光谱(FTIR)、拉曼光谱(Raman spectroscopy)和EPMA分析方法，对伊朗乌鲁木齐-多赫塔尔岩浆弧(ulumieh - dokhtar magma Arc)瓦兰地区天然绿帘石中的铁含量进行了测定。FTIR光谱数据计算的Fe3+浓度在0.96 ~ 1 apfu之间。结果与EPMA数据完全一致。研究的绿帘石颗粒拉曼光谱与RRUFF数据库的拉曼光谱对比表明，瓦兰地区的绿帘石富含Fe3+。高Fe3+含量可能反映了绿帘石结晶过程中高氧逸度。这篇简短的文章证明了FTIR方法对绿帘石中铁含量的定量与EPMA方法一样好，而利用低成本的拉曼光谱仪有助于快速区分富铁和贫铁绿帘石，这甚至可以在现场研究的情况下有用。光谱仪有助于快速区分富铁和贫铁绿帘石，这甚至可以在现场研究的情况下有用。关键词:绿帘石，红外光谱，拉曼光谱，铁含量，乌鲁木齐-多克塔尔岩浆弧，伊朗
{"title":"Identification of Fe3+ content in Epidote from Varan, Urumieh-Dokhtar Magmatic Arc, Iran: using FTIR and Raman spectroscopy","authors":"B. Rahimzadeh, Zheira Ghosoun, F. Masoudi","doi":"10.30495/IJES.2021.685387","DOIUrl":"https://doi.org/10.30495/IJES.2021.685387","url":null,"abstract":"This study is aimed to determine the Fe content in natural epidote from Varan area (Urumieh-Dokhtar Magmatic Arc, Iran) by using vibrational FTIR and Raman spectroscopy and EPMA analyses. Fe3+ concentration calculated from FTIR spectroscopic data is in the range of 0.96 to 1 apfu. The results are in complete agreement with EPMA data. The comparison between obtained Raman spectra of studied epidote grains and those from the RRUFF database suggest that epidote from Varan area is rich in Fe3+. High Fe3+ content might reflect moderate to high oxygen fugacity during the crystallization of epidote. This short paper demonstrates that the quantification of the Fe content in epidote via FTIR method is as good as EPMA, whereas the utilization of a low-cost Raman spectrometer helps in quickly distinguishing between Fe-rich and Fe-poor epidote, which even could be useful in the case of field studies.spectrometer helps in quickly distinguishing between Fe-rich and Fe-poor epidote, which even could be useful in the case of field studies.Key-words: Epidote, FTIR, Raman spectroscopy, Iron content, Urumieh-Dokhtar Magmatic Arc, Iran.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44005062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.685394
Majid Niromand, M. Behyari, Yusef Rahim Souri
The closure of the Neo-Tethys ocean associated with the ophiolite obduction and the Oshnavieh ophiolite is the unknown part of the Neo-Tethys suture zone. Three well-known band ratio combinations applied to ASTER satellite image the result shows the ((2+4) /3, (5+7) /6, (7+9) /8) band ratio is the proper combination for the reorganization of rock units in the ophiolite regions. Principal component analysis of the (PC2, PC4 and PC 5) is well discriminated against to the rock unit contacts. The general trend of thrust faults is the NW-SE and dip direction is toward the NE. The rake of slickenline on the fault plane is 80°-90° and the mechanism of movement is the pure thrust. The shear sense indicator such as Z-type parasitic folds or mica-fish and S-C fabrics confirm right-lateral shearing sense in the shear zone. Strain geometry on the obducted slab evaluated by the shape of the mineral grains. In the shear zone strain ellipsoid shape is the prolate type and formed under constrictional regime, the Flinn K-value of these samples changes between 2.71 to 11.67 and lode ratio between -0.42 to -0.63. Most of the samples taken from the thrust fault zone located in the flattening zone and strain ellipsoid are pancake-shaped and formed under contractional regime the k-value varied between 0.44 to 0.80 and Lode ratio range is 0.32 to 0.5. The displacement in the thrust zone and shearing by the shear zone disrupted the ophiolite sequence and created an ophiolite melange.
{"title":"Strain geometry and structural analysis of the Oshnavieh ophiolite: A new segment of the Neo-Tethys puzzle","authors":"Majid Niromand, M. Behyari, Yusef Rahim Souri","doi":"10.30495/IJES.2021.685394","DOIUrl":"https://doi.org/10.30495/IJES.2021.685394","url":null,"abstract":"The closure of the Neo-Tethys ocean associated with the ophiolite obduction and the Oshnavieh ophiolite is the unknown part of the Neo-Tethys suture zone. Three well-known band ratio combinations applied to ASTER satellite image the result shows the ((2+4) /3, (5+7) /6, (7+9) /8) band ratio is the proper combination for the reorganization of rock units in the ophiolite regions. Principal component analysis of the (PC2, PC4 and PC 5) is well discriminated against to the rock unit contacts. The general trend of thrust faults is the NW-SE and dip direction is toward the NE. The rake of slickenline on the fault plane is 80°-90° and the mechanism of movement is the pure thrust. The shear sense indicator such as Z-type parasitic folds or mica-fish and S-C fabrics confirm right-lateral shearing sense in the shear zone. Strain geometry on the obducted slab evaluated by the shape of the mineral grains. In the shear zone strain ellipsoid shape is the prolate type and formed under constrictional regime, the Flinn K-value of these samples changes between 2.71 to 11.67 and lode ratio between -0.42 to -0.63. Most of the samples taken from the thrust fault zone located in the flattening zone and strain ellipsoid are pancake-shaped and formed under contractional regime the k-value varied between 0.44 to 0.80 and Lode ratio range is 0.32 to 0.5. The displacement in the thrust zone and shearing by the shear zone disrupted the ophiolite sequence and created an ophiolite melange.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45092599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.685383
Vahid Ahadnejad
Tourmaline minerals are a main petrogenetic tool because of their refractory nature, chemical variability, and extensive occurrence in various geological settings. The Middle-Jurassic Boroujerd igneous rocks are one of the largest bodies that located in the middle part in the Sanandaj-Sirjan Magmatic Arc (SSMA) that introduced into regional metamorphic rocks. They are mostly composed of granitoids (granodiorite, quartz-diorite, and monzogranite) and contain apatite, zircon and tourmaline as abounadant accessory minerals. Tourmalines occur in varying types of mineral assemblages, chemical compositions and individual forms including tourmalinite, quartz-tourmaline vein, as accessory mineral in the more evolved granitoids, and schists. Tourmaline crystal sizes in these rocks varies from very fine to coarse-grained. The colour is brown to black and some crystals displaying a finescale chemical zonation. Tourmaline crystals commonly exhibit cellular features. Based on electron probe microanalysis (EPMA) analyses, schorl is the most abundant type of tourmaline in granitoids but foitite and dravite are common compositions in the pegmatite and schist, respectively. Presence of several tourmaline generations and their compositional trend may indicate time-varying relatively acidic boron-bearing fluids and reflects an anatexic melts influence in their crystallization.
{"title":"Origin and significance of tourmaline-bearing rocks in Boroujerd region, Sanandaj-Sirjan zone, western Iran","authors":"Vahid Ahadnejad","doi":"10.30495/IJES.2021.685383","DOIUrl":"https://doi.org/10.30495/IJES.2021.685383","url":null,"abstract":"Tourmaline minerals are a main petrogenetic tool because of their refractory nature, chemical variability, and extensive occurrence in various geological settings. The Middle-Jurassic Boroujerd igneous rocks are one of the largest bodies that located in the middle part in the Sanandaj-Sirjan Magmatic Arc (SSMA) that introduced into regional metamorphic rocks. They are mostly composed of granitoids (granodiorite, quartz-diorite, and monzogranite) and contain apatite, zircon and tourmaline as abounadant accessory minerals. Tourmalines occur in varying types of mineral assemblages, chemical compositions and individual forms including tourmalinite, quartz-tourmaline vein, as accessory mineral in the more evolved granitoids, and schists. Tourmaline crystal sizes in these rocks varies from very fine to coarse-grained. The colour is brown to black and some crystals displaying a finescale chemical zonation. Tourmaline crystals commonly exhibit cellular features. Based on electron probe microanalysis (EPMA) analyses, schorl is the most abundant type of tourmaline in granitoids but foitite and dravite are common compositions in the pegmatite and schist, respectively. Presence of several tourmaline generations and their compositional trend may indicate time-varying relatively acidic boron-bearing fluids and reflects an anatexic melts influence in their crystallization.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45937927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.685393
M. Nedaei, H. Alizadeh, M. Jahangiri
The 11th August 2012 Ahar-Varzaghan earthquake doublet Mw 6.4 and 6.2 occurred near the city of Ahar, northwest Iran, in a region where there was no major mapped fault or any well-documented historical seismicity. To investigate the active tectonics and the state of pre and post-seismic stress distribution of the source region, we applied a combination of Coulomb stress change, b-value mapping, and the Fry method. Inferred Coulomb stress field reveals the E–W-striking (dextral) fault responsible for the first event and the NNE–SSW-striking (sinistral reverse) fault for the second event. The high slip stress-released regions in the obtained b-value map and the dominant anisotropies of aftershocks on regional stress-parallel cross-sections achieved by the Fry method, together with the distribution of aftershocks mechanisms, merely highlight the particular wedge-shaped structures namely the rhombic structures. The clockwise block rotation about the vertical axis under the right-lateral regional shear between the Kura basin to the north and the Central Iranian Block to the south and NW-oriented coeval shortening leads to the formation of rhombic structures. The results of this study improve our understanding of the kinematics of active deformation in NW Iran and have important implications for seismic hazard assessment of the region and potential future failure areas.
{"title":"The Pattern and Kinematics of Deep Deformation of 2012 Ahar-Varzaghan Earthquake Doublet (MW 6.4 and 6.2), a New Seismotectonic Interpretation","authors":"M. Nedaei, H. Alizadeh, M. Jahangiri","doi":"10.30495/IJES.2021.685393","DOIUrl":"https://doi.org/10.30495/IJES.2021.685393","url":null,"abstract":"The 11th August 2012 Ahar-Varzaghan earthquake doublet Mw 6.4 and 6.2 occurred near the city of Ahar, northwest Iran, in a region where there was no major mapped fault or any well-documented historical seismicity. To investigate the active tectonics and the state of pre and post-seismic stress distribution of the source region, we applied a combination of Coulomb stress change, b-value mapping, and the Fry method. Inferred Coulomb stress field reveals the E–W-striking (dextral) fault responsible for the first event and the NNE–SSW-striking (sinistral reverse) fault for the second event. The high slip stress-released regions in the obtained b-value map and the dominant anisotropies of aftershocks on regional stress-parallel cross-sections achieved by the Fry method, together with the distribution of aftershocks mechanisms, merely highlight the particular wedge-shaped structures namely the rhombic structures. The clockwise block rotation about the vertical axis under the right-lateral regional shear between the Kura basin to the north and the Central Iranian Block to the south and NW-oriented coeval shortening leads to the formation of rhombic structures. The results of this study improve our understanding of the kinematics of active deformation in NW Iran and have important implications for seismic hazard assessment of the region and potential future failure areas.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43027584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.1919627.1581
A. Chegini, I. M. Moghaddam, H. Sajjadi
Seven genera and seventeen species of marine Ostracoda are reported for the first time from the Attari section (Qom Formation), northeast of the Semnan, Central Iran. In this section, the Qom Formation outcrops with 280 m thickness lies on the Eocene volcanic and under the Upper Red formation. According to the distribution of index foraminifera, there is conspicuous similarity between larger bentic foraminifera assemblages of the Qom Formation foraminifera and those of the Zagros basin, such as Borelis melo curdica the age of Qom Formation in the Attari section is Early Miocene (Burdigalian). The Miocene and even Oligocene Ostracoda fauna, relatively similar to the Attari section, have been reported from the Mediterranean area and the Proto- Indo- Pacific Ocean. The presence of one species with Paratethian origin in the Qom Formation is strong evidence that during the Burdigalian stage, the sea way between Central Iran and Paratethys basin still existed.
{"title":"Systematic of the Early-Miocene (Burdigalian) Ostracoda from Northeastern Semnan, Central Iran","authors":"A. Chegini, I. M. Moghaddam, H. Sajjadi","doi":"10.30495/IJES.2021.1919627.1581","DOIUrl":"https://doi.org/10.30495/IJES.2021.1919627.1581","url":null,"abstract":"Seven genera and seventeen species of marine Ostracoda are reported for the first time from the Attari section (Qom Formation), northeast of the Semnan, Central Iran. In this section, the Qom Formation outcrops with 280 m thickness lies on the Eocene volcanic and under the Upper Red formation. According to the distribution of index foraminifera, there is conspicuous similarity between larger bentic foraminifera assemblages of the Qom Formation foraminifera and those of the Zagros basin, such as Borelis melo curdica the age of Qom Formation in the Attari section is Early Miocene (Burdigalian). The Miocene and even Oligocene Ostracoda fauna, relatively similar to the Attari section, have been reported from the Mediterranean area and the Proto- Indo- Pacific Ocean. The presence of one species with Paratethian origin in the Qom Formation is strong evidence that during the Burdigalian stage, the sea way between Central Iran and Paratethys basin still existed.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45931898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.1931062.1610
A. Chegini, I. M. Moghaddam, Mohamahosein Adabi, M. Lotfpour
This study provides a evaluation of the initial carbonate mineralogy, and diagenetic condition of the Ruteh Formation, a middle-late Permian carbonate sequence, in the Emarat section in Central Alborz, northern Iran. 200 samples were examined for petrographical contents and thirty-four samples were collected for geochemical analysis. The high Sr and Na contents, Sr/Na>1, and the presence of dolomites and dissolution fractures are indicative aragonite early mineralogy. The diagenetic process in the Ruteh Fm. are an indication of the marine, meteoric and burial diagenetic environments. The original carbonate texture in the Ruteh Fm. are Severely affected by diagenetic process. The data obtained from the values of the Major (Ca and Mg), minor (Sr, Na, Fe, and Mn), oxygen and carbone isotopes show the initial aragonite composition of the Ruteh Fm. deposited in a subtropical shallow water. An open diagenetic system was indicated by changes in the values of Sr / Ca and δ18O vs. Mn. The shallow burial diagenetic temperature of the Ruteh carbonate was approximate 28.6°C with the maximum diagenetic temperature of 53.4°C.
{"title":"Geochemistry and Diagenetic Evidence of Middle-Late Permian Deposits, Northern Iran","authors":"A. Chegini, I. M. Moghaddam, Mohamahosein Adabi, M. Lotfpour","doi":"10.30495/IJES.2021.1931062.1610","DOIUrl":"https://doi.org/10.30495/IJES.2021.1931062.1610","url":null,"abstract":"This study provides a evaluation of the initial carbonate mineralogy, and diagenetic condition of the Ruteh Formation, a middle-late Permian carbonate sequence, in the Emarat section in Central Alborz, northern Iran. 200 samples were examined for petrographical contents and thirty-four samples were collected for geochemical analysis. The high Sr and Na contents, Sr/Na>1, and the presence of dolomites and dissolution fractures are indicative aragonite early mineralogy. The diagenetic process in the Ruteh Fm. are an indication of the marine, meteoric and burial diagenetic environments. The original carbonate texture in the Ruteh Fm. are Severely affected by diagenetic process. The data obtained from the values of the Major (Ca and Mg), minor (Sr, Na, Fe, and Mn), oxygen and carbone isotopes show the initial aragonite composition of the Ruteh Fm. deposited in a subtropical shallow water. An open diagenetic system was indicated by changes in the values of Sr / Ca and δ18O vs. Mn. The shallow burial diagenetic temperature of the Ruteh carbonate was approximate 28.6°C with the maximum diagenetic temperature of 53.4°C.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48862899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.685382
Rasool Yazarloo, M. Khamehchiyan, M. Nikudel
Engineering properties of soils and the 3D modeling of geological formations are widely used in site investigations and the preparation of geological hazard maps. The present study was conducted to characterize the engineering geological properties of the young surface alluviums of the Gorgan city (Iran) to a depth of 25 m and 3D modeling of their geology using boreholes data. To this end, after determining the location of the available boreholes on the aerial map of Gorgan, four hypothetical cross-sections were considered in the North-South and East-West directions. Then, the borehole data were marked on each section and their 2D geological cross-sections were manually drawn using correlation of the similar layers. In the next step, by expanding the information of these sections, a 3D geological model of Gorgan city was prepared using a conceptual-observational method. According to the evidence from the boreholes and field observations, the depositional environment of Gorgan alluviums was an alluvial fan created by the Ziarat River. Additionally, in terms of engineering characteristics of alluviums, the Gorgan subsurface soils can be divided into four engineering units, including upper clay unit (UCU), middle gravel unit (MGU), lower clay unit (LCU), and sandy unit (SU), which share the same engineering characteristics. Finally, the results of tests performed on samples from different depths were employed to calculate the engineering geological characteristics of each unit, including Atterberg limits, compressibility, undrained shear strength, and drained shear strength parameters.
{"title":"Geological and engineering geological characteristics of surface alluviums in the Gorgan city","authors":"Rasool Yazarloo, M. Khamehchiyan, M. Nikudel","doi":"10.30495/IJES.2021.685382","DOIUrl":"https://doi.org/10.30495/IJES.2021.685382","url":null,"abstract":"Engineering properties of soils and the 3D modeling of geological formations are widely used in site investigations and the preparation of geological hazard maps. The present study was conducted to characterize the engineering geological properties of the young surface alluviums of the Gorgan city (Iran) to a depth of 25 m and 3D modeling of their geology using boreholes data. To this end, after determining the location of the available boreholes on the aerial map of Gorgan, four hypothetical cross-sections were considered in the North-South and East-West directions. Then, the borehole data were marked on each section and their 2D geological cross-sections were manually drawn using correlation of the similar layers. In the next step, by expanding the information of these sections, a 3D geological model of Gorgan city was prepared using a conceptual-observational method. According to the evidence from the boreholes and field observations, the depositional environment of Gorgan alluviums was an alluvial fan created by the Ziarat River. Additionally, in terms of engineering characteristics of alluviums, the Gorgan subsurface soils can be divided into four engineering units, including upper clay unit (UCU), middle gravel unit (MGU), lower clay unit (LCU), and sandy unit (SU), which share the same engineering characteristics. Finally, the results of tests performed on samples from different depths were employed to calculate the engineering geological characteristics of each unit, including Atterberg limits, compressibility, undrained shear strength, and drained shear strength parameters.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48558692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.685398
R. Mahari, Youssef Mohammadi Moghaddas, R. Shabanian, Adel Najafzadeh
The Permian Ruteh Formation is known as one of the most significant successions in northwestern Iran. In the studied area it exposed a thick succession (201 m) of medium to thick-bedded carbonate sedimentary rocks in the west of Kuseh-Kahrizeh village in the north of Mahabad city. This formation unconformably overlain the Cambrian Mila Formation and it is unconformably underlain by the Oligo-Miocene Qom Formation The laboratory studies on the thin sections led to the identification of 15 microfacies that are arranged in three facies associations: inner ramp, mid-ramp and outer ramp. The petrographic results and facies analysis demonstrate that the depositional environment of Ruteh Formation in the studied area exhibits the characteristics of a homoclinal carbonate ramp platform of a gentle slope. This platform is mainly composed of supratidal, intertidal, lagoon, shoal, open marine, mid-ramp, and outer ramp environments. According to facies frequency analysis, the lagoon environment accounts for the highest abundance of facies (33%), whearas the outer ramp environment shows the least abundance (2%).Vertical distribution analysis of sedimentary facies led to the identification of transgressive and regressive depositional patterns. Accordingly, a total of 4 depositional sequences of third-order, 5 sequence boundaries and 4 maximum flooding surfaces were identified. The boundaries between all sequences are identified as SB1.
{"title":"Facies Analysis, Depositional Environment and Sequence Stratigraphy of the Permian Ruteh Formation in North of Mahabad (Northwestern Iran)","authors":"R. Mahari, Youssef Mohammadi Moghaddas, R. Shabanian, Adel Najafzadeh","doi":"10.30495/IJES.2021.685398","DOIUrl":"https://doi.org/10.30495/IJES.2021.685398","url":null,"abstract":"The Permian Ruteh Formation is known as one of the most significant successions in northwestern Iran. In the studied area it exposed a thick succession (201 m) of medium to thick-bedded carbonate sedimentary rocks in the west of Kuseh-Kahrizeh village in the north of Mahabad city. This formation unconformably overlain the Cambrian Mila Formation and it is unconformably underlain by the Oligo-Miocene Qom Formation The laboratory studies on the thin sections led to the identification of 15 microfacies that are arranged in three facies associations: inner ramp, mid-ramp and outer ramp. The petrographic results and facies analysis demonstrate that the depositional environment of Ruteh Formation in the studied area exhibits the characteristics of a homoclinal carbonate ramp platform of a gentle slope. This platform is mainly composed of supratidal, intertidal, lagoon, shoal, open marine, mid-ramp, and outer ramp environments. According to facies frequency analysis, the lagoon environment accounts for the highest abundance of facies (33%), whearas the outer ramp environment shows the least abundance (2%).Vertical distribution analysis of sedimentary facies led to the identification of transgressive and regressive depositional patterns. Accordingly, a total of 4 depositional sequences of third-order, 5 sequence boundaries and 4 maximum flooding surfaces were identified. The boundaries between all sequences are identified as SB1.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44509453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.1901981.1490
Malihe Nazari, M. Lotfi, N. Nezafati, Nemat Allah Rashid Nejad Omran
The Band-e-Narges magnetite deposit is located in the central part of Urumieh–Dokhtar Magmatic Arc. Wide I-type calk-alkaline and alkalin magmatic activity in the Koh-e Latif region has been reported due to Eocene intrusive processes in UDMA. Five stages of paragenesis have been observed in the mineralization in this area: prograde stage, retrograde stage, sulfide- quartz stage, carbonate stage and Oxidation stage.The result of all δ34S values of pyrite and anhydrite + pyrite shows values are positive with a magmatic sulfur origin in these deposits. fluid inclusions have been observed according to the petrographic and microtermometric inclusions within garnet, quartz, and calcite minerals at various stages. According to high temperature and middle salinity of fluid inclusions in prograde skarn-stage, the fluid inclusions shows reaction with the calcareous wall rock and fluid inclusions were trapped at pressures of 400 to 500 bars, corresponding to depths of 1.5 to 2 km .Fluid inclusions in quartz have moderate temperatures and low salinity indicating quartz-sulfide stage and late retrograde stage. fluid inclusions with moderate homogenization temperature (300 to 350 oC ) suggest that reboiling coccurred under hydrostatic pressure of 150 to 250 bars, equivalent to a depth of 1 to 1.5 km in the late retrograde skarn and quartz-sulfide stages. Fluid inclusions in calcite have moderate temperatures and low to high salinities . The geology, mineralogy, geochemistry, salinities and homogenization-temperatures from the fluid inclusions populations at the Band-e-Narges iron deposit are follows a model of boiling as a result of decrease pressure, mixing and cooling.
{"title":"Origin and Development of Skarn-Forming Fluids from the Band-e-Narges Skarn Iron Ore- Central Iran","authors":"Malihe Nazari, M. Lotfi, N. Nezafati, Nemat Allah Rashid Nejad Omran","doi":"10.30495/IJES.2021.1901981.1490","DOIUrl":"https://doi.org/10.30495/IJES.2021.1901981.1490","url":null,"abstract":"The Band-e-Narges magnetite deposit is located in the central part of Urumieh–Dokhtar Magmatic Arc. Wide I-type calk-alkaline and alkalin magmatic activity in the Koh-e Latif region has been reported due to Eocene intrusive processes in UDMA. Five stages of paragenesis have been observed in the mineralization in this area: prograde stage, retrograde stage, sulfide- quartz stage, carbonate stage and Oxidation stage.The result of all δ34S values of pyrite and anhydrite + pyrite shows values are positive with a magmatic sulfur origin in these deposits. fluid inclusions have been observed according to the petrographic and microtermometric inclusions within garnet, quartz, and calcite minerals at various stages. According to high temperature and middle salinity of fluid inclusions in prograde skarn-stage, the fluid inclusions shows reaction with the calcareous wall rock and fluid inclusions were trapped at pressures of 400 to 500 bars, corresponding to depths of 1.5 to 2 km .Fluid inclusions in quartz have moderate temperatures and low salinity indicating quartz-sulfide stage and late retrograde stage. fluid inclusions with moderate homogenization temperature (300 to 350 oC ) suggest that reboiling coccurred under hydrostatic pressure of 150 to 250 bars, equivalent to a depth of 1 to 1.5 km in the late retrograde skarn and quartz-sulfide stages. Fluid inclusions in calcite have moderate temperatures and low to high salinities . The geology, mineralogy, geochemistry, salinities and homogenization-temperatures from the fluid inclusions populations at the Band-e-Narges iron deposit are follows a model of boiling as a result of decrease pressure, mixing and cooling.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48412437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-01DOI: 10.30495/IJES.2021.682863
T. Adewumi, K. Salako, U. D. Alhassan, A. A. Adetona, A. A. Rafiu, E. Udensi
A new exploration technique called Thorium Normalisation Method has been applied on the airborne radiometric data of the Bornu basin and its environs to delineate favourable zones for hydrocarbon accumulations within the study area. This method is significant because it indicates the probable presence of hydrocarbon in a sedimentary basin. Separation of the radiospectrometric measurements over each lithologic unit and the estimation of the characteristic statistics of these units were carried out. The statistical treatment applied on the radioelements (K, eTh and eU) of the study area shows a relatively low coefficient of variability (CV%) value for K, eTh and eU signifying their high degree of homogeneity. The mean value of the radioelements (K ranging from 0.6 to 2.0 %; Th ranging from 9.6 to 15.9 ppm and U ranging from 2.2 to 3.8 ppm) obtained from the statistical analysis correlates with the mean of natural radioelement (K ranging from 0.1 to 2.7 %; Th ranging from 0.4 to 11.2 ppm and U ranging from 0.1 to 3.7 ppm) content of sedimentary rocks which corresponds to shale, the main source rock for hydrocarbon accumulation in the study area. The DRAD (delineation of radioactive anomalies) result ranges from -0.77 to 1.83. The positive values are indicators of favourable zones for the presence of hydrocarbon accumulations. These results suggest that the preliminary information obtained from the use of the thorium normalisation method will guide the exploration of hydrocarbon in the study area.
{"title":"Interpretation of Airborne Radiometric data for possible hydrocarbon presence over Bornu basin and its environs, Northeast Nigeria using Thorium normalisation method","authors":"T. Adewumi, K. Salako, U. D. Alhassan, A. A. Adetona, A. A. Rafiu, E. Udensi","doi":"10.30495/IJES.2021.682863","DOIUrl":"https://doi.org/10.30495/IJES.2021.682863","url":null,"abstract":"A new exploration technique called Thorium Normalisation Method has been applied on the airborne radiometric data of the Bornu basin and its environs to delineate favourable zones for hydrocarbon accumulations within the study area. This method is significant because it indicates the probable presence of hydrocarbon in a sedimentary basin. Separation of the radiospectrometric measurements over each lithologic unit and the estimation of the characteristic statistics of these units were carried out. The statistical treatment applied on the radioelements (K, eTh and eU) of the study area shows a relatively low coefficient of variability (CV%) value for K, eTh and eU signifying their high degree of homogeneity. The mean value of the radioelements (K ranging from 0.6 to 2.0 %; Th ranging from 9.6 to 15.9 ppm and U ranging from 2.2 to 3.8 ppm) obtained from the statistical analysis correlates with the mean of natural radioelement (K ranging from 0.1 to 2.7 %; Th ranging from 0.4 to 11.2 ppm and U ranging from 0.1 to 3.7 ppm) content of sedimentary rocks which corresponds to shale, the main source rock for hydrocarbon accumulation in the study area. The DRAD (delineation of radioactive anomalies) result ranges from -0.77 to 1.83. The positive values are indicators of favourable zones for the presence of hydrocarbon accumulations. These results suggest that the preliminary information obtained from the use of the thorium normalisation method will guide the exploration of hydrocarbon in the study area.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":"13 1","pages":"161-172"},"PeriodicalIF":0.8,"publicationDate":"2021-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48561504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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