Pub Date : 2021-09-24DOI: 10.30495/IJES.2021.685397
P. Afzal, Farshid Koohzadi, D. Jahani, M. Pourkermani
The main aim of this study was to outline the lithium anomalies by a regional exploration, at an area of 7800 km2, in Semnan province (north central Iran) using the Staged Factor Analysis (SFA) and Spectrum-Area (S-A) fractal model based on stream sediments and rock samples. Results derived via the SFA denote that Li was located in a factor as F2-4 with B, Cs, U and Rb which was utilized for calculation of the threshold values by the S-A method. The F2-4 data were classified by the fractal model for determination of the Li anomalies. Main anomaly for F2-4≥ 1.5 was situated in the SW and northern parts of this region. Furthermore, Li high grades of rock samples were correlated with main F2-4 anomalies. The main anomalies were correlated with geological particulars of Li mineralization types which represent that the main F2-4 anomalies associate with volcanic and tuff units in the SW part, and overlapped with clay minerals in the northern sector of this region. On the other hand, there are proper potential for Li mineralization which is demonstrated by this method.
{"title":"Geochemical exploration for Li in regional scale utilizing Staged Factor Analysis (SFA) and Spectrum-Area (S-A) fractal model in north central Iran","authors":"P. Afzal, Farshid Koohzadi, D. Jahani, M. Pourkermani","doi":"10.30495/IJES.2021.685397","DOIUrl":"https://doi.org/10.30495/IJES.2021.685397","url":null,"abstract":"The main aim of this study was to outline the lithium anomalies by a regional exploration, at an area of 7800 km2, in Semnan province (north central Iran) using the Staged Factor Analysis (SFA) and Spectrum-Area (S-A) fractal model based on stream sediments and rock samples. Results derived via the SFA denote that Li was located in a factor as F2-4 with B, Cs, U and Rb which was utilized for calculation of the threshold values by the S-A method. The F2-4 data were classified by the fractal model for determination of the Li anomalies. Main anomaly for F2-4≥ 1.5 was situated in the SW and northern parts of this region. Furthermore, Li high grades of rock samples were correlated with main F2-4 anomalies. The main anomalies were correlated with geological particulars of Li mineralization types which represent that the main F2-4 anomalies associate with volcanic and tuff units in the SW part, and overlapped with clay minerals in the northern sector of this region. On the other hand, there are proper potential for Li mineralization which is demonstrated by this method.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49098195","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.2021.685388
Mersana Keshavarz, F. Ghaemi, A. Faghih, M. Ghanadian
In mountain ranges, recent and active tectonics can be viewed as the main factor contributing to rock uplift, their present-day topography being the result of the competition between tectonic and erosional processes. The region coincides with three faults which show signs of activity during the late Quaternary period: The Astaneh, North Damghan, and Damghan faults, which collectively make up the SW section of the left‐lateral Shahrud fault system. In this study we have analyzed morphotectonic and neotectonic indices to evaluate tectonic activity of the study area.Tectonic geomorphological indices that are used in this study are drainage basin based (drainage basin asymmetry factor (Af), Hypsometric integral (Hi)) and mountain front based (mountain-front sinuosity (Smf), valley floor width – valley height ratio (Vf)) which can be useful tools for studying active tectonics. The study area includes pop-up structures that are formed during inverse tectonic activities of Alborz mountain belt. Strike-slip faults and flower structures suggest transpressional tectonic regime at eastern part of Alborz.
{"title":"Tectonic geomorphology assessment of neotectonics in the north of Damghan Region, Alborz Mountain Belt, Northern Iran","authors":"Mersana Keshavarz, F. Ghaemi, A. Faghih, M. Ghanadian","doi":"10.30495/IJES.2021.685388","DOIUrl":"https://doi.org/10.30495/IJES.2021.685388","url":null,"abstract":"In mountain ranges, recent and active tectonics can be viewed as the main factor contributing to rock uplift, their present-day topography being the result of the competition between tectonic and erosional processes. The region coincides with three faults which show signs of activity during the late Quaternary period: The Astaneh, North Damghan, and Damghan faults, which collectively make up the SW section of the left‐lateral Shahrud fault system. In this study we have analyzed morphotectonic and neotectonic indices to evaluate tectonic activity of the study area.Tectonic geomorphological indices that are used in this study are drainage basin based (drainage basin asymmetry factor (Af), Hypsometric integral (Hi)) and mountain front based (mountain-front sinuosity (Smf), valley floor width – valley height ratio (Vf)) which can be useful tools for studying active tectonics. The study area includes pop-up structures that are formed during inverse tectonic activities of Alborz mountain belt. Strike-slip faults and flower structures suggest transpressional tectonic regime at eastern part of Alborz.","PeriodicalId":44351,"journal":{"name":"Iranian Journal of Earth Sciences","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2021-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49446484","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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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.2021.685398
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":null,"pages":null},"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":null,"pages":null},"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 : 2021-09-24DOI: 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":null,"pages":null},"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 : 2021-07-01DOI: 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":null,"pages":null},"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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：