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Enhanced water saturation evaluation method using an improved electrical efficiency model: A case study of the Mishrif Formation, Iraq
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-18 DOI: 10.1016/j.jappgeo.2025.105656
Jianhong Guo , Zhansong Zhang , Chaomo Zhang , Qing Zhao , Xiao Tang
{"title":"Enhanced water saturation evaluation method using an improved electrical efficiency model: A case study of the Mishrif Formation, Iraq","authors":"Jianhong Guo ,&nbsp;Zhansong Zhang ,&nbsp;Chaomo Zhang ,&nbsp;Qing Zhao ,&nbsp;Xiao Tang","doi":"10.1016/j.jappgeo.2025.105656","DOIUrl":"10.1016/j.jappgeo.2025.105656","url":null,"abstract":"<div><div>The accurate prediction of water saturation in reservoir exploration and development remains a significant challenge, particularly in regions like the Middle East with complex carbonate formations such as the Mishrif Formation. While geophysical logging data is widely utilized for this purpose, however, the complex pore structures render Archie's formula unsuitable, leading to non-Archie phenomenon in rock-electrical experiments. Although the electrical efficiency model has been employed in calculating water saturation in carbonate reservoirs, there has been no prior study incorporating electrical porosity for its refinement. This study enhances the conventional electrical efficiency model by introducing the concept of electrical porosity. The improvement aims to mitigate the impact of isolated mold pores and sparse regions of current density distribution on electrical efficiency, focusing on the Mishrif Formation and quantitatively computing water saturation. Initially, the study area is categorized into three distinct rock-physics types of reservoirs using the Winland R35 method, with respective electrical porosities calculated. Subsequently, these results are integrated with the enhanced electrical efficiency model, and trial calculations are performed using geophysical well-logging data, followed by a comparison with core data. The findings reveal that the improved electrical efficiency model yields an average relative error of only 10.36 % compared to core data, whereas the respective errors for Archie's formula and traditional electrical efficiency models are 17.65 % and 20.92 %, indicating enhanced accuracy with the improved approach. Across different reservoir types, a decrease in electrical porosity proportion is observed with diminishing pore-throat radius. Additionally, the consistency of this trend is validated by nuclear magnetic resonance logging data. Lastly, the necessity of reservoir rock-physics type classification for electrical porosity computation is confirmed. For heterogeneous reservoirs, direct calculation of electrical porosity is infeasible, thus underscoring the essential groundwork of reservoir rock-physics type delineation. This study improves water saturation prediction accuracy and applicability by introducing electrical porosity to refine the conventional electrical efficiency model, holding significant implications for the exploration and development of complex reservoirs.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"236 ","pages":"Article 105656"},"PeriodicalIF":2.2,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143480348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Subsurface structure identification at the blind prediction site of ESG in Kumamoto under the diffuse field assumption
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-17 DOI: 10.1016/j.jappgeo.2025.105658
Alejandro Vargas-Colorado , Mohsen Kazemnia Kakhki , José E. Barradas-Hernández , Sergio Márquez-Domínguez , Franco A. Carpio-Santamaría , José Piña-Flores
{"title":"Subsurface structure identification at the blind prediction site of ESG in Kumamoto under the diffuse field assumption","authors":"Alejandro Vargas-Colorado ,&nbsp;Mohsen Kazemnia Kakhki ,&nbsp;José E. Barradas-Hernández ,&nbsp;Sergio Márquez-Domínguez ,&nbsp;Franco A. Carpio-Santamaría ,&nbsp;José Piña-Flores","doi":"10.1016/j.jappgeo.2025.105658","DOIUrl":"10.1016/j.jappgeo.2025.105658","url":null,"abstract":"<div><div>A representative velocity profile for Kumamoto city is presented in this study, derived from ambient seismic noise data collected by three sizes sensor arrays SM, M, and LL. Phase and group velocity dispersion curves for both Rayleigh and Love waves were estimated using techniques such as SPAC and cross-correlations. Additionally, Horizontal-to-Vertical Spectral Ratio (HVSR) analysis was performed individually for each array, and the resulting data were averaged to generate a single representative HVSR curve. By employing joint inversion under the diffuse field assumption, dispersion curves and HVSR data were concurrently fitted, allowing for the estimation of a 1D velocity profile. This approach effectively addresses the non-uniqueness inherent in inversion problems. Furthermore, upper modes were identified, and a comparative analysis of dispersion and HVSR curves was conducted against those of an established model, revealing notable discrepancies requiring thorough examination. Subsequently, seismic energy partitioning analysis was carried out, focusing on the vertical component. The findings were correlated with dispersion diagrams to confirm consistency in mode identification.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"235 ","pages":"Article 105658"},"PeriodicalIF":2.2,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
New traveltime approximations for VTI media and estimation of the Thomsen parameters VTI 介质的新旅行时间近似值和汤姆森参数估计
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-16 DOI: 10.1016/j.jappgeo.2025.105654
Francisco Gamboa Ortega , Amin Bassrei , Francisco Cabrera Zambrano
{"title":"New traveltime approximations for VTI media and estimation of the Thomsen parameters","authors":"Francisco Gamboa Ortega ,&nbsp;Amin Bassrei ,&nbsp;Francisco Cabrera Zambrano","doi":"10.1016/j.jappgeo.2025.105654","DOIUrl":"10.1016/j.jappgeo.2025.105654","url":null,"abstract":"<div><div>Conventional velocity analysis estimates the normal moveout velocity which corresponds to a combination of the P-wave vertical velocity and the anisotropy parameter δ for a transversely isotropic medium with a vertical axis of symmetry. We propose in this study a joint estimation of (pseudo-acoustic) P-wave velocity and Thomsen parameters with new traveltime approximations and a deterministic inversion algorithm with regularization by derivative matrices. The new traveltime expressions are based on rational approximations, with analytical expressions that are simple to use. Therefore, the new approximations improved the joint inversion performance by reducing algebraic complexity. Computationally, the algorithm is efficient due to the use of small matrices; it simplifies calculations without losing precision. The experiments with synthetic models validated the approach and the numerical simulations indicated that the proposed approximations have in average an accuracy similar to the expressions available in the literature. The tested model considered lateral velocity variation, increasing the challenge in relation to a flat-layered model. In particular, the phase and group velocity approximations presented better accuracy between 40 and 60 degrees. For traveltime computation the proposed approach presented better accuracy for offsets greater than 4 km.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"235 ","pages":"Article 105654"},"PeriodicalIF":2.2,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Deep site characterization with full-waveform inversion of SH- and Love-waves induced by large mobile shaker
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-16 DOI: 10.1016/j.jappgeo.2025.105657
Aidin Kahbasi , Khiem T. Tran , Brady R. Cox , Aser Abbas
{"title":"Deep site characterization with full-waveform inversion of SH- and Love-waves induced by large mobile shaker","authors":"Aidin Kahbasi ,&nbsp;Khiem T. Tran ,&nbsp;Brady R. Cox ,&nbsp;Aser Abbas","doi":"10.1016/j.jappgeo.2025.105657","DOIUrl":"10.1016/j.jappgeo.2025.105657","url":null,"abstract":"<div><div>The ability to reliably image the subsurface is critical for designing and constructing infrastructure, especially in seismically active regions and areas with karstic geologies and underground anomalies. This study explores the application of 2D full-waveform inversion (FWI) of shear horizontal (SH) and Love waves to characterize shear wave velocity (<em>Vs</em>) and density down to a depth of 50 m. The FWI approach employs 2D elastic SH-wave equations for wave simulation and the adjoint-state gradient method with Tikhonov regularization for model updates. The applicability of this FWI approach was first verified using a synthetic four-layer subsurface model representing typical geology of north-central Florida, with soil overlying highly variable limestone. Following promising results from the synthetic study, the approach was applied to a dataset collected at a site near Newberry, Florida using a powerful mobile shaker source (T-Rex). The T-Rex vibroseis truck was instrumental in providing the low-frequency components (down to 5 Hz) essential for deep subsurface characterization. FWI successfully identified an underground anomaly and the depth to bedrock, which were verified through Standard Penetration Testing (SPT).</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"235 ","pages":"Article 105657"},"PeriodicalIF":2.2,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Radioactivity of Outcropping Rock Formations / Iraqi Southern Desert
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-13 DOI: 10.1016/j.jappgeo.2025.105646
Hayder Abdulzahra Al-Dabbagh , Emad H. Al-Khersan , Eman Ali Al-Kanaan
{"title":"Radioactivity of Outcropping Rock Formations / Iraqi Southern Desert","authors":"Hayder Abdulzahra Al-Dabbagh ,&nbsp;Emad H. Al-Khersan ,&nbsp;Eman Ali Al-Kanaan","doi":"10.1016/j.jappgeo.2025.105646","DOIUrl":"10.1016/j.jappgeo.2025.105646","url":null,"abstract":"<div><div>The study area located between latitude (29<sup>o</sup>-31<sup>o</sup>) N and longitudes (42<sup>o</sup>-47<sup>o</sup>) E within the Mesopotamian zone inside Stable and Unstable Shelves. Airborne radioactivity survey of Iraq prepared by French Company (C.G.G.), (1974) was used to acquire the total count readings on a scale of 1:200.000 for Iraqi southern Desert. A regional radio-geological study was carried out to determine the relationship between various radioactive levels and the general structural and geological framework in the study area. The natural radiation background was calculated using trend surface analysis method, it ranged between (890) cps in Hour Al-Hammar region and (1160) cps in Iraqi-Saudi border of the area. The total radioactivity of the exposed geologic units and formations were ranged between (800_900) cps in Dibddiba Formation and (1100_1200) cps in Umm Er-Radhuma Formation, as well as that for Quaternary deposits it was found between (700_900) cps in slope deposits in Al-Salman region and (1100_1300) cps in valley fill deposits in Middle Member of Dammam Formation. Six sites of radiometric anomalies were noticed in the third order residual anomaly map. After the analysis of available geologic, structure and geophysical information of the study area, the nature and cause of these normally occurring anomalies and their relations with the mineral and lithological constituents of the rocks and their relation to the structural and geologic setting of the region was established and analyzed.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105646"},"PeriodicalIF":2.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Electrical resistivity structure of the Meizhuang geothermal field in South Poyang Depression, China, revealed by 3-D magnetotelluric inversion
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-11 DOI: 10.1016/j.jappgeo.2025.105653
Chaofeng Wu , Dong Xu , Hailong Ye , Xiuquan Qiu , Hua Zhang
{"title":"Electrical resistivity structure of the Meizhuang geothermal field in South Poyang Depression, China, revealed by 3-D magnetotelluric inversion","authors":"Chaofeng Wu ,&nbsp;Dong Xu ,&nbsp;Hailong Ye ,&nbsp;Xiuquan Qiu ,&nbsp;Hua Zhang","doi":"10.1016/j.jappgeo.2025.105653","DOIUrl":"10.1016/j.jappgeo.2025.105653","url":null,"abstract":"<div><div>The Meizhuang area, located in the South Poyang Depression, is characterized by the widespread occurrence of fold-fault systems and carbonate strata. With an average surface heat flow of 72 mW/m<sup>2</sup>, this region presents promising potential for developing geothermal energy. Our study aims to delineate the stratigraphic features and the components of the hydrothermal system through the interpretation of 117 broadband magnetotelluric (MT) soundings within this area. Prior dimensionality analysis using phase tensor revealed that the MT data reflects substantial lateral heterogeneities in the resistivity structure, necessitating a three-dimensional resistivity inversion. We employed the ModEM program to invert the off-diagonal components of MT impedance tensor data and comprehensively interpreted the electrical structure combined with geological information. The resistivity model major includes one low-resistivity anomaly and two high-resistivity anomalies. The conductive anomaly was attributed to the Cretaceous sandy mudstone overlaid on Permian limestone, suggesting a favorable reservoir-cap system in this location. The two high-resistivity bodies are distributed on either side of the conductive anomaly, corresponding to the Junshanhu uplift and the Meizhuang anticline respectively. These structures are mainly oriented in a northeast direction, forming a pattern of “two uplifts sandwiching one sag”. Results from this study indicate that the Permian carbonate rocks are regarded as the geothermal reservoir, while the overlying Quaternary and Cretaceous sediments serve as suitable caprocks. The presence of the Meizhuang anticline and the Junshanhu uplift facilitates deep hydrothermal circulation of groundwater along the faults.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105653"},"PeriodicalIF":2.2,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Seismological geothermometer. Part I: Neural network modeling of the temperature prediction from seismic velocity data at borehole depth scale
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-04 DOI: 10.1016/j.jappgeo.2025.105644
Viacheslav V. Spichak, Olga K. Zakharova
{"title":"Seismological geothermometer. Part I: Neural network modeling of the temperature prediction from seismic velocity data at borehole depth scale","authors":"Viacheslav V. Spichak,&nbsp;Olga K. Zakharova","doi":"10.1016/j.jappgeo.2025.105644","DOIUrl":"10.1016/j.jappgeo.2025.105644","url":null,"abstract":"<div><div>A feasibility study is carried out to assess the possibility of predicting the subsurface temperatures from seismic tomography data. To this end, we used seismic velocity data along the W-E profile in the Northern Tien Shan and geotherms from three boreholes located at different distances from the profile. To model the temperature prediction from seismic velocity data, we used a supervised artificial neural network (ANN) approach. Estimation of the temperature prediction accuracy was fulfilled in two modes: (1) extrapolation in depth, and (2) assessment in another geological environment. The accuracy estimates of the temperature predictions at depth have shown that the relative errors depend on the ratio between the depth for which the data are available and the target depth. In particular, temperature prediction from seismic <em>S</em>-wave velocity data is markedly more accurate than the prediction from <em>P</em>-wave velocity if the target depth exceeds the source depth 5–10 times. On the other hand, in extrapolation to a depth less than twice the initial depth the average relative errors are 1 % and 2 %, accordingly. The accuracy analysis of temperature predictions in different geological environments showed that the accuracy of temperature prediction practically does not depend on the spacing between the locations of the “source” and “target” boreholes. On average, the accuracy of the prediction from <em>P</em>- and <em>S</em>-waves is approximately similar, with average relative errors of 4.8 and 4.7 %, respectively. It can be concluded that neural network prediction of the subsurface temperature from seismic velocity data can be performed with acceptable accuracy (at least, at borehole depth scale) and can be used as a seismological geothermometer.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105644"},"PeriodicalIF":2.2,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Comparison of soil-structure interaction obtained from spectral ratio methods applied to earthquake and microtremor records
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-04 DOI: 10.1016/j.jappgeo.2025.105645
Erkan Ateş , Osman Uyanık
{"title":"Comparison of soil-structure interaction obtained from spectral ratio methods applied to earthquake and microtremor records","authors":"Erkan Ateş ,&nbsp;Osman Uyanık","doi":"10.1016/j.jappgeo.2025.105645","DOIUrl":"10.1016/j.jappgeo.2025.105645","url":null,"abstract":"<div><div>Installing strong ground motion measuring devices in existing structures is significant for earthquake engineering and building safety to monitor whether the structures can be damaged or not. This study determined with different spectral ratio methods the dominant vibration period and amplification characteristics of both the structure and the ground from earthquake and noise records and compared the results. For this purpose, online-monitored accelerometer devices were placed on the top floor of a 5-story public building that was improved in 2008, on the ground where it was built, and on the rock approximately 1 km away from this building. MASW measurement was taken to determine the ground class of the area where the accelerometer device was installed on the ground right next to the building. Many earthquake records of different distances and magnitudes were obtained by the fixed devices located in the building, on the ground, and the rock. Spectral ratio methods were applied to the recorded earthquakes according to the reference station method and horizontal/vertical ratio methods according to the single station method. In addition to the analyses applied to the earthquake records, noise measurements were taken at night on the building floors and ground, and these measurements were evaluated according to the horizontal/vertical spectral ratio method and floor spectral ratio methods. As a result of all the analyses, the amplifications, dominant frequencies, and damping ratio of the building and the ground were determined, and the interference status of the building and the ground was examined. As a result, it was observed that the dominant frequency of the building, the spectral ratio amplification, and the damping ratio values of the building were approximately the same by using different spectral ratio methods for earthquake and noise data. In addition, there was a slight increase in the building's dominant period as a result of earthquakes that occurred at different times.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105645"},"PeriodicalIF":2.2,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143372063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Gravity gradient signal extraction based on time-frequency feature threshold method
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-03 DOI: 10.1016/j.jappgeo.2025.105643
Tao Jiang , Bohai Ke , Xiaobing Yu , Li Yu , Meng Yang , Ji Fan , Chenyuan Hu , Wei Feng , Huafeng Liu , Min Zhong , Liangcheng Tu , Zebing Zhou
{"title":"Gravity gradient signal extraction based on time-frequency feature threshold method","authors":"Tao Jiang ,&nbsp;Bohai Ke ,&nbsp;Xiaobing Yu ,&nbsp;Li Yu ,&nbsp;Meng Yang ,&nbsp;Ji Fan ,&nbsp;Chenyuan Hu ,&nbsp;Wei Feng ,&nbsp;Huafeng Liu ,&nbsp;Min Zhong ,&nbsp;Liangcheng Tu ,&nbsp;Zebing Zhou","doi":"10.1016/j.jappgeo.2025.105643","DOIUrl":"10.1016/j.jappgeo.2025.105643","url":null,"abstract":"<div><div>Gravity gradient, defined as the spatial derivative of gravitational acceleration, represents the detailed variation of the gravity field and plays a significant role in resource exploration and auxiliary navigation. Airborne gravity gradient measurement is an important method for obtaining high-precision gravity gradient data. Compared to traditional gravity measurement techniques, it offers superior measurement efficiency and provides high-frequency information of gravity field which reveals small-scale terrain features. However, it also introduces more high-frequency measurement noise. Due to the randomness of Earth's topography and resource distribution, the high-frequency characteristics of gravity gradient signals are mainly concentrated in specific time and frequency ranges, exhibiting distinct time-frequency features. This paper employs the VMD and Hilbert transform to obtains the time-frequency features of gravity gradient signal, and proposes a time-frequency feature threshold method to extract gravity gradient signal. This method can accurately analyze and extract the gravity gradient signals components without being affected by the same frequency noise, suppressing 78 % of the noise in simulation data. Additionally, the proposed method is validated in the gravity gradient data of actual terrain, demonstrating over 19 % improvement compared to traditional smooth filter and wavelet threshold methods. Furthermore, it effectively retains the high-frequency characteristics of gravity gradient signal, enhancing the advantages of airborne gravity gradient signals</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"234 ","pages":"Article 105643"},"PeriodicalIF":2.2,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143349184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Application of 3-D inversion of AMT data in exploration of concealed nonmetallic deposits: A Case Study on the Huashitou Mountain fluorite deposit in Beishan metallogenic belt, China
IF 2.2 3区 地球科学
Journal of Applied Geophysics Pub Date : 2025-02-01 DOI: 10.1016/j.jappgeo.2025.105632
Jianhui Hu , Liuyang Xu , Yaotian Yin , Xu Jia , Ping Qi , Zhan Liang , Peng Su , Cheng Liu , Weidong Tang , Long Chen , Yanzhou Wang , Lin Liu
{"title":"Application of 3-D inversion of AMT data in exploration of concealed nonmetallic deposits: A Case Study on the Huashitou Mountain fluorite deposit in Beishan metallogenic belt, China","authors":"Jianhui Hu ,&nbsp;Liuyang Xu ,&nbsp;Yaotian Yin ,&nbsp;Xu Jia ,&nbsp;Ping Qi ,&nbsp;Zhan Liang ,&nbsp;Peng Su ,&nbsp;Cheng Liu ,&nbsp;Weidong Tang ,&nbsp;Long Chen ,&nbsp;Yanzhou Wang ,&nbsp;Lin Liu","doi":"10.1016/j.jappgeo.2025.105632","DOIUrl":"10.1016/j.jappgeo.2025.105632","url":null,"abstract":"<div><div>This study utilized audio-frequency magnetotelluric (AMT) data collected from a concealed fluorite deposit on Huashitou Mountain in the Beishan metallogenic belt to obtain a 3-D resistivity model beneath the deposit. The fluorite ore-forming mechanism was determined and is discussed in combination with previous high-resolution magnetic and induced-polarization imaging results. Our study revealed a large high-resistivity body, R2 (&gt; 1000 Ω·m), corresponding to the low induced-polarization and low-magnetic region that extends from 40 to &gt; 80 m in depth. We suggest that this corresponds to the Indosinian intrusive granite, and potentially serves as a fluorite mineralization rock mass. A highly conductive zone, C3 (&lt; 3 Ω·m), extending from approximately 20 to 300 m, or even deeper, was interpreted as a deep fault/fracture zone functioning as a fluid pathway for fluorite mineralization. Two smaller conductive zones, C1 and C2 (&lt; 20 Ω·m), appear above the high-resistivity granite intrusion. These zones correspond well with high induced-polarization anomalies (&gt; 2.5 % threshold), relatively high-△T anomalies (−50 nT), and hematite alteration areas shown on the geological cross-sections. These zones were interpreted as two near-surface secondary fault structures. The aforementioned fault structures are believed to have formed before the main mineralization period of the fluorite deposit and were subsequently reactivated during intense tectonic-magmatic activity in the Late Hercynian. Hot fluids enriched with volatile components (e.g., F and CO<sub>2</sub>) were transported along the deep fault, represented by C3, from the lower crust to the near-surface secondary fault zones (represented by C1 and C2). These fluids interacted with the calcic plagioclase in alkaline granite magma to form fluorite (mainly composing CaF<sub>2</sub>) through calcium extraction. Further, the process led to hydrothermal alteration, resulting in associated iron-oxide mineralization or silicification alteration zones, as well as alterations related to a sedimentary layer such as kaolinization and chloritization. These zones exhibit high conductivity because of their significant porosity and the presence of fluids or metal sulfides.</div></div>","PeriodicalId":54882,"journal":{"name":"Journal of Applied Geophysics","volume":"233 ","pages":"Article 105632"},"PeriodicalIF":2.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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