Chemie Der Erde-Geochemistry最新文献

{"title":"Soil CO2 fluxes measured in the Acoculco Geothermal System, Mexico: Baseline emissions from a long-term prospection programme","authors":"D. Pérez-Zárate ,&nbsp;E. Santoyo ,&nbsp;M.P. Jácome-Paz ,&nbsp;M. Guevara ,&nbsp;F. Guerero ,&nbsp;D. Yáñez-Dávila ,&nbsp;G. Santos-Raga","doi":"10.1016/j.chemer.2024.126112","DOIUrl":"10.1016/j.chemer.2024.126112","url":null,"abstract":"<div><p>The Acoculco Caldera Complex is considered a promissory hidden high-temperature geothermal system in Mexico. To support the geothermal prospection of this anomalous area, a comprehensive programme of soil CO₂ flux measurements was performed. A long-term measurement programme was conducted to determine the baseline of natural soil CO₂ effluxes. Significant efforts were devoted both to measuring the CO₂ fluxes between 2015 and 2022 and interpreting their origin. Eighteen soil gas surveys of CO₂ were carried out by using the accumulation chamber method. &gt;1200 diffuse CO₂ fluxes were measured in six different areas of the Acoculco Caldera. Two areas (Los Azufres and Alcaparrosa) exhibited cold degassing sites, acid-sulphate springs, and gas bubbling in surface water bodies. The soil CO₂ fluxes ranged from 1 to 26,000 g m⁻² d⁻¹, whereas lower fluxes &lt;29 g m⁻² d⁻¹ were determined as the degassing baseline. A total CO₂ output of 492 t d⁻¹ km⁻¹ was estimated using an integrated SGS-GSA approach, where the highest total soil CO₂ fluxes were obtained for Alcaparrosa (299 t d⁻¹ km⁻²) compared with Los Azufres (164 t d⁻¹ km⁻²), and Surroundings (29 t d⁻¹ km⁻²). Such results agree well with those values measured in other worldwide volcanic and active geothermal ecosystems. The range of CO₂ isotopic composition values from −28.83 ‰ to −3.11 ‰, together with their statistical distribution, suggests multiple CO₂ production sources feeding soil degassing. The combined interpretation of flux and isotopic data allowed us to identify two distinct gas sources: endogenous and biogenic. The present study highlights the importance of using soil CO₂ monitoring to determine baseline emissions at the early exploration stage of geothermal systems.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126112"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140205123","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}

{"title":"A comprehensive evaluation of OPTICS, GMM and K-means clustering methodologies for geochemical anomaly detection connected with sample catchment basins","authors":"Mahsa Hajihosseinlou ,&nbsp;Abbas Maghsoudi ,&nbsp;Reza Ghezelbash","doi":"10.1016/j.chemer.2024.126094","DOIUrl":"10.1016/j.chemer.2024.126094","url":null,"abstract":"<div><p>The process of data-driven clustering to uncover geochemical anomalies linked to sample catchment basins (SCBs) includes a comprehensive framework to discern areas exhibiting unique geochemical attributes within a specified study area. The Ordering Points to Identify the Clustering Structure (OPTICS) method can serve as a robust methodology for detecting geochemical anomalies in SCBs. This is attributed to its capacity to effectively manage varying cluster densities, adaptively identify cluster numbers, exhibit resilience to noise, and display minimum sensitivity to parameters. A comparison was conducted in this research between the outcomes of the OPTICS clustering algorithm and two traditional clustering techniques, namely the Gaussian Mixture Model (GMM) and K-means clustering. In the following, the Expectation-Maximization (EM) technique is employed to train the GMM for clustering. Moreover, the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) as two validate statistical metrics implemented to ascertain the optimal number of components (clusters) belong to the GMM. It should be noted that the effectiveness of the clustering algorithms was further assessed using the Calinski-Harabasz (CH) index and the success-rate curves. OPTICS, a density-based clustering approach, was confirmed to be more effective than K-means and GMM for identifying MVT Pb<img>Zn anomalies in Varcheh district, western Iran. Furthermore, the specified anomalies show a geo-spatial correspondence with the geological facts, and it has been observed that strong anomalies are more discoverable in close proximity to MVT Pb<img>Zn occurrences. This work suggests a novel anomaly detection approach based on OPTICS, which exhibits superior performance and data-modeling efficiency. The main emphasis is on effectively distinguishing geochemical anomalies from sample data originating from populations with uncertain distributions.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126094"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139948727","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}

{"title":"Melt inclusions in spinel from a composite mantle xenolith","authors":"Ioannis Baziotis ,&nbsp;Myrto Simopoulou ,&nbsp;Constantinos Mavrogonatos ,&nbsp;Stephan Klemme ,&nbsp;Jasper Berndt ,&nbsp;Paul D. Asimow","doi":"10.1016/j.chemer.2024.126118","DOIUrl":"10.1016/j.chemer.2024.126118","url":null,"abstract":"<div><p>Composite mantle xenoliths from the Cima Volcanic Field (CA, USA) contain a variety of melt (now glassy) inclusions hosted within mantle phases. The compositions and textures of these melt inclusions have the potential to constrain their trapping processes, melt sources, and the rates of ascent of their parent xenoliths. Here we focus on unusual spinel-hosted melt inclusions from one composite xenolith, reporting glass and daughter mineral compositions and textures and attempting to reconstruct inclusion bulk compositions. The xenolith contains spinel-hosted melt inclusions in its harzburgite, olivine-websterite and lherzolite layers; there are none in its orthopyroxenite layer.</p><p>The glass compositions and reconstructed bulk compositions of the partly-crystallized inclusions correspond to alkaline intermediate melts, mostly trachyandesites. Such melts are most likely to be generated and trapped by vapor-undersaturated phlogopite or amphibole dehydration melting to an assemblage of liquid + spinel + olivine ± pyroxenes. We modeled the near-liquidus phase relations of the inclusion bulk compositions and noted the closest approach of each inclusion to simultaneous saturation with spinel and either phlogopite or amphibole, resulting in estimated trapping pressures of ∼0.5–1.5 GPa and temperatures of ∼1000–1100 °C. The large size of the hosting spinel grains suggests a slow process associated with these breakdown reactions, probably thinning of the lithosphere and steepening of the geotherm during regional extension.</p><p>A linear correlation between the vesicle area and inclusion area (as proxies for volume) suggests an in-situ exsolution process from melts of relatively uniform volatile initial contents, consistent with trapping of vapor-undersaturated melts that later exsolve vapor during cooling and daughter crystal growth. A negative correlation between the glass content in melt inclusions and the size of the inclusion itself suggests a control on the degree of crystallinity with the size. There appears to be a two-stage cooling history captured by the inclusions, forming first prismatic daughter crystals and large round vesicles at the wall of the inclusion, followed by quenching to form a mat of fine crystallites and small vesicles in most inclusions. We connect the final quench to rapid ascent of the xenolith in its host melt, which also triggered partial breakdown of remaining amphibole to fine glassy symplectites.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126118"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140763431","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}

{"title":"U-Pb and Re-Os geochronology and lithogeochemistry of granitoid rocks from the Burnthill Brook area in central New Brunswick, Canada: Implications for critical mineral exploration","authors":"Nadia Mohammadi ,&nbsp;David R. Lentz ,&nbsp;Kathleen G. Thorne ,&nbsp;Jim Walker ,&nbsp;Neil Rogers ,&nbsp;Brian Cousens ,&nbsp;Christopher R.M. McFarlane","doi":"10.1016/j.chemer.2024.126087","DOIUrl":"10.1016/j.chemer.2024.126087","url":null,"abstract":"&lt;div&gt;&lt;p&gt;The Burnthill Brook area of central New Brunswick contains four Late Devonian intrusions (Burnthill, Buttermilk Brook, Dungarvon, and Sisters Brook plutons) emplaced into greenschist-facies Cambro-Ordovician graphite-bearing meta-sedimentary rocks of the Miramichi Group and/or Middle Ordovician bimodal metavolcanic rocks of the Tetagouche Group. To help resolve the complex nature of molybdenite (± tungsten) mineralization and its relationship with the magmatic evolution of the Burnthill Brook area, this study combines whole-rock geochemistry (major- and trace-elements, and Sr-Nd-Hf-Pb isotopes) with U-Pb zircon and Re-Os molybdenite analyses of samples collected from the Falls Creek occurrence (Mo ± W), the Burnthill Sn-W-Mo deposit, and previously obtained Re-Os ages from the Sisson Brook W-Mo-Cu deposit.&lt;/p&gt;&lt;p&gt;New geochronological data from the Burnthill Brook area, in combination with previous published Ar-Ar and U-Pb data, defines a protracted (25 Ma) period of magmatism from 396 to 371 Ma. These data indicate that peaks of mineralization, at ca. 380 and 378 Ma, correlate with distinct pulses of magmatism. The younger mineralization corresponds with the final magmatic pulse in the area and is likely genetically related to aplite dykes present within the Falls Creek (FC) occurrence. Furthermore, this study has identified a younger generation of Mo-W-REE mineralization that is hosted by FC aplite dykes.&lt;/p&gt;&lt;p&gt;Burnthill Brook plutons are highly evolved, high-silica peraluminous A-type granites that have undergone extensive fractionation, leading to elevated concentrations of incompatible elements (e.g., Rb, Y, Nb, Cs, Th, and U) and fluorine (mean = 0.08 ± 0.05 wt%), as well as economically important elements, such as Sn, Ta, W, Mo, Zn, and Pb. The enrichment of these elements is primarily associated with fractional crystallization, a process that was amplified by repeated magmatic pulses over a protracted period, resulting in Mo + W saturation.&lt;/p&gt;&lt;p&gt;The evolution of granite-related mineral deposits in the Burnthill Brook area is attributed to a regional-scale metallogenic epoch associated with the Neoacadian Orogeny. This same metallogenic epoch is likely responsible for the formation of numerous granite-related mineral deposits across the Canadian Appalachians, and further reinforces the conclusion that pulsed magmatism during the Neoacadian Orogeny (390–350 Ma) played an integral role in the formation of these deposits.&lt;/p&gt;&lt;p&gt;Geochemical and geochronological evidence collectively suggests that the various plutons are individual components of a Middle to Late Devonian batholith that underlies this region, and is provisionally herein referred to as the Peaked Mountain Batholith. In addition to the area encompassing the exposed Burnthill, Buttermilk Brook, Dungarvon and Sisters Brook granites, this presumptive batholith is projected to extend at least 24 km to the south-southwest to include the unidentified, buried pluton(s) responsible","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126087"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281924000114/pdfft?md5=532df599252b6df6310199fe1c40537c&pid=1-s2.0-S0009281924000114-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139813376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Whole-rock geochemical and zircon U-Pb-Hf isotopic compositions of the Yunlougang and Wucun granitic plutons in the Hetai area of South China: Implications for petrogenesis and geodynamic setting","authors":"Lixing Wang ,&nbsp;Deru Xu ,&nbsp;Hai Lin ,&nbsp;Xinyu Wang ,&nbsp;Genwen Chen ,&nbsp;Qianqian Jiao","doi":"10.1016/j.chemer.2024.126085","DOIUrl":"10.1016/j.chemer.2024.126085","url":null,"abstract":"<div><p>In the Nanling tectono-magmatic belt of South China, the geodynamic settings and tectonic style of Indosinian and Yanshanian magmatism remain debatable. Hereby, an integrated study of zircon U-Pb ages and Lu-Hf isotopes as well as whole-rock elemental and Sr-Nd isotopic compositions was carried out on the Yunlougang (Late Permian) and the Wucun (Late Jurassic) granitic plutons in the Hetai area, located to southwest of the Nanling region. Zircon U-Pb dating yielded emplacement ages of 255 Ma for the Yunlougang biotite monzogranite, 240 Ma for the Yunlougang granodiorite as dyke crosscutting the former, and 155 Ma for the Wucun two-mica granite. The biotite monzogranite and the two-mica granite are strongly peraluminous S-type granites (A/CNK ratios of 1.06–1.21) with a relatively low zircon saturation temperature (631–741 °C). The high initial ⁸⁷Sr/⁸⁶Sr ratios (0.71733 to 0.73383) and low ε_Nd(t) values (−14.6 to −8.69) suggest a crustal protolith. However, the Wucun biotite granite is highly fractionated I-type one (most samples are metaluminous with A/CNK &lt; 1.1) with a relatively high zircon saturation temperature (762–770 °C). Additionally, they exhibit less radiogenic ⁸⁷Sr/⁸⁶Sr_i ratios (0.70724–0.70786) and higher ε_Nd(t) values (−5.34 to −4.94) as well as zircon ε_Hf(t) values of −5.67 to −2.44, suggesting an origin of a crustal source with extra input from mantle. Based on the tectonic history of South China, we infer that the Yunlougang granite occurred in a compressive setting and might be produced by partial melting of a thickened ancient crust during the collision between the South China and the Indochina blocks, while the Wucun complex granites generated in an extensional environment that was influenced by the paleo-Pacific tectonic regime. Combined with previous studies, a NE-oriented I-type granite belt probably existed along the juncture belt of the Yangtze and Cathaysia blocks, which was respond to the foundering rather than rollback of the paleo-Pacific plate that led to the rapid change of the temperature of granite precursor and the involvement of mantle components into the Hetai region.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126085"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140004560","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}

{"title":"Geochemical survey data cube: A useful tool for lithological classification and geochemical anomaly identification","authors":"Ying Xu,&nbsp;Renguang Zuo","doi":"10.1016/j.chemer.2023.125959","DOIUrl":"10.1016/j.chemer.2023.125959","url":null,"abstract":"<div><p>Geochemical survey<span> data play a critical role in geological studies, mineral exploration<span><span>, and environmental applications by providing information on geological events and processes such as mineralization and pollution. A typical geochemical survey dataset contains the analysis of multiple elements. For example, the National Geochemical Mapping Project of China comprises 39 major and trace element concentrations. Multiple geochemical maps can be generated by interpolating geochemical samples into raster maps to constitute a geochemical survey data cube in which elements are sorted by their atomic numbers. A geochemical spectrum can be created using these geochemical maps in which each pixel that records geochemical characteristics. In this study, a convolutional neural network<span> (CNN) that considers the geochemical spectrum and spatial pattern of geological objects was employed to mine a geochemical survey data cube, aiming of geological mapping and geochemical anomalies identification associated with mineralization in the eastern part of Hubei Province of China. The results showed that (1) a geochemical survey data cube which built based on various geochemical exploration data provided vital information on mineralization process and the formation of </span></span>geological features; and (2) a CNN had a strong ability to recognize high-level features in the geochemical survey data cube, and it showed excellent performance in mineral exploration and related geological studies.</span></span></p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 125959"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83142599","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}

{"title":"Monazite and zircon UPb and muscovite 40Ar/39Ar geochronology constraints on the timing of magmatism and mineralization in the Huxingshan tungsten deposit, South China","authors":"Lei Zhu ,&nbsp;Bin Li ,&nbsp;An-Huai Lu ,&nbsp;De-Xian Zhang ,&nbsp;Jun-Wei Xu","doi":"10.1016/j.chemer.2024.126091","DOIUrl":"10.1016/j.chemer.2024.126091","url":null,"abstract":"<div><p>The Huxingshan W deposit (0.21 Mt. WO₃ @ 0.3 %) in northeastern Hunan province is located at the western margin of the Jiangnan tungsten belt (JNB), South China. It consists of a series of magma-derived scheelite-quartz-muscovite (SQM) veins in the F1 fault (which contains over 60 % of the W resource), beneath Niutitang Formation (Fm.) carbonate rocks, and above Yijiaqiao Fm. slate (sub-economic), distal from the concealed two-mica granite, which is thought to be responsible for the tungsten mineralization. In this study, we employ LA-ICP-MS zircon and monazite U<img>Pb, and muscovite ⁴⁰Ar/³⁹Ar dating to constrain the timing of magmatism and W mineralization at the Huxingshan deposit. Monazite and zircon dating yield coeval ages of 137.6 ± 0.5 Ma and 138.0 ± 0.5 Ma, respectively. Our muscovite ⁴⁰Ar/³⁹Ar dating yielded well plateau ages of 132.9 ± 0.6 Ma, 132.2 ± 0.6 Ma, 130.7 ± 0.5 Ma, and 129.7 ± 0.6 Ma for four representative SQM vein ore samples occurring in the Niutitang Fm. carbonate, F1 fault, and Yijiaqiao Fm. slate, indicating multiple pulses of ore-forming fluid infiltration at Huxingshan. Our age data demonstrate that the two-mica granite emplaced at ∼137.6 Ma, significantly earlier than the pulsed W mineralization at ca. 132.9–129.7 Ma. The lack of spatial and temporal association precludes any genetic link between them. Thus, we infer that the ore-forming fluids likely originated from undiscovered deep plutons and ascended through the F1 fault. Besides, our reliable ages coincide with the two periods of large-scale Mesozoic magmatism and W mineralization phases in the JNB, with the 137.6 Ma magmatism falling within the first phase (150–135 Ma), while the W mineralization (ca.132.9–129.7 Ma) falls within the second phase (130–125 Ma). Of which, the second phase, including the Huxingshan, Xianglushang, Dongping, and Jianfengpo deposits, are situated in the western JNB and show further potential in this region.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126091"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139830578","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}

{"title":"Recognition of REEs anomalies using an image Fusion fractal-wavelet model in Tarom metallogenic zone, NW Iran","authors":"Mohammad Mahdi Pourgholam ,&nbsp;Peyman Afzal ,&nbsp;Ahmad Adib ,&nbsp;Kambiz Rahbar ,&nbsp;Mehran Gholinejad","doi":"10.1016/j.chemer.2024.126093","DOIUrl":"10.1016/j.chemer.2024.126093","url":null,"abstract":"<div><p>This study aims to detect REE geochemical anomalies in relationship to Iron-apatite ores utilizing an image Fusion based on Deep Learning (FDL). The geochemical data was modeled for elements related to Iron-apatite mineralization using multi b Spline B. The results were fusioned in applying the Deep learning method based on pre-trained networks. Wavelet-Number (W<img>N) fractal model classified the best results based on the combination of a two-dimensional Discrete Wavelet Transformation (DWT) signal analysis and a Concentration-Area (C-A) fractal modeling. Sym8 carried the DWT as a selected wavelet pattern for REE based on Stream sediment samples collected from the Tarom region (NW Iran). In addition, the DWT was decomposed by wavelet coefficients at five levels. Furthermore, the DWT data were classified using a fractal-wavelet model to delineate REE anomalies from background levels in this region. Overlayed with the catchment basins model and weighted using the upstream and downstream parts. As a result, the prominent REE source anomalies are located in the southern parts of the study area. The results obtained by the proposed fractal-wavelet modeling are in connection with field check anomaly samples and the rock samples collected from the Iron-Apatite ore deposits.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126093"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139923577","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}

{"title":"Assessment of potential cobalt zones by modeling radiometric and ASTER data using the AHP method: A case of the Bou Azzer El Grara inlier, Central Anti-Atlas, Morocco","authors":"A. Bajadi ,&nbsp;D. El Azzab ,&nbsp;M. Ouchchen ,&nbsp;Y. Mamouch ,&nbsp;L. Achkouch ,&nbsp;B. Dadi ,&nbsp;N. El Moutaouakkil ,&nbsp;B. Sadeghi","doi":"10.1016/j.chemer.2024.126105","DOIUrl":"10.1016/j.chemer.2024.126105","url":null,"abstract":"<div><p>The Bou Azzer El Grara inlier belongs to the Central Anti-Atlas range, renowned for its mineral deposits. The study carried out on the inlier aims to identify potential areas of cobalt mineralization based on a multi-source methodology of radiometric and remote sensing data processing. The data used includes hydrothermal alteration minerals (argillic, phyllic, propylitic, iron oxides) mapped with Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery using band ratio and principal component analysis (PCA) techniques, potassium enrichment zones through K/eTh and K/eU ratios calculated from radiometric data, as well as geological data (serpentinite outcrops and geological faults). The analytic hierarchy process (AHP) was used to combine the various thematic layers. Validation was carried out through the field studies in several anomalous zones. The mineral prospectivity map generated highlights nine major zones that appear the most favorable for mineralization, some of which coincide with zones in production and others requiring further exploration.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126105"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281924000291/pdfft?md5=7ebc5fdec8232d275db8cd737fe065fa&pid=1-s2.0-S0009281924000291-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140205159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geology, mineralogy, and alteration of the Cu-Pb veins, and their significance in mineral exploration: A case study in the Khajeh-Nezam area, SE Iran","authors":"Afshin Akbarpour ,&nbsp;Majid Vanaei ,&nbsp;Behnam Sadeghi","doi":"10.1016/j.chemer.2023.126041","DOIUrl":"10.1016/j.chemer.2023.126041","url":null,"abstract":"<div><p>Khajeh-Nezam area is situated within the Bam 1:100,000 geological sheet, SE Iran. The area was the subject of silt geochemical studies and consists of highly prospective Cu, Pb, Ba, and Fe veins and veinlets that demonstrate a northwest-southeast trend. A total of 149 silt samples were collected from the area and analyzed for 7 elements (As, Cu, Mo, Pb, Zn, Sb, Ba) using Inductively Coupled Plasma-Optical Emission Spectrometry. Univariate-multivariate statistical analysis the majority of variables demonstrate a distribution that is slightly too moderately positively skewed, which can be accurately explained using a log-normal model. Only Cu, Zn, and Pb demonstrate a normal distribution. The number-size (N-S) fractal model show that. The variables can be classified into two main groups. The first group comprises the main ore-forming elements, namely Cu, Ba, As, and Sb, which are associated with the epithermal system. On the other hand, Mo, Pb, and Zn demonstrate a stronger affiliation with vein and veinlet mineralization that could be linked to the margin of a possible hidden porphyry system. The geochemical halo in the southwestern part of the study area, which overlaps with volcanic rocks, has experienced significant alterations attributed to local intrusions, leading to a level of modification. A secondary weak anomaly, of relatively lesser significance, is observed in Pb, Zn, and Mo. Although these elements are not the primary constituents of the ore, they serve as pathfinder elements in marginal copper porphyry. The results obtained from the study have been utilized to identify concealed ore bodies using the classes defined by N-S classification model. Fieldwork conducted in the area confirms the presence of Fe oxide veins and veinlets that contain copper mineralization, along with carbonate Pb and Cu minerals. Various types of alteration have been identified, including argillic alteration accompanied by quartz and hematite in the vicinity of the veins and veinlets. The findings serve as probable evidence for the existence of a new copper porphyry system in the study area.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126041"},"PeriodicalIF":0.0,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281923000922/pdfft?md5=9033700b76745e0dcffc548da0bf9d05&pid=1-s2.0-S0009281923000922-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136093672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}