Chemie Der Erde-Geochemistry最新文献

{"title":"Sideritization and silification of unconformity-related hydrothermal baryte veins near Grünau, south Namibia","authors":"Benjamin F. Walter ,&nbsp;Manuel Scharrer ,&nbsp;R. Johannes Giebel ,&nbsp;Aratz Beranoaguirre ,&nbsp;Jorge C.L. Arthuzzi ,&nbsp;Lorenz Kemmler ,&nbsp;Andreja Ladisic ,&nbsp;Saskia Dück ,&nbsp;Michael Marks ,&nbsp;Gregor Markl","doi":"10.1016/j.chemer.2024.126244","DOIUrl":"10.1016/j.chemer.2024.126244","url":null,"abstract":"<div><div>The development of economic mineralization within unconformity related hydrothermal vein type deposits is a topic of basic (but also economic) significance. In particular late-stage processes like pseudo- or perimorphic replacements can significantly influence the mineralogy and hence processability of ore deposits. This study aims to shed light on such late stage processes leading to the mineralogical modification of primary hydrothermal veins by pseudomorphous and perimorphous replacements of quartz after hydrothermal gangue minerals like carbonates, baryte and fluorite; whereas the genesis of pseudomorphic replacements of baryte by siderite and a contemporaneous perimorphic overgrowth of quartz has not been studied in detail so far. To study this process, hydrothermal veins of the south Namibian hydrothermal vein type district, which are related to the breakup of Pangea are chosen as natural laboratories.</div><div>Fluid inclusion data together with a detailed petrography of the paragenetic sequence and fluid inclusion assemblages reveal a temperature drop from early quartz I at ∼170 °C down to ∼80 °C in quartz III at almost constant salinities of 23.1 to 24.5 wt% (NaCl+CaCl₂). The chemistry of the observed fluid inclusion assemblages is in accordance with previous microthermometry studies carried out in the same hydrothermal vein type district indicating an identical provenance of the fluids recognized in the other deposits (e.g., Aukam and Garub). Hence it is likely that a high salinity basement brine of cryogenic origin has been mixed with a Nama Group limestone derived fluid to form the primary mineralization. Mixing of two chemically-contrasted fluids is also depicted by the trace elements studied in the youngest quartz generation whereas the application of the TitaniQ thermometer provide evidence for a temperature of about 320 °C in the deep-seated reservoir which became afterwards mixed with Nama Group limestone derived fluids. Thermodynamic modelling based on the gathered fluid data and data from analogue studies, provide evidence that siderite pseudomorphs after baryte form under reducing conditions, under which sulfate is reduced and the dissolution of baryte promotes siderite and pyrite precipitation. Hence, the present study contributes to the still weakly developed understanding how post-precipitation processes influences the mineralogy of hydrothermal veins.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126244"},"PeriodicalIF":2.6,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149983","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":"Geochemical signature of hydrothermal alteration in surface rocks of Cerritos Colorados geothermal field of Mexico","authors":"Kailasa Pandarinath ,&nbsp;Alexis Cuestas Mundo ,&nbsp;Sanjeet K. Verma ,&nbsp;Eduardo Gonzalez-Partida ,&nbsp;Sumit Mishra ,&nbsp;David Yáñez-Dávila ,&nbsp;E. Santoyo ,&nbsp;José R. Torres-Hernández","doi":"10.1016/j.chemer.2024.126200","DOIUrl":"10.1016/j.chemer.2024.126200","url":null,"abstract":"<div><div>Several reliable and extensively applied traditional geochemical, mineralogical, and petrography methods exist for identifying hydrothermal alteration of rocks. However, many of these methods require tedious and laborious sample preparation and analysis procedures. Therefore, there is a need for faster methods and reliable in their application. Binary diagrams of felsic vs mafic components, Na₂O content, porosity, and permeability of the rocks are newer methods that are faster in their application and more reliable and have the potential to be considered for this purpose. These methods are successfully applied to the surface rocks of Cerritos Colorados Geothermal Field (CCGF) providing consistent results that are comparable to those obtained by extensively applied and highly reliable mineralogical and geochemical methods. Most of these altered rocks are from the formation of the Post-Tala Quaternary Lacustrine Sediments and are located near the faults and fumaroles. Evaluation of the results obtained by all applied methods confirms that the new methods are easy to measure and reliable, which can be useful as additional tools during the initial stage of geothermal exploration in identifying altered rocks and zones of hydrothermal alteration. Mass change values reveal the highest mobility for the major elements and the lowest mobility for the trace elements in the rocks of the study area.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126200"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140522","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":"Mineralogical and geochemical characteristics of alteration minerals related to fossil geothermal activities in the Kızıldere geothermal field, Western Turkey","authors":"Ömer Bozkaya ,&nbsp;Gülcan Bozkaya ,&nbsp;Taylan Akın ,&nbsp;Halil Atan","doi":"10.1016/j.chemer.2024.126082","DOIUrl":"10.1016/j.chemer.2024.126082","url":null,"abstract":"<div><div><span><span><span>The Kızıldere geothermal field, located at the eastern part of the Büyük Menderes graben in Western Turkey, is the most important geothermal reservoir suitable for electricity generation. Fossil </span>fumarole fields and alteration or mineralization zones are directly related to the tectonic zones influenced by N-S directional extension. Associated to fossil geothermal activities, </span>calcite<span><span>, dolomite, strontianite, quartz, gypsum, anhydrite, celestine, </span>kaolinite, </span></span>smectite<span><span>, boehmite<span><span> and goethite/limonite were occurred in the form of void or crack fill within the Paleozoic metamorphic and Miocene-Quaternary clastic and carbonate host rocks. The current mineralogical composition indicates temperature conditions of 100–250 °C which close to current reservoir temperatures. Some of minerals with fossil geothermal origin, i.e. calcite, anhydrite, dolomite, celestine, amorphous silica and quartz, are compatible for mineral precipitations estimated from mineral equilibrium modeling, and scale mineralogy of wells, as well. The formation order of the most common geothermal minerals is determined as calcite → gypsum → anhydrite → quartz direction indicating that alkaline conditions were followed by acidic conditions. The blade-like/prismatic rhombohedral calcites replaced by quartz occurrences in siliceous‑carbonate veins indicate the boiling was occurred in the field. The geothermal mineral zoning determined from drilling samples is anhydrite-dolomite-calcite from shallow to deeper parts. The lateral and vertical distribution of mineral zoning is related to the fact that geothermal waters are mainly affected by host rock compositions, i.e. dissolution from the host rocks and precipitation along the cracks/fractures and </span>bedding planes. Mineralizations in the Kızıldere geothermal field mainly represent the direct precipitations from hot geothermal waters rather than transformations of minerals in the host rocks. Si, Al, Mg, K and Na concentrations in carbonate and sulfate minerals show a positive correlation relationship and are derived from </span></span>metapelites. Whereas Ca is negatively related to these elements and it is derived from metacarbonate and/or carbonate host rocks. According to the current geothermal water composition, Ca enriches in the deeper parts, while Mg and B enrichment in shallow depths near the basin edge that indicates the different composition of the host rocks where minerals precipitated. The relatively high boron contents at shallow depth indicate that it is retained by the minerals precipitated this level and causes less release to the surface.</span></div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126082"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139469453","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":"Mineral chemistry and garnet U-Pb dating in the Bizmişen iron skarn deposit, Erzincan, East-Central Türkiye","authors":"Ömer Bozkaya ,&nbsp;Gülcan Bozkaya ,&nbsp;Namık Aysal ,&nbsp;Nurullah Hanilçi ,&nbsp;Hüseyin Yılmaz","doi":"10.1016/j.chemer.2024.126163","DOIUrl":"10.1016/j.chemer.2024.126163","url":null,"abstract":"&lt;div&gt;&lt;div&gt;&lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;span&gt;In Bizmişen area, Middle Eocene (46.3–42.0 Ma) &lt;/span&gt;plutonic rocks (quartz diorite) were intruded into Triassic-Cretaceous limestones and &lt;/span&gt;Upper Cretaceous&lt;span&gt; ophiolites&lt;span&gt; and caused to skarn zones containing prograde (garnet, clinopyroxene) and retrograde (amphibole, epidote, &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;calcite&lt;span&gt;, magnetite, phlogopite, &lt;/span&gt;&lt;/span&gt;serpentinite&lt;span&gt; and chlorite) minerals. Due to contact relationships of quartz diorites with both serpentinized ultramafic rocks&lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;span&gt; and limestone blocks, the mineralogical associations represent calcic (grossular/andradite, amphibole, chlorite and epidote) as well as magnesian (diopside, serpentine, phlogopite, talc) skarns. During the skarnization process, &lt;/span&gt;garnet, &lt;/span&gt;diopside, epidote, &lt;/span&gt;scapolite&lt;span&gt; and amphibole minerals developed in the endoskarn zone within quartz-diorite, and diopside, tremolite, serpentine, phlogopite, talc, Mg-chlorite and calcite minerals developed in the exoskarn zones in ophiolites (serpantinite and listwaenite) and limestones. Skarn and magmatic clinopyroxenes in serpentinized ultramafic hosted exoskarn zone have a compositional range of Wo&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;sub&gt;45-53&lt;/sub&gt;En&lt;sub&gt;35-53&lt;/sub&gt;Fs&lt;sub&gt;0&lt;/sub&gt;&lt;sub&gt;–&lt;/sub&gt;&lt;sub&gt;15&lt;/sub&gt; and Wo&lt;sub&gt;24-51&lt;/sub&gt;En&lt;sub&gt;38-76&lt;/sub&gt;Fs&lt;sub&gt;0&lt;/sub&gt;&lt;sub&gt;–&lt;/sub&gt;&lt;sub&gt;11&lt;/sub&gt;&lt;span&gt;, and classified as diopside and augite, respectively. The end members of garnets are Adr&lt;/span&gt;&lt;sub&gt;46–54&lt;/sub&gt;Grs&lt;sub&gt;43–50&lt;/sub&gt;Prp&lt;sub&gt;1–2&lt;/sub&gt;Sps&lt;sub&gt;1.1–5&lt;/sub&gt; in amphibole-epidote-calcite-garnet skarn in endoskarn zone, whereas Adr&lt;sub&gt;40–93&lt;/sub&gt;Grs&lt;sub&gt;4–57&lt;/sub&gt;Prp&lt;sub&gt;0.2–2.3&lt;/sub&gt;Sps&lt;sub&gt;0.9–2&lt;/sub&gt; in epidote-calcite-garnet skarn in exoskarn zone, and classified as andradite-rich grandite garnets. FeO, MnO and partially MgO contents gradually increase from the edges to the center in zoned garnet grains. Amphibole compositions represent to calcic (Ca &gt;1 atoms per formula unit) group (pargasite) and indicate the high oxygen fugacity conditions which caused the increase in the rate of magnetite crystallization. Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;&lt;span&gt; and FeO contents of epidotes range 23.68–27.63 and 9.10–14.45 wt%, respectively, correspond to composition of epidote and clinozoisite&lt;span&gt;. The iron oxide contents (FeO, wt%) of magnetites change from 91.72 to 98.36 correspond to structural Fe&lt;/span&gt;&lt;/span&gt;&lt;sup&gt;3+&lt;/sup&gt;&lt;sub&gt;1.88&lt;/sub&gt;&lt;sub&gt;–&lt;/sub&gt;&lt;sub&gt;1.97&lt;/sub&gt; and Fe&lt;sup&gt;2+&lt;/sup&gt;&lt;sub&gt;0.91&lt;/sub&gt;&lt;sub&gt;–&lt;/sub&gt;&lt;sub&gt;1.0&lt;/sub&gt;&lt;span&gt; values. The contents of Ti, divalent and trivalent metal cations correspond to ulvospinel-magnetite compositional line at the magnetite end-member. The mineral chemistry of skarn minerals shows similarities to those of most iron skarn deposits. Garnet U-Pb ages (46.95–45.63 Ma) are consistent with the cooling ages of the Bizmişen pluton. The prograde stage of skarn should be occurred &lt;/span&gt;&lt;em&gt;syn&lt;/em&gt;-intrusion, whereas retrogr","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126163"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141695965","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":"Exploring Optical and Geochemical Zoning Variation in Chromite: Metasedimentary vs. Orthomagmatic Origins in Singhbhum Craton, Eastern India","authors":"Asish Kumar Das ,&nbsp;Jiten Pattnaik ,&nbsp;Birendra Kumar Mohapatra ,&nbsp;Somnath Khaoash ,&nbsp;Patitapaban Mishra ,&nbsp;Fanus Viljoen ,&nbsp;Henriette Ueckermann","doi":"10.1016/j.chemer.2024.126214","DOIUrl":"10.1016/j.chemer.2024.126214","url":null,"abstract":"<div><div>The Banded Chromite-Quartzite (BCQ) deposits of Ghutrigaon, Singhbhum Craton, exhibit a metasedimentary geneology, diverging significantly from the world's well-established orthomagmatic deposits of Sukinda located in the southern fringe of the Singhbhum Craton, Eastern India. This study explores the zoning characteristics of chromite grains from Sukinda and Ghutrigaon in the Singhbhum Craton, revealing insights into their genetic evolution. It aims to elucidate the connection between their development and the physico-chemical changes that occurred during post-protolithic processes. Petrography and mineral chemistry analysis reveal two distinct features i.e., Ghutrigaon chromite displays a brighter core zone and is in sharp contrast with Sukinda chromite grains that show greater marginal reflectivity. The zoning of Ghutrigaon chromite follows an aluminium trend, with a core enrichment of Cr and Fe and a rim concentration of Al and Mg. The iron trend is evident in the zoned chromite of Sukinda, with concentrations of Mg, Al, and Ni dominating at the core, while Cr, Fe, Ti, and Mn are enriched at the periphery. In Ghutrigaon chromite, there is a preferential migration of Mg ions from the core to the altered rim, while trace elements such as Sc, Nb, and U move from rim to core, and Sr, Hf, and Zr increase from core to rim. In contrast, Sukinda chromite experiences leaching of Cr and Fe from the core, with subsequent precipitation in the rim. Trace elements in Sukinda chromite show a decreasing trend for Cu, Sr, Zr, Hf, and La with Mg#, indicating that Mg variations also influence these trace and rare earth elements during alteration. Ghutrigaon chromite likely originated in a Supra-Subduction Zone environment and zoning in its Cr-spinel is attributed to solid-state diffusion during metamorphism. In contrast, the Sukinda chromite is associated with boninitic magma in a back-arc rifting environment and its chromite zoning is the product of secondary changes that occurred during serpentinisation.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126214"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140371","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":"New bulk rock and age data on the changes in magma evolution during the Miocene, Galatean volcanic area, central Anatolia, Turkey: A review","authors":"Cahit Helvacı ,&nbsp;Yeşim Yücel-Öztürk ,&nbsp;Willis Hames ,&nbsp;Ioan Seghedi","doi":"10.1016/j.chemer.2024.126205","DOIUrl":"10.1016/j.chemer.2024.126205","url":null,"abstract":"<div><div>The Galatean Volcanic Province (GVP) lies within the Sakarya tectonic belt in the northwest of central Anatolia, Turkey, south of the North Anatolian Fault, cropping out over 12,000 km². It consists of Early Miocene intermediate to acid lavas, pyroclastic rocks, volcaniclastic deposits, and Late Miocene OIB-like basalts. Our study is based on new bulk geochemistry, Sr<img>Nd isotopes, and ⁴⁰Ar/³⁹Ar dating of the volcanic rocks from the south-western part of GVP, but integrates all the available previous data to understand how magmas evolved in the post-collisional geodynamic condition in the GVP. The initial eruptions were rhyolitic, as domes or pyroclastic deposits (Group 1) and basaltic lavas (Group 2) during the Early Miocene. Group 2 is also represented by large volumes of basaltic-andesitic, trachyandesite-dacite/trachydacite lava flows, small intrusions, and pyroclastic deposits as generated between 21 and 14 Ma. Relatively low ⁸⁷Sr/⁸⁶Sr ratios (0.705–0.706) of the early rhyolites (Group 1), similar to all the rocks from Group (2), suggest the generation of hybrid melts with variable contributions of mantle-derived and crustal material. The volcanic activity ends with OIB-like basalts (11–7 Ma) showing the lowest ⁸⁷Sr/⁸⁶Sr (∼0.703) suggesting an asthenospheric origin.</div><div>The geodynamic model, based on post-Cyprian slab rollback, results in long-term (22–13 Ma) post-collisional delamination/drip processes that support magmatism. This magmatism is generated in the lithospheric mantle, with the formation of basaltic melts and acid hybrid melts showing variable contributions of mantle-derived and crustal materials in a complex trans-crustal magma plumbing system. Complex mixing of various intra-crustal magmas and fractional crystallization processes generated a huge volume of volcanic rocks. The Late Miocene small-volume OIB basalts were asthenospheric melts that during the late stage recorded localized decompression melting processes.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126205"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140422","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":"Unique achondritic impact debris in the CH3 chondrite Acfer 182","authors":"Kainen L. Utt ,&nbsp;Ryan C. Ogliore ,&nbsp;Michael J. Krawczynski ,&nbsp;Paul K. Carpenter ,&nbsp;Alian Wang","doi":"10.1016/j.chemer.2024.126202","DOIUrl":"10.1016/j.chemer.2024.126202","url":null,"abstract":"<div><div>The metal-rich CH carbonaceous chondrites contain abundant xenolithic clasts originating from different regions of the Solar System. In the CH3 chondrite Acfer 182, we identified two phosphide spherules (one 95-μm in diameter and the other <span><math><mn>50</mn><mspace></mspace><mi>μm</mi><mo>×</mo><mn>60</mn><mspace></mspace><mi>μm</mi></math></span>) of schreibersite ((Fe,Ni)₃P) and barringerite ((Fe,Ni)₂P) with kamacite eutectic structures. These objects are likely to have formed during an impact between planetesimals during the debris-disk phase of the protoplanetary disk before being incorporated into the CH chondrite parent body. In the same sample we identified a <span><math><mn>130</mn><mspace></mspace><mi>μm</mi><mo>×</mo><mn>60</mn><mspace></mspace><mi>μm</mi></math></span> heideite grain (iron‑titanium sulfide: (Fe,Cr)_1.15(Ti,Fe)₂S₄) with exsolution lamellae of calcium-rich titanium oxide. Thin veins of shock-induced kamacite cross-cut the oxide lamellae, suggesting that it was ejected into the protoplanetary debris disk during an impact event before eventually being accreted by the CH chondrite parent body. This assemblage is distinct from heideite grains found in enstatite chondrites, aubrites, and the Kaidun meteorite. We propose that this object originated from a highly-reduced planetesimal in the inner Solar System that may have been similar to proto-Mercury.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126202"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140423","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":"3D mineral prospectivity modeling at the Axi epithermal gold deposit, NW China by using a feature adaptive fusion strategy","authors":"Xiancheng Mao,&nbsp;Jiaxuan Song,&nbsp;Zhankun Liu,&nbsp;Hao Deng,&nbsp;Jin Chen,&nbsp;Shuyan Yu,&nbsp;Yanan Wang,&nbsp;Ruike Xu,&nbsp;Yuanqian Nie,&nbsp;Yang Zheng","doi":"10.1016/j.chemer.2024.126190","DOIUrl":"10.1016/j.chemer.2024.126190","url":null,"abstract":"<div><div>Mineralization distribution is always intricately affected by multiple ore-controlling geological units that play different roles in a mineral system (e.g., driver, trap, and throttle). How to effectively balance and integrate ore-controlling features from various 3D geological models during 3D mineral prospectivity modeling (MPM) is still a challenging task. In this paper, we introduce a novel approach, the feature adaptive fusion convolutional neural networks (CNN), which is designed to learn multiple 3D geological models with ore-controlling functions. The method is validated in the Axi epithermal gold deposit, northwestern China that mineralization distribution is jointly controlled by fault, volcanic phase, and phyllic alteration. The geology units are firstly constructed by explicit-implicit modeling and their ore-controlling features are subsequently described by high-frequency Laplace-Beltrami eigenfunctions and reassembled into multi-channel images as input to CNN. To learn the differences in ore-controlling effects among various geological units, we designed a fully connected layer to achieve adaptive quantification and weighted integration of the ore-controlling features by automatically optimizing weight allocation parameters and bias vectors using the neural network intelligence. Comparison results between the proposed method and other prospectivity methods suggest that the feature adaptive fusion CNN produces more reliable predictions, characterized by: (1) high consistency with known mineralization, (2) the highest AUC value and success rate, and (3) accurate prediction of deep voxels explored by drilling. Therefore, the proposed method effectively integrates the ore-controlling effects of multiple geological units and is suitable for complex scenarios of 3D MPM. Utilizing the prospectivity results generated by our method, we identified five potential mineralization in the Axi gold deposit, laying a robust foundation for future gold exploration.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126190"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143140762","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":"In-situ LA-ICP-MS UPb dating and geochemistry of garnet skarn occurrences related to South Yenice plutons, NW Türkiye","authors":"Namık Aysal ,&nbsp;Nurullah Hanilçi ,&nbsp;Sinan Öngen ,&nbsp;Cem Kasapçı ,&nbsp;Fatma Şişman Tükel ,&nbsp;Marcel Guillong ,&nbsp;Mayuko Fukuyama ,&nbsp;Nicole Leonard ,&nbsp;Elif Varol","doi":"10.1016/j.chemer.2024.126169","DOIUrl":"10.1016/j.chemer.2024.126169","url":null,"abstract":"<div><div>On the Biga Peninsula (NW Türkiye) Oligo-Miocene felsic plutonic intrusions extend vast regions. Skarn zones have developed around South Yenice plutons in this zone, which Show a rich potential for contact metamorphic diversity and mineralization, depending the host rock variety. Contact metamorphic zones and skarn occurrences have been mapped and determined. U<img>Pb dating was performed on garnets, and ages of 25.26 ± 0.30 Ma and 26.01 ± 1.02 Ma were yielded from Islıkçatıdere, and 24.85 ± 1.68 Ma, 25.81 ± 3.97 Ma and 21.03 ± 0.38 Ma from Namazgah skarn zones, respectively. U<img>Pb zircon dating of the Hıdırlar, Kurtlar and Namazgah plutons yielded ages of 26.33 ± 0.3, 25.39 ± 055 and 24.79 ± 0.38 Ma. These ages prove that the ages obtained from the skarn zone and the parent plutons are compatible. Garnet mineral chemistry and trace element analyses, when evaluated together with limited fluid inclusion data, indicate that the study area may be important in terms of potential iron, copper, lead and zinc mineralization.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126169"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187188","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 characteristics and mapping of Reşadiye (Tokat-Türkiye) bentonite deposits using machine learning and sub-pixel mixture algorithms","authors":"Oktay Canbaz ,&nbsp;Muhittin Karaman","doi":"10.1016/j.chemer.2024.126123","DOIUrl":"10.1016/j.chemer.2024.126123","url":null,"abstract":"<div><div><span><span><span>Reşadiye bentonite deposits, which play a significant role in Türkiye's bentonite production, are situated in Central Anatolia. Geochemical, mineralogical, and </span>remote sensing<span> data have been integrated to map the spatial distribution of clay minerals in the bentonite deposits and argillic areas. It is hypothesized that the bentonite samples occurred by the in-situ diagenetic alteration of rhyolite-dacite, trachyte, and andesite/basaltic andesitic composition pyroclastic rocks (ash-flow tuff). Biotite, </span></span>clinoptilolite, </span>calcite<span>, dolomite, K-feldspar, opal-CT, quartz, and clay minerals are detected in most bentonite samples. The clay patterns determined in the bentonite samples in the X-ray diffraction (XRD) diagrams were 12.3–12.6 Å and were interpreted as being rich in Na-smectites. Mineral mapping in these deposits is essential for mining operations since the high-grade bentonite deposits can be affected by the other clay, gang, and ore minerals<span><span> they contain in addition to the smectite. The sample spectra measurements matched montmorillonite and kaolin/smectite spectra. This study tests support vector machine<span> (SVM) and artificial neural network (ANN) machine learning and MTMF subpixel algorithms in </span></span>lithology and mineral mapping in Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite data. It combines the power of subpixel unmixing algorithms to determine the distribution of clay and high-grade bentonites in argillic areas discriminated by machine learning. The results showed that the SVM algorithm can map better than ANN for argillic areas. Additionally, the distribution of high-grade bentonite and kaolin/smectite bearing sites in the study area is discriminated by the mixture-tuned matched filtered (MTMF) spectral classification method. As a result, this study shows that remote sensing studies can be utilized for the exploration and monitoring of high-grade bentonite sites during and/or post-mining operations.</span></span></div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126123"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140792489","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}