Chemie Der Erde-Geochemistry最新文献

{"title":"Quartz textures, mineral chemistry and fluid inclusion features of Tuztaşı low-sulphidation Au mineralization: Implication to it's formation","authors":"Fatih Özbaş,&nbsp;Nurullah Hanilçi","doi":"10.1016/j.chemer.2024.126220","DOIUrl":"10.1016/j.chemer.2024.126220","url":null,"abstract":"<div><div>The Tuztaşı gold mineralization, within the Main Quartz Vein (MQV), is located within the amphibolite schist of the Sütüven Formation along a structural zone trending K50D. The vein is inclined approximately 40° to the northeast, exhibits a thickness ranging from 3 to 8 m with 2 km lenght. Gangue minerals within the vein primarily consist of quartz, chalcedony, and opal. In MQV, crustiform, feathery, colloform textures indicating boiling and massive chalcedony, comb, textures in restricted zones, as well as replacement textures and brecciation in later stages have been identified.</div><div>In the amphibolite, the host rock around the MQV, while weak argillic alteration developed represented by quartz, montmorillonite, kaolinite mineral associations, this alteration is surrounded by propylitic alteration represented by quartz, albite, orthoclase, chlorite, calcite, and ankerite mineral associations.</div><div>LA-ICP-MS studies on quartz of the MQV revealed the gold values up to 4.02 ppm and silver values reaching 100 ppm, predominantly enriched in secondary voids (vugs) and iron-rich fracture zones. SEM-EDX analyses of gold-bearing quartz have identified chromite, chalcopyrite, native platinum, and Ni-Fe-Cr alloy, suggesting interactions with ore-forming fluids potentially originating from the mafic-ultramafic levels of the Sütüven Formation and Çetmi Melange.</div><div>Fluid inclusion studies show that liquid-rich inclusions dominate in MQV, but vapour-rich inclusions also occur together in genetically. According to microthermometric data, Th values of quartz vary between 186 and 330 °C, but the majority of the data (89 %) fall within the 180–260 °C range (aver. 213 °C, n = 104). The salinity of the fluids ranges from 0.18 % to 2.74 %, with an average of 0.63 % wt. NaCl equivalent. The dominant temperature range (180–260 °C) corresponds to a salinity of 0.35 wt% NaCl equivalent. An average Th (221 °C) and salinity (0.63 % wt. NaCl equivalent) values are resemble typical of low-sulphidation gold deposits.</div><div>Oxygen isotope (δ¹⁸O) data of quartz from the MQV, ranging between 6.6 ‰ and 8.6 ‰, indicating a meteoric origin for the fluids. This is indicated by the δ¹⁸O_SMOW values of waters in equilibrium with quartz, falling between δ¹⁸O_water − 6.8 ‰ and 0.7 ‰.</div><div>Collevtively, fluid inclusions, oxygen isotope data, quartz textures in MQV and alteration features are evaluated together, the Tuztaşı Au mineralization exhibits the characteristics of a low-sulphidation type Au deposit rather than an orogenic type Au deposit.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126220"},"PeriodicalIF":2.6,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561709","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":"Wall rock assimilation in carbonatite magmas: Textural, mineral and whole-rock geochemical signatures in the Jacupiranga complex, Brazil","authors":"Luanna Chmyz ,&nbsp;Rogério Guitarrari Azzone ,&nbsp;Excelso Ruberti ,&nbsp;Vincenza Guarino","doi":"10.1016/j.chemer.2024.126218","DOIUrl":"10.1016/j.chemer.2024.126218","url":null,"abstract":"<div><div>Carbonatite magmas, with their unique low SiO₂ and high volatile compositions, can be extremely reactive with silicate country rocks, driving large chemical exchanges through processes such as magmatic assimilation and fenitization. In this study, we investigate the assimilation process between Jacupiranga carbonatite and clinopyroxenite xenoliths, focusing on the textural, mineralogical, and whole-rock geochemical features of the resulting reaction rocks. These data are compared with those from fluid-derived phlogopitites from the Alto Paranaíba Igneous Province, to evaluate the processes behind the reaction between carbonatite magma and ultramafic rocks. We report the first trace element data on phlogopites from Brazilian carbonatites and associated reaction rocks. Textural, mineralogical and whole-rock geochemical features can be interpreted as the effect of carbonatite magma assimilation of ultramafic rocks, as seen in the Jacupiranga complex. Thermal and chemical gradients promote unidirectional solidification, allowing the comb-layering formation. Xenolith boundaries act as orbicule cores, favoring nucleation and the crystallization of the reaction assemblage. Phlogopites from Jacupiranga reaction rocks exhibit a wide range of estimated temperatures (550 up to &gt;1000 °C), although diffusive re-equilibration during magmatic and post-magmatic cooling cannot be ruled out. Reaction phlogopites are enriched in Ni and Co near the clinopyroxenite, with depletion of these elements towards the carbonatite front. Conversely, reaction phlogopites near the carbonatite are enriched in Ba, highlighting the effect of the carbonatite melt in the generation of the reaction rocks, which gradually decreases towards the clinopyroxenite contact. The reaction rocks have whole-rock major and trace element contents intermediate between those of the clinopyroxenites and the carbonatite front. Partition coefficients between calcite and apatite in the reaction rocks have flat, somewhat U-shaped patterns for REE, typical signatures of primary igneous calcite and consistent with an origin by magmatic assimilation. This study shows that several imprints of assimilation of ultramafic wall rocks by carbonatite magmas are preserved in the resulting reaction rocks, allowing such a mechanism to be traced by using textural, mineralogical, and whole-rock geochemical evidence.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126218"},"PeriodicalIF":2.6,"publicationDate":"2024-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561823","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":"Application and electrochemical depression mechanism of sodium sulfite on the flotation separation of galena–pyrite mixed concentrate in Yiliang typical high‑sulfur lead–zinc deposit","authors":"Zhicheng Liu ,&nbsp;Fen Jiao ,&nbsp;Yanfang Cui ,&nbsp;Xiang Lin ,&nbsp;Wenqing Qin ,&nbsp;Qian Wei","doi":"10.1016/j.chemer.2024.126219","DOIUrl":"10.1016/j.chemer.2024.126219","url":null,"abstract":"<div><div>The high content of pyrite in high‑sulfur lead–zinc sulfide resources affects the electrochemical properties and floatability of galena and sphalerite, which results in difficult flotation separation. In this study, the negative effects of a high-alkaline process were weakened by introducing an efficient mixed depressant CaO + Na₂SO₃ in selective flotation separation of galena from pyrite. Flotation separation tests of real ore samples showed that the mixed depressant was more efficient than single CaO (5000 g/t), and the best process conditions of Pb grade 64.01 % and Pb recovery 88.45 % were obtained. The effects of Na₂SO₃ on the electrochemical interaction between the two minerals were studied by micro-flotation tests, electrochemical, ion dissolution, UV–Vis measurements, zeta potential measurements, and X-ray photoelectron spectroscopy (XPS) detections. Results indicated that Na₂SO₃ could weaken the galvanic interaction between galena–pyrite and reduce the Pb²⁺ dissolution from the galena surface. Na₂SO₃ could desorb the collector ethyl xanthate pre-adsorbed on the pyrite surface.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 1","pages":"Article 126219"},"PeriodicalIF":2.6,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143561820","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":"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":"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}

{"title":"Machine learning models to predict rare earth elements distribution in Tethyan phosphate ore deposits: Geochemical and depositional environment implications","authors":"Nasreddine Tahar-Belkacem ,&nbsp;Ouafi Ameur-Zaimeche ,&nbsp;Rabah Kechiched ,&nbsp;Abdelhamid Ouladmansour ,&nbsp;Salim Heddam ,&nbsp;David A. Wood ,&nbsp;Roberto Buccione ,&nbsp;Giovanni Mongelli","doi":"10.1016/j.chemer.2024.126128","DOIUrl":"10.1016/j.chemer.2024.126128","url":null,"abstract":"<div><div><span><span>The global market for rare earth elements (REE) is growing rapidly, driven by rising demand and limited production sources, prompting interest in recovering REE from secondary sources such as phosphate deposits. The Tethyan belt, extending across </span>North Africa<span> and the Middle East contains substantial Upper Cretaceous<span><span> to Eocene REE-rich </span>phosphorite deposits but with limited geochemical data available. This study provides a novel machine-learning (ML) method to predict REE contents in these deposits and verify a useful geochemical classification based on the concentrations of nine major element oxides. Four ML models are developed to achieve this: eXtreme Gradient Boosting (XGBoost), Random Forest (RF), Support Vector Regression (SVR), and Decision Tree (DT). The datasets are divided geochemically into oxic and sub-oxic patterns and these are evaluated with the ML models separately and in combination to accurately predict light REE (LREE), heavy REE (HREE), and total REE contents (∑REE). For the oxic pattern dataset, Fe</span></span></span>₂O₃ and K₂<span>O exhibit the highest feature importance consistent with a glauconite influence. For the sub-oxic pattern dataset, MnO and SiO</span>₂<span> exhibit the highest feature importance consistent with high terrigenous inputs (MnO), and silicification<span>. The ML results support the importance of the local deposition environment in determining REE distributions in these deposits. Paleogeography<span>, ocean-margin tectonics, sea-level oscillations, and marine currents exert influence on the local depositional environments. The eXtreme Gradient Boosting model generates the lowest REE prediction errors for all the datasets evaluated.</span></span></span></div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126128"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141048440","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":"Petrochemistry and age of garnet-bearing xenoliths and their host volcanic rocks of Central Anatolia, Turkey: Implications for the evolution of magma-hydrothermal systems","authors":"Aslıhan Korkmaz Eryılmaz ,&nbsp;Elif Varol ,&nbsp;G. Deniz Doğan-Külahcı ,&nbsp;Sibel Erkül ,&nbsp;Chris Harris","doi":"10.1016/j.chemer.2024.126165","DOIUrl":"10.1016/j.chemer.2024.126165","url":null,"abstract":"<div><div><span><span><span><span>The Hisarlıkaya volcanic rocks (HVR) are located southwest of Ankara, and presents a complex magmatic and metamorphic evolution. Understanding its petrogenesis provides crucial insights into the </span>geological processes and </span>magma evolution in Central Anatolia. This paper presents </span>mineral chemistry, whole-rock major, trace element and Sr-Nd-O isotope, </span>⁴⁰Ar-³⁹<span>Ar age of host volcanic rocks for magmatism<span> and U-Pb dating of garnet<span> for crystallization of contact metamorphosed rocks to constrain the magma source and the metasomatic processes in the contact zone of magma intrusion. The HVR samples have SiO</span></span></span>₂ from 60 to 64 wt%, Al₂O₃<span> (16–18 wt%), MgO (1.1–2.4 wt%), high concentrations of Large Ion Lithophile Elements<span> (LILEs) and Light Rare Earth Elements (LREEs), and low concentrations of High Field Strength Elements (HFSEs) and Heavy Rare Earth Elements (HREEs), and high Sr/Y (70–90) and La/Yb (43–55) ratios. The HVR consists of trachytes and trachyandesites, displaying calc-alkaline characteristics with adakitic features with these geochemical properties. Initial </span></span>¹⁴³Nd/¹⁴⁴Nd, ⁸⁷Sr/⁸⁶Sr ratios, and δ¹⁸<span><span><span>O values of HVR rocks are between 0.51263–0.51271, 0.70537–0.70542, and 8.60–9.20 ‰, respectively. These features together with geothermobarometric estimates suggest that the crystallization depth of the HVR's plagioclases and amphiboles was ∼25–30 km. Magmatism was initiated by partial melting of hydrated lithospheric mantle wedge in the </span>Early Cretaceous followed by magmatic underplating and eruption of more felsic magma derived partly from the thickened </span>lower crust.</span></div><div><span><span><span>These volcanic rocks contain xenoliths of </span>quartzite, </span>hornfels<span>, and garnet-bearing skarn presumed to be from the contact zone. These were metamorphosed during earlier subduction and were subsequently assimilated and extruded by HVR magma. The </span></span>⁴⁰Ar-³⁹Ar plateau age of the HVR is 20.25 ± 0.10 Ma and the U-Pb dating of two garnet crystals from the skarn xenoliths are determined to be 22.08 ± 0.18 Ma to 21.30 ± 0.17 Ma, indicating that mineralization in the hydrothermal-metasomatic alteration zone is older and/or approximately contemporaneous with magmatism.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 4","pages":"Article 126165"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141715476","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}