The Nanling WSn belt, a world-class metallogenic province, hosts multi-stages WSn mineralization, accurately constraining the evolutionary history of these polymetallic deposits is essential for understanding mineralization processes and building up their metallogenic models. The Xianghualing orefield, a significant Sn-polymetallic district within the Nanling WSn belt, displays notable multistage Sn mineralization. Cassiterite UPb geochronology on sulfide-type cassiterite ores from the Xinfeng mining area, skarn-type Sn ores from the Tangguanpu mining area, and F1 fault-controlled sulfide-type cassiterite ores in the Xianghualing orefield were involved in this study. The obtained cassiterite UPb ages are 147.8 ± 1.2 Ma, 145.2 ± 2.8 Ma, and 141 ± 23 Ma, respectively, while a vesuvianite dating result yields 154.7 ± 1.9 Ma. These ages are consistent with previously reported cassiterite UPb dates from the Tieshaping deposit within the orefield and the Xitian deposit in the northern part of the orefield, extending the temporal frame-work of the Xianghualing Sn mineralization and the southern Hunan Sn-polymetallic mineralization system into the Early Cretaceous. Combined with previous studies on magmatic-hydrothermal fluids associated with Sn mineralization in southern Hunan, we propose that highly evolved Cretaceous granites represent prime exploration targets for Sn deposits in this region.
{"title":"The multi-stages Sn mineralization process in the Xianghualing orefield: Constraints from cassiterite and vesuvianite UPb geochronology","authors":"Zhang Dexian , Zhou Jialing , Fang Ruize , Xiao Dian , Hu Ziqi","doi":"10.1016/j.chemer.2025.126360","DOIUrl":"10.1016/j.chemer.2025.126360","url":null,"abstract":"<div><div>The Nanling W<img>Sn belt, a world-class metallogenic province, hosts multi-stages W<img>Sn mineralization, accurately constraining the evolutionary history of these polymetallic deposits is essential for understanding mineralization processes and building up their metallogenic models. The Xianghualing orefield, a significant Sn-polymetallic district within the Nanling W<img>Sn belt, displays notable multistage Sn mineralization. Cassiterite U<img>Pb geochronology on sulfide-type cassiterite ores from the Xinfeng mining area, skarn-type Sn ores from the Tangguanpu mining area, and F1 fault-controlled sulfide-type cassiterite ores in the Xianghualing orefield were involved in this study. The obtained cassiterite U<img>Pb ages are 147.8 ± 1.2 Ma, 145.2 ± 2.8 Ma, and 141 ± 23 Ma, respectively, while a vesuvianite dating result yields 154.7 ± 1.9 Ma. These ages are consistent with previously reported cassiterite U<img>Pb dates from the Tieshaping deposit within the orefield and the Xitian deposit in the northern part of the orefield, extending the temporal frame-work of the Xianghualing Sn mineralization and the southern Hunan Sn-polymetallic mineralization system into the Early Cretaceous. Combined with previous studies on magmatic-hydrothermal fluids associated with Sn mineralization in southern Hunan, we propose that highly evolved Cretaceous granites represent prime exploration targets for Sn deposits in this region.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126360"},"PeriodicalIF":2.9,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571631","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}
The hydrothermal fluids of the Trans-Himalayan region host rich deposits of critical elements (e.g. Li, Cs, B, W, etc.), that forms critical energy minerals. We characterize geochemical evolution of hydrothermal waters in Trans-Himalayan region, delineating the origin and dissemination of critical energy minerals as epithermal deposits in the region. Thermal fluids exhibit enrichment in W with maximum value of 1603 μg/L and rare alkalis like Cs and Li, whose peak concentrations reach upto 6976 μg/L, and 6.8 mg/L, respectively. Similarly, soils/altered rocks are characterized by significant levels of Li (116–911 mg/kg), Cs (632.56–3317 mg/kg), Cu (181–343 mg/kg), Hg (11–2540 μg/kg), Sb (108.94–6602 mg/kg), BaSO4 (27.49–71.13 %), S (37.3 %), and F (84–3848 mg/kg). This study identifies Li-bearing mica minerals in considerable concentrations, alongside epithermal minerals attributing to a paleo-high-temperature regime in the Himalayan geothermal field. A conceptual model has been developed to trace the origin of critical minerals in thermal fluids and spring deposits, suggesting that metals and metalloids degas from felsic magmatic melts, through less-denser geological vapours, primarily as vapour-soluble chloride and sulfide complexes, which mixes with genetically evolved secondary fluids undergoing gas-solution-rock interactions and gets enriched in liquid phase after steam segregation, mainly due to decompression boiling.
{"title":"Geochemical evolution of geothermal waters in Trans-Himalayas: Implications for critical mineral deposition","authors":"Archisman Dutta , Parashar Mishra , Abhijit Mukherjee , Vivek P. Malviya , Sanjeet Kumar Verma , P.K. Singh , Biswajit Ray","doi":"10.1016/j.chemer.2025.126348","DOIUrl":"10.1016/j.chemer.2025.126348","url":null,"abstract":"<div><div>The hydrothermal fluids of the Trans-Himalayan region host rich deposits of critical elements (e.g. Li, Cs, B, W, etc.), that forms critical energy minerals. We characterize geochemical evolution of hydrothermal waters in Trans-Himalayan region, delineating the origin and dissemination of critical energy minerals as epithermal deposits in the region. Thermal fluids exhibit enrichment in W with maximum value of 1603 μg/L and rare alkalis like Cs and Li, whose peak concentrations reach upto 6976 μg/L, and 6.8 mg/L, respectively. Similarly, soils/altered rocks are characterized by significant levels of Li (116–911 mg/kg), Cs (632.56–3317 mg/kg), Cu (181–343 mg/kg), Hg (11–2540 μg/kg), Sb (108.94–6602 mg/kg), BaSO<sub>4</sub> (27.49–71.13 %), S (37.3 %), and F (84–3848 mg/kg). This study identifies Li-bearing mica minerals in considerable concentrations, alongside epithermal minerals attributing to a paleo-high-temperature regime in the Himalayan geothermal field. A conceptual model has been developed to trace the origin of critical minerals in thermal fluids and spring deposits, suggesting that metals and metalloids degas from felsic magmatic melts, through less-denser geological vapours, primarily as vapour-soluble chloride and sulfide complexes, which mixes with genetically evolved secondary fluids undergoing gas-solution-rock interactions and gets enriched in liquid phase after steam segregation, mainly due to decompression boiling.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126348"},"PeriodicalIF":2.9,"publicationDate":"2025-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519728","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}
Pub Date : 2025-11-10DOI: 10.1016/j.chemer.2025.126345
Long Zhang , Dong Li , Juquan Zhang , Yongkui Wang , Ning Xu , Junfeng Li
On the western margin of the Jiaolai Basin (JLB), acidic volcanic rocks in the Shiqianzhuang Formation of the Qingshan Group are exposed to the eastern part of the Tan-lu fault zone. Bulk element analyses reveal that the rare earth element (REE) distribution pattern exhibits enrichment in light REEs, depletion in heavy REEs and are enriched in high field strength elements (HFSEs) and depleted in large ion lithophile elements (LILEs). The δEu values indicate negative Eu anomalies. The LA–ICP–MS zircon UPb ages are 109 ± 1.8 Ma, 115 ± 1.6 Ma and 126 ± 1 Ma, respectively, which are consistent with the range of gold mineralization in Jiaodong Peninsula (JEP). Comparison with the widespread mafic-intermediate-felsic dikes and the regional tectonic evolution of Tan-lu fault, it is concluded that the episodic developments of lithospheric thinning are in accordance with the extensive gold mineralization in the JEP during the Early Cretaceous. The acidic volcanic rocks documented that the JLB evolved from prototype into a volcanic basin, meanwhile, large-scale gold mineralization formed along the secondary branches of the Tan-lu fault in the Early Cretaceous, due to the combined effects of changes in the subduction angle of the Paleo-Pacific Plate, trench migration and changes in the subduction direction.
{"title":"Early Cretaceous volcanism and correlation with large-scale Au mineralization in the Jiaolai basin, Jiaodong Peninsula: Evidences of geochronology and geochemistry from the Qingshan Group","authors":"Long Zhang , Dong Li , Juquan Zhang , Yongkui Wang , Ning Xu , Junfeng Li","doi":"10.1016/j.chemer.2025.126345","DOIUrl":"10.1016/j.chemer.2025.126345","url":null,"abstract":"<div><div>On the western margin of the Jiaolai Basin (JLB), acidic volcanic rocks in the Shiqianzhuang Formation of the Qingshan Group are exposed to the eastern part of the Tan-lu fault zone. Bulk element analyses reveal that the rare earth element (REE) distribution pattern exhibits enrichment in light REEs, depletion in heavy REEs and are enriched in high field strength elements (HFSEs) and depleted in large ion lithophile elements (LILEs). The δEu values indicate negative Eu anomalies. The LA–ICP–MS zircon U<img>Pb ages are 109 ± 1.8 Ma, 115 ± 1.6 Ma and 126 ± 1 Ma, respectively, which are consistent with the range of gold mineralization in Jiaodong Peninsula (JEP). Comparison with the widespread mafic-intermediate-felsic dikes and the regional tectonic evolution of Tan-lu fault, it is concluded that the episodic developments of lithospheric thinning are in accordance with the extensive gold mineralization in the JEP during the Early Cretaceous. The acidic volcanic rocks documented that the JLB evolved from prototype into a volcanic basin, meanwhile, large-scale gold mineralization formed along the secondary branches of the Tan-lu fault in the Early Cretaceous, due to the combined effects of changes in the subduction angle of the Paleo-Pacific Plate, trench migration and changes in the subduction direction.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126345"},"PeriodicalIF":2.9,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519727","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}
Pub Date : 2025-11-09DOI: 10.1016/j.chemer.2025.126351
P. Cachapuz , M. Chichorro , T. Bento dos Santos , D.R. Carvalho , U. Linnemann , M. Zieger-Hofmann , J. Zieger , E. Dantas , R.V. Santos , P. Moita , M. Beltrame , A.R. Solá , M. Díaz-Azpíroz , C. Fernández
This study focuses on bimodal meta-volcanic rocks present in the Iberian Massif, in the Évora-Aracena Metamorphic Belt of the Ossa-Morena Zone (OMZ), near the boundary with the South Portuguese Zone. New petrological, geochemical (whole-rock and SrNd isotopes) and LA-ICP-MS UPb zircon geochronology data are presented to track the magmatic evolution of both felsic and mafic rocks and their respective geodynamic setting during the transition between the Cadomian Orogeny and subsequent Palaeozoic rifting events.
Our research shows that the Évora-Aracena Metamorphic Belt (EAMB) in the southwestern OMZ possesses a significant record of the transition between the Cadomian and Variscan cycles. UPb geochronological data confirm the existence of both felsic and mafic Ediacaran igneous rocks (546 and 556 Ma, respectively), a novelty in the region. The Cadomian-related felsic rocks show geochemical similarities to meta-felsic rocks formed during the initial phases of the Cambrian rifting event, namely very negative εNd values (−10.1 to −11.8), depleted HREE patterns and orogenic signatures. Such similarities imply that meta-felsic rocks formed in the earliest stages of the Cambrian Rift-to-Drift event resulted from a shallower melting.
Moreover, meta-felsic rocks formed in the early stages of the Cambrian rifting (525 Ma) present a significant amount of Ediacaran aged zircons, whereas the Cadomian-related counterparts display a few discordant Cambrian ages, likely a consequence of Pb-loss. This indicates that the convergent, subduction-related regime that prevailed during most of the Cryogenian-Ediacaran times along the boundaries of NW Gondwana was swiftly supplanted by a rift-dominated regime during the Cambrian, with no substantial gap between these two thermal events. Meanwhile, meta-felsic rocks formed during the Rift-to-Drift (525–480 Ma) event exhibit progressively higher εNd values (−5.0 to +3.0), HREE-enrichment, as well as anorogenic signatures, denoting an increasing contribution of mantle-derived melts. This increasing mantle contribution eventually led to the occurrence of bimodal magmatism in the Middle Cambrian Main Rift event. Such Cambrian mafic rocks, unlike the Ediacaran mafic rocks that present flat REE patterns and continental arc signatures, display varying degrees of LREE enrichment and N-MORB to E-MORB signatures.
{"title":"Ediacaran and early-palaeozoic bimodal volcanism in the Ossa-Morena Zone, SW Iberian Massif: New clues for intraplate rifting shortly after the Cadomian Orogeny","authors":"P. Cachapuz , M. Chichorro , T. Bento dos Santos , D.R. Carvalho , U. Linnemann , M. Zieger-Hofmann , J. Zieger , E. Dantas , R.V. Santos , P. Moita , M. Beltrame , A.R. Solá , M. Díaz-Azpíroz , C. Fernández","doi":"10.1016/j.chemer.2025.126351","DOIUrl":"10.1016/j.chemer.2025.126351","url":null,"abstract":"<div><div>This study focuses on bimodal meta-volcanic rocks present in the Iberian Massif, in the Évora-Aracena Metamorphic Belt of the Ossa-Morena Zone (OMZ), near the boundary with the South Portuguese Zone. New petrological, geochemical (whole-rock and Sr<img>Nd isotopes) and LA-ICP-MS U<img>Pb zircon geochronology data are presented to track the magmatic evolution of both felsic and mafic rocks and their respective geodynamic setting during the transition between the Cadomian Orogeny and subsequent Palaeozoic rifting events.</div><div>Our research shows that the Évora-Aracena Metamorphic Belt (EAMB) in the southwestern OMZ possesses a significant record of the transition between the Cadomian and Variscan cycles. U<img>Pb geochronological data confirm the existence of both felsic and mafic Ediacaran igneous rocks (546 and 556 Ma, respectively), a novelty in the region. The Cadomian-related felsic rocks show geochemical similarities to meta-felsic rocks formed during the initial phases of the Cambrian rifting event, namely very negative εNd values (−10.1 to −11.8), depleted HREE patterns and orogenic signatures. Such similarities imply that meta-felsic rocks formed in the earliest stages of the Cambrian Rift-to-Drift event resulted from a shallower melting.</div><div>Moreover, meta-felsic rocks formed in the early stages of the Cambrian rifting (525 Ma) present a significant amount of Ediacaran aged zircons, whereas the Cadomian-related counterparts display a few discordant Cambrian ages, likely a consequence of Pb-loss. This indicates that the convergent, subduction-related regime that prevailed during most of the Cryogenian-Ediacaran times along the boundaries of NW Gondwana was swiftly supplanted by a rift-dominated regime during the Cambrian, with no substantial gap between these two thermal events. Meanwhile, meta-felsic rocks formed during the Rift-to-Drift (525–480 Ma) event exhibit progressively higher εNd values (−5.0 to +3.0), HREE-enrichment, as well as anorogenic signatures, denoting an increasing contribution of mantle-derived melts. This increasing mantle contribution eventually led to the occurrence of bimodal magmatism in the Middle Cambrian Main Rift event. Such Cambrian mafic rocks, unlike the Ediacaran mafic rocks that present flat REE patterns and continental arc signatures, display varying degrees of LREE enrichment and N-MORB to <em>E</em>-MORB signatures.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126351"},"PeriodicalIF":2.9,"publicationDate":"2025-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571633","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}
Pub Date : 2025-11-07DOI: 10.1016/j.chemer.2025.126349
Zhihao Sun , Huan Li , Yuxuan Huang , Thomas J. Algeo , Wei Quan , Tao Xiao , Buqing Wang , Wenbo Sun , Weidong Ren
The Guangning area of the Yunkai Massif is rich in mineral resources and extensively intruded by granites that played a crucial role in the ore mineralization process. However, the high-precision geochronology and isotopic geochemistry of these granites remain understudied. This study presents the first detailed geochronological and geochemical characterization of Early Paleozoic granites from the Guangning area of the Yunkai Massif, South China Craton (SCC). Our results address a significant knowledge gap with regard to the magmatic history of this region and provide crucial geological evidence elucidating the Early Paleozoic tectonic evolution of the SCC. Via LA-ICP-MS UPb zircon geochronology, our study constrains the emplacement age of the Early Paleozoic Guangning granitic pluton to between 452.3 ± 1.3 Ma and 448.5 ± 1.6 Ma. Integrating these results with previous studies, we identify a prominent magmatic event in the Yunkai Massif during the Late Ordovician (~458–444 Ma). The Guangning granites display geochemical signatures typical of the high‑potassium calc-alkaline series and possess strong peraluminous affinities. These rocks are characterized by high SiO₂ (71.1–77.9 wt%) and Al₂O₃ (10.3–14.5 wt%) and low MgO (0.03–0.90 wt%), CaO (0–1.42 wt%), and total FeO contents (0.58–1.89 wt%). The samples show enrichment in high-field-strength elements and Pb, and depletion in Nb, Ce, P, and large-ion lithophile elements. The rare earth element (REE) patterns indicate significant fractionation, with enrichment in light REEs (LREEs) and negative Eu anomalies. The whole-rock εNd(t) values of the Guangning granites range from −9.8 to −8.7 with notable negative fSm/Nd anomalies (−0.4 to −0.3), and two-stage Nd model ages (TDM2) of ~1614–1528 Ma. The zircon εHf(t) values mostly range from −5.5 to −0.5, and the initial (176Hf/177Hf)i values are concentrated in the range of 0.28234 to 0.28248, with the two-stage depleted mantle model ages (TDM2) of ~1783–1468 Ma. These characteristics are typical of strongly peraluminous S-type granites, likely derived from mica dehydration melting at low temperatures of aluminous pelitic rocks in the Paleoproterozoic–Mesoproterozoic crust of the Cathaysia Block, and having undergone fractional crystallization episodes characterized by the involvement of plagioclase, K-feldspar, and biotite. Comprehensive analysis of the regional geological context indicates that the SCC experienced a dynamic shift from orogenic compression to post-orogenic extension at ~450–435 Ma, with the Guangning Early Paleozoic S-type granites forming during this transitional period.
{"title":"Geochemistry and petrogenesis of the Early Paleozoic Guangning granitic pluton in the Yunkai Massif, South China: Insights into magma evolution and tectonic setting","authors":"Zhihao Sun , Huan Li , Yuxuan Huang , Thomas J. Algeo , Wei Quan , Tao Xiao , Buqing Wang , Wenbo Sun , Weidong Ren","doi":"10.1016/j.chemer.2025.126349","DOIUrl":"10.1016/j.chemer.2025.126349","url":null,"abstract":"<div><div>The Guangning area of the Yunkai Massif is rich in mineral resources and extensively intruded by granites that played a crucial role in the ore mineralization process. However, the high-precision geochronology and isotopic geochemistry of these granites remain understudied. This study presents the first detailed geochronological and geochemical characterization of Early Paleozoic granites from the Guangning area of the Yunkai Massif, South China Craton (SCC). Our results address a significant knowledge gap with regard to the magmatic history of this region and provide crucial geological evidence elucidating the Early Paleozoic tectonic evolution of the SCC. Via LA-ICP-MS U<img>Pb zircon geochronology, our study constrains the emplacement age of the Early Paleozoic Guangning granitic pluton to between 452.3 ± 1.3 Ma and 448.5 ± 1.6 Ma. Integrating these results with previous studies, we identify a prominent magmatic event in the Yunkai Massif during the Late Ordovician (~458–444 Ma). The Guangning granites display geochemical signatures typical of the high‑potassium calc-alkaline series and possess strong peraluminous affinities. These rocks are characterized by high SiO₂ (71.1–77.9 wt%) and Al₂O₃ (10.3–14.5 wt%) and low MgO (0.03–0.90 wt%), CaO (0–1.42 wt%), and total FeO contents (0.58–1.89 wt%). The samples show enrichment in high-field-strength elements and Pb, and depletion in Nb, Ce, P, and large-ion lithophile elements. The rare earth element (REE) patterns indicate significant fractionation, with enrichment in light REEs (LREEs) and negative Eu anomalies. The whole-rock εNd(t) values of the Guangning granites range from −9.8 to −8.7 with notable negative f<sub>Sm/Nd</sub> anomalies (−0.4 to −0.3), and two-stage Nd model ages (T<sub>DM2</sub>) of ~1614–1528 Ma. The zircon εHf(t) values mostly range from −5.5 to −0.5, and the initial (<sup>176</sup>Hf/<sup>177</sup>Hf)<sub>i</sub> values are concentrated in the range of 0.28234 to 0.28248, with the two-stage depleted mantle model ages (T<sub>DM2</sub>) of ~1783–1468 Ma. These characteristics are typical of strongly peraluminous S-type granites, likely derived from mica dehydration melting at low temperatures of aluminous pelitic rocks in the Paleoproterozoic–Mesoproterozoic crust of the Cathaysia Block, and having undergone fractional crystallization episodes characterized by the involvement of plagioclase, K-feldspar, and biotite. Comprehensive analysis of the regional geological context indicates that the SCC experienced a dynamic shift from orogenic compression to post-orogenic extension at ~450–435 Ma, with the Guangning Early Paleozoic S-type granites forming during this transitional period.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126349"},"PeriodicalIF":2.9,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519725","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}
Pub Date : 2025-11-07DOI: 10.1016/j.chemer.2025.126350
Hang Yang , Peng Wu , Anlin Liu , Zhigang Kong , Xinfu Wang , Shoukui Li , Yu Jiang , Jianjun Liu , Jiaan Qu
In collisional zones, potassic-ultrapotassic intrusions with high K2O contents and K2O/Na2O ratios commonly provide insights into magmatic evolution following collision and regional Au polymetallic mineralization. Here, we report a systematic dataset for the petrology, geochronology, and geochemistry of the Oligocene Yao'an complex (YAC), which is genetically related to the Indo-Asia collision within the western Yangtze Craton (WYC). The YAC includes shoshonitic syenite porphyries, shoshonitic mafic microgranular enclaves (MMEs), and potassic-ultrapotassic lamprophyres. Zircon UPb dating yields crystallization ages of ca. 33 Ma for MME and host syenite porphyries, which coincide with those of potassic-ultrapotassic mafic rocks (PUPMR) in this complex. The YAC samples have high K2O and elevated K2O/Na2O ratios, and show enriched SrNd isotopic signatures [(87Sr/86Sr)i = 0.7087–0.7107, εNd(t) = −12.1 to −8.2] as well as variable zircon εHf(t) values (−19.0 to −6.1). The lamprophyres are enriched in large ion lithophile elements (LILEs) and depleted in high field strength elements (HFSEs), as well as characterized by high Rb/Sr, and low Ba/Rb and Nb/U ratios, most likely originating from partial melting of an enriched lithospheric mantle with abundant metasomatic phlogopite, formed by subduction-related fluids. The syenite porphyries have high SiO2 (65.24–69.70 wt%) contents without adakite-like affinities. They define linear trends on Harker diagrams, and display similar SrNd isotope compositions, REE and trace-element patterns compared to the published data of coeval PUPMR, which can be attributed to fractional crystallization processes. MMEs hosted in the syenite porphyries exhibit disequilibrium textures, implying origin from magma mingling between potassic-ultrapotassic mafic and primitive shoshonitic felsic end-members in varying proportions. Thus, we conclude that fractional crystallization of K-rich, mantle-derived mafic melts, together with the injection of ultrapotassic mafic melts (UPMM) leads to the enrichment of K2O in the shoshonitic felsic intrusions, and may promote the enrichment of Au. Besides, the presence of sulfides in the least altered MME indicates that the mafic melts probably supplied part of metal to the Yao'an porphyry Au system. Our data reinforce previously proposed models and help elucidate the origin, evolution, potassium enrichment mechanism, and associated Au polymetallic mineralization of potassic magmas in post-collisional settings.
{"title":"Genesis of potassic-ultrapotassic intrusions and associated Au polymetallic mineralization in collision zones: An example from the Oligocene Yao'an complex in western Yangtze Craton, SW China","authors":"Hang Yang , Peng Wu , Anlin Liu , Zhigang Kong , Xinfu Wang , Shoukui Li , Yu Jiang , Jianjun Liu , Jiaan Qu","doi":"10.1016/j.chemer.2025.126350","DOIUrl":"10.1016/j.chemer.2025.126350","url":null,"abstract":"<div><div>In collisional zones, potassic-ultrapotassic intrusions with high K<sub>2</sub>O contents and K<sub>2</sub>O/Na<sub>2</sub>O ratios commonly provide insights into magmatic evolution following collision and regional Au polymetallic mineralization. Here, we report a systematic dataset for the petrology, geochronology, and geochemistry of the Oligocene Yao'an complex (YAC), which is genetically related to the Indo-Asia collision within the western Yangtze Craton (WYC). The YAC includes shoshonitic syenite porphyries, shoshonitic mafic microgranular enclaves (MMEs), and potassic-ultrapotassic lamprophyres. Zircon U<img>Pb dating yields crystallization ages of ca. 33 Ma for MME and host syenite porphyries, which coincide with those of potassic-ultrapotassic mafic rocks (PUPMR) in this complex. The YAC samples have high K<sub>2</sub>O and elevated K<sub>2</sub>O/Na<sub>2</sub>O ratios, and show enriched Sr<img>Nd isotopic signatures [(<sup>87</sup>Sr/<sup>86</sup>Sr)<sub><em>i</em></sub> = 0.7087–0.7107, <em>ε</em><sub>Nd</sub>(t) = −12.1 to −8.2] as well as variable zircon <em>ε</em><sub>Hf</sub>(t) values (−19.0 to −6.1). The lamprophyres are enriched in large ion lithophile elements (LILEs) and depleted in high field strength elements (HFSEs), as well as characterized by high Rb/Sr, and low Ba/Rb and Nb/U ratios, most likely originating from partial melting of an enriched lithospheric mantle with abundant metasomatic phlogopite, formed by subduction-related fluids. The syenite porphyries have high SiO<sub>2</sub> (65.24–69.70 wt%) contents without adakite-like affinities. They define linear trends on Harker diagrams, and display similar Sr<img>Nd isotope compositions, REE and trace-element patterns compared to the published data of coeval PUPMR, which can be attributed to fractional crystallization processes. MMEs hosted in the syenite porphyries exhibit disequilibrium textures, implying origin from magma mingling between potassic-ultrapotassic mafic and primitive shoshonitic felsic end-members in varying proportions. Thus, we conclude that fractional crystallization of K-rich, mantle-derived mafic melts, together with the injection of ultrapotassic mafic melts (UPMM) leads to the enrichment of K<sub>2</sub>O in the shoshonitic felsic intrusions, and may promote the enrichment of Au. Besides, the presence of sulfides in the least altered MME indicates that the mafic melts probably supplied part of metal to the Yao'an porphyry Au system. Our data reinforce previously proposed models and help elucidate the origin, evolution, potassium enrichment mechanism, and associated Au polymetallic mineralization of potassic magmas in post-collisional settings.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126350"},"PeriodicalIF":2.9,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519726","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}
Pub Date : 2025-11-05DOI: 10.1016/j.chemer.2025.126347
Yu-hang Liu , Ke-yong Wang , Zhi-gao Wang , Jun-chi Chen , Xue Wang , Fa-Zhen Ma
The Sandaocha gold deposit is located in the Jiapigou mining district and is considered a highly representative deposit. Gold mineralization is hosted in the Neoarchean Jiapigou Group of Sandaogou Formation supracrustal rocks. The orebody is predominantly governed by a series of brittle-ductile structures oriented along a NNE-strike. The geological and petrographic features of the deposit reveal that the mineralization process at Sandaocha can be divided into four stages: (I) Pyrite-milky quartz stage, (II) Quartz-pyrite stage, (III) Quartz-polymetallic sulfide stage and (IV) Quartz‑carbonate stage. Four types of primary fluid inclusions were identified in the quartz vein: liquid-rich two-phase aqueous inclusions (L-type), mixed aqueous‑carbonic inclusions (C-type), rich carbonic inclusions (RC-type) and pure carbonic inclusions (PC-type). C-type, RC-type, PC-type and L-type inclusions are captured in stage I, stage II and stage III quartz sample, while only L-type inclusions are found in stage IV quartz. During the mineralization process, the influx of atmospheric precipitation led to the transformation of the fluid system from the moderate-temperature and moderate-low salinity NaCl-H2O-CO2 system to the low-temperature and low-salinity NaCl-H2O system. The results of C-H-O-He-Ar isotopes collectively indicate that the ore-forming fluid of the Sandaocha gold deposit is magmatic water formed from the differentiation of a mantle-crust mixed magma. LA-ICP-MS data indicates that gold mineralization primarily occurred during the stage II and stage III. Additionally, continuous input of meteoric water led to immiscibility of the fluids. The physical and chemical conditions of the ore-forming fluid changed as significant gas-phase components escaped, leading to the decomposition of AuS complexes and a reduction in gold solubility, which facilitated the deposition of gold and other ore-forming elements.
{"title":"Fluid origin and ore genesis of the Sandaocha gold deposit in Jilin Province, Northeast China: Constraints from C-H-O-He-Ar isotopes and trace element compositions of pyrite and fluid inclusion","authors":"Yu-hang Liu , Ke-yong Wang , Zhi-gao Wang , Jun-chi Chen , Xue Wang , Fa-Zhen Ma","doi":"10.1016/j.chemer.2025.126347","DOIUrl":"10.1016/j.chemer.2025.126347","url":null,"abstract":"<div><div>The Sandaocha gold deposit is located in the Jiapigou mining district and is considered a highly representative deposit. Gold mineralization is hosted in the Neoarchean Jiapigou Group of Sandaogou Formation supracrustal rocks. The orebody is predominantly governed by a series of brittle-ductile structures oriented along a NNE-strike. The geological and petrographic features of the deposit reveal that the mineralization process at Sandaocha can be divided into four stages: (I) Pyrite-milky quartz stage, (II) Quartz-pyrite stage, (III) Quartz-polymetallic sulfide stage and (IV) Quartz‑carbonate stage. Four types of primary fluid inclusions were identified in the quartz vein: liquid-rich two-phase aqueous inclusions (L-type), mixed aqueous‑carbonic inclusions (C-type), rich carbonic inclusions (RC-type) and pure carbonic inclusions (PC-type). C-type, RC-type, PC-type and L-type inclusions are captured in stage I, stage II and stage III quartz sample, while only L-type inclusions are found in stage IV quartz. During the mineralization process, the influx of atmospheric precipitation led to the transformation of the fluid system from the moderate-temperature and moderate-low salinity NaCl-H<sub>2</sub>O-CO<sub>2</sub> system to the low-temperature and low-salinity NaCl-H<sub>2</sub>O system. The results of C-H-O-He-Ar isotopes collectively indicate that the ore-forming fluid of the Sandaocha gold deposit is magmatic water formed from the differentiation of a mantle-crust mixed magma. LA-ICP-MS data indicates that gold mineralization primarily occurred during the stage II and stage III. Additionally, continuous input of meteoric water led to immiscibility of the fluids. The physical and chemical conditions of the ore-forming fluid changed as significant gas-phase components escaped, leading to the decomposition of Au<img>S complexes and a reduction in gold solubility, which facilitated the deposition of gold and other ore-forming elements.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126347"},"PeriodicalIF":2.9,"publicationDate":"2025-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145571632","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}
Pub Date : 2025-11-03DOI: 10.1016/j.chemer.2025.126346
Mohammed Z. El-Bialy , Abdel-Aal Abdel-Karim , Mokhles Azer
The Younger Granite plutons of Gabal Um Erjaj (GUE) and Gabal Um Sudaydat (GUS) in the Eastern Desert of Egypt provide key insights into the geological history and crustal evolution of the Arabian-Nubian Shield (ANS). These granitic intrusions represent the final phase of magmatic activity in the region, cutting through older Neoproterozoic basement rocks. Both plutons exhibit sharp, non-reactive contacts with the surrounding rocks, with no evidence of thermal alteration. Based on modal analysis, these granites are primarily alkali feldspar granites and syenogranites. The GUS granites display more deformation features and inequigranular textures, suggesting a shallower level of intrusion compared to GUE. Electron microprobe analyses reveal significant compositional variations between the two plutons, particularly in feldspar and biotite chemistry. Geochemically, both granitoid suites exhibit peraluminous, ferroan A-type characteristics, with distinct geochemical signatures that differentiate them from other A-type granites. Geothermometric analyses indicate moderate to high crystallization temperatures for accessory minerals, suggesting a highly fractionated magmatic origin. Trace element distributions, including pronounced negative Nb, Ti, and Eu anomalies, coupled with high Y/Nb ratios (>1.2), indicate a predominantly crustal-derived melt. The post-collisional geodynamic setting of these granitoids within the ANS aligns with lithospheric delamination and slab breakoff processes, contributing to the extensive crustal melting. The geotectonic discrimination diagrams support their classification as A2-type granites, reinforcing their post-collisional evolution. These findings emphasize the significance of crustal processes in the formation of post-collisional A-type granites, contributing to a broader understanding of the crustal evolution within the ANS.
埃及东部沙漠Gabal Um Erjaj （GUE）和Gabal Um Sudaydat （GUS）的年轻花岗岩岩体为研究阿拉伯-努比亚地盾（ANS）的地质历史和地壳演化提供了重要的线索。这些花岗岩侵入物代表了该地区岩浆活动的最后阶段，穿过了更古老的新元古代基底岩。这两个岩体都表现出与周围岩石尖锐的非反应性接触，没有热蚀变的证据。模态分析表明，这些花岗岩主要为碱长石花岗岩和正长花岗岩。GUS花岗岩表现出更多的变形特征和非等粒状结构，表明其侵入程度较GUE浅。电子探针分析揭示了两种岩体在长石和黑云母化学成分上的显著差异。地球化学特征表明，这两组花岗岩均表现出过铝、铁a型特征，具有明显的地球化学特征，区别于其他a型花岗岩。地热分析表明，副矿物的结晶温度适中至较高，表明其岩浆成因高度分异。微量元素分布，包括明显的负Nb， Ti和Eu异常，加上高Y/Nb比率（>1.2），表明主要是地壳衍生的熔融。这些花岗岩类在ANS内的碰撞后地球动力学背景与岩石圈分层和板块断裂过程一致，导致了广泛的地壳融化。大地构造判别图支持其a2型花岗岩的分类，加强了其后碰撞演化。这些发现强调了地壳过程在碰撞后a型花岗岩形成中的重要性，有助于更广泛地了解ANS内部的地壳演化。
{"title":"Petrogenesis of post-collisional granites in the Arabian-Nubian Shield: The peraluminous A-type granites of the mounts Um-Sudaydat and Um-Erjaj plutons, South Eastern Desert, Egypt","authors":"Mohammed Z. El-Bialy , Abdel-Aal Abdel-Karim , Mokhles Azer","doi":"10.1016/j.chemer.2025.126346","DOIUrl":"10.1016/j.chemer.2025.126346","url":null,"abstract":"<div><div>The Younger Granite plutons of Gabal Um Erjaj (GUE) and Gabal Um Sudaydat (GUS) in the Eastern Desert of Egypt provide key insights into the geological history and crustal evolution of the Arabian-Nubian Shield (ANS). These granitic intrusions represent the final phase of magmatic activity in the region, cutting through older Neoproterozoic basement rocks. Both plutons exhibit sharp, non-reactive contacts with the surrounding rocks, with no evidence of thermal alteration. Based on modal analysis, these granites are primarily alkali feldspar granites and syenogranites. The GUS granites display more deformation features and inequigranular textures, suggesting a shallower level of intrusion compared to GUE. Electron microprobe analyses reveal significant compositional variations between the two plutons, particularly in feldspar and biotite chemistry. Geochemically, both granitoid suites exhibit peraluminous, ferroan A-type characteristics, with distinct geochemical signatures that differentiate them from other A-type granites. Geothermometric analyses indicate moderate to high crystallization temperatures for accessory minerals, suggesting a highly fractionated magmatic origin. Trace element distributions, including pronounced negative Nb, Ti, and Eu anomalies, coupled with high Y/Nb ratios (>1.2), indicate a predominantly crustal-derived melt. The post-collisional geodynamic setting of these granitoids within the ANS aligns with lithospheric delamination and slab breakoff processes, contributing to the extensive crustal melting. The geotectonic discrimination diagrams support their classification as A<sub>2</sub>-type granites, reinforcing their post-collisional evolution. These findings emphasize the significance of crustal processes in the formation of post-collisional A-type granites, contributing to a broader understanding of the crustal evolution within the ANS.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126346"},"PeriodicalIF":2.9,"publicationDate":"2025-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467039","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}
Pub Date : 2025-10-25DOI: 10.1016/j.chemer.2025.126344
Nils Reinhardt , Jens Gutzmer , Marcus Oelze , Joachim Krause , Mathias Burisch
Polymetallic W-(Sn), Sn-Zn±(In), and Zn-Pb±(Sn) skarns in the Schwarzenberg District of the western Erzgebirge are expressions of a polyphase mineral system that formed between >330 Ma and ~295 Ma. Due to the polyphase nature of the skarns, the physicochemical conditions of skarn formation and the actual timing of ore formation have remained poorly constrained. To better understand skarn-forming processes in the Erzgebirge, we obtained new mineral chemical data of prograde garnet from all major skarns across the Schwarzenberg District by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry. Results illustrate that the oldest generation of skarns formed under relatively fluid-buffered conditions and high fluid/rock ratios. Associated garnet has a pronounced andradite component, contains low concentrations of HFSE, Mn, and Ga and is variably enriched in Sn, W, As, and Li. Elevated concentrations of HFSE, Mn, and Ga in garnet from skarns with skarnoid textures indicate that these formed under mainly rock-buffered conditions (low fluid/rock ratios). Associated garnet is dominantly grossular and invariably low in Sn and W concentrations. The mineral chemistry of garnet from the youngest skarn bodies indicates renewed ingress of magmatic-hydrothermal fluids marked by an intermediate grandite composition, low HFSE, Al, and Ga concentrations as well as a variable enrichment of Sn and W. Although these general patterns are well defined, our data also clearly reveal considerable variability of garnet compositions on the local scale. The same is true for Sn and W concentrations in garnet of all stages. These are found to be too variable as to constitute meaningful exploration vectors. However, they are well suited to place general constraints on the physicochemical conditions of polyphase skarn formation in the Schwarzenberg District.
二日格西施瓦施贝格地区多金属W-(Sn)、Sn- zn±（In）和Zn-Pb±（Sn）夕卡岩是形成于>；330 Ma ~ ~295 Ma之间的多相矿物体系的表现。由于矽卡岩的多相性质，矽卡岩形成的物理化学条件和成矿的实际时间仍然缺乏限制。为了更好地了解Erzgebirge矽卡岩的形成过程，我们利用电子探针和激光烧蚀-电感耦合等离子体质谱技术，从Schwarzenberg地区所有主要矽卡岩中获得了新的顺行石榴石矿物化学数据。结果表明，最老一代夕卡岩形成于相对流体缓冲条件和高液岩比条件下。伴生石榴石具有明显的赤铁矿成分，含有低浓度的HFSE、Mn和Ga，并以不同的方式富集Sn、W、As和Li。在具有类矽卡岩结构的矽卡岩中，石榴石中HFSE、Mn和Ga的浓度升高表明它们主要是在岩石缓冲条件下形成的（低流体/岩石比）。伴生石榴石以粗晶为主，且总是低锡、低钨浓度。来自最年轻矽卡岩体的石榴石的矿物化学表明岩浆热液流体的重新进入，其特征是中等花岗岩组成，低HFSE， Al和Ga浓度，以及Sn和w的可变富集。尽管这些一般模式被很好地定义，但我们的数据也清楚地揭示了石榴石组成在局部尺度上的相当大的变化。各阶段石榴石中锡、钨的浓度也是如此。人们发现这些变量太大，无法构成有意义的勘探向量。然而，它们很适合于对施瓦岑贝格地区多相矽卡岩形成的物理化学条件进行一般约束。
{"title":"Garnet mineral chemistry as proxy for skarn-forming processes in the Schwarzenberg District, Erzgebirge, Germany","authors":"Nils Reinhardt , Jens Gutzmer , Marcus Oelze , Joachim Krause , Mathias Burisch","doi":"10.1016/j.chemer.2025.126344","DOIUrl":"10.1016/j.chemer.2025.126344","url":null,"abstract":"<div><div>Polymetallic W-(Sn), Sn-Zn±(In), and Zn-Pb±(Sn) skarns in the Schwarzenberg District of the western Erzgebirge are expressions of a polyphase mineral system that formed between >330 Ma and ~295 Ma. Due to the polyphase nature of the skarns, the physicochemical conditions of skarn formation and the actual timing of ore formation have remained poorly constrained. To better understand skarn-forming processes in the Erzgebirge, we obtained new mineral chemical data of prograde garnet from all major skarns across the Schwarzenberg District by electron microprobe and laser ablation-inductively coupled plasma-mass spectrometry. Results illustrate that the oldest generation of skarns formed under relatively fluid-buffered conditions and high fluid/rock ratios. Associated garnet has a pronounced andradite component, contains low concentrations of HFSE, Mn, and Ga and is variably enriched in Sn, W, As, and Li. Elevated concentrations of HFSE, Mn, and Ga in garnet from skarns with skarnoid textures indicate that these formed under mainly rock-buffered conditions (low fluid/rock ratios). Associated garnet is dominantly grossular and invariably low in Sn and W concentrations. The mineral chemistry of garnet from the youngest skarn bodies indicates renewed ingress of magmatic-hydrothermal fluids marked by an intermediate grandite composition, low HFSE, Al, and Ga concentrations as well as a variable enrichment of Sn and W. Although these general patterns are well defined, our data also clearly reveal considerable variability of garnet compositions on the local scale. The same is true for Sn and W concentrations in garnet of all stages. These are found to be too variable as to constitute meaningful exploration vectors. However, they are well suited to place general constraints on the physicochemical conditions of polyphase skarn formation in the Schwarzenberg District.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126344"},"PeriodicalIF":2.9,"publicationDate":"2025-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145467011","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}
Pub Date : 2025-10-22DOI: 10.1016/j.chemer.2025.126343
Makoto Kimura , Michael K. Weisberg , Richard C. Greenwood , Akira Yamaguchi
In this paper, we examine the diverse features of CM (Mighei-type) and related carbonaceous chondrites, including their petrologic classification, secondary heating, brecciation, and we explore anomalous CM-like chondrites. CM chondrites experienced varying degrees of aqueous alteration, resulting in a range of petrologic subtypes from 3.0 to 2.0. The most abundant subtypes are 2.3–2.0, which may reflect melting of significant amounts of ice, resulting in the formation of the heavily altered CM chondrites in the inner regions of the parent body. Additionally, some CM and related chondrites have undergone secondary heating after aqueous alteration. The source of heat for these chondrites is still uncertain, but impacts are the most likely the cause due to the evidence for a short duration of heating. CM chondrites are mainly genomict breccias and contain clasts of various petrologic grade and degree of heating, though some CMs contain xenolithic clasts. Highly recrystallized clasts are particularly important, as they might have formed in the interior, hotter regions of the CM parent body. Subsequently, these clasts may have been mixed with other typical CM lithologies due to impact events. CM chondrite fragments are commonly found in other meteorites, such as HED meteorites and ordinary chondrites. This indicates a widespread distribution of CM chondrite fragments in the main asteroid belt, with incorporation into other meteorites taking place significantly later than chondrule formation. There have been numerous descriptions of anomalous CM or related chondrites. We tentatively classify these anomalous CMs into four categories: highly 16O-rich, medium 16O-rich, an unusual mineral group, and others. However, the processes involved in the formation of these anomalous chondrites and their relationships to the more typical CMs remain unclear, as detailed documentation of most of the anomalous CMs is currently lacking. CM chondrites primarily consist of chondrules, refractory inclusions, opaque minerals, and a matrix material, similar to other C chondrites. The petrographic and bulk chemical features of CMs are most similar to CO chondrites. However, CM and CO chondrites did not originate from a single parent body. CM chondrites provide valuable information about the conditions and processes that operated in the outer region of the early solar system.
{"title":"The diversity, classification, and formation of the CM chondrite group: A review","authors":"Makoto Kimura , Michael K. Weisberg , Richard C. Greenwood , Akira Yamaguchi","doi":"10.1016/j.chemer.2025.126343","DOIUrl":"10.1016/j.chemer.2025.126343","url":null,"abstract":"<div><div>In this paper, we examine the diverse features of CM (Mighei-type) and related carbonaceous chondrites, including their petrologic classification, secondary heating, brecciation, and we explore anomalous CM-like chondrites. CM chondrites experienced varying degrees of aqueous alteration, resulting in a range of petrologic subtypes from 3.0 to 2.0. The most abundant subtypes are 2.3–2.0, which may reflect melting of significant amounts of ice, resulting in the formation of the heavily altered CM chondrites in the inner regions of the parent body. Additionally, some CM and related chondrites have undergone secondary heating after aqueous alteration. The source of heat for these chondrites is still uncertain, but impacts are the most likely the cause due to the evidence for a short duration of heating. CM chondrites are mainly genomict breccias and contain clasts of various petrologic grade and degree of heating, though some CMs contain xenolithic clasts. Highly recrystallized clasts are particularly important, as they might have formed in the interior, hotter regions of the CM parent body. Subsequently, these clasts may have been mixed with other typical CM lithologies due to impact events. CM chondrite fragments are commonly found in other meteorites, such as HED meteorites and ordinary chondrites. This indicates a widespread distribution of CM chondrite fragments in the main asteroid belt, with incorporation into other meteorites taking place significantly later than chondrule formation. There have been numerous descriptions of anomalous CM or related chondrites. We tentatively classify these anomalous CMs into four categories: highly <sup>16</sup>O-rich, medium <sup>16</sup>O-rich, an unusual mineral group, and others. However, the processes involved in the formation of these anomalous chondrites and their relationships to the more typical CMs remain unclear, as detailed documentation of most of the anomalous CMs is currently lacking. CM chondrites primarily consist of chondrules, refractory inclusions, opaque minerals, and a matrix material, similar to other C chondrites. The petrographic and bulk chemical features of CMs are most similar to CO chondrites. However, CM and CO chondrites did not originate from a single parent body. CM chondrites provide valuable information about the conditions and processes that operated in the outer region of the early solar system.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126343"},"PeriodicalIF":2.9,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145417462","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号