Chemie Der Erde-Geochemistry最新文献

{"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 ,&nbsp;Huan Li ,&nbsp;Yuxuan Huang ,&nbsp;Thomas J. Algeo ,&nbsp;Wei Quan ,&nbsp;Tao Xiao ,&nbsp;Buqing Wang ,&nbsp;Wenbo Sun ,&nbsp;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_Sm/Nd anomalies (−0.4 to −0.3), and two-stage Nd model ages (T_DM2) 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 (T_DM2) 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}

{"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 ,&nbsp;Peng Wu ,&nbsp;Anlin Liu ,&nbsp;Zhigang Kong ,&nbsp;Xinfu Wang ,&nbsp;Shoukui Li ,&nbsp;Yu Jiang ,&nbsp;Jianjun Liu ,&nbsp;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 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 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 K₂O and elevated K₂O/Na₂O ratios, and show enriched Sr<img>Nd isotopic signatures [(⁸⁷Sr/⁸⁶Sr)_<em>i</em> = 0.7087–0.7107, <em>ε</em>_Nd(t) = −12.1 to −8.2] as well as variable zircon <em>ε</em>_Hf(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 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 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.</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}

{"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 ,&nbsp;Ke-yong Wang ,&nbsp;Zhi-gao Wang ,&nbsp;Jun-chi Chen ,&nbsp;Xue Wang ,&nbsp;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-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 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}

{"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 ,&nbsp;Abdel-Aal Abdel-Karim ,&nbsp;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 (&gt;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.</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}

{"title":"Garnet mineral chemistry as proxy for skarn-forming processes in the Schwarzenberg District, Erzgebirge, Germany","authors":"Nils Reinhardt ,&nbsp;Jens Gutzmer ,&nbsp;Marcus Oelze ,&nbsp;Joachim Krause ,&nbsp;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 &gt;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}

{"title":"The diversity, classification, and formation of the CM chondrite group: A review","authors":"Makoto Kimura ,&nbsp;Michael K. Weisberg ,&nbsp;Richard C. Greenwood ,&nbsp;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 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.</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}

{"title":"Magmatic evolution and molybdenum mineralization potential analysis in the Mangling granite, northern Qinling orogenic belt, China","authors":"Rui-Yang Liu","doi":"10.1016/j.chemer.2025.126338","DOIUrl":"10.1016/j.chemer.2025.126338","url":null,"abstract":"<div><div>The Qinling orogenic belt experienced magmatic remelting and intrusion, forming Mo mineralization belt associated with Late Yanshanian magmatism, highlighting the role of Yanshan period in Mo enrichment. Ore-bearing granitic rocks (monzogranite and granite porphyry) from northern Qinling were analyzed using petrography, SEM, TIMA, whole-rock geochemistry, Sr-Nd-Pb isotopes, zircon and titanite U<img>Pb dating, zircon Lu<img>Hf isotopes, and EMPA of key minerals (zircon, titanite, pyrite, plagioclase, quartz, biotite). These data constrain the petrogenesis and metallogenic mechanisms of Mo mineralization in the region. The Mangling granites (SiO₂ = 64.78–73.36 wt%, Mg# = 34.02–40.65, A/CNK = 1.24–1.67) originated from the lower crust, as indicated by isotopic data (Isr = 0.7064–0.7087, εNd(t) = −7.05 to ∼ −13.97). Magmatic-hydrothermal processes, including ascent (155.7 Ma), emplacement (152.1 Ma), and mixing, formed highly differentiated Mo-bearing granite porphyry (TE_1,3 = 1.03–1.45). Partial melting and cooling produced monzogranite as the parental rock at 135.6 Ma. Under favorable conditions, crystallization and differentiation enriched Mo in the residual melt, leading to the formation of ore-bearing granite porphyry during the Early Cretaceous (133.8 Ma). These processes highlight the magmatic controls on Mo enrichment in Mangling area.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126338"},"PeriodicalIF":2.9,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145325618","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":"Chemistry and He isotope systematics of olivine as tracers of source in mantle xenoliths from Harrat Hutaymah and Harrat Kishb Cenozoic lava fields, Western Saudi Arabia","authors":"Ahmed Hasan Ahmed ,&nbsp;Abdel-Kader M. Moghazi ,&nbsp;Finlay M. Stuart ,&nbsp;Shehta Abdallah ,&nbsp;Moustafa Hashad ,&nbsp;Kamal A. Ali","doi":"10.1016/j.chemer.2025.126342","DOIUrl":"10.1016/j.chemer.2025.126342","url":null,"abstract":"<div><div>Mantle xenoliths from the Cenozoic volcanic fields of Harrat Hutaymah and Harrat Kishb, located in the western part of the Arabian Shield, consist of proto-granular lherzolite, harzburgite, and to a lesser extent dunite and wehrlite. The olivine displays variations in Mn, Ni, and Ca contents relative to the forsterite (Fo) content that is similar to that of residual mantle olivine, which crystallized after being exposed to low to intermediate degrees of melt derived from mantle peridotite. The elemental ratios of Ca-Fe-Ni-Mg-Mn in the olivine further indicate a contribution from peridotite. Pressure-temperature calculations and previous geochemical studies indicate that the peridotite xenoliths were entrained from below the crust-mantle boundary (~35 km in the mantle lithosphere) under the Arabian Shield. Olivine ³He/⁴He ratios range from 6.1 to 8.5 R_a, which overlap the range of &lt;7 to 9 R_a recently reported for off-craton-derived subcontinental lithospheric mantle (SCLM) xenoliths and is consistent with mantle beneath the region. This tends to rule out the overprinting of the SCLM by fluids/melts derived from the deep upwelling mantle sampled by the Afar plume. However, the influence of deep mantle fluid may be cryptic and warrants further exploration because the He content of the Afar mantle plume is unknown.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126342"},"PeriodicalIF":2.9,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269661","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":"Geochemistry and U-Pb geochronology of the Neoproterozoic aluminous A-type granite in the south-western Tanzania: Implications to the Tonian geodynamic evolution of Southern Africa","authors":"Emmanuel O. Kazimoto ,&nbsp;Charles H. Kasanzu ,&nbsp;Ernest Mulaya ,&nbsp;Remigius Gama ,&nbsp;Rachid Benaouda","doi":"10.1016/j.chemer.2025.126339","DOIUrl":"10.1016/j.chemer.2025.126339","url":null,"abstract":"<div><div>This study presents new insights on the Litembo granite, a 30 km wide pluton located south of the Ubendian Belt in the southern Tanzania, East Africa. Whole-rock geochemistry, U-Pb zircon geochronology, and the Rb-Sr isotope system were used to determine its geochemical composition, age, and origin, contributing to regional geological and geodynamic context. The granite is metaluminous to peraluminous, ferroan, and calc-alkalic with high concentrations of Sr, Rb, Ba, High Field Strength Elements (HFSE; e.g., Zr, Y, Nb, and Ta), and high Ga/Al ratios. The total Rare Earth Element (REE) concentrations of the granite range from 335 to 693 ppm, showing fractionated REE patterns in the chondrite-normalized spider diagram ((La/Yb)_CN = 9.40–15.41) and a negative Eu anomaly (Eu/Eu*; mean = 0.87). Primitive mantle-normalized spidegrams reveal negative patterns for Ti, Sr, P, Y, and Cs, along with enrichment in Large Ion Lithophile Elements (LILE; e.g. Rb and Ba). Geochemical features of the rock are akin to anorogenic (A-type) granites, implying formation of Litembo granite from a deep source melt, involving plagioclase, garnet, and amphibole and/or complex differentiation processes, under extensional tectonics. An initial ⁸⁷Sr/⁸⁶Sr ratio (∼0.7113) suggests evolved crustal origins, with a Rb–Sr imprecise age of about 658 ± 20 Ma. Laser ablation ICP-MS U-Pb zircon dating yields crystallisation ages of 737.1 ± 2.9 Ma and 730.1 ± 3.0 Ma, indicating emplacement between 730 and 740 Ma, followed thermal diffusion of Rb and Sr in the rock at about 660 Ma. These ages and compositional features align with the Tonian intraplate (alkaline and carbonatite magmatism) in southern Africa and support for a thermal event linked to Rodinia's breakup, preceding development of the Mozambique Belt.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126339"},"PeriodicalIF":2.9,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269663","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":"Coupling hydrolyzed rice husk and ferric oxidation to enhance bio-oxidation of gold concentrate with high arsenic and sulfur","authors":"Shiqi Zhang ,&nbsp;Hongying Yang ,&nbsp;Linlin Tong ,&nbsp;Zhenan Jin ,&nbsp;Pengcheng Ma","doi":"10.1016/j.chemer.2025.126341","DOIUrl":"10.1016/j.chemer.2025.126341","url":null,"abstract":"<div><div>The bio-oxidation efficiency of refractory gold concentrate with high arsenic and sulfur is generally limited. In present study, the two-step ferric-biological process was employed to treat this gold concentrate, with an emphasis on investigating the impact of different organic nutrients on bio-oxidation performance. The results indicated that the addition of appropriate dosage of hydrolyzed rice husk (HRH, 1.2 g/L) combined with ferric oxidation significantly improved the bio-oxidation efficiency. The microbial growth rate and adsorption capacity were increase by 1.75 and 1 times, respectively. Specifically, it effectively facilitated the growth and adsorption of <em>Sulfobacillus</em> spp., while exhibiting no significant inhibitory effect on <em>Leptospirillum</em> spp. growth. Consequently, the homogeneity of the planktonic microbial community was improved. These effects resulted in a 0.06, 0.84, and 1.03 times increase in the oxidation efficiency of As, Fe, and S compared with one-step bio-oxidation, achieving extraction levels of 98.4 ± 0.2 %, 74.5 ± 0.1 %, and 60.4 ± 1.0 %, respectively. In consequence, the extraction levels of Au and Ag increased by 63.0 % and 51.3 %, respectively, reaching 93.7 ± 0.6 % and 91.6 ± 0.5 %. This study elucidated the enhancement mechanism of HRH on bio-oxidation and provided a theoretical basis for the efficient utilization of refractory gold ores and the application of lignocellulose in biohydrometallurgy.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 4","pages":"Article 126341"},"PeriodicalIF":2.9,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145269662","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}