Lithos最新文献

{"title":"Lead isotope systematics of galena from pegmatites in the Larvik Plutonic Complex (LPC)","authors":"Emil H. Gulbransen ,&nbsp;Tom Andersen ,&nbsp;Henrik Friis ,&nbsp;Liu Xuan","doi":"10.1016/j.lithos.2025.108079","DOIUrl":"10.1016/j.lithos.2025.108079","url":null,"abstract":"<div><div>The Larvik Plutonic Complex (LPC) is situated in the southernmost parts of the Carboniferous-Permian Oslo Rift, Norway. The alkaline complex is host to several suites of pegmatites ranging from miaskitic to agpaitic, and much is unknown of the origin and source of these pegmatites. Compared to granitic pegmatites, alkaline pegmatites are commonly intraplutonic and cogenetic to the host rock. This makes alkaline pegmatites such as the ones in the LPC important indicators of the evolution of the alkaline complexes as a whole, and towards our understanding of their formation and source. This study aims to utilize Pb-Pb isotope geochemistry on galena crystals from selected pegmatites in the LPC, to investigate possible sources to the pluton. The LPC pegmatite data was modelled using a 295 Ma paleoisochron, which represents the lead isotope composition at the time of formation. The 295 Ma paleoisochron is significantly more radiogenic than the upper mantle, indicating a need of another component to the source. This have been investigated by extrapolating the 295 Ma paleoisochron to the intercept point of the global average juvenile lithosphere, which gave an initial lead composition of ²⁰⁶Pb/²⁰⁴Pb ₌ 16.819, ²⁰⁷Pb/²⁰⁴Pb = 15.482 and ²⁰⁸Pb/²⁰⁴Pb = 36.490. The intersection is at ∼1140 Ma which correlates well with the duration of the Sveconorwegian orogeny that occurred between ∼1290–1000 Ma and gives μ₂^min of 13.880 and μ₂^max of 14.658 which shows that these values are realistic in terms of what can be expected growth of a LILE-enriched, crustal domain in such a system. Galena from hydrothermal ore at Konnerud has similar lead isotope compositions as in the LPC pegmatites, suggesting an almost purely magmatic source, whereas galena in the Kongsberg silver deposit is more radiogenic, suggesting contamination by Cambrian-Ordovician alum shale.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"508 ","pages":"Article 108079"},"PeriodicalIF":2.9,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143823469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High field strength element systematics of rutile in cratonic eclogites: Evidence for NbTa disequilibrium","authors":"Robert W. Nicklas ,&nbsp;Sonja Aulbach ,&nbsp;Ethan F. Baxter","doi":"10.1016/j.lithos.2025.108080","DOIUrl":"10.1016/j.lithos.2025.108080","url":null,"abstract":"<div><div>Recycled oceanic crust sampled as eclogite xenoliths is an important component of cratonic mantle lithosphere. The high field-strength elements (HFSE: Nb, Ta, Zr, Hf, V… etc.) in eclogite xenoliths have been used to trace processes such as melt depletion and metasomatism, and their importance for terrestrial mass balance has been recognized. The accessory mineral rutile is known to concentrate the HFSE in eclogite. However, it is currently unclear if the HFSE are readily equilibrated between eclogitic minerals even at the high temperatures typical of the cratonic lithosphere. To elucidate this issue, here are reported the HFSE systematics of rutile, garnet, and clinopyroxene in twelve texturally well-equilibrated kimberlite-borne eclogite xenoliths from the Slave and West African cratons. Despite its low modal abundance, rutile is the major host for the HFSE Nb and Ta (&gt;95 % of Nb<img>Ta budgets), while other HFSE such as Zr and Hf are mostly hosted in silicate phases (&gt;60 % of Zr<img>Hf budgets). The redox-sensitive element V behaves compatibly in all major minerals making rutile only a minor host of the V budget in the eclogites (&lt;2 %). Within both rutile and silicate grains in both suites of eclogites, Zr and Hf are homogenized on the xenolith scale, whereas Nb and Ta abundances in rutile in eclogite xenoliths from the Koidu kimberlite, but not from the Diavik kimberlite show very large scatter between analyses. Similarly, within- and inter-sample rutile Nb/Ta ratios vary widely in Koidu samples at 14.9 ± 24.3 to 424 ± 463 (Average of grains per sample; 2SD) while Diavik rutile had Nb/Ta only varying between 15.4 ± 0.6 and 90.7 (single analysis). In contrast, average rutile Zr/Hf ratios in each xenolith are more consistent, with Diavik at 33.3 ± 1.3 to 76.3 ± 9.6 and Koidu at 32.0 ± 1.5 to 55.3 ± 7.9 (Average of grains per sample; 2SD). Additionally, Zr<img>Hf systematics correlate well with indices of melt depletion and metasomatism, indicating equilibrium processes, while the same indices show no correlation with Nb<img>Ta systematics. The range of Nb/Ta in rutile from Koidu eclogites includes strongly supra-chondritic Nb/Ta ratios (&gt; &gt; 100), which are difficult to explain by typical metamorphic or mantle metasomatic processes. These ratios are here tentatively ascribed to differential diffusion of Nb and Ta from a grain-boundary melt. Disequilibrium is preserved if the last metasomatic event is young relative to xenolith entrainment and if ascent is faster than the timescales required for Nb<img>Ta equilibration. Studies using Nb/Ta ratios in rutile-bearing samples as petrogenetic tracers must be careful to reconstruct whole rock signatures from a representative number of rutile grains and must carefully screen for Nb<img>Ta disequilibrium.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"508 ","pages":"Article 108080"},"PeriodicalIF":2.9,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Near-infrared spectral characterization of the abyssal serpentinites and its implications for Martian exploration","authors":"De-Xiang Hong ,&nbsp;Chuan-Zhou Liu ,&nbsp;Hong-Lei Lin ,&nbsp;Alessio Sanfilippo","doi":"10.1016/j.lithos.2025.108077","DOIUrl":"10.1016/j.lithos.2025.108077","url":null,"abstract":"<div><div>Serpentinization processes can produce localized habitable environments and thus serpentinite becomes an important target for Martian exploration. Identification of serpentinite on Mars primarily relies on the detection of characteristics absorption bands in near-infrared spectra, leveraging laboratory data of pure serpentines. However, serpentinites are mixtures of various hydrous minerals produced during serpentinization processes and primary minerals, resulting in complex spectral features. In this study, extensive mineralogical and spectroscopic analyses, including Micro-X-ray fluorescence (μXRF), near-infrared (NIR) spectroscopy, Raman spectroscopy, and scanning electron microscopy (SEM), have been conducted on abyssal serpentinite recovered from the Doldrums Transform Fault at the Mid-Atlantic Ridge (7–8°N). The results show that both orthopyroxene and magnetite in serpentinites have strong influences on serpentine identification using NIR spectroscopy. The absorption feature at 2.12 μm disappears diagnostic for serpentine in the samples containing impure serpentine. Our results call in question the reliance on the presence of 2.12 μm absorption band for detection of serpentine on Mars. In contrast, both sharp absorption at 1.39 μm and asymmetric absorption at 2.32 μm are prevalent in serpentines, even when they are mixed with orthopyroxenes. More importantly, the band depth at 1.39 μm increases with the modal abundance of serpentine and display a strong linear correlation with an R² of 0.82. Although the situation on the unknown Martian surface is more complex, our findings provide a valuable reference for detecting serpentinites using hyperspectral remote sensing data for future exploration on Mars.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"508 ","pages":"Article 108077"},"PeriodicalIF":2.9,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of redox state on chromium isotope fractionation in the mantle: Insights from spinel peridotite xenoliths","authors":"Qiuxia Wang ,&nbsp;Jianping Zheng ,&nbsp;Xianquan Ping ,&nbsp;Hongkun Dai ,&nbsp;Qing Xiong ,&nbsp;Xiangli Wang","doi":"10.1016/j.lithos.2025.108065","DOIUrl":"10.1016/j.lithos.2025.108065","url":null,"abstract":"<div><div>Chromium (Cr) isotope fractionation in the mantle is generally interpreted as induced by mantle processes like partial melting and metasomatism, but the influence of oxygen fugacity remains poorly understood. Here, we report whole-rock and minerals elemental concentrations, minerals Fe³⁺/ΣFe ratios and whole-rock Cr isotope compositions for Late Cretaceous-Cenozoic basalt-borne spinel peridotite xenoliths from the North China Craton (NCC). The results show that the northwest and eastern NCC is underlain by a newly fertile lithospheric mantle (olivine Mg# = 0.89–0.91), while the central NCC retains shallow relics of ancient refractory mantle (olivine Mg# = ∼0.92). The two mantle types show some overlapping in the range of oxygen fugacity (fertile: FMQ-1.61 to FMQ-0.19; refractory: FMQ-0.92 to FMQ + 1.58), but the fertile one (mean FMQ-0.75) tends to be more reduced than the refractory one (mean FMQ + 0.20). Furthermore, the former shows a relatively wide range of Cr isotopic values from −0.27 ± 0.03 ‰ to −0.03 ± 0.04 ‰ than the latter (ẟ⁵³Cr = −0.20 ± 0.06 ‰ to −0.13 ± 0.06 ‰), but the ẟ⁵³Cr values of these peridotites are not correlated with the indices for partial melting (e.g., whole-rock Mg# and Al₂O₃ contents) and metasomatism (e.g., (La/Yb)_N). These lines of observation jointly suggest that the Cr isotope variations may be influenced by the redox state of the lithospheric mantle, and isotope fractionation tends to be restricted under oxidized conditions.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"508 ","pages":"Article 108065"},"PeriodicalIF":2.9,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Testing in-situ UPb garnet geochronology on a polymetamorphic schist from the Grenvillian basement of the Western Sierras Pampeanas, Argentina","authors":"Sebastián O. Verdecchia ,&nbsp;Cesar Casquet ,&nbsp;Richard Albert ,&nbsp;Axel Gerdes ,&nbsp;Edgardo G. Baldo ,&nbsp;Carlos D. Ramacciotti ,&nbsp;Robert J. Pankhurst","doi":"10.1016/j.lithos.2025.108069","DOIUrl":"10.1016/j.lithos.2025.108069","url":null,"abstract":"<div><div>Garnet, a common mineral in metamorphic rocks, frequently records complex textural and chemical zoning resulting from polymetamorphism. Dating metamorphic events using conventional methods (e.g., U<img>Pb zircon or Lu<img>Hf garnet) is challenging and often fails to yield an accurate reconstruction of the <em>P-T-t</em> history in complex metamorphic regions. Recently, a technique has been developed for in situ U<img>Pb LA-ICP-MS dating in garnets with very low concentrations of U and Pb. In this work we tested the method on polymetamorphic garnet from a sample of garnet-biotite schist from the Sierra de Maz (Western Sierras Pampeanas, Argentina). This rock belongs to a Grenvillian-age tectonic unit (nappe) that was reworked by the Famatinian orogeny (Ordovician-Silurian). The garnet porphyroblasts show a complex internal arrangement with three textural and compositional zones: Grt₁ (cores), Grt₂ (replacements) and Grt₃ (overgrowths). Dating of a single porphyroblast yielded ages of 1045 ± 31 Ma for Grt₁ and 476 ± 18 Ma for Grt₂, confirming polymetamorphism resulting from the two main tectono-metamorphic events recorded in the Western Sierras Pampeanas. The garnet core (Grt₁) age is within error of a 1037 ± 7 Ma zircon-rim U<img>Pb age from the same rock. However, garnet (Grt₂) is slightly older than ages recorded by different methods from the same tectonic unit (nappe), that are mostly in the range ca. 440–410 Ma including a CHIME monazite age of 426 ± 15 Ma from the same schist This discrepancy remains open to question, as Ordovician ages of metamorphism of ca. 470 Ma are common elsewhere in the Sierras Pampeanas.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"506 ","pages":"Article 108069"},"PeriodicalIF":2.9,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143748037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intraplate magmatic processes associated with crustal accretion at the West Philippine Basin, Western Pacific","authors":"Long Yuan ,&nbsp;Quanshu Yan ,&nbsp;Xuefa Shi","doi":"10.1016/j.lithos.2025.108068","DOIUrl":"10.1016/j.lithos.2025.108068","url":null,"abstract":"<div><div>The West Philippine Basin (WPB), located in the west half of the Philippine Sea Plate (PSP), experienced the superposition effects of back-arc spreading and intraplate processes. However, the magmatic processes for the intraplate geodynamics are unclear. In this study, we analyzed the major and trace element compositions of the plagioclase and clinopyroxene, and the Sr isotopic composition of the plagioclase in basalts collected from the Benham Rise (Site 292) during DSDP (Deep Sea Drilling Program) Expedition 31 and the off-spreading axis Vinogradov seamount (Site 100DS). The results show that clinopyroxene and plagioclase from the Benham Rise exhibit various disequilibrium characteristics, and their zoned textures were produced by multiple phases of magma replenishment in the magma chamber. The calculated parental magmas for clinopyroxenes in lavas from the Benham Rise and Vinogradov seamount show that they are produced by 10–20 % and 1–5 % partial melting of garnet pyroxenite, respectively. The Sr isotopic composition of plagioclase phenocrysts from the Benham Rise lavas showed that their parental magma could have originated from the same mantle source. The geochemical study of plagioclase and clinopyroxene implies the Benham Rise and Vinogradov seamount could be formed by the head and tail of the Benham mantle plume, respectively.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"506 ","pages":"Article 108068"},"PeriodicalIF":2.9,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Decoding the primary magma composition and petrogenesis of the Neoarchean TTG rocks in the eastern North China Craton","authors":"Ying Chen ,&nbsp;Jian Zhang ,&nbsp;Peng Gao ,&nbsp;Changqing Yin ,&nbsp;Jiahui Qian ,&nbsp;Jin Liu ,&nbsp;Shuhui Zhang ,&nbsp;Xiao Wang ,&nbsp;Changquan Cheng","doi":"10.1016/j.lithos.2025.108063","DOIUrl":"10.1016/j.lithos.2025.108063","url":null,"abstract":"<div><div>The primary magma of Archean tonalite-trondhjemite-granodiorite (TTG) is considered to originate from the partial melting of mafic crust. This process is pivotal for deciphering the formation and evolution of the Archean continental crust. However, defining the TTG primary magma is challenging due to the superposition of magmatic evolution and subsequent geological events. Based on detailed field survey and sampling, and subsequent petrological, geochemical and isotopic analyses, as well as extensive data compilation, we recently identified a suite of TT (tonalite-trondhjemite) rocks in the eastern Hebei region. These rocks are indicative of a primary medium-pressure (MP) TT magma composition. LA-ICP-MS zircon U–Pb dating shows that the TT samples emplaced at 2560–2507 Ma and metamorphosed at 2494–2473 Ma. Geochemically, these TT samples exhibit typical characteristics of MP-type TTG, with moderate SiO₂ (56.1–64.7 wt%) and Al₂O₃ contents (15.5–17.5 wt%), elevated Na₂O contents (4.04–5.17 wt%), low MgO contents (1.03–3.36 wt%), insignificant Eu/Eu* anomalies (0.94–1.1), near-chondritic Nb/Ta ratios (14.8–19.4), homogenous Dy/Yb ratios (2.10–2.75), and low Sr/Y (30.1–105) and (La/Yb)_N (7.45–30.1) ratios. Whole-rock Nd and zircon Hf isotopes indicate that their precursors were extracted from the depleted mantle at 2850–2650 Ma. By combining experimental petrology findings, geochemical data with Ti-in-zircon thermometer calculations, we suggest that these samples most likely originated from the partial melting of the mafic lower crust (ca. 10–12 kbar) in a high-temperature and dry to damp environment, with amphibole, plagioclase, and minor garnet as residual minerals. Their compositions have not been significantly influenced by magmatic mixing, contamination, and fractional crystallization (e.g., plagioclase or amphibole). Amphibole barometer calculations indicate that these MP-type TT magmas may have been emplaced at a mid-crustal depth of 20–26 km. Compared with globally reported TTG primary compositions, we propose that these TT samples can serve as archetypes of MP-type TT primary magma formed by the partial melting of mafic lower crust in the late Neoarchean. They could provide valuable insights in further examining the characteristics and evolution of TTG primary magmas in other ancient cratons globally.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"508 ","pages":"Article 108063"},"PeriodicalIF":2.9,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Timing of subduction along the northern margin of the Siberian craton: Lu-Hf and Sm-Nd isochrons for kimberlite-borne mantle eclogite xenoliths","authors":"Jing Sun ,&nbsp;Sebastian Tappe ,&nbsp;Sergey Kostrovitsky ,&nbsp;Tatiana Kalashnikova ,&nbsp;Sheng-Hua Zhou ,&nbsp;Katie A. Smart","doi":"10.1016/j.lithos.2025.108062","DOIUrl":"10.1016/j.lithos.2025.108062","url":null,"abstract":"<div><div>Eclogitic mantle xenoliths brought up by the ca. 152 Ma old Obnazhennaya kimberlite on the Siberian craton are examples of metamorphosed basaltic oceanic crust, and their formation is commonly attributed to ancient subduction regimes along the northeastern craton margin. In this study, Lu-Hf and Sm-Nd isotope data for clinopyroxene and garnet were obtained for high-MgO and low-MgO eclogite xenoliths from the Obnazhennaya kimberlite. Although the majority of eclogite samples are characterized by equilibrium temperatures higher than the closure temperatures of the Lu-Hf and Sm-Nd isotope systems, they might have experienced rapid cooling and uplift to shallower lithospheric mantle depths, or fast heating immediately prior to kimberlite eruption, without resetting of the isotopic systems. If this assumption is correct, then the mineral pair two-point isochron ages represent a cooling episode during the Proterozoic between 2.2 and 0.8 Ga. The age peak at 1.9 Ga for the Obnazhennaya eclogites falls within the 2.1–1.8 Ga age range for eclogite xenolith suites from cratons worldwide, which supports the evidence for widespread oceanic lithosphere subduction during the Paleoproterozoic. The timing of this global subduction event coincides with the formation of orogenic belts at ca. 1.8 Ga during the final assembly of the Paleoproterozoic Columbia supercontinent, which was completed by 1.6 Ga. Age complexity is revealed by the majority of eclogite samples, which equilibrated close to or above the closure temperatures for the Lu-Hf and Sm-Nd isotope systems. Isochron ages as young as 185 Ma for a single low-MgO eclogite xenolith suggest that these mantle-derived materials resided deep within the Siberian cratonic root, and that radiogenic Hf and Nd only accumulated in the constituent garnet and clinopyroxene after xenolith entrainment into the host kimberlite magma. The presence of garnet exsolution lamellae in clinopyroxene also records protracted cooling, but presents a challenge for producing clean mineral separates in an attempt to obtain robust Lu-Hf and Sm-Nd isochron ages.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"508 ","pages":"Article 108062"},"PeriodicalIF":2.9,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143783628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of giant gold deposits driven by delamination of carbonated cratonic lithosphere","authors":"Meiqing Yao ,&nbsp;Hongjie Wu ,&nbsp;Shuguang Li ,&nbsp;Yanhong Liu ,&nbsp;Sheng-Ao Liu ,&nbsp;Yongsheng He ,&nbsp;Jingao Liu","doi":"10.1016/j.lithos.2025.108070","DOIUrl":"10.1016/j.lithos.2025.108070","url":null,"abstract":"<div><div>Delamination of the thick continental lithosphere of the craton is an important geological process that accounts for the recycling of continental materials. However, links between such a process and the formation of giant ore deposits are controversial. Although a recent study suggests the base of the cratonic lithospheric mantle at depths of 160–190<!--> <!-->km is particularly enriched in sulfur and could be a significant gold reservoir, the mechanisms responsible for gold release are poorly understood. The Jiaodong gold deposits in the eastern North China Craton (NCC) are defined as a giant gold province with approximately 5000 tons of Au. Using new advanced Au analytical technologies, we measured the Au concentrations of 86 samples to determine the Au background values of possible source candidates. The crustal candidates, including Precambrian metamorphic crustal basement (average Au: 0.20 ng/g) and Mesozoic granites (average Au: 0.05 ng/g) from the Jiaodong area, as well as supracrustal rocks from the northern South China Block (SCB) (average Au: 0.12 ng/g), exhibit no discernible Au anomalies. Nevertheless, local mafic dikes, spatiotemporally associated with Au mineralization, exhibit slightly higher Au contents (up to 3.13 ng/g) than other candidates. In-situ laser ablation analyses of S-rich minerals in the mafic dikes reveal heavy sulfur isotopic compositions (δ³⁴S ranging from −3.4 to 17.4 ‰), systematically higher than the mantle value (δ³⁴S = −1.4 ± 0.5 ‰). Since the effects of crustal contamination and sulfide segregation are negligible, the heavy S isotopic compositions of Jiaodong mafic dikes may indicate a potential contribution of heavy sulfur isotopes from marine carbonates or sulfide oxidation in the mantle. The high Fe³⁺/∑Fe values (up to 0.43) of the mafic dikes also indicate derivation from a highly oxidized mantle source. Given that their low δ²⁶Mg values (−0.59 ‰ to −0.24 ‰) have indicated a mantle source partially metasomatized by recycled carbonates, we hypothesize that the reduction of carbonates in deep (&gt;250 km) delaminated cratonic lithosphere may have facilitated the oxidation of sulfides to sulfate, potentially providing a mechanism for the liberation of gold from the mantle.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"506 ","pages":"Article 108070"},"PeriodicalIF":2.9,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two stages of magmatism at the northern edge of Gondwana (SE Iran): New insights into tectono-magmatic evolution from UPb zircon geochronology","authors":"Parisa Gharibnejad ,&nbsp;Wenjiao Xiao ,&nbsp;Zhou Tan ,&nbsp;Jafar Omrani ,&nbsp;Ali Kananian ,&nbsp;Reza Nozaem ,&nbsp;M. Zakaria Pirkhezranian","doi":"10.1016/j.lithos.2025.108066","DOIUrl":"10.1016/j.lithos.2025.108066","url":null,"abstract":"<div><div>The magmatic and geochemical evolution of the Golgohar granitoids in the southern Sanandaj-Sirjan Zone (SE Iran) were investigated through zircon U<img>Pb ages, Hf isotopic analyses, and whole-rock chemistry, providing insights into their petrogenesis and tectonic context. The geochronological results revealed two distinct stages of magmatism: the late Neoproterozoic-early Cambrian (568.4 ± 7.3–535.9 ± 9 Ma) and the late Carboniferous (311.8 ± 5–305.8 ± 3.9 Ma). The Precambrian rocks are predominantly composed of granite, and the late Carboniferous rocks are primarily monzonite; both sheared, deformed and strongly shuffled together. The bulk-rock chemical characteristics of these rocks overlap to some extent, predominantly displaying peraluminous and calc-alkaline signatures with similar element abundances, though with subtle distinctions. Both rock suites show positive anomalies in Cs, Rb, Pb, U, and Th, and negative anomalies in Ba, Eu, Sr, Nb, and Ta, with the late Carboniferous samples exhibiting relatively greater enrichment in Cs, Ba, Sr, and Eu. The Precambrian rocks are characterized by arc-like affinities, whereas the late Carboniferous samples can be categorized as within-plate rocks. Despite the geochemical similarities, the zircon Hf isotopic compositions reflect different source materials. The Precambrian samples mostly yield negative Ɛ_Hf(t) values, with some positive inputs (−6.24 to +17.74) indicating a crustal contribution in their source. In contrast, the late Carboniferous zircon grains show dominant positive Ɛ_Hf(t) values (+5.86 to +12.93), suggesting a juvenile mantle source. The obtained isotopic data and geochemical results correspond the Precambrian rocks to the Prototethyan subduction along the northern edge of Gondwana and plausibly attribute the late Carboniferous samples to the early stages of Neotethyan rifting. The observed uniform geochemical characteristics suggest that the late Carboniferous rocks formed from a hybrid parental magma created by mixing the late Carboniferous mantle-derived melts with the Precambrian crustal materials.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"506 ","pages":"Article 108066"},"PeriodicalIF":2.9,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}