Gondwana Research最新文献

{"title":"Decoding cycling and enrichment of boron and associated lithium in waters of the Tibetan Plateau with boron isotopes","authors":"Yu Zhang ,&nbsp;Hongbing Tan ,&nbsp;Zhiwei Shi ,&nbsp;Fei Xue ,&nbsp;Xiying Zhang ,&nbsp;Huiying Ma","doi":"10.1016/j.gr.2025.02.006","DOIUrl":"10.1016/j.gr.2025.02.006","url":null,"abstract":"<div><div>The Tibetan Plateau (TP), which has various water bodies exhibiting extreme enrichment of boron (B), lithium (Li) and other elements, is a unique and cost-effective supplier of B and Li globally. However, the sources and enrichment mechanisms of these elements remain disputed. Herein, big data on B isotopes and geochemistry were compiled to reveal cycling and enrichment of B and associated Li in the complex mountain-basin systems of the TP. Various water bodies on the TP show remarkably high B and Li concentrations compared with the global average levels. B and Li are supernormally enriched or even mineralized in some salt lakes, oilfield brines, and geothermal systems. Water with high B concentrations exhibits simultaneous ¹¹B depletion. The spatial patterns of B-Li concentrations and δ¹¹B values are characterized by a westward increase and a southward decrease, respectively. The mechanisms of B and Li cycling and enrichment, from source to sink, on the TP can be summarized as follows: 1) Slab subduction and following continental collisions induced partial melting of the mid-lower crust, resulting in late-stage highly differentiated crust-derived magma upwelling and invasion into the mid-upper crust. Hot springs thereby maintain an efficient release of abnormally abundant B and Li from magmatic fluids to the surface through deep geothermal circulation. 2) In the eastern and southeastern TP, Massive degassing of mantle fractions prevails along large strike-slip faults. B and Li enriched from mantle- or crust-derived fluids can reach the surface via local volcanism. 3) Water-rock interaction and weathering trigger further activation, mobilization, and enrichment of B and Li in water. The aforementioned geological processes supply constantly deep-source B and Li to rivers and groundwater as cold-hot springs. Eventually, B and Li are fed into the lake basin jointly with supergene processes; after prolonged evaporation-concentration, excellent B-Li-rich salt lake resources are formed.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 120-134"},"PeriodicalIF":7.2,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A review of Mesozoic geodynamic evolution of the North Makran (SE Iran): A tale of a Neo-Tethyan ocean vanished due to two coexisting subduction zones","authors":"Edoardo Barbero ,&nbsp;Luca Pandolfi ,&nbsp;Morteza Delavari ,&nbsp;Asghar Dolati ,&nbsp;Emilio Saccani ,&nbsp;Maria Di Rosa ,&nbsp;Michele Marroni","doi":"10.1016/j.gr.2025.01.016","DOIUrl":"10.1016/j.gr.2025.01.016","url":null,"abstract":"<div><div>This paper presents a synthesis of the geological features of each tectonic unit of the North Makran (SE Iran), integrating results of multidisciplinary analyses, including structural and stratigraphic studies, petrographic and geochemical analyses, thermobarometric studies, as well as biostratigraphic and geochronological dating. This wealth of data forms the basis for a novel geodynamic model of the Jurassic − Eocene evolution of the Neo-Tethys realm, which evolved between the Arabian Plate and the Lut Block. The features of the North Makran tectonic units support the existence of a mid-ocean ridge setting during the Jurassic – Early Cretaceous. Contrary to previous interpretations, the data from these tectonic units suggests a single oceanic basin separating the Arabian and Lut continental margins, without the interposition of a microcontinental block. In the Early Cretaceous, subduction initiation is recorded by volcanic arc assemblages accommodating the convergence between the Arabian Plate and Lut Block. The nucleation of an intra-oceanic subduction marked the separation of the North Makran Ocean from the Neo-Tethys. The Late Cretaceous was characterized by plume-related magmatism and the onset of the convergence in the North Makran Ocean, inducing its subduction beneath the Lut Block. This subduction is recorded by volcanic arc assemblage and high pressure and low-temperature metamorphism within a subduction complex. Meanwhile, intra-oceanic subduction persisted within the Neo-Tethys, accompanied by a subduction complex and arc magmatism. The final closure of the North Makran Ocean occurred during the Late Cretaceous –Late Paleocene with the progressive amalgamation of the two subduction complexes and the deformation of the interposing oceanic lithosphere. This study suggests that the subduction of a seamount chain in the North Makran Ocean played a key role in the shortening and closure of this basin. This research emphasizes the importance of considering multiple factors in understanding the tectonic evolution of the Neo-Tethys realm.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 74-101"},"PeriodicalIF":7.2,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reactionary interaction of upper mantle minerals with SiC at 6 GPa and 1100–1500 °C: Implication for moissanite appearance in ophiolitic peridotite and other uncommon natural environments","authors":"K.D. Litasov ,&nbsp;A. Shatskiy ,&nbsp;A.V. Arefiev ,&nbsp;H. Kagi","doi":"10.1016/j.gr.2025.02.005","DOIUrl":"10.1016/j.gr.2025.02.005","url":null,"abstract":"<div><div>Experiments were carried out on the interaction of mantle rocks and minerals with SiC at 6 GPa and 1100–1500 °C. Fine powders of natural peridotites and eclogites from kimberlites with the addition of 10 wt% SiC, as well as monomineralic powders and crystals of chromite, olivine, and garnet, were used as starting materials. The experiments were carried out on a 1500-ton multianvil press. In all experiments, the reduction of silicates and chromite was observed with an increase in the magnesium number (Mg#=100 Mg/(Mg + Fe)) of minerals to 97–100 % and the precipitation of metallic phases − alloys in the Fe-Ni and Fe-Si-Cr systems. The most pronounced reactions occurred at 1500 °C. Equilibrium was not reached in all the studied systems even after 72 h of annealing at 1300 °C. Instead, reaction rims were formed on mineral grains and finely dispersed iron alloys were precipitated throughout the volume of crystals. The reaction between SiC and chromite was fastest. The Mg# of chromite changed from 57 (in the initial chromite) to 80–94 %. It was shown that at 6 GPa, SiC reacted quickly with minerals and mantle rocks to form metal phases, high-magnesian silicates, and chromite. This means that they cannot be in equilibrium, as was previously stated for ophiolite peridotite and chromitite, and volcanic rocks such as basalts and kimberlites. The kinetic relationships indicate that a few millimeter grains of SiC can survive in the fluid-free mantle during subduction-exhumation only in cold environments below 700–800 °C. We believe that SiC in most natural rocks is related to anthropogenic contamination. In rare cases, which should be carefully documented, moissanite may have a natural terrestrial origin related to very localized events of formation of highly reduced hydrogen-bearing fluids.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 102-119"},"PeriodicalIF":7.2,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143429079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recent increase in soil moisture levels concerning climate variability in the karst region of southwest China using wavelet coherence and multi-linear regression","authors":"Azfar Hussain ,&nbsp;Huizeng Liu ,&nbsp;Jianhua Cao ,&nbsp;Hui Yang ,&nbsp;Abolfazl Rezaei ,&nbsp;Pei Wang ,&nbsp;Qukan Luo ,&nbsp;Mengxia Zhou ,&nbsp;Zhong Liang","doi":"10.1016/j.gr.2025.02.002","DOIUrl":"10.1016/j.gr.2025.02.002","url":null,"abstract":"<div><div>Classifying climate-induced variations in soil moisture (SM) is vital in the face of climate change to enhance vegetation restoration and decrease rocky desertification in karst areas. In this paper, the Monotonic Mann-Kendall and Sen’s Slope test are used to assess the changes in SM and regional climatic variables from 1981 to 2019 across the karst region of southwest China (KRSC) using the ERA5 SM at 0–7, 7–28 and 28–100 cm. By utilizing wavelet coherence and multi-linear regression (MLR), we assess the association of SM with local climatic factors and teleconnections. Our findings indicate increased SM, NDVI, temperature (TMP), and precipitation (PCP) from 2002 to 2019 in the KRSC. The combined variance of the first and second EOF for 0–7, 7–28, and 28–100 cm showed 55 %, 52 %, and 44 %, respectively. The findings revealed a dominant influence of PCP and sensible heat fluxes (SHF) in SM for 8–120 months (∼1–10 years) periodic cycles, whereas the teleconnections showed consistent patterns in karst and non-karst regions. For integrated factors, PCP + actual evapotranspiration (AET), NDVI + SHF and long-wave radiation (LWR) + SHF showed mean significant coherences between 0.70 and 0.80, whereas ENSO + PDO + NAO (0.71–0.76) explained high coherence in comparison to other combinations. The karst SM showed a significant correlation with PCP (0.63–0.89), LWR (0.59–0.77), and SHF (0.76–0.95), while non-karst exhibited a significant correlation with ENSO (0.07–0.49), PDO (0.16–0.41) and PNA (0.10–0.38) in all seasons. The MLR identified PCP, SHF and LWR as the leading influencing variables in the karst region, whereas PCP and LWR showed more influence in the non-karst region for 0–7 cm. Our findings give valuable insights regarding sustainable SM management to promote vegetation and reduce rocky desertification.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 40-54"},"PeriodicalIF":7.2,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143376839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial and temporal distribution, fate, and potential health risks of microplastics in urban indoor air","authors":"Liyuan Peng ,&nbsp;Na Zheng ,&nbsp;Qirui An ,&nbsp;Xiaoqian Li ,&nbsp;Siyu Sun ,&nbsp;Yunyang Li ,&nbsp;Jingze Yu ,&nbsp;Fan Shao ,&nbsp;Yingxi Qiu ,&nbsp;Shuyue Zhang","doi":"10.1016/j.gr.2025.01.015","DOIUrl":"10.1016/j.gr.2025.01.015","url":null,"abstract":"<div><div>The growing awareness of microplastics (MPs) in indoor residential environments stems from their pervasive presence and potential health risks. MPs were collected from living rooms and bedrooms, and their accumulation in the lungs of residents in three urban cities during summer and winter was assessed. The abundance of MPs at ≤ 2.5 μm and ≤ 10 μm was determined (Changchun: 713 ± 477 and 4239 ± 2420, Xingtai: 1003 ± 726 and 3781 ± 2070, Guangzhou: 492 ± 479 and 2446 ± 903, item/m³/day). Nearly 50 % of the total abundance of MPs discovered in this study were ≤ 10 μm in size. Considerable differences in MPs abundance were observed between summer and winter (<em>p</em> &lt; 0.01). The quantity of MPs in residential settings correlated with lifestyle choices and ventilation time (<em>p</em> &lt; 0.05). Fragments represented the primary shape of MPs (45 % – 68 %), with polyamide (PA; 5 % – 35 %) and polycarbonate (PC; 5 % – 33 %) being the predominant polymers. Indoor uptake of MPs in lungs varied by age group. Adults had the highest intake, followed by teenagers and older individuals, while children had the lowest intake. Children and adults were estimated to intake 530 – 2060 and 1046 – 4068 items/day of MPs, respectively. Additionally, living rooms and bedrooms exhibited medium to extreme hazards according to the pollutant loading index (PLI) and polymer hazard index (PHI) assessments. This study deepens our understanding of MPs pollution in urban indoor air, raises awareness of the health risks to lungs associated with MPs exposure, and provides data to support these findings.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 1-12"},"PeriodicalIF":7.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143372090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pre-Himalayan crustal evolution in the northern margin of India: Implications from zircon U–Pb, Hf and O isotope study of Chhota Shigri granitoids, Himachal Himalaya, Northwest India","authors":"Waikhom Nongdon ,&nbsp;Bidyananda Maibam ,&nbsp;Pankaj Kumar ,&nbsp;Yoann Gréau ,&nbsp;Jasper Berndt ,&nbsp;Stephen Foley ,&nbsp;Atul Kumar Singh ,&nbsp;Deeksha Khandelwal","doi":"10.1016/j.gr.2025.02.001","DOIUrl":"10.1016/j.gr.2025.02.001","url":null,"abstract":"<div><div>A systematic geochemical, geochronological (U−Pb), and isotopic study (Lu−Hf and O) of zircons from the northern margin of India has been carried out to understand the pre-Himalayan crustal evolution along the area. The rocks were characterized as granitoid and yielded two significant age peaks: 1018–715 Ma and 516–476 Ma, with sparse inherited cores of Paleoproterozoic to Archean ages, defining two major magmatic events (Tonian and Cambro-Ordovician) in the NW Himalaya. While Tonian ages are preserved in the zircon cores, the rims and numerous whole grains record the younger Cambro-Ordovician event. The Tonian zircon cores display εHf values ranging from –5.9 to +8.3, indicating both juvenile mantle-derived and recycled crustal sources. The Tonian zircon cores yield single-stage Hf model (T_DM) ages of 1.66–1.19 Ga and δ¹⁸O values of 5.75–10.88‰, suggesting that Tonian granitoids formed from mixed sources comprising juvenile material, recycled ancient crust and δ¹⁸O-rich supracrustal components. The Cambro-Ordovician zircons yielded εHf values from –27.4 to –4.0 and single-stage Hf model (T_DM) ages of 2.16–1.21 Ga, demonstrating extensive reworking of both Neoproterozoic crust and ancient crust occurred during the Cambro-Ordovician magmatism. Their elevated δ¹⁸O values (8.05–11.35‰) further support widespread crustal remelting with substantial incorporation of δ¹⁸O-rich supracrustal materials. These evidence the preservation of supercontinent (Rodinia) components within the NW Himalaya.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 55-73"},"PeriodicalIF":7.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 Ediacaran Enigma: Gondwana paleogeography revisited through a provenance study of the Salt Range Formation (Salt Range, western Himalayas, Pakistan)","authors":"Waseem Khan ,&nbsp;Licheng Wang ,&nbsp;Eduardo Garzanti ,&nbsp;Salman Ahmed Khattak ,&nbsp;Abdus Saboor ,&nbsp;Heng Peng ,&nbsp;Lin Ding","doi":"10.1016/j.gr.2025.02.004","DOIUrl":"10.1016/j.gr.2025.02.004","url":null,"abstract":"<div><div>The relative positioning of the different fragments of Gondwana prior to its amalgamation remains controversial, and geological research from the Ediacaran Salt Range Formation (SRF) in the Pakistan Himalayas, which may help to solve this issue has been limited. An integrated approach including petrography, U-Pb zircon geochronology, and Hf isotopic analyses was needed to provide information about the depositional age, provenance, tectonic setting, regional correlation, and paleogeographic position of the SRF within the Gondwana supercontinent. SRF sandstones range from feldspatho-litho-quartzose to quartz-rich litho-quartzose. Detrital zircon U-Pb results reveal an Ediacaran (&lt;551) maximum depositional age of the SRF, with major age clusters at 2550–2450 Ma, 1970–1800 Ma, 1050–900 Ma, 900–700 Ma, 695–542 and both positive (52 %) and negative (48 %) εHf(t) values, indicating juvenile and recycle of both eastern (Indian Shield) and western (Arabian Nubian Shield) Gondwana terranes. Zircon-age peaks at 900–700 Ma, and 695–542 Ma, suggesting provenance from the Malani igneous suite, Oman, Madagascar, Seychelles and from the Pan-African belt include Arabian-Nubian shield and Iran, respectively. The SRF displays lithological, biogeographic, geochronological, and provenance similarities with coeval formations in Oman, India, and the Yangtze Block of South China, indicating that the SRF was deposited onto a carbonate-evaporite platform during the collision of eastern (Indian Shield) and western (Arabian Nubian Shield Gondwana. We suggest that the western Himalayas were positioned on the northern margin of Indian Shield during the Ediacaran and provide a revised paleogeographic framework for the tectonic evolution during the amalgamation of the Gondwana supercontinent.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"140 ","pages":"Pages 244-263"},"PeriodicalIF":7.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ecological carrying capacity evaluation from the perspective of social-ecological coupling in the Qilian Mountains, northwest China","authors":"Qinqin Du,&nbsp;Qingzheng Wang,&nbsp;Qingyu Guan,&nbsp;Yunfan Sun,&nbsp;Lushuang Liang,&nbsp;Ninghui Pan,&nbsp;Yunrui Ma,&nbsp;Huichun Li","doi":"10.1016/j.gr.2025.01.013","DOIUrl":"10.1016/j.gr.2025.01.013","url":null,"abstract":"<div><div>With population growth and rapid socio-economic development, mountainous areas are facing significant challenges in terms of their ecological environment. The ecological carrying capacity (ECC) serves as a key indicator for assessing the social, economic, and ecological sustainability of a region. Exploring the spatial and temporal changes in ECC can enhance our understanding of ecological transformations in mountainous areas. It also provides a comprehensive reference for evaluating ecological management and restoration efforts, as well as for studying overall environmental sustainability. In this study, we focused on the Qilian Mountains (QLMs), a representative alpine mountainous region, and established a composite, multi-perspective coupled ECC evaluation index system. By integrating remote sensing (RS) data and geographic information system (GIS) technology, we quantitatively analyzed the spatial heterogeneity of ECC in the QLMs using the fuzzy analytic hierarchy process (FAHP) and entropy weight method. The results showed that from 2000 to 2018, the ECC in the QLMs exhibited a spatial distribution pattern characterized by high values in the southeast and low values in the northwest. Regions with bad and medium ECC dominated, accounting for over 69% of the total area, and their gravity centers shifted towards the northwest. Approximately 85% of the regions showed an increasing trend in ECC, primarily located in the western and southern parts of the QLMs, indicating a gradual improvement in the state of the ecology and environment. However, continuous ecological control and management are still necessary in the western and northeastern regions of the QLMs. In conclusion, these findings provide valuable insights for safeguarding ecological environment security and promoting green development in the QLMs.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 26-39"},"PeriodicalIF":7.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143376838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoposition and initial rifting of the Yangtze Block in Columbia Supercontinent: Discovery of Paleo- and Mesoproterozoic metasediments in the Ailaoshan Metamorphic Belt","authors":"Jing Chen ,&nbsp;Dapeng Li ,&nbsp;Jiarun Tu ,&nbsp;Jifeng Xu ,&nbsp;Huan Kang ,&nbsp;Jianzhen Geng ,&nbsp;Benyan Xu ,&nbsp;Chao Zhang ,&nbsp;Dongping Wang","doi":"10.1016/j.gr.2025.01.014","DOIUrl":"10.1016/j.gr.2025.01.014","url":null,"abstract":"<div><div>Supercontinent cycle is one of the most spectacular processes that govern the assembly and dispersion of continental blocks globally and drives intensive crustal-mantle interactions. Numerous magmatic and sedimentary records documented the involvement of the Yangtze Block and the Ailaoshan Metamorphic Belt (AMB) to the southwest in the Precambrian supercontinent cycles (i.e., Columbia and Rodinia). However, the paleoposition and geodynamic processes of the Yangtze Block in the Columbia cycle remain controversial. Moreover, whether and how the AMB participated in the Precambrian Columbia and Rodinia cycles remain largely disputed. In this paper, we report the first identification of the Paleoproterozoic-Mesoproterozoic <em>meta</em>-sediments within the AMB that was intruded by Neoproterozoic magmatic rocks locally. This provides a prime opportunity to resolve the above issues through sedimentary correlation and comparison. Our comprehensive zircon trace element and U-Pb-Lu-Hf isotopic study on these <em>meta</em>-sediments in the AMB allow us to reach the following conclusions. The youngest magmatic zircon age populations indicate these <em>meta</em>-sediments deposited during the Paleo- to Mesoproterozoic. Therefore, they are the oldest geological records in the AMB that have ever been reported. These Paleo- and Mesoproterozoic <em>meta</em>-sediments in the AMB share uniform zircon U-Pb age peaks at ∼ 2.3 Ga and 1.85 Ga. Circa 1.6–1.4 Ga age population and an increase of the ca. 2.5 Ga population are also detected in the Mesoproterozoic sample. These <em>meta</em>-sediments in the AMB could be most plausibly interpreted as the southwestward extension of the contemporaneous depositions in the SW Yangtze Block given their identical depositional ages, age distribution pattern, and source areas with concurrent strata in the SW Yangtze Block. Accordingly, the Neoproterozoic magmatic rocks in the AMB should document the southward extension of the supra-subduction zone along the northern to western margin of the Yangtze Block. Lines of evidence reveal that the SW Yangtze Block and the NW Laurentia shared an adjacent paleoposition in Columbia. Changes of detrital zircon <em>ε</em>_Hf(<em>t</em>) values, Eu/Eu* and ¹⁷⁶Lu/¹⁷⁷Hf ratios trends through time support the onset of an extensional tectonic at 1.75 Ga in the SW Yangtze Block. Matched magmatic and sedimentary records documented the onset of early rifting processes at 1.75 Ga in the SW Yangtze Block and the NW Laurentia during the breakup of Columbia.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"141 ","pages":"Pages 13-25"},"PeriodicalIF":7.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143376837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Granitoid genesis and related rare metal mineralization of the Shihuiyao Rb–Ta–Nb deposit in the Southern Great Xing’an Range, NE China","authors":"Shi-Heng Bai ,&nbsp;Yu Huang ,&nbsp;Zhi-Jie Feng ,&nbsp;Matthew J. Brzozowski ,&nbsp;Yao-Hui Jiang ,&nbsp;Ru-Xiong Lei ,&nbsp;Chang-Zhi Wu","doi":"10.1016/j.gr.2025.02.003","DOIUrl":"10.1016/j.gr.2025.02.003","url":null,"abstract":"<div><div>The Shihuiyao deposit, located in the southern Great Xing’an Range (SGXR) in China, is an important Rb–Ta–Nb polymetallic deposit hosted by Li–F-bearing granites in the eastern portion of the Central Asian Orogenic Belt. However, its emplacement history and petrogenesis, and mechanisms of rare metal enrichment remain controversial. This study presents a systemic petrographic, geochronological, mineralogical, and geochemical study on mineralized amazonite-bearing albitized granite, albitized granite, and greisen, as well as barren biotite granite in the Shihuiyao deposit. Uranium–Pb geochronological results for zircon, columbite-group minerals, and cassiterite demonstrate that both emplacement and mineralization occurred between ca. 145–140 Ma. The high TE_1,3 values, and low Zr/Hf and Nb/Ta ratios of the biotite granite suggest that it crystallized from a highly evolved magma. Based on the late-stage crystallization of Fe-rich biotite, the depleted ε_Hf(t) values of zircon (+6.5 to + 8.3), and the elevated bulk-rock F and alkali contents, it is inferred that the parental magma to the biotite granite originated from the partial melting of residual granulite-facies rocks within the lower crust. The distinct Zr/Hf, K/Rb, and Y/Ho ratios of barren and fertile granitoids suggest that they evolved independently as these ratios typically vary continuously within a magmatic system. The presence of snowball quartz, fluorite, and topaz suggest that the mineralized granites formed within a magmatic–hydrothermal system enriched in Na, F, and H₂O. Such a Na-, F-, and volatile-rich melt (represented by the magma parental to the ore-bearing granitoids) would have separated from a conventional silicate melt (represented by the magma parental to the biotite granite), generating a scenario in which two immiscible silicate melts were present (melt-melt immiscibility). The increasing bulk-rock concentration of Rb, Ta, and Nb from the barren biotite granite to the fertile (amazonite-bearing) albitized granite indicates that melt–melt immiscible processes led to a significant enrichment of rare metals.</div></div>","PeriodicalId":12761,"journal":{"name":"Gondwana Research","volume":"140 ","pages":"Pages 264-278"},"PeriodicalIF":7.2,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143379387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}