IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-05 DOI: 10.1016/j.lithos.2025.108363

Pradip Kumar Singh , Ajay Kumar , Balaram Sahoo , Kumar Batuk Joshi , Sanjiv Kumar , Debajyoti Paul , Elson P. Oliveira , Dakshita , Vinod Kumar Singh , Arvind Kumar Gond , Archana Nikita Kispotta , Ishwar Chandra Rahi , Ramesh Chandra Patel

We present an integrated study combining field observations, petrography, mineral chemistry, whole-rock geochemistry, of tonalite–trondhjemite–granodiorites (TTGs), sanukitoids, high-K granitoids and U-Pb geochronology of a high-K granitoid from the Madawara domain, Southern Bundelkhand Craton. Zircon of a high-K granitoid yields a U–Pb emplacement age of 2.47 Ga, marking the terminal phase of Archean magmatism as well as crustal stabilization in the craton. The TTGs exhibit adakitic signatures with low to moderate Sr/Y (8–88) and (La/Yb)_CN (15–30) consistent with garnet-amphibolite melting, while negative Eu anomalies suggest plagioclase fractionation or residual source effects.

This study provides the first account of sanukitoids from the southern Bundelkhand Craton, revealing their limited occurrence and highlighting their association with shear zones and granite–greenstone sequences in the Madawara domain. The low-Ti sanukitoids (TiO₂ = 0.59–0.63 wt%) display a hybrid mantle-crustal affinity, with elevated Mg# (60–66), Ba+Sr (1198–1261), Cr-Ni-V concentrations, indicative of metasomatized mantle sources. The results support a model of TTG melt-peridotite interaction followed by shallow-level homogenization. Their sporadic distribution suggests formation in a microplate tectonic regime with warm, shallow subduction. The high-K granitoids (SiO₂ = 72–75 wt%) are characterized by low Mg# (16–31), Sr (9–123 ppm) with pronounced negative Eu and Ti anomalies, indicating a purely crustal origin. They also display enriched light rare earth elements, sharp negative Eu anomalies, and relatively flat heavy rare earth elements patterns, consistent with A-type granite characteristics. Our findings bridge the compositional gap between TTGs and high-K granites, documenting the transition from primitive Archean geodynamics to modern-style plate interactions. This study advances the petrogenetic framework for late-Archean granitoids, offering new insights into crust-mantle processes during craton stabilization.

本文综合野外观测、岩石学、矿物化学、全岩地球化学等资料，对南本德尔坎德克拉通Madawara域高钾花岗岩（TTGs）、sanukitoids、高钾花岗岩及U-Pb年代学进行了综合研究。高钾花岗岩类锆石的U-Pb侵位年龄为2.47 Ga，标志着太古宙岩浆活动末期和克拉通地壳稳定。TTGs表现出低至中等Sr/Y（8-88）和（La/Yb）CN（15-30）特征，与石榴石-角闪石熔融相一致，而负Eu异常表明斜长石分馏或残留源效应。本研究首次记录了南本德尔坎德克拉通的sanukitoids，揭示了其有限的产状，并强调了其与Madawara域剪切带和花岗岩-绿岩层序的联系。低钛类岩浆岩（TiO2 = 0.59 ~ 0.63 wt%）表现出混合的地幔-地壳亲和关系，Mg#（60 ~ 66）、Ba+Sr（1198 ~ 1261）、Cr-Ni-V浓度升高，表明地幔源具有交代作用。结果支持TTG熔体-橄榄岩相互作用，然后是浅层均质化的模型。它们的零星分布表明形成于一个温暖的浅俯冲的微板块构造体系。高钾花岗岩类（SiO2 = 72 ~ 75 wt%）具有低Mg#（16 ~ 31）、Sr （9 ~ 123 ppm）、明显的Eu、Ti负异常等特征，表明纯地壳成因。轻稀土元素富集，Eu负异常明显，重稀土元素格局相对平坦，符合a型花岗岩特征。我们的发现弥补了ttg和高钾花岗岩之间的成分差距，记录了从原始太古代地球动力学到现代板块相互作用的转变。该研究提出了晚太古代花岗岩类的岩石成因框架，为克拉通稳定过程中的壳幔过程提供了新的认识。

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引用次数: 0

Evidence of heterogeneity in the mantle source of Quaternary Naozhou Island basalts from REEs and Sr-Nd-Pb isotopes 从稀土和Sr-Nd-Pb同位素看第四系脑洲岛玄武岩幔源非均质性

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-05 DOI: 10.1016/j.lithos.2025.108372

Cui Xiao-Ge , Li Zhi-Hua , Xie Shi-Xiong , Yang Wen-Jian , Wang Ming-Qiu , Cheng Liu-San , Gao Cai-Xia , Jiang Hong-Liang

Integrated studies of trace-element and isotopic compositions in basalts can be used to investigate the mantle source heterogeneity and constrain the magma compositions of ocean-island basalt (OIB) -type basalts. In this study, we analyze the major and trace elements in the Naozhou Island basalts and present new Sr-Nd-Pb isotopic data to identify the recycled materials in the source and elucidate the origin of the basalts. Quaternary basalts from the Naozhou Island are predominantly tholeiitic. The Sr, Nd, and Pb isotopic compositions clustered around the depleted mantle (DM)- enriched mantle II (EM2) mixing trends indicate that the Naozhou Island basalts originated from a mixed source involving DM and EM2 components. Comparisons of major and trace element parameters (e.g., FeO/CaO − 3 × MgO/SiO₂ (FC3MS) values, Zn/Fe and Zn/Mn ratios), as well as CaO contents in estimated primary magma with experimental peridotite melt suggest that the source lithologies in this region necessitate contributions from both silica-deficient pyroxenite and peridotite. The Naozhou Island basalts exhibit elevated Sr_N/Sr* (>1) and Eu_CHUR/Eu* (>1) ratios, and the (Th/Nb)_N and ²⁰⁷Pb/²⁰⁴Pb values surpass those of the igneous oceanic crust (IOC), indicating the presence of recycled oceanic crust (ROC) and recycled sediment (RS) in their source. Quantitative NdPb isotopic mixing model suggests that the mantle source heterogeneity recorded in the Naozhou Island basalts requires the involvement of three mantle end-members: DM, ROC, and a small amount of RS. A rare earth element (REE) modeling method applied in this study shows that the (La/Sm)_N and (Dy/Yb)_N ratios of the Naozhou Island basalts can be generated by mixing of peridotite-derived melts (F ≈ 0–1 %) and pyroxenite-derived melts (F ≈ 20–25 %). Our findings provide insights into the role of recycled materials in mantle heterogeneity of the Naozhou Island basalts, the REE modeling method further offers trace-element constraints on magma compositions, which are applicable not only to the Naozhou Island basalts but also to basalts throughout the Leiqiong Volcanic Area.

玄武岩中微量元素和同位素组成的综合研究可用于研究海岛玄武岩（OIB）型玄武岩的地幔源非均质性和约束岩浆组成。本文对州岛玄武岩进行了主微量元素分析，并提出了新的Sr-Nd-Pb同位素数据，以识别源区中的再生物质，阐明玄武岩的成因。本州岛第四纪玄武岩以拉斑岩为主。Sr、Nd和Pb同位素组成聚集在贫地幔(DM)-富地幔II （EM2）混合趋势周围，表明本州岛玄武岩的源源是DM和EM2组分的混合源。与实验橄榄岩熔体对比的原生岩浆主微量元素参数（FeO/CaO−3 × MgO/SiO2 （FC3MS）值、Zn/Fe和Zn/Mn比值）和CaO含量表明，该地区的烃源岩既有缺硅辉石岩，也有缺硅橄榄岩。州岛玄武岩SrN/Sr* (>1)和EuCHUR/Eu* (>1)比值升高，（Th/Nb）N和207Pb/204Pb值超过火成岩洋壳（IOC）值，表明源区存在再循环洋壳（ROC）和再循环沉积（RS）。定量NdPb同位素混合模型表明，州岛玄武岩的地幔源非均质性需要3个地幔端元的参与：DM、ROC和少量RS。本文应用稀土元素（REE）模拟方法表明，州岛玄武岩的（La/Sm）N和（Dy/Yb）N比值可以由橄榄岩衍生熔体（F≈0 ~ 1%）和辉石岩衍生熔体（F≈20 ~ 25%）混合产生。研究结果揭示了回收物质在脑洲玄武岩地幔非均质性中的作用，稀土元素模拟方法进一步提供了岩浆组成的微量元素约束，不仅适用于脑洲玄武岩，也适用于雷琼火山区的玄武岩。

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引用次数: 0

Late Cretaceous granitic magmatism and W-Sn mineralization in Northeast Vietnam: similarity and differences with SW South China 越南东北部晚白垩世花岗岩岩浆作用与钨锡成矿作用：与华南西南部的异同

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-04 DOI: 10.1016/j.lithos.2025.108362

DinhLuyen Nguyen , Rucheng Wang , Jinhai Yu , Xiao-Lei Wang , TrungHieu Pham , Truong Xuan Le , Lang Xia , VanNam Pham

Northeast Vietnam hosts Late Cretaceous granitic magmatism and genetically related W-Sn mineralization. Detailed zircon U-Pb analyses indicate that the Thien Ke granites were formed at 89–87 Ma and the Da Lien granites formed at 89–88 Ma, making them synchronous with the Pia Oac granites in NE Vietnam and numerous Late Cretaceous granites in Southwest South China. Cassiterite U-Pb dating constrains a later mineralization age of ∼82 Ma for Thien Ke W deposit, implying ca 5–7 Myr evolution from high-temperature magmatism to low-temperature mineralization. In contrast, the formation of the Nui Phao W-polymetallic deposit was nearly synchronous with the intrusion of the Da Lien granite, consistent with high-temperature mineralization. These granites have high A/CNK (>1.1), K₂O/Na₂O, Rb/Sr and Rb/Ba, low CaO/Na₂O ratios (<0.3) and variable zircon Hf isotopic compositions (Ԑ_Hf(t) = −6.0 to −14.2), characteristic of S-type granites. Integrating the geochemical and Hf-isotope compositions of the basement metamorphic rocks confirms that Late Cretaceous granites in NE Vietnam originated from partial melting of Neoproterozoic metapelitic sedimentary rocks. Although the Late Cretaceous granites in NE Vietnam have similar S-type granitic geochemistry, crystallization ages and associated rare-metal deposits to those in SW South China, the latter exhibit greater bulk-compositional complexity, extended formation durations and contrasting deposit types. Late Cretaceous granites in NE Vietnam are generally associated with W-polymetallic mineralization, whereas those in SW South China are associated with giant Sn-polymetallic mineralization. The differences in deposit type between the two regions are attributed to the different Sn and W abundances and rock types (pelitic/psammitic) of their sources and different melting conditions. The high-temperature melting of psammitic sources with high Sn abundances in SW South China generated Sn-rich magmas, whereas low-temperature melting of pelitic sources with high W abundances in NE Vietnam led to the production of W-rich melts.

越南东北部发育晚白垩世花岗岩岩浆活动和与成矿有关的钨锡成矿作用。详细的锆石U-Pb分析表明，天克花岗岩形成于89 ~ 87 Ma，大连花岗岩形成于89 ~ 88 Ma，与越南东北部的Pia Oac花岗岩和华南西南部的大量晚白垩世花岗岩同步。锡石U-Pb定年限制了天克钨矿的成矿年龄（~ 82 Ma），暗示其由高温岩浆作用向低温成矿作用演化约5-7 Myr。Nui hao钨多金属矿床的形成与大连山花岗岩的侵入几乎同步，与高温成矿作用一致。A/CNK （>1.1）、K2O/Na2O、Rb/Sr和Rb/Ba较高，CaO/Na2O比值较低（<0.3），锆石Hf同位素组成变化较大（ԐHf(t) =−6.0 ~−14.2），具有s型花岗岩的特征。综合基底变质岩的地球化学和hf同位素组成，证实越南东北部晚白垩世花岗岩起源于新元古代变质岩的部分熔融。越南东北部晚白垩世花岗岩具有与华南西南部相似的s型花岗岩地球化学特征、结晶年龄和相关的稀有金属矿床，但后者具有更大的体成分复杂性、更长的形成时间和不同的矿床类型。越南东北部晚白垩世花岗岩一般与w多金属成矿作用有关，而华南西南部花岗岩则与巨大的sn多金属成矿作用有关。矿床类型的差异主要是由于锡、钨丰度、源岩类型（泥质/砂质）的不同和熔融条件的不同所致。华南西南部高锡丰度泥质源高温熔融生成富锡岩浆，越南东北部高W丰度泥质源低温熔融生成富W熔体。

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引用次数: 0

Equilibrium tellurium isotope fractionation in tellurides: A first-principles study 碲化物中平衡碲同位素分馏：第一性原理研究

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-04 DOI: 10.1016/j.lithos.2025.108355

Jiaxin Liang , Yang Zhao , Huiquan Tian , Shanqi Liu , Yongbing Li

Tellurium is a critical metal that is highly concentrated in tellurides, which also serve as important hosts of gold, silver, and platinum-group elements. Understanding the stable isotopic behavior of Te in tellurides is crucial not only for elucidating the formation and evolution of Te-bearing hydrothermal ore systems but also for constraining the genetic mechanisms of gold deposits. However, Te isotope fractionation in tellurides remains poorly characterized and inadequately understood. In this study, first-principles calculations were used to determine Te isotope fractionation between tellurides and native tellurium. The reduced partition function ratios of ¹³⁰Te/¹²⁵Te are found to decrease in the following order: frohbergite (FeTe₂) > mattagamite (CoTe₂) > vulcanite (CuTe) > pampaloite (AuSbTe) > petzite (Ag₃AuTe₂) > melonite (NiTe₂) > sylvanite (AuAgTe₄) ≥ coloradoite (HgTe) ≥ stützite (Ag₅Te₃) > krennerite (Au₃AgTe₈) > hessite (Ag₂Te) > calaverite (AuTe₂) ≥ montbrayite (Au₂Te₃) > tellurantimony (Sb₂Te₃) ≥ skippenite (Bi₂Se₂Te) ≥ Joséite-A (Bi₄TeS₂) > tellurobismuthite (Bi₂Te₃) > native tellurium ≥ tsumoite (BiTe) > altaite (PbTe). The β₁₃₀_–₁₂₅ factors of tellurides show a weak correlation with Te coordination number, but they exhibit a negative correlation with the average length of chemical bonds formed by Te when minerals are grouped by Te coordination number and oxidation state. Our results provide a theoretical basis for determining whether isotopic equilibrium has been achieved in natural samples and enable more accurate interpretations of variations in Te isotopic compositions. This, in turn, advances our understanding of the formation and evolution of gold-telluride deposits.

碲是一种重要的金属，高度集中在碲化物中，碲化物也是金、银和铂族元素的重要宿主。了解碲化物中Te的稳定同位素行为，不仅对阐明含Te热液矿系的形成与演化具有重要意义，而且对制约金矿床的成因机制具有重要意义。然而，碲化物中Te同位素分馏的特征仍然很差，认识也不充分。在这项研究中，第一性原理计算用于确定碲化物和天然碲之间的Te同位素分馏。130Te/125Te的减配函数比依次减小：闪辉石（FeTe2） >；麦辉石（CoTe2） >；火山石（CuTe） >；棕长石（AuSbTe） >；贝氏石（Ag3AuTe2） >；麦氏石（NiTe2） >；褐煤（AuAgTe4） >；硅长石（AuAgTe4） >；钙长石（AuAgTe4） >；钙长石（augte） >；钙长石（au2te2） >；钙长石（au2te2） >；碲锑(Sb2Te3)≥闪辉石（Bi2Se2Te） >；碲锑(Sb2Te3)≥闪辉石（bi2tes2） >；碲化物的β130 ~ 125因子与Te配位数呈弱相关，而与Te配位数和氧化态分组时Te形成的平均化学键长度呈负相关。我们的结果为确定自然样品是否达到同位素平衡提供了理论基础，并能够更准确地解释Te同位素组成的变化。这反过来又促进了我们对碲化金矿床的形成和演化的理解。

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引用次数: 0

Pressure-temperature stability and equation of state of staurolite: Implications for the water transport during cold slab subduction 沸石的压力-温度稳定性和状态方程：对冷板块俯冲过程中水输运的启示

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-03 DOI: 10.1016/j.lithos.2025.108361

Shijie Huang , Jingui Xu , Dongzhou Zhang , Shanrong Zhang , Yufeng Liu , Yikui Liang , Zimo Li , Wenge Zhou , Dawei Fan

The stability and thermal equation of state (EoS) of synthetic staurolite were investigated under high pressure and temperature (P–T) conditions up to ∼23 GPa and 850 K. no phase transition was observed within the experimental P–T range. The thermal EoS parameters, including the bulk modulus, pressure and temperature derivatives, and thermal expansion coefficient, were determined by fitting the pressure–volume–temperature data to high-temperature third-order Birch–Murnaghan EoS. Integrating the results of this study with those of previous studies led to an updated P–T phase diagram for staurolite. This diagram suggests that staurolite may have potential metastability extending to the depth of the Earth's mantle. The density and bulk sound velocity profiles along the Tonga slab geotherm indicate that staurolite could serve as an effective water carrier to sub-arc mantle depths. Notably, staurolite exhibits higher bulk sound velocities than most hydrous minerals do, implying that its presence in medium- to high-pressure metamorphic rocks may increase seismic velocities in corresponding lithologies.

在高达~ 23 GPa和850 k的高压和高温（P-T）条件下，研究了合成橄榄石的稳定性和热态方程（EoS），在实验P-T范围内未观察到相变。通过将压力-体积-温度数据拟合到高温三阶Birch-Murnaghan方程中，确定了热方程参数，包括体积模量、压力和温度导数以及热膨胀系数。将本研究的结果与先前的研究结果相结合，得出了一个更新的锆石P-T相图。这张图表明，橄榄石可能具有潜在的亚稳性，延伸到地幔的深处。汤加板块地热密度和整体声速剖面表明，锆石可以作为弧下地幔深度的有效水载体。值得注意的是，相较于大多数含水矿物，星橄榄石表现出更高的体声速，这意味着它在中高压变质岩中的存在可能会增加相应岩性的地震速度。

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引用次数: 0

The Vitória dike swarm – A key piece in the puzzle of low-Ti tholeiitic magmatism of the South Atlantic Magmatic Province Vitória岩脉群-南大西洋岩浆省低钛拉斑岩浆活动之谜的关键部分

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-03 DOI: 10.1016/j.lithos.2025.108360

Antomat A. Macêdo Filho , Valdecir A. Janasi , Alisson L. Oliveira , Elton L. Dantas , Dawid Szymanowski , Lucas M. Lino , Mário Neto Cavalcanti de Araújo , Maria Helena Hollanda

During the Early Cretaceous, widespread tectono-magmatic activity along the South Atlantic Rift System led to the development of a complex system of sedimentary basins accompanied by basaltic, silicic, and alkaline magmatism. In the northern Mantiqueira Province (Espírito Santo, Brazil), the Vitória–Ecoporanga belt marks an intensely fractured/faulted NW–SE structural belt that hosts the Vitória dikes, representing the northernmost mafic dike swarm of the Paraná–Etendeka Magmatic Province (PEMP). The dikes are microgabbros composed of plagioclase, clinopyroxene, and FeTi oxides, with MgO contents of 3.8–7.2 wt% and total alkalis of 2.4–4.8 wt%, consistent with subalkaline/tholeiitic basaltic compositions. They display enrichment in large-ion lithophile elements and pronounced negative NbTa anomalies relative to Rb, Ba, U, Th, K, La, Ce, and Pb. Isotopic compositions show variable ⁸⁷Sr/⁸⁶Sr_(i) (0.70575–0.70994), εNd_(i) (−11.4 to −0.95), and heterogeneous Pb isotopic ratios (²⁰⁶Pb/²⁰⁴Pb = 16.7–18.2; ²⁰⁷Pb/²⁰⁴Pb = 15.4–15.6; ²⁰⁸Pb/²⁰⁴Pb = 37.6–38.9). KAr and ⁴⁰Ar/³⁹Ar data constrain the emplacement to the Early Cretaceous. Comparative geochemical, isotopic, and geochronological data reveal strong affinities between the Vitória and Riacho do Cordeiro dikes of the Equatorial Atlantic Magmatic Province (EQUAMP). These similarities indicate that both systems share a common evolutionary history, representing remnants of a possibly interconnected low-Ti tholeiitic magma plumbing system active during the early stages of West Gondwana breakup. Comparable compositional affinities are also recognized in other low-Ti tholeiites across the PEMP and EQUAMP. Collectively, this transcontinental low-Ti tholeiitic event represents the earliest stage of the South Atlantic Magmatic Province (SAMP).

在早白垩世，沿南大西洋裂谷系广泛的构造岩浆活动导致了一个复杂的沉积盆地体系的发展，伴随着玄武岩、硅质和碱性岩浆作用。在Mantiqueira省北部（Espírito Santo, Brazil）， Vitória-Ecoporanga带标志着一个强烈断裂/断裂的NW-SE构造带，其中包含Vitória岩脉，代表了Paraná-Etendeka岩浆省（PEMP）最北端的基性岩脉群。岩脉为由斜长石、斜辉石和FeTi氧化物组成的微辉长岩，MgO含量为3.8 ~ 7.2 wt%，总碱度为2.4 ~ 4.8 wt%，与亚碱性/拉斑玄武岩成分一致。大离子亲石元素富集，NbTa相对Rb、Ba、U、Th、K、La、Ce、Pb呈负异常。同位素组成表现为87Sr/86Sr(i)（0.70575 ~ 0.70994）、εNd(i)（- 11.4 ~ - 0.95）和非均质Pb同位素比值（206Pb/204Pb = 16.7 ~ 18.2、207Pb/204Pb = 15.4 ~ 15.6、208Pb/204Pb = 37.6 ~ 38.9）。KAr和40Ar/39Ar资料限定其侵位在早白垩世。对比地球化学、同位素和地质年代学数据显示，Vitória和赤道大西洋岩浆省（EQUAMP）的Riacho do Cordeiro岩脉之间具有很强的亲和力。这些相似性表明，这两个系统具有共同的进化史，代表了在西冈瓦纳破裂早期活跃的可能相互连接的低钛拉斑岩浆管道系统的残余。在PEMP和EQUAMP的其他低钛拉斑岩中也发现了类似的成分亲和力。总的来说，这个横贯大陆的低钛拉斑事件代表了南大西洋岩浆省（SAMP）的最早阶段。

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引用次数: 0

Petrogenesis of early Paleozoic mafic rocks in the North Qaidam, NW China: Evidence for lithosphere–asthenosphere interaction in continental arc–back-arc settings 柴达木北部早古生代基性岩的岩石成因：大陆弧-弧后背景下岩石圈-软流圈相互作用的证据

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-02 DOI: 10.1016/j.lithos.2025.108359

Lei Wang , Manlan Niu , Xiucai Li , Chen Li , Zhen Yan , Hang Liu , Zhe Heng , Taichang Zhu

The North Qaidam tectonic belt preserves a series of Early Paleozoic syn-subduction continental arc mafic rocks that provide key insights into the compositional evolution of mantle sources within the overlying mantle wedge. Herein, we present an integrated petrographic, geochronological, and geochemical study of gabbro within the North Wulan metamorphic complex to investigate crust–mantle interaction processes and elucidate the geodynamic mechanisms operating in the North Qaidam tectonic belt during the tectonic transition from the subduction of the Proto-Tethyan oceanic slab to slab rollback. Zircon UPb isotopic dating constrains the emplacement time of the mafic rocks at ∼499–479 Ma. These intrusions exhibit enriched mid-ocean ridge basalt (E-MORB)-like trace element patterns, coupled with slightly enriched NdHf isotopic compositions (εNd(t) of −5.3 to −1.1; εHf(t) of −2.8 to −2.6). These geochemical signatures were likely derived from an enriched mantle source metasomatized by subduction-related materials from the dehydration melting of the oceanic slab outside the rutile stability field. Geochemical simulations further indicate that the magmas were generated by ∼12–20 % partial melting of a pyroxenite-dominated mantle source at the lithosphere–asthenosphere boundary (LAB). We attribute this magmatism to lithospheric partial melting induced by asthenospheric upwelling in response to the rollback of the Proto-Tethyan oceanic slab. By synthesizing the records in arc-like and ocean-island basalt (OIB)-like mafic rocks, we can establish an arc–MORB–OIB geochemical progression to illuminate the spatiotemporal evolution of the mantle underlying an Early Paleozoic continental arc–back-arc setting in the North Qaidam.

柴达木北缘构造带保存了一系列早古生代同俯冲大陆弧基性岩，为研究上覆地幔楔内地幔源成分演化提供了重要线索。本文对北乌兰变质杂岩中的辉长岩进行了岩石学、年代学和地球化学的综合研究，探讨了原特提斯洋板块俯冲到板块回退的构造转换过程中壳幔相互作用过程，阐明了柴达木北构造带的地球动力学机制。锆石UPb同位素定年将基性岩石的侵位时间限定在~ 499 ~ 479 Ma。这些侵入体表现出富集的洋中脊玄武岩（E-MORB）样微量元素模式，并伴有少量富集的NdHf同位素组成(εNd(t)在−5.3 ~−1.1之间；εHf(t) =−2.8 ~−2.6)。这些地球化学特征可能来源于金红石稳定场外洋板脱水熔融的俯冲相关物质交代的富集地幔源。地球化学模拟进一步表明，岩浆是由岩石圈-软流圈边界（LAB）以辉石岩为主的地幔源的~ 12 - 20%部分熔融产生的。我们认为这种岩浆活动是由软流圈上升流引起的岩石圈部分熔融引起的，这是对原特提斯大洋板块回退的响应。通过对类弧玄武岩和类洋岛玄武岩（OIB）基性岩记录的综合分析，建立了弧- morb - OIB地球化学进阶，阐明了柴达木北部早古生代陆相弧-弧后背景下地幔的时空演化。

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引用次数: 0

Titanium isotope fractionation during granitic magma evolution: A case study of the Fangshan pluton, North China craton 花岗质岩浆演化过程中钛同位素分馏——以华北克拉通房山岩体为例

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-02 DOI: 10.1016/j.lithos.2025.108357

Chunxia Yi , Xinmiao Zhao , Tao Shi , Jin Li , Bing Liu , Junjie Luo , Jian Zhao , Xiaojun Wang , Fang Liu , Xiangkun Zhu , Hongfu Zhang

To elucidate the geochemical behavior and fractionation mechanisms of titanium (Ti) isotopes during granitic magma evolution, we conducted a systematic Ti isotopic analysis of I-type granodiorites, quartz diorites, and their associated mafic microgranular enclaves (MMEs), along with major Ti-bearing minerals biotite, hornblende, and titanite from the Early Cretaceous Fangshan pluton, North China Craton (NCC). The granodiorites and quartz diorites exhibit a narrow range of δ^49/47Ti values (+0.14 ‰ to +0.25 ‰; average + 0.18 ± 0.07 ‰, 2SD, n = 15), comparable to that of the upper continental crust (UCC, δ^49/47Ti = +0.18 ± 0.07 ‰; 2SD). These values show no discernible correlation with conventional magmatic differentiation indices (e.g., SiO₂, TiO₂, MgO), suggesting limited Ti isotope fractionation during I-type granite differentiation. Thermodynamic modeling and mass balance calculations indicates that the isotopically enriched Ti signatures of the Fangshan granodiorites and quartz diorites result from partial melting (5–20 %) of rutile-bearing eclogitic sources in a thickened lower crust. In contrast, the MMEs display a wider range of δ^49/47Ti values (+0.04 ‰ to +0.33 ‰) that correlates with SiO_2, TiO₂, and MgO contents, consistent with mixing between mantle-derived mafic and crustal-derived felsic magma, coupled with fractional crystallization. Mineral separates reveal clear intra-mineral Ti fractionation: titanite is consistently enriched in lighter Ti isotopes (δ^49/47Ti = −0.09 ‰ to +0.09 ‰) relative to coexisting biotite (+0.22 ‰ to +0.44 ‰) and hornblende (+0.16 ‰ to +0.35 ‰), consistent with differences in the Ti coordination environments between the melt and crystallizing mineral. Taken together with previous studies, our results demonstrate that although Ti isotopes alone offer limited discrimination between I- and S-type granites, they act as a reliable tracer of A-type granites, where extensive fractional crystallization produces pronounced Ti isotope fractionation. Overall, these findings advance our understanding of Ti isotope behavior in granitic systems and highlight their potential as a tracer for granite petrogenesis and crustal evolution.

为了阐明花岗质岩浆演化过程中钛同位素的地球化学行为和分选机制，对华北克拉通早白垩世方山岩体中i型花岗闪长岩、石英闪长岩及其伴生基性微粒包体（MMEs）以及主要含钛矿物黑云母、角闪石和钛矿进行了系统的钛同位素分析。花岗闪长岩和石英闪长岩的δ49/47Ti值范围较窄（+0.14‰~ +0.25‰，平均值+0.18±0.07‰，2SD, n = 15），与上陆地壳的δ49/47Ti值范围相当（UCC, δ49/47Ti = +0.18±0.07‰，2SD）。这些数值与常规岩浆分异指标（如SiO2、TiO2、MgO）没有明显的相关性，表明ⅰ型花岗岩分异过程中Ti同位素分异有限。热力学模拟和质量平衡计算表明，房山花岗闪长岩和石英闪长岩的同位素富集Ti特征是由增厚下地壳中含金红石的榴辉岩源部分熔融（5 ~ 20%）所致。MMEs δ49/47Ti值变化范围较宽（+0.04‰~ +0.33‰），与SiO2、TiO2和MgO含量有关，与幔源基性岩浆和壳源长英质岩浆混合作用一致，并伴有分馏结晶作用。矿物分选显示出明显的矿物内Ti分选：相对于共存的黑云母（+0.22‰~ +0.44‰）和角闪石（+0.16‰~ +0.35‰），钛矿的Ti同位素δ49/47Ti =−0.09‰~ +0.09‰，钛矿的Ti同位素δ49/47Ti = +0.09‰，与熔融矿物和结晶矿物之间的Ti配位环境差异一致。结合之前的研究，我们的研究结果表明，尽管Ti同位素单独对I型和s型花岗岩的区分有限，但它们作为a型花岗岩的可靠示踪剂，在a型花岗岩中，广泛的分馏结晶产生明显的Ti同位素分馏。总的来说，这些发现促进了我们对花岗岩系统中Ti同位素行为的理解，并突出了它们作为花岗岩岩石成因和地壳演化示踪剂的潜力。

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引用次数: 0

Sediment Metasomatism in the early Mesozoic Mafic–Ultramafic Intrusions of the Zhangguangcai Range (NE China): Constraints on the subduction of the Mudanjiang Ocean 张广才山脉早中生代基性-超基性侵入体的沉积交代作用：对牡丹江洋俯冲的制约

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-02 DOI: 10.1016/j.lithos.2025.108356

Guang-Ying Feng , Fei Liu , Yildirim Dilek , Dong-Yang Lian , Xiao-Lu Niu , Jing-Sui Yang

The involvement of crustal components in subduction systems (e.g., altered oceanic crust, pelagic and terrigenous sediments) plays a key role in generating mantle heterogeneity. However, identification of these components during subduction processes remains insufficiently studied. This study presents a systematic analysis of mineral chemistry, whole-rock major and trace elements, and Sr–Nd–O isotopic compositions of four subduction-related Late Triassic–Early Jurassic (209–202 Ma) mafic–ultramafic intrusions exposed in the eastern margin of the Zhangguangcai Range in NE China, in order to constrain primarily the mode and nature of the modification of their mantle sources by crustal materials and also to provide new constraints on the tectonomagmatic evolution of the study area. Amphibole compositions indicate that the primary magmas had high water contents of 4.0–8.4 %. Together with their trace element characteristics, the data suggest that these rocks represent typical arc magmatic rocks whose mantle source was significantly modified by fluids/melts derived from subducted sediments, while their elevated δ¹⁸O values further indicate contribution from terrigenous sediments. The relatively enriched SrNd isotopic features of these intrusions clearly distinguish them from other Mesozoic mafic–ultramafic rocks in the Zhangguangcai Range that exhibit depleted geochemical signatures. Furthermore, some of the analyzed rocks show evidence for crustal contamination, with mixing trends pointing to the Mashan Complex—the crystalline basement of the Jiamusi Block. These observations collectively suggest that the eastern Zhangguangcai Range shares similar characteristics with the Jiamusi Block and should be considered part of the Paleo-Jiamusi Block. The data further imply that the opening of the Mudanjiang Ocean occurred within the western margin of the Paleo-Jiamusi block, and the westward subduction of the Mudanjiang oceanic plate commenced around 209 Ma.

俯冲系统中地壳成分的参与（例如蚀变的洋壳、远洋和陆源沉积物）在地幔非均质性的产生中起着关键作用。然而，在俯冲过程中对这些成分的识别研究仍然不够充分。本文系统分析了中国东北张广才山脉东缘4个与俯冲有关的晚三叠世—早侏罗世（209-202 Ma）基性—超基性侵入岩的矿物化学、全岩主微量元素和Sr-Nd-O同位素组成。为了初步约束其地幔源受地壳物质改造的方式和性质，并为研究区构造岩浆演化提供新的约束条件。闪孔组成表明，原生岩浆含水量较高，为4.0% ~ 8.4%。这些岩石的微量元素特征表明，这些岩石是典型的弧型岩浆岩，其地幔源受到俯冲沉积流体/熔体的明显改变，δ18O值的升高进一步表明了陆源沉积的贡献。其相对富集的SrNd同位素特征与张光彩山脉其他中生代基性-超基性岩石的地球化学特征明显不同。此外，分析的一些岩石显示出地壳污染的证据，混合趋势指向马山杂岩——佳木斯地块的结晶基底。综上所述，张广才山脉东部与佳木斯地块具有相似的特征，应视为古佳木斯地块的一部分。资料进一步表明，牡丹江洋的开闭发生在古佳木斯地块西缘，牡丹江洋板块在209 Ma左右开始向西俯冲。

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引用次数: 0

Mid-Neoproterozoic extensional tectonics in the Larsemann Hills, East Antarctica: Implications for Indo-Antarctic correlation in Rodinia 东南极洲Larsemann山中-新元古代伸展构造：对Rodinia地区印-南极对比的启示

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-02 DOI: 10.1016/j.lithos.2025.108358

Sandro Chatterjee , J. Amal Dev , Aishi Debnath , Anuj Ghosh , Soham Dey , Anik Mukherjee , Devsamridhi Arora , J.K. Tomson , Fernanda Guimarães , Naresh Chandra Pant , Saibal Gupta

The supercontinents Rodinia and Gondwana are believed to have assembled through orogenic events at ∼1000 Ma and ∼550 Ma, respectively. The Larsemann Hills, part of the extended Rayner Complex of East Antarctica, is a Neoproterozoic granulite terrane that was a part of both supercontinents. The tectonic evolution of the terrane in the Rodinia to Gondwana interval remains uncertain. This study integrates new field, microstructural, metamorphic and geochronological information to unveil a previously undocumented mid-Neoproterozoic thermo-tectonic event in the Larsemann Hills. Granulite facies metamorphism (M₁), synchronous with the deformation, D₁, is interpreted to have occurred in the Larsemann Hills at ∼1000 Ma, followed by a crustal shortening (D₂) event that continued from ∼990–900 Ma, signifying the incorporation of the Rayner crustal unit into Rodinia. Subsequent mid-Neoproterozoic extensional deformation (D₃), characterized by NW-SE trending S₃ shear zones, reoriented pre-existing structural fabrics. The extensional deformation operated under amphibolite facies metamorphic conditions (M₂) and resulted in a post-peak decompressive P-T trajectory. UPb LA-ICPMS dates on zircons separated from metapelites within high D₃ strain zone yield clusters at ∼700 Ma; zircons immediately adjacent to the shear zone yield ages around ∼990–900 Ma. A thermal overprint at ∼550 Ma is evident but weakly manifested in the western Larsemann Hills, with no unambiguously correlatable structural or metamorphic evidence, suggesting distance from the Gondwana orogenic front. The extensional deformation documented here is contemporaneous with extension in the northern Eastern Ghats Province, India that was contiguous with the Rayner Complex in the Neoproterozoic. This suggests that a major terrane-wide extensional event was associated with the disintegration of Rodinia. In the Neoproterozoic, the EGP-Rayner unit was therefore a tectonic entity distinct from cratonic India, with only the former being an integral component of Rodinia.

超大陆Rodinia和Gondwana分别被认为是在~ 1000 Ma和~ 550 Ma的造山活动中形成的。拉尔森山是东南极洲延伸的雷纳杂岩的一部分，是一个新元古代的麻粒岩地体，是两个超大陆的一部分。罗迪尼亚至冈瓦纳段地体的构造演化仍不确定。本研究整合了新的领域、微观构造、变质和地质年代学信息，揭示了Larsemann Hills中新元古代热构造事件。与变形D1同步的麻粒岩相变质作用（M1）被解释为在~ 1000 Ma时发生在Larsemann Hills，随后是持续在~ 990-900 Ma的地壳缩短（D2）事件，标志着Rayner地壳单元并入Rodinia。随后的中新元古代伸展变形（D3）以NW-SE走向的S3剪切带为特征，对原有构造进行了重新定向。张拉变形作用于角闪岩相变质条件下（M2），形成峰后减压P-T轨迹。UPb LA-ICPMS对高D3应变区产率团簇中超长粒分离的锆石进行了年代测定；紧靠剪切带的锆石年龄约为~ 990-900 Ma。在~ 550 Ma的热叠印很明显，但在Larsemann Hills西部表现不明显，没有明确相关的构造或变质证据，表明与冈瓦纳造山带有距离。这里记录的伸展变形与印度东高止山脉北部的伸展是同时期的，该伸展与新元古代的雷纳杂岩相邻。这表明与罗迪尼亚的解体有关的是一次重大的全地范围的伸展活动。因此，在新元古代，EGP-Rayner单元是一个不同于克拉通印度的构造实体，只有前者是Rodinia的一个组成部分。

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引用次数: 0

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