IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2026-01-07 DOI: 10.1016/j.lithos.2026.108405

Hayden Dalton , Marshall C. Palmer , Nadine P. Cooper , Andrew J. Locock , Yan Luo , D. Graham Pearson , Orion K.W. Marshall , Petrus J. le Roux , Thomas W. Ritchie , Joshua J. Schwartz , Tingting Wang , Sarah Woodland , James M. Scott

Tracing detrital mineral sources is important for understanding economically prospective rare earth element (REE)-rich placers, but identifying their origins in complex geological settings remains challenging. Prospective amounts of detrital REE minerals occur in some of New Zealand's beach sands. However, other than coming from the actively exhuming Southern Alps, their sources are poorly characterised. Here, we attempt to constrain the sources of a fluvial REE (xenotime and monazite) placer within this active orogen using textural, elemental and isotopic compositions of these and associated heavy minerals. Prominent Eu anomalies and U-Pb dating of xenotime (∼101 Ma) and monazite (∼112 Ma), along with their euhedral textures, are consistent with two distinct but proximal igneous sources. Garnet major element compositions also point to a magmatic source, and although Cretaceous plutons outcrop extensively in the catchment, the detrital zircon population has only a very weak Cretaceous signal (n = 6/121). Furthermore, although xenotime bulk rock εNd_(i) compositions (average = −5.0) do align with local plutons, the ∼101 Ma age is approximately 10 Myr younger than that of the known plutons. The xenotime source may therefore be a suite of granitic pegmatitic dikes that cross-cut these the plutons and gneisses. In contrast, the monazite ages overlap those of the locally dominant plutonic rocks but their in-situ εNd_(i) values (−11 to +0.9) extend to much more radiogenic values. These data point to an as yet undiscovered proximal magmatic source rock with a strong depleted mantle component, in part mixed with crustal material to yield the spread in εNd. Although the specific sources of the REE minerals remain unknown, the mineral textures and isotopes strongly indicate that these sources are proximal, largely magmatic zircon-free, and not related to the most abundant mapped rocks in the region. Single grain textural, elemental and isotopic data therefore provide constraints on the origins of different mineral sources, and the implications of these data would be useful in future, advanced exploration.

追踪碎屑矿物来源对于了解具有经济前景的富含稀土元素（REE）的砂矿非常重要，但在复杂的地质环境中确定它们的起源仍然具有挑战性。在新西兰的一些海滩砂中发现了预期数量的碎屑REE矿物。然而，除了来自积极挖掘的南阿尔卑斯山，它们的来源特征很差。在这里，我们试图利用这些和伴生重矿物的结构、元素和同位素组成来限制该活动造山带内河流REE （xenotime和monazite）砂矿的来源。突出的Eu异常和xenotime （~ 101 Ma）和monazite （~ 112 Ma）的U-Pb定年，以及它们的自面体结构，与两个不同的近端火成岩来源一致。石榴石主元素组成也指向岩浆源，尽管汇水区大量露出白垩系岩体，但碎屑锆石种群只有非常微弱的白垩系信号（n = 6/121）。此外，尽管xenotime大块岩石的εNd(i)组成（平均= - 5.0）确实与当地的岩体一致，但其~ 101 Ma年龄比已知的岩体年轻约10 Myr。因此，xenotime源可能是一套与这些岩体和片麻岩交叉的花岗质伟晶岩岩脉。与此相反，独居石的年龄与局部优势的深成岩年龄重叠，但它们的原位εNd(i)值（- 11 ~ +0.9）扩展到更大的放射性成因值。这些数据指向一个尚未发现的近端岩浆源岩，它具有强烈的衰竭地幔成分，部分与地壳物质混合，产生了εNd的扩展。虽然稀土矿物的具体来源尚不清楚，但矿物结构和同位素强烈表明，这些来源是近端，大部分是岩浆无锆石，与该地区最丰富的已映射岩石无关。因此，单粒结构、元素和同位素数据对不同矿物来源的来源提供了限制，这些数据的含义将对未来的高级勘探有用。

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引用次数: 0

Charnockite magmatism from partial melting of UHT granulites: metamorphic modelling and geochemical insights from the southern Brasília Orogen, Brazil 来自UHT麻粒岩部分熔融的沙诺克岩岩浆作用：来自巴西Brasília造山带南部的变质模拟和地球化学见解

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2026-01-06 DOI: 10.1016/j.lithos.2026.108401

Rafael G. Motta , Renato Moraes , Ian C.W. Fitzsimons , Frederico Castro Jobim Vilalva , Renata Ferreira Barros , Zorano Sérgio Souza , Rodrigo Schwantes Marimon

A large section of the continental lower crust is exposed in the southernmost Brasília Orogen, Brazil, where rocks in the Guaxupé Domain experienced ultra-high temperature (UHT) metamorphism. These metamorphic rocks are dominated by felsic granulites and migmatites and exhibit a prolonged history of melt crystallization between 630 and 595 Ma, during which several granitic bodies, including charnockites, were emplaced. Two newly identified charnockite intrusions outcrop in the eastern part of the domain, displaying similarities with the previously described Divinolândia Suite. The data collected in this study, combined with previous research, indicate that charnockitic magmatism was coeval with the metamorphic peak. The isotopic signatures of Nd and Sr in whole rock, along with Hf in zircon suggest derivation from crustal sources with a long crustal residence history. Metamorphic modelling of felsic granulites shows that garnet and K-feldspar served as reactant phases during melt-producing reactions, and a significant amount of zircon was dissolved at peak metamorphic conditions, whereas plagioclase and orthopyroxene became concentrated in the residual granulite. The resulting partial melt would have been enriched in elements such as Fe, Mg, K, Rb, Ba, Zr, and Hf, but depleted in Ca and Sr, a pattern that matches the geochemistry of the charnockites. Thus, the charnockite magmatism was likely generated by the migration and crystallization of partial melts derived predominantly from felsic granulites and subordinately from other ancient sources.

巴西最南端Brasília造山带暴露出一大块大陆下地壳，瓜苏普构造域的岩石经历了超高温变质作用。这些变质岩以长英质麻粒岩和混辉岩为主，在630 ~ 595 Ma之间表现出较长的熔融结晶史，其间嵌套了包括绿粒岩在内的若干花岗岩体。2个新发现的charnockite侵入体在该区东部露头，与先前描述的divinol ndia套件有相似之处。本研究收集的资料，结合前人的研究，表明炭质岩浆活动与变质峰发生在同一时期。整个岩石的Nd、Sr同位素特征以及锆石中的Hf同位素特征表明其来源于地壳，具有较长的地壳居住史。长英质麻粒岩的变质模拟表明，在熔融反应中，石榴石和钾长石是主要的反应相，在变质峰期，大量的锆石被溶解，而斜长石和正辉石则集中在残余的麻粒岩中。由此产生的部分熔体可能富含Fe、Mg、K、Rb、Ba、Zr和Hf等元素，但缺乏Ca和Sr，这一模式与charnockites的地球化学特征相符。因此，绿辉岩岩浆活动可能是由长英质麻粒岩的部分熔体的迁移和结晶作用产生的，其次是其他古源。

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引用次数: 0

Complex crystal textures and zoning patterns in the Saillipu potassic rocks (southern Tibet) and petrological implications 藏南塞力浦钾质岩石的复杂晶体结构、分带模式及其岩石学意义

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2026-01-06 DOI: 10.1016/j.lithos.2026.108404

Jinsheng Zhou , Qiang Wang , Qiwei Li , Tongyu Huang , Zilong Wang , Pengli He

Mafic potassic rocks are generally considered to be derived from a metasomatized mantle source, making them particularly suitable for revealing mantle heterogeneity and dynamic processes. However, the presence of minerals with complex textures and zoning patterns poses a challenge for such studies, as their compositions may have been modified by magma chamber processes and may not reflect primary melts. This study investigated olivine and clinopyroxene crystals in the Sailipu mafic potassic rocks of southern Tibet, which contain abundant minerals with complex textures. We applied Kd_Fe2+-Mg and Kd_FeT-Mg to determine the parental magma compositions for diverse olivine crystal populations. We found that while some analyzed olivines were in equilibrium with whole-rock compositions, others showed characteristics of olivine accumulation. Both Kd_Fe2+-Mg and Kd_FeT-Mg proved effective in evaluating the equilibrium between olivine and melt. Our results suggest that the olivine-melt FeMg exchange coefficient is an effective criterion for identifying primary melt compositions. Furthermore, many crystals with complex textures and zoning patterns were likely formed by dynamic crystal growth rather than complex magma chamber processes, such as magma mixing or magma replenishment. Consequently, the mafic and intermediate potassic rocks in the Sailipu volcanic field most likely reflect the diversity of primary melt compositions rather than the effects of crystal fractionation. Our results suggest that mafic potassic rocks remain a powerful tool for identifying mantle processes.

镁铁质钾质岩通常被认为来自交代地幔源，因此它们特别适合揭示地幔非均质性和动力学过程。然而，具有复杂结构和分带模式的矿物的存在对这类研究提出了挑战，因为它们的成分可能已被岩浆房过程改变，可能不反映原始熔体。本文研究了藏南塞力堡基性钾质岩石中的橄榄石和斜辉石晶体，这些岩石矿物丰富，结构复杂。我们用KdFe2+-Mg和KdFeT-Mg测定了不同橄榄石晶体群的母岩浆组成。研究发现，部分分析橄榄石与整岩成分处于平衡状态，部分分析橄榄石具有成藏特征。KdFe2+-Mg和KdFeT-Mg均能有效评价橄榄石与熔体之间的平衡。结果表明，橄榄石与熔体的交换系数是鉴定原生熔体成分的有效判据。此外，许多具有复杂结构和分带模式的晶体可能是由动态晶体生长形成的，而不是岩浆混合或岩浆补充等复杂的岩浆房过程。因此，塞力堡火山田的镁铁质和中钾质岩石很可能反映了原生熔体成分的多样性，而不是晶体分馏的影响。我们的结果表明，基性钾质岩石仍然是识别地幔过程的有力工具。

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引用次数: 0

Petrogenesis and magmatic-hydrothermal evolution of the Dahongliutan pegmatite-type lithium deposit, Western Kunlun, NW China: A tourmaline perspective 西昆仑大红柳滩伟晶岩型锂矿床岩石成因及岩浆-热液演化：电气石视角

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2026-01-06 DOI: 10.1016/j.lithos.2026.108403

Yong-Qi Xia , Ming-Jie Tuo , Nuerkanati Madayipu , Jianatiguli Wusiman , Dong-Mei Qi , Nuo Li

The Dahongliutan district, located in the Western Kunlun Orogen of NW China, hosts a giant pegmatite-type Li (Be) ore cluster, yet its petrogenesis and the role of fluids in Li mineralization remain controversial. Competing models attribute the pegmatites to either two-mica granite or biotite granite of the Dahongliutan pluton. To resolve this issue, we conducted detailed textural, electron-microprobe, and boron-isotope analyses of tourmaline from two-mica granite (Tur₁), barren pegmatite (Tur₂), and Li-mineralized pegmatite (Tur₃). All tourmaline samples belong to the alkali group. Tur₁ and Tur₂ are schorl-series tourmalines with homogeneous textures, high Na/(Na + Ca) and low Mg/(Mg + Fe) ratios, consistent with a magmatic origin. In contrast, Tur₃ exhibits pronounced core-and-rim zoning, with schorl cores (Tur_3C) overgrown by Li-F-rich elbaite rims (Tur_3R), indicative of a transition from magmatic to magmatic-hydrothermal conditions. Boron isotopic values of tourmaline (δ¹¹B = −10.37 ‰ to −7.11 ‰) together with Rayleigh fractionation modeling support a genetic relationship between the pegmatites and two-mica granite. Elevated Li and heavier δ¹¹B in Tur_3R, together with its spatial association with spodumene, underscore the critical role of magmatic-hydrothermal process in concentrating lithium in rare-metal pegmatite systems.

位于西昆仑造山带的大红柳滩地区发育巨型伟晶岩型锂（Be）矿群，其成因及流体在锂成矿中的作用一直存在争议。相互竞争的模式将伟晶岩归因于大红柳滩岩体的二云母花岗岩或黑云母花岗岩。为了解决这个问题，我们对来自双云母花岗岩（Tur1）、光秃秃伟晶岩（Tur2）和锂矿化伟晶岩（Tur3）的电气石进行了详细的结构、电子探针和硼同位素分析。所有电气石样品都属于碱类。Tur1和Tur2为岩系电气石，结构均匀，Na/(Na + Ca)比值高，Mg/(Mg + Fe)比值低，与岩浆成因一致。而图3则表现出明显的岩心-岩缘分带，岩核（图3c）被富含li - f的铁白石岩心（图3r）所覆盖，表明其岩浆条件向岩浆-热液条件过渡。电气石的硼同位素值（δ11B = - 10.37‰~ - 7.11‰）和瑞利分选模型支持伟晶岩与二云母花岗岩的成因关系。Tur3R中Li的升高和δ11B的变重，以及其与锂辉石的空间关联，强调了岩浆热液过程在稀土伟晶岩体系中富集锂的关键作用。

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引用次数: 0

Discovery of hidden Dayingezhuang granites in the Jiaodong peninsula, Northern China: Implications for the petrogenesis and geodynamics of the early cretaceous Guojialing granite 胶东半岛隐伏大营二庄花岗岩的发现：对早白垩世郭家岭花岗岩岩石成因及地球动力学的启示

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2026-01-06 DOI: 10.1016/j.lithos.2026.108402

Hui Chen , Bin Li

The northwestern Jiaodong Peninsula hosts extensive Mesozoic collision-related igneous rocks formed by subduction and rollback of the paleo-Pacific plate. Among them, the early Cretaceous Guojialing granite is closely associated with major gold mineralization in the region. Recent drilling at the Dayingezhuang gold deposit revealed a previously undocumented concealed granitic intrusion. Zircon UPb dating yields crystallization ages of 130–125 Ma, with inherited cores showing multiple age populations (140–170 Ma, ∼400 Ma, 2.0–2.8 Ga), indicating complex crustal sources. Geochemically, the Dayingezhuang granite is similar to the Shangzhuang granite of the Guojialing suite, characterized by high K₂O + Na₂O and Mg# enrichment in light rare earth elements and large-ion lithophile elements, depletion in high-field-strength elements, and positive Eu anomalies. Both display adakitic affinities with high Sr/Y ratios and low εNd(t) values (−15.7 to −16.8). These features suggest derivation mainly from partial melting of the lower crust of the North China Craton, with variable mantle contributions. We propose that paleo-Pacific slab rollback at ∼145 Ma induced asthenospheric upwelling, triggering melting of the subduction-modified lower crust to generate compositionally diverse Early Cretaceous magmas. The resulting back-arc extension provided the geodynamic setting for the formation of the Guojialing adakitic granites. The Dayingezhuang and Shangzhuang granites are I-type, crystallized under high oxygen fugacity (fO₂), creating favorable conditions for Cu–Au–Mo mineralization.

胶东半岛西北部发育大量由古太平洋板块俯冲和回滚作用形成的中生代碰撞火成岩。其中，早白垩世郭家岭花岗岩与区内主要金矿化密切相关。近期在大营尔格庄金矿床的钻探中发现了以前未记载的隐伏花岗岩侵入体。锆石UPb定年结果显示结晶年龄为130 ~ 125 Ma，继承的岩心显示多个年龄群（140 ~ 170 Ma, ~ 400 Ma, 2.0 ~ 2.8 Ga），表明地壳来源复杂。大营尔格庄花岗岩地球化学特征与郭家岭套上庄花岗岩相似，均表现为轻稀土元素和大离子亲石元素K2O + Na2O和Mg#富集，高场强元素亏缺，Eu正异常。两者均具有高Sr/Y比和低εNd(t)值（- 15.7 ~ - 16.8）的亲和性。这些特征表明其主要来源于华北克拉通下地壳的部分熔融作用，地幔的贡献是可变的。我们认为，古太平洋板块在~ 145 Ma的回滚引起了软流圈上升流，引发了俯冲修正下地壳的融化，从而产生了成分多样的早白垩世岩浆。弧后伸展为郭家岭埃达克质花岗岩的形成提供了地球动力学背景。大营二庄和上庄花岗岩为i型，在高氧逸度（fO2）条件下结晶，为Cu-Au-Mo成矿创造了有利条件。

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引用次数: 0

Time-dependent changes in the origin of aqueous fluids in the shallow mantle wedge: Evidence from noble gas and halogen compositions of the Kamabuseyama serpentinite, Kanto Mnts., Japan 浅层地幔楔中含水流体起源的随时间变化：来自关东山镰山蛇纹岩稀有气体和卤素组成的证据。,日本

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2026-01-05 DOI: 10.1016/j.lithos.2026.108400

Koki Aida , Simon Richard Wallis , Hirochika Sumino , Mari Yokota

Blocks of serpentinite derived from the mantle wedge are widely distributed throughout the Sanbagawa metamorphic belt of SW Japan and the contact domains with surrounding schists represent the paleo subduction zone boundary. This paleo subduction boundary is well exposed in the Kamabuseyama area of the Kanto mountains and originally formed at relatively shallow mantle depths of ∼25 km. The contact zone between the serpentinite and slab-derived schists is characterized by a domain of fluid-mediated metasomatism. Noble gas and halogen analyses of different lithologies from this domain suggest fluid influx occurred in two distinct stages represented by formation of (1) serpentinite and (2) boundary domain metasomatic rocks. Stage (2) metasomatism can be further divided into two substages: (2–1) associated with chlorite rock formation and (2–2) associated with talc rock formation. The origins of the dominant fluids involved in these different stages can be identified as: (1) altered oceanic crust, (2–1) altered oceanic crust + pore fluids in oceanic sediments, and (2–2) pore fluids in oceanic sediments + fluids derived from serpentinized domains of the slab mantle. These results indicate that the origin of the dominant fluid along the paleo subduction boundary changed with time reflecting the development of different fluid pathways. The identification of fluid derived from the dehydration of serpentinite of the slab mantle during the youngest fluid inflow event suggests changes in fluid pathways may be controlled by the progressive development of a boundary shear zone that introduces a permeability anisotropy that allows deep sourced fluids to flow laterally along the subduction boundary.

源自地幔楔体的蛇纹岩块体广泛分布于日本西南部三巴川变质带，其与周围片岩的接触域代表了古俯冲带的边界。这个古俯冲边界在关东山脉的Kamabuseyama地区很好地暴露出来，最初形成于相对较浅的地幔深度，约25公里。蛇纹岩与板源片岩的接触带以流体交代为特征。该区不同岩性的稀有气体和卤素分析表明，流体流入发生在(1)蛇纹岩和(2)边界区交代岩形成的两个不同阶段。阶段(2)交代作用可进一步分为两个亚阶段：（2 - 1）与绿泥石岩形成有关，（2 - 2）与滑石岩形成有关。这些不同阶段主要流体的来源可确定为：(1)蚀变洋壳，（2-1）蚀变洋壳+海洋沉积物孔隙流体，（2-2）海洋沉积物孔隙流体+板块地幔蛇纹化域流体。这些结果表明，沿古俯冲边界的优势流体的来源随着时间的变化而变化，反映了不同流体路径的发展。在最年轻的流体流入事件中，由板块地幔蛇纹岩脱水产生的流体的识别表明，流体路径的变化可能受到边界剪切带逐渐发展的控制，该剪切带引入了渗透率各向异性，使深部流体能够沿着俯冲边界横向流动。

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引用次数: 0

Discovery of a Late Eocene–Early Oligocene ultra-high temperature (UHT) migmatite in the Gangdese batholith at Nyingchi, southern Tibet and its tectonic implications 藏南林芝冈底斯基晚始新世—早渐新世超高温混辉岩的发现及其构造意义

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2026-01-02 DOI: 10.1016/j.lithos.2025.108399

Hehe Jiang , Xu Chu , Jia-Min Wang , Wei-Qiang Ji , Wenrong Cao , Fangyang Hu , Xiao-Chi Liu , Fu-Yuan Wu

Ultra-high temperature (UHT) metamorphism (> 900 °C) represents extreme crustal thermal conditions that provide key constraints on orogenic belt evolution. We report a newly identified Late Eocene–Early Oligocene UHT–HT record from the eastern Gangdese batholith near Nyingchi, southern Tibet, preserved within a garnet-bearing migmatite. Peak metamorphic conditions are evidenced by petrographic features in a K-feldspar-rich domain, including rutile exsolution needles in garnet and perthitic textures. Zr-in-rutile and ternary feldspar thermometry yield temperatures of 879–921 °C at 1.0 GPa, providing a robust minimum estimate that the system reached UHT conditions via near-anhydrous melting. This K-feldspar-rich assemblage is complemented by a more voluminous, plagioclase-rich lithology, which records higher melt fractions and mobility under subsequent, cooler, and more hydrous conditions. Zircon and monazite U-Pb geochronology, zircon–garnet REE equilibrium, combined with garnet diffusion modeling, reveal that the UHT pulse was short-lived (< 8 Myr), culminated shortly before ca. 31 Ma, and was followed by extremely rapid cooling (ca. 25 kyr) to 700 °C. The brevity of the UHT pulse, high geothermal gradient (∼25 °C/km assuming rock density of 2.8 g/cm³), and its localized extent collectively point to a transient advective heat source. We correlated this thermal pulse with slab breakoff of the subducting Indian lithosphere as proposed by previous studies. This UHT event likely representing an early manifestation of the Late Oligocene–Miocene crustal thermal reorganization in the Tibetan plateau, highlighting the role of mantle-derived heat in collisional orogenic processes.

超高温（UHT）变质作用（> 900°C）代表了极端的地壳热条件，为造山带演化提供了关键的约束条件。本文报道了西藏南部林芝附近冈底斯岩基东部晚始新世-早渐新世的高温-高温记录，保存在含石榴石的杂岩中。富钾长石区域的岩石学特征证明了峰变质条件，包括石榴石和perthitic织构中的金红石脱溶针。金红石中锆和三元长石测温在1.0 GPa下的产温为879-921℃，提供了系统通过近无水熔融达到UHT条件的可靠最小估计。这种富含钾长石的组合与体积更大、富含斜长石的岩性相辅相成，在随后、更冷、更含水的条件下，记录了更高的熔体分数和流动性。锆石和独石U-Pb年代学、锆石-石榴石REE平衡以及石榴石扩散模型表明，UHT脉冲是短暂的（< 8myr），在约31 Ma之前达到顶峰，随后迅速冷却（约25 kyr）至700°C。UHT脉冲的短暂性、高地温梯度（假设岩石密度为2.8 g/cm3，地温梯度约为25°C/km）及其局部范围共同指向一个瞬态对流热源。我们将这一热脉冲与先前研究提出的俯冲印度岩石圈的板块断裂联系起来。该UHT事件可能代表了青藏高原晚渐新世-中新世地壳热重组的早期表现，突出了地幔热在碰撞造山过程中的作用。

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引用次数: 0

Geochemical and mineralogical study of zircon, apatite, and wolframite in the Xiatongling W-Mo-Be deposit, South China: Implications for key factors to W-Mo-Be mineralization 下铜岭钨钼be矿床锆石、磷灰石、黑钨矿地球化学与矿物学研究：对钨钼be成矿关键因素的启示

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-30 DOI: 10.1016/j.lithos.2025.108398

Yiming Chen , Xiaoyong Yang , Jiandong Sun , Yu Wang

The Xiatongling tungsten‑molybdenum‑bismuth (W-Mo-Be) deposit, located in the Nanling metallogenic belt, is a stockwork and quartz vein-type W-Mo-Be system developed within and along the contact zone of a medium- to fine-grained granite intrusion. Although previous studies have focused on the magmatic age and geochemical features of the intrusion, and indirectly constrained the mineralization age using molybdenite geochronology, the precise metallogenic chronology, sources of ore-forming materials, and key factors controlling W-Mo-Be mineralization remain poorly understood. This study presents an integrated geochemical and geochronological investigation of zircon, apatite, and wolframite from the deposit to constrain its petrogenesis and mineralization. The zircon U–Pb age of the granite (ca. 154 Ma) corresponds to the wolframite U–Pb age (ca. 154 Ma), establishing a genetic link between magmatism and tungsten mineralization. Geochemical data indicate that the granite is weakly peraluminous (A/CNK = 1.03 to 1.08), characterized by high SiO₂, U, and Ta, and low Ba, Sr, and Zr + Nb + Ce + Y, typical of highly fractionated S-type granites. Zircon ε_Hf(t) values of −7.75 to −10.64 and apatite ε_Nd(t) values of −15.56 to −8.97 indicate derivation from the Proterozoic metasedimentary basement of the Wugongshan area, which was characterized by pre-enrichment in W, Mo, and Be. Integrated whole-rock and wolframite geochemical data reveal consistent and pronounced negative Eu anomalies in both wolframite and the Xiatongling granite. Combined with robust geochronological constraints, these findings support the interpretation that the reduced ore-forming fluids were directly exsolved from the reduced, granitic magma. Based on the integrated evidence, we conclude that pre-enrichment of the source and extensive fractional crystallization were key factors for the formation of the Xiatongling W-Mo-Be deposit.

下铜岭钨钼铋（W-Mo-Be）矿床位于南岭成矿带，是发育在中细粒花岗岩岩体接触带内及沿接触带发育的网状石英脉型W-Mo-Be矿床。虽然前人的研究主要集中在岩浆年龄和侵入岩地球化学特征上，并通过辉钼矿年代学间接约束了成矿年龄，但对确切的成矿年代学、成矿物质来源以及控制W-Mo-Be成矿的关键因素仍知之甚少。本文对该矿床的锆石、磷灰石和黑钨矿进行了地球化学和年代学的综合研究，以限制其岩石成因和成矿作用。花岗岩锆石U-Pb年龄（约154 Ma）与黑钨矿U-Pb年龄（约154 Ma）相对应，建立了岩浆作用与钨矿化的成因联系。地球化学资料表明，该花岗岩为弱过铝质花岗岩（A/CNK = 1.03 ~ 1.08），具有高sio2、U、Ta、低Ba、Sr、低Zr + Nb + Ce + Y的特征，属于高分馏s型花岗岩。锆石εHf(t)值介于- 7.75 ~ - 10.64之间，磷灰石εNd(t)值介于- 15.56 ~ - 8.97之间，表明其来源于武工山地区元古代变质沉积基底，具有W、Mo、Be的预富集特征。综合全岩和黑钨矿地球化学资料显示，黑钨矿和下铜岭花岗岩均存在一致且明显的Eu负异常。结合强大的地质年代学约束，这些发现支持了还原成矿流体直接从还原的花岗质岩浆中溶解的解释。综合分析认为，下铜岭钨钼be矿床形成的关键因素是物源的预富集和广泛的分步结晶。

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引用次数: 0

Roles of magmatic sources and processes for tungsten mineralization: Implication from the weakly differentiated ore-bearing Xiaoyao granite in the Jiangnan Orogenic Belt, China 岩浆源与成矿过程在钨矿化中的作用——来自江南造山带弱分异含矿姚花岗岩的启示

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-30 DOI: 10.1016/j.lithos.2025.108397

Keqin Tao , Jun Yan , Linyu Xu , Wangfei Weng , Jiancheng Xie

Tungsten (W) mineralization is typically associated with highly fractionated granites. However, numerous W deposits in the eastern Jiangnan Orogenic Belt (EJOB) are genetically linked to Late Mesozoic weakly differentiated granites, whose petrogenesis and ore-controlling factors remain poorly understood. This study investigates the Xiaoyao granodiorite (149.8 ± 1.9 Ma), associated with a large skarn W deposit, to elucidate key ore-forming controls. Mineralogical evidence (plagioclase reverse zoning, acicular apatite, amphibole embaying biotite) confirms its crust-mantle mixing origin. Inherited zircons (peak at 780–800 Ma), weakly enriched whole-rock Sr–Nd–Pb and zircon Hf isotopes, and high magmatic zircon δ¹⁸O values (7.92 ‰–9.51 ‰) identify the crustal source as Early Neoproterozoic sedimentary strata. The mantle-derived component is volcanic arc basalt, evidenced by enrichment in large-ion lithophile elements, depletion in high-field-strength elements, and high magmatic H₂O, Cl, and fO₂. Thermodynamic modeling indicates the Xiaoyao pluton formed by fluid-absent melting of pelite.

W-enriched magmatic and inherited zircons reveal significant W enrichment in both the primary magma and its crustal source. Batch melting modeling demonstrates that W enrichment of Xiaoyao granodiorite was dominated by source pre-enrichment (factor = 5.9) and partial melting (factor = 5.3), with fractional crystallization playing a minor role. Across the EJOB, partial melting uniformly enhances W enrichment but does not differentiate mineralization potential; source pre-enrichment is prerequisite for mineralization; fractional crystallization governs deposit scale. Mantle-derived high fO₂ and H₂O–Cl signatures drove effective hydrothermal W–Cu–Mo enrichment during ore formation.

钨矿化通常与高分异花岗岩有关。然而，在江南造山带东部（EJOB）地区，大量钨矿床与晚中生代弱分异花岗岩有关，其成因及控矿因素尚不清楚。本文对与大型矽卡岩型钨矿有关的姚姚花岗闪长岩（149.8±1.9 Ma）进行了研究，以阐明关键的成矿控制因素。矿物学证据（斜长石逆分带、针状磷灰石、闪孔含黑云母）证实了其壳幔混合成因。继承的锆石（峰值在780 ~ 800 Ma）、弱富集的全岩Sr-Nd-Pb和锆石Hf同位素、高岩浆锆石δ18O值（7.92‰~ 9.51‰）确定了地壳源为早新元古代沉积地层。幔源成分为火山弧玄武岩，表现为大离子亲石元素富集，高场强元素亏缺，岩浆水、氯、fO2含量高。热力模拟表明，逍遥岩体是由无流体熔融的泥岩形成的。富W岩浆和继承锆石显示，原生岩浆和地壳源均富集W。批量熔融模拟结果表明，姚姚花岗闪长岩W富集以源预富集（因子= 5.9）和部分熔融（因子= 5.3）为主，分级结晶作用较小。在整个EJOB中，部分熔融均匀地增强了W的富集，但不区分成矿潜力；矿源预富集是成矿的先决条件；分级结晶支配着矿床的规模。在成矿过程中，地幔源的高fO2和H2O-Cl特征驱动了有效的热液W-Cu-Mo富集。

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From oceanic subduction to continental collision: Revisiting the Permian–Triassic magmatism of the Indosinian orogenic belt, Vietnam 从大洋俯冲到大陆碰撞：重新考察越南印支造山带二叠纪-三叠纪岩浆活动

IF 2.5 2区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Lithos

Pub Date : 2025-12-30 DOI: 10.1016/j.lithos.2025.108383

Lingtong Meng , Wei Lin , Nguyen Van Vuong , Michel Faure , Yin Wang , Fei Liu , Luong Thi Thu Hoai

Indosinian orogenic belt resulted from the Early Mesozoic collision between the South China block and the Indochina block, driven by the closure of Eastern Paleo-Tethys Ocean. In this study, we revisit Early Permian to Middle Triassic magmatic rocks in the Western Ailaoshan–Truong Son–Sam Nua magmatic unit (North Vietnam segment), Indosinian orogenic belt. New petrological, geochronological, geochemical, and zircon Hf isotopic data are integrated with previous studies to understand tectono-magmatic evolution from oceanic subduction to continental collision and its geodynamic implications. Two episodes of arc-related magmatism were identified: 300–270 Ma and 265–250 Ma, separated by a 270–265 Ma magmatic lull. These magmatic rocks exhibit intermediate-felsic, low- to moderate-K calc-alkaline, metaluminous to weakly peraluminous, and I-type to A-type in compositions. Zircon Hf isotopes indicate 300–270 Ma arc-related magmatism derived from partial melting of underplated juvenile mafic crust, while the 265–250 Ma ones sourced from increased contribution of ancient continental crust. The NE-younging trend of arc magmatism, repeated (S)–I–A-type magmatic sequences and systemic variations of ε_Hf(t) values, collectively suggest two episodes (290–270 Ma and 265–250 Ma) of slab roll-back interrupted by a period of flat-slab subduction (270–265 Ma), during the SW-directed subduction of Paleo-Tethys. Syn-collisional 250–240 Ma I-type granitoids are characterized by higher SiO₂, high-K calc-alkaline to shoshonitic affinities and negative ε_Hf(t) values, pointing to source from partial melting of ancient crust. This process was likely enhanced by slab-derived fluids from ongoing oceanic subduction beneath the collisional zone.

印支造山带是在早中生代东古特提斯洋闭合的推动下，华南地块与印度支那地块碰撞形成的。本文对印支造山带西哀牢山—张山—三努阿岩浆单元（北越南段）早二叠世—中三叠世岩浆岩进行了研究。新的岩石学、年代学、地球化学和锆石Hf同位素数据与以往的研究相结合，以了解从大洋俯冲到大陆碰撞的构造-岩浆演化及其地球动力学意义。确定了两期与弧相关的岩浆活动：300-270 Ma和265-250 Ma，中间隔着270-265 Ma的岩浆间歇期。这些岩浆岩具有中长英质、低至中钾钙碱性、铝质至弱过铝质、i型至a型组成。锆石Hf同位素表明，300 ~ 270 Ma与弧相关的岩浆活动来源于下镀期幼年基性地壳的部分熔融，而265 ~ 250 Ma与弧相关的岩浆活动来源于古大陆地壳的增加贡献。弧岩浆活动的ne -young化趋势、重复的(S) - i - a型岩浆序列和εHf(t)值的系统性变化，共同表明古特提斯期西南向俯冲期间的两期（290 ~ 270 Ma和265 ~ 250 Ma）板块回滚被一段（270 ~ 265 Ma）平板俯冲所中断。同碰撞250 ~ 240 Ma的i型花岗岩具有较高的sio2、高钾钙碱性与粗玄岩的亲和关系和负的εHf(t)值，表明其来源为古地壳部分熔融。碰撞带下面正在进行的海洋俯冲产生的板块衍生流体很可能加强了这一过程。

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