Precambrian Research最新文献_第4页

Detrital apatite records 1.9–1.8 Ga orogenesis in ‘tectono-thermal-event-poor’ region of southern margin of the North China craton 碎屑磷灰石记录了华北克拉通南缘“构造-热事件贫”地区1.9 ~ 1.8 Ga造山活动

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-04-01 Epub Date: 2026-02-04 DOI: 10.1016/j.precamres.2026.108037

Fengbo Sun , Peng Peng , Deshun Zheng , Boyang Xu

The late Paleoproterozoic Trans-North China Orogen (TNCO) records the amalgamation of the Western and Eastern blocks of the North China Craton (NCC). As a “tectono-thermal-event-poor” segment within the southern TNCO, the Wangwu-Zhongtiao Mountains region serves as a critical focus for tectonic investigations. Given that sediments are integrated archives of provenance lithologies, here we utilize U-Pb geochronology and trace and rare earth element geochemistry (TREE) of detrital apatite and zircon from clastic rocks of the Paleoproterozoic Dagushi Formation to constrain the evolutionary history of their source regions. This formation is the first fluvial-lacustrine system in the study area since the Paleoproterozoic orogenesis in the NCC. Analyses indicate that the 2.7–1.9 Ga zircon grains with multiple peaks inside the formation were from the nearby or proximal Archean-Paleoproterozoic basement; yet they show few coeval apatites. While the newly reported younger 1.9–1.8 Ga U-Pb ages of detrital apatite are abundant in the clastic rocks. Based on their TREE signatures (e.g., LREE enrichment, Sr depletion), as well as the fact of lacking contemporaneous zircon ages from the same samples, it provides critical insights into the geology of low- to high-grade metamorphic events of the Wangwu-Zhongtiao Mountains region. Three distinct metamorphic stages respectively at 1940–1930 Ma, 1890–1860 Ma, and 1840–1810 Ma can be differentiated, demonstrating that the late Paleoproterozoic tectono-thermal events in the Wangwu-Zhongtiao Mountains region are synchronous with those in the central and northern parts of the TNCO. The minor population of detrital apatite grains with ages of ca. 1770 Ma and younger grains may reflect the overprinting or alteration by post-orogenic thermal events. These events could potentially be linked to thermal effects associated with the volcanism of the Xiong’er Group, and 1.8–1.6 Ga anorogenic magmatism in the southern NCC. This study thus provides an indirect methodological framework for deciphering tectono-thermal events in less exposed/preserved regions.

晚古元古代跨华北造山带（TNCO）记录了华北克拉通（NCC）东、西地块的融合。王武-中条山地区作为TNCO南部的“构造-热事件贫”区，是构造调查的重点。鉴于沉积物是物源岩性的综合档案，本文利用古元古代大孤石组碎屑岩中磷灰石和锆石的U-Pb年代学和微量稀土元素地球化学（TREE）来约束其源区的演化历史。该组是北陆古元古代造山运动以来研究区首次形成的河湖体系。分析表明，组内2.7 ~ 1.9 Ga多峰锆石颗粒来自近、近太古代-古元古代基底；然而，它们几乎没有显示出同时期的磷灰石。碎屑磷灰石的U-Pb年龄为1.9 ~ 1.8 Ga，在碎屑岩中较为丰富。基于它们的TREE特征（如LREE富集、Sr亏缺），以及缺少同时期锆石的事实，为王武—中条山脉地区低—高变质事件的地质提供了重要的见解。可以区分出1940 ~ 1930 Ma、1890 ~ 1860 Ma和1840 ~ 1810 Ma三个不同的变质期，表明王武—中条山地区晚古元古代构造—热事件与TNCO中北部地区的构造—热事件是同步的。碎屑磷灰石颗粒数量较少，年龄约为1770 Ma或更年轻，可能反映了造山后热事件的叠印或蚀变。这些事件可能与熊耳群火山活动的热效应和北陆南部1.8 ~ 1.6 Ga造山岩浆活动有关。因此，本研究提供了一种间接的方法框架，用于破译暴露/保存较少的地区的构造-热事件。

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引用次数: 0

Corrigendum to “A window on the amalgamation of Western Gondwana: Geological history of the Ouaddaï massif (E. Chad)”. [Precam. Res. 434 (2026) 108000] “西冈瓦纳合并的窗口：Ouaddaï地块（乍得东部）的地质历史”的勘误表。[Precam。第434(2026)108000条]

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-04-01 Epub Date: 2026-01-29 DOI: 10.1016/j.precamres.2026.108017

Alexis Plunder , Olivier Blein , Moussa Isseini , Issaka Ousman Al-Gadam , Mathieu Chevillard , Emanuel Djedouboum , Philippe Lach , Abdeltif Lahfid , Jérémie Melleton , Olivier Rouzeau , Guillaume Vic

引用次数: 0

A window on the amalgamation of Western Gondwana: Geological history of the Ouaddaï massif (E. Chad) 西冈瓦纳合并的窗口：Ouaddaï地块（乍得东部）的地质历史

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-03-01 Epub Date: 2026-01-05 DOI: 10.1016/j.precamres.2025.108000

Alexis Plunder , Olivier Blein , Moussa Isseini , Issaka Ousman Al-Gadam , Matthieu Chevillard , Emanuel Djedouboum , Philippe Lach , Abdeltif Lahfid , Jérémie Melleton , Olivier Rouzeau , Guillaume Vic

The Saharan metacraton was assembled during pre-Neoproterozoic to Neoproterozoic times and was strongly remobilised during the Pan African orogeny. The Ouaddaï massif in eastern Chad represents the core of the Saharan metacraton, yet its geological history remains poorly documented. In this study, we combine of field observations, petrological analysis of metamorphic rocks, and geochemical and geochronological constraints to reconstruct the tectono-metamorphic evolution of the Ouaddaï massif. The study area is dominated by collision-related plutonic rocks and migmatitic gneisses, within which inliers of older basement occur. Geochemical data indicate a transition from active-margin to collisional magmatism, with a compositional evolution from diorite to granite. This suite is cross-cut by syenogranites and alkaline granites with shoshonitic affinities, interpreted as post-collisional granitoids derived from tonalitic rocks to sedimentary protoliths. Geochronological data (U-Pb on zircon and monazite) point to a ca. 1000 Ma age for orthogneisses inliers. Granitoids of the Ouaddaï massif record emplacement ages from 620 to 590 Ma, coeval with high-temperature metamorphism characterized by peak pressure–temperature conditions of 1.2 GPa and 850 °C (mafic granulite) and around 0.8 GPa and 700 °C (sillimanite-garnet bearing migmatites). Integrating our new results with regional data, we discuss the existence and geodynamic evolution of the Saharan Metacraton. Our findings emphasize the significance of the Saharan Metacraton as a key region for understanding the extensive reworking of cratonic lithosphere during both a Tonian magmatic phase prior and the assembly of Gondwana.

撒哈拉变质克拉通形成于前新元古代至新元古代，在泛非造山运动期间发生了强烈的再活动。乍得东部的Ouaddaï地块代表了撒哈拉元克拉通的核心，但其地质历史仍然缺乏记录。本研究结合野外观测、变质岩岩石学分析、地球化学和年代学约束，重建了Ouaddaï地块的构造变质演化过程。研究区以碰撞成因的深成岩和混染岩片麻岩为主，其中有较老的基底内层。地球化学资料表明岩浆活动由活动边缘向碰撞岩浆作用过渡，成分由闪长岩向花岗岩演化。该套花岗岩由正长花岗岩和碱性花岗岩交叉切割而成，具有玄武岩的亲缘关系，可解释为由调质岩到沉积原岩的后碰撞花岗岩。地质年代学数据（锆石和独居石上的U-Pb）表明，垂直度在1000 Ma左右。Ouaddaï地块的花岗岩类记录就位年龄为620 ~ 590 Ma，与高温变质作用同期发生，峰值压力-温度条件为1.2 GPa和850℃（基性麻粒岩），峰值压力-温度条件为0.8 GPa和700℃（硅线石-石榴石混合岩）。结合区域资料，讨论了撒哈拉变克拉通的存在及其地球动力学演化。我们的研究结果强调了撒哈拉变克拉通作为理解在托尼岩浆期之前和冈瓦纳组合期间克拉通岩石圈广泛改造的关键区域的重要性。

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引用次数: 0

New occurrence of a postglacial Ediacaran macrofossil assemblage from North China and its evolutionary implication 华北冰期后埃迪卡拉系大化石组合的新发现及其演化意义

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-03-01 Epub Date: 2026-01-03 DOI: 10.1016/j.precamres.2025.107992

Xin Wang , Xingliang Zhang , Tao Dai , Wei Liu , Yuan Zhang , Luoyang Li

The late Ediacaran witnessed a significant evolutionary junction, characterized by a pronounced decline in the diversity of Ediacara-type macrofossils and macroalgae, coinciding with the expansion of tubular organisms and mobile bilaterians as evidenced by trace fossils. The North China Craton (NCC), one of the oldest cratons with a geological history spanning more than 3.8 billion years, contains extensively distributed Ediacaran deposits along its western and southern margins. However, the Ediacaran fossil assemblages in NCC remain poorly understood, particularly due to the absence of Ediacara-type fossils. Here, we report a newly discovered macrofossil assemblage, the Dongpo biota (ca. 550–538.8 Ma), from the terminal Ediacaran Dongpo Formation, a shale-dominated sequence exposed along the southern margin of NCC. The biota comprises a diverse assemblage that includes frondose fossils, macroalgae, tubular forms, bilaterian trace fossils, and various problematic fossils, demonstrating a clear stratigraphic overlap. The new biota expands the known paleogeographic distribution of the Ediacaran macrofossils and offers crucial evidence enhancing our understanding of biotic communities inhabiting siliciclastic-dominated seafloors during the terminal Ediacaran period. Moreover, the fossil-bearing horizon conformably overlies the Luoquan diamictite, indicating that the Dongpo biota represents a postglacial Ediacaran macrofossil assemblage. Thus, this new biota provides key insights into the recovery and flourishing of benthic marine ecosystems after the ‘Great Ediacaran Glaciation’.

埃迪卡拉晚期是一个重要的进化交汇点，埃迪卡拉型大型化石和大型藻类的多样性明显下降，与此同时，管状生物和可移动的双边动物的扩张得到了化石痕迹的证明。华北克拉通（NCC）是中国最古老的克拉通之一，其地质历史超过38亿年，在其西缘和南缘广泛分布着埃迪卡拉沉积。然而，由于缺乏埃迪卡拉型化石，人们对北古陆埃迪卡拉纪的化石组合仍然知之甚少。在此，我们报道了一个新发现的大化石组合——东坡生物群（约550-538.8 Ma），它们来自埃迪卡拉系末段东坡组，这是一个暴露在NCC南缘的页岩为主的层序。生物群组成多样，包括叶状化石、大型藻类化石、管状化石、双边化石和各种问题化石，显示出明显的地层重叠。新的生物群扩展了已知的埃迪卡拉纪宏观化石的古地理分布，并提供了重要的证据，增强了我们对埃迪卡拉纪末期以硅塑料为主的海底生物群落的理解。此外，含化石层位整合覆盖在罗泉二晶岩上，表明东坡生物群为冰期后埃迪卡拉系大化石组合。因此，这种新的生物群为“埃迪卡拉大冰川”后底栖海洋生态系统的恢复和繁荣提供了关键的见解。

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引用次数: 0

Marine evaporitic borate mineralization during the Lomagundi–Jatuli Event, Liaodong Peninsula, northeast China 辽东半岛洛马岗地-加图里事件期间海相蒸发硼酸盐成矿作用

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-03-01 Epub Date: 2025-12-31 DOI: 10.1016/j.precamres.2025.107998

Guyue Hu , Chunlian Wang , Kuidong Zhao , Qian Li , Yanhe Li , Xinsheng Sun , Jun Zheng , Kunming Wang , Jianghua Gong , Peng Li , Yue Zhao

Many Paleoproterozoic borate deposits are hosted within the lower units of the volcanic–sedimentary sequence (ca. 2.2 Ga) of the Liaohe Group, Liaodong Peninsula, northeast China. It is debated as to whether these deposits were affected by marine evaporation. The borate ore bodies of the Zhuanmiao deposit in the Liaohe Group have stratiform or lenticular shapes and occur in serpentinized carbonates, with the ores being bordered by layered leptynites, leptites, amphibolites, and migmatites. We carried out a C–O–Mg stable isotope study of the ores and carbonate rocks in the Zhuanmiao deposit. The δ¹³C values of unserpentinized magnesite marbles in the ores of the Errengou block in the Zhuanmiao deposit range from +3.2 ‰ to +6.0 ‰ and preserve a positive C isotopic anomaly typical of the Lomagundi–Jatuli Event (2.306–2.057 Ga). The δ²⁶Mg values of these unserpentinized magnesite marbles in the Zhuanmiao borate deposit range from –1.01 ‰ to –0.84 ‰, which are typical of marine sediments. The positive C isotopic anomaly of the magnesite marbles in the Zhuanmiao deposit indicates that the C isotopic anomaly of magnesite that formed during the Lomagundi–Jatuli Event is not only a result of global oxygenation of the ocean–atmosphere, but also marine evaporation in individual basins. This evaporation even led to rare examples of borate mineralization.

辽东半岛辽河群火山-沉积层序（约2.2 Ga）下部单元内赋存大量古元古代硼酸盐矿床。关于这些沉积物是否受到海洋蒸发的影响，存在争论。辽河群转庙矿床硼酸矿体呈层状或透镜状，赋存于蛇纹岩碳酸盐中，矿缘为层状细斑岩、细斑岩、角闪岩和杂岩。对拐庙矿床的矿石和碳酸盐岩进行了C-O-Mg稳定同位素研究。转庙矿床二人沟块体矿石中未蛇纹化菱镁矿大理岩的δ13C值在+3.2‰~ +6.0‰之间，保持了典型的lomagundy - jatuli事件（2.306 ~ 2.057 Ga）的正C同位素异常。转庙硼酸矿床中未蛇纹石化菱镁矿大理岩的δ26Mg值在-1.01‰~ -0.84‰之间，具有典型的海相沉积特征。转庙矿床菱镁矿大理岩的正C同位素异常表明，lomagunti - jatuli事件期间形成的菱镁矿C同位素异常不仅是全球海洋-大气氧化作用的结果，而且是个别盆地海洋蒸发作用的结果。这种蒸发甚至导致了罕见的硼酸盐矿化。

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引用次数: 0

Crustal structure in the Quadrilátero Ferrífero mineral province, SE Brazil: differentiating preserved and reworked Archean crust 巴西东南部Quadrilátero Ferrífero矿省的地壳结构：保存太古宙地壳与改造太古宙地壳的区分

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-03-01 Epub Date: 2026-01-02 DOI: 10.1016/j.precamres.2025.108003

Taghi Shirzad , Marcelo Assumpção , Marcelo B. Bianchi , Bruno Collaço , Fernando Alkmim , Dionísio U. Carlos , Luciano Assis , Maximiliano Simão

The Quadrilátero Ferrífero (QF; Iron Quadrangle) on the southeastern São Francisco craton exposes Paleoarchean to Paleoproterozoic rocks shaped by multiple Precambrian tectonic events. Despite extensive mapping, its deeper crustal structure remains poorly constrained, limiting insights into Archean stabilization and later Paleoproterozoic reworking. Clarifying whether the QF greenstone belt preserves Mesoarchean lithosphere or later modification is key to understanding the region’s tectonic evolution. The deeper crustal structure also informs mineral potential, as crustal architecture governs ore localization in stable cratons. Here we study the deep crustal structure using teleseismic receiver functions (RF), recorded at six stations of the VALE QF seismic network, together with Rayleigh and Love wave dispersion curves. We retrieved group velocities of Rayleigh and Love waves from ambient noise of local and regional stations between 0.3 and 4.4 s, sampling the upper crust. For longer periods (5 to 100 s), we used group and phase velocities of continental-scale tomography models. Joint inversion of receiver functions and surface-wave dispersion curves showed a thin crust (∼35 km) in the middle of the QF province, beneath the Rio das Velhas greenstone belt, and a thicker crust (∼42 km) in the eastern and western areas of the QF. The variations of crustal thickness resulting from the joint inversion are consistent with H-k stacking of receiver functions. Other stations in the São Francisco craton, outside the QF, show intermediate thicknesses of 36–39 km. Bulk crustal Vp/Vs ranged from 1.72 to 1.74, with no systematic variation across the QF. The QF central area, beneath the Rio das Velhas greenstone belt, has thin crust and normal S-wave velocities in the lower crust Vs (3.8–3.9 km/s) consistent with intermediate granulite composition, whereas the stations with thick crust, on either side of the central greenstone belt, show high Vs (∼3.9–4.1 km/s) in the lowermost crust suggesting a more mafic composition. This contrast in the lower crust properties can be interpreted as preservation of the stabilized Mesoarchean crust beneath the greenstone belt. Alternatively, the crust in the middle of the QF could have been thinned during the extensional collapse at the end of the Minas orogeny in the Paleoproterozoic.

位于 o Francisco克拉通东南部的Quadrilátero Ferrífero （QF; Iron Quadrangle）暴露了古太古代和多次前寒武纪构造事件形成的古元古代岩石。尽管进行了广泛的测绘，但对其深层地壳结构的了解仍然很少，这限制了对太古宙稳定和后来的古元古代改造的认识。厘清青岩带是保存了中太古代岩石圈还是后来的改造，是认识该区构造演化的关键。由于地壳结构控制着稳定克拉通中的矿石定位，因此更深的地壳结构也决定着矿物潜力。本文利用VALE QF地震台网6个台站记录的远震接收函数（RF），结合Rayleigh波和Love波频散曲线，研究了深部地壳结构。我们从0.3 ~ 4.4 s的局部和区域台站环境噪声中提取了瑞利波和洛夫波的群速度，对上地壳进行了采样。对于较长的周期（5到100秒），我们使用了大陆尺度层析模型的群速度和相速度。接收函数和表面波频散曲线的联合反演显示，在QF省中部，在里约热内卢das Velhas绿岩带下方，地壳较薄（~ 35 km），而在QF东部和西部地区，地壳较厚（~ 42 km）。联合反演引起的地壳厚度变化与接收函数的H-k叠加一致。在QF外的弗朗西斯科克拉通的其他台站，显示出36-39公里的中等厚度。整体地壳Vp/Vs范围为1.72 ~ 1.74，在整个QF中没有系统变化。位于里约热内卢das Velhas绿岩带下方的QF中心区地壳薄，下地壳s波速度正常（3.8 ~ 3.9 km/s），与中间麻粒岩组成一致，而位于中央绿岩带两侧的厚地壳站，在最下层地壳中显示出高v (~ 3.9 ~ 4.1 km/s)，表明更具基性成分。下地壳性质的这种对比可以解释为在绿岩带下保存了稳定的中太古宙地壳。另一种可能是，在古元古代米纳斯造山末期的伸展崩塌中，QF中部的地壳变薄。

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引用次数: 0

Corrigendum to “Eoarchean low δ18O zircon indicates emergent land at 3.73 Ga” [Precambrian Res. 408 (2024) 107416] “始太古代低δ18O锆石显示3.73 Ga的出露陆”的勘误表[前寒武纪Res. 408 (2024) 107416]

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-03-01 Epub Date: 2026-01-19 DOI: 10.1016/j.precamres.2026.108014

Piotr Król , Monika A. Kusiak , Martin J. Whitehouse , Daniel J. Dunkley , Simon A. Wilde

引用次数: 0

Identification of eclogites that record Palaeoproterozoic and Triassic metamorphism in the Dabie UHP orogenic belt, eastern-central China 大别超高压造山带记录古元古代和三叠纪变质作用的榴辉岩鉴定

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-02-01 Epub Date: 2025-12-09 DOI: 10.1016/j.precamres.2025.107990

Jianhui Liu , Wei Jin , Fulai Liu , Zhengjiang Ding , Yuanshuo Li , Weinan Xu

In this study, zircon U–Th–Pb dating coupled with zircon morphology and texture observations, and trace element and Hf isotope analyses conducted on ultrahigh-pressure (UHP) eclogites and the host granitic gneiss in the central Dabie UHP belt has identified Neoarchean (ca. 2.5 Ga), Palaeoproterozoic (ca. 1.9 Ga) metamorphic events and Triassic UHP metamorphism at ca. 236 Ma. The Palaeoproterozoic metamorphic zircons from two eclogite samples and one granitic gneiss sample have consistent weighted mean ages of 1871 ± 26, 1890 ± 15, and 1915 ± 41 Ma, respectively. They exhibit low Th/U ratios (mostly < 0.1), depletions in light rare earth elements (LREE) and enrichments in heavy rare earth elements (HREE) characterized by steep chondrite-normalized patterns, and yielded a large range of Ti-in-zircon temperatures varying from 892 ℃ to 642 ℃, indicating their metamorphic recrystallization or growth under wide metamorphic condition. The Palaeoproterozoic metamorphic zircons from the eclogites have mostly uniform Hf compositions and positive ε_Hf(t) values distinctly different from the Palaeoproterozoic metamorphic zircons with variable Hf compositions and negative ε_Hf(t) values from the host granitic gneiss. The Triassic metamorphic zircons from two eclogite samples and one granitic gneiss sample gave weighted-mean ages of 236 ± 2, 236 ± 1 and 234 ± 3 Ma, respectively. They exhibit low Th/U ratios (mostly < 0.1), depletions in LREE and distinctively flat chondrite-normalized HREE patterns, and mostly consistent Hf isotope compositions with extremely low ¹⁷⁶Lu/¹⁷⁷Hf ratios and negative ε_Hf(t) values, and yielded Ti-in-zircon temperature of ca. 724℃ consistent with Triassic UHP metamorphic temperature, thus, these zircons is interpreted to be formed under Triassic UHP metamorphism. The host granitic gneiss has a minimum estimate of magmatic crystallization age of 2723 Ma. Therefore, it can be concluded that mafic protolith of the eclogite and the host granitic gneiss together experienced Palaeoproterozoic metamorphism at ca. 1.9 Ga and then Triassic UHP metamorphism at ca. 236 Ma. Additionally, it has further been suggested that the Early Precambrian basement exists and was involved in Triassic UHP metamorphism in the central Dabie UHP belt.

利用锆石U-Th-Pb定年、锆石形态和结构观测、微量元素和Hf同位素分析等方法，对大别超高压带中部的超高压榴辉岩和主花岗质片麻岩进行了鉴定，确定了新太古代（约2.5 Ga）、古元古代（约1.9 Ga）变质事件和三叠纪（约236 Ma）超高压变质事件。2个榴辉岩和1个花岗片麻岩变质锆石的加权平均年龄分别为1871±26 Ma、1890±15 Ma和1915±41 Ma。它们具有较低的Th/U比值（大部分为<； 0.1），轻稀土元素（LREE）的消耗和重稀土元素（HREE）的富集特征，具有陡峭的球粒陨石归一化模式，并产生了大范围的ti -in-锆石温度，从892℃到642℃不等，表明它们的变质再结晶或在宽变质条件下生长。来自榴辉岩的古元古代变质锆石的Hf组成基本一致，且εHf(t)值为正，与来自围岩花岗片岩的Hf组成变化较大、εHf(t)值为负的古元古代变质锆石有明显差异。2份榴辉岩和1份花岗质片麻岩变质锆石的加权平均年龄分别为236±2、236±1和234±3 Ma。它们具有较低的Th/U比值（多为<； 0.1），低稀土元素（LREE）呈明显的扁平球粒归一化模式，Hf同位素组成基本一致，176Lu/177Hf比值极低，εHf(t)值为负，锆石ti -in-锆石温度约为724℃，与三叠纪UHP变质温度一致，因此这些锆石被解释为在三叠纪UHP变质作用下形成的。寄主花岗岩片麻岩的岩浆结晶年龄最小估计为2723 Ma。因此，该榴辉岩基性原岩与寄主花岗质片麻岩共同经历了约1.9 Ga的古元古代变质作用和约236 Ma的三叠纪超高压变质作用。此外，大别超高压带中部存在早前寒武纪基底，并参与了三叠纪超高压变质作用。

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引用次数: 0

South China in the Rodinia-Gondwana transition: Constrains from the Ediacaran Doushantuo Formation of the north Yangtze Block 罗迪尼-冈瓦纳过渡时期的华南：来自北扬子地块埃迪卡拉系陡山沱组的约束

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-02-01 Epub Date: 2025-12-19 DOI: 10.1016/j.precamres.2025.107996

Lisha Hu , Jie Yang , Yuansheng Du , Zuozhen Han , Hongwei Kuang , Yongqing Liu , Chao Han , Yi Zhang , Wei Jin , Le Wan

The paleogeographic position of South China and its tectonic affinity with other continental blocks during the Rodinia-Gondwana transition remain not well established. This study reports new zircon U-Pb ages and Lu-Hf isotopic data from the Ediacaran Doushantuo Formation in the Chengkou-Zhenba area on the northern margin of the Yangtze Block. Detrital zircons yield concordant ages ranging from 2654 to 596 Ma, with 95 % of the grains clustering in the range of 1066 and 596 Ma. The age spectrum exhibits two major peaks at 633 Ma and 609 Ma, along with three minor peaks at 893 Ma, 851 Ma, and 749 Ma. The ε_Hf(t) values are predominantly positive, with 92 % of the analyses ranging from + 1.1 to + 13.6. The detrital zircon age distribution of the Doushantuo Formation is largely consistent with that of magmatic rocks from the Panxi-Hannan belt, supplemented by an additional Pan-African age population (ca. 630–600 Ma). Integrated U-Pb–Hf isotopic provenance analysis of Neoproterozoic rocks from the north Yangtze Block suggests that, aside from the ca. 630–600 Ma detritus, most detrital zircons were likely derived from nearby magmatic rocks in the Panxi-Hannan belt of the north Yangtze Block. Qualitative comparisons of detrital zircon age distributions between our samples and contemporaneous Ediacaran sedimentary strata in South China and other continental blocks indicate that the ca. 630–600 Ma detritus likely originated from Pan-African orogens in northern Gondwana, particularly the East African Orogen in southern India. These findings support a close paleogeographic and tectonic connection between South China and India during the Rodinia–Gondwana transition.

华南在罗迪尼-冈瓦纳过渡时期的古地理位置及其与其他大陆块体的构造亲缘关系尚不明确。本文报道了扬子地块北缘城口-镇坝地区埃迪卡拉系陡山沱组锆石U-Pb年龄和Lu-Hf同位素的新数据。碎屑锆石年龄在2654 ~ 596 Ma之间，95%的颗粒聚集在1066 ~ 596 Ma之间。年龄谱在633 Ma和609 Ma处有两个主峰，在893 Ma、851 Ma和749 Ma处有三个小峰。εHf(t)值主要是正的，92%的分析在+ 1.1到+ 13.6之间。陡山沱组碎屑锆石年龄分布与攀西—汉南带岩浆岩年龄分布基本一致，并补充有泛非洲年龄群（约630 ~ 600 Ma）。北扬子地块新元古代岩石U-Pb-Hf同位素综合物源分析表明，除约630 ~ 600 Ma碎屑岩外，大部分碎屑锆石可能来源于附近的北扬子地块攀西—汉南带岩浆岩。通过与中国南部和其他大陆块体同时期埃迪卡拉纪沉积地层的锆石年龄分布进行定性比较，表明约630 ~ 600 Ma的碎屑可能来源于冈瓦纳北部泛非造山带，特别是印度南部的东非造山带。这些发现支持了在罗迪尼-冈瓦纳过渡时期华南与印度之间密切的古地理和构造联系。

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Tonian intra-oceanic subduction initiation at the northwestern Yangtze Block: Evidence from forearc ophiolite fragments in the Bikou microblock 扬子地块西北部冬期洋内俯冲起始：碧口微地块弧前蛇绿岩碎片证据

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research

Pub Date : 2026-02-01 Epub Date: 2025-12-18 DOI: 10.1016/j.precamres.2025.107997

Li Qin , Xianzhi Pei , Ruibao Li , Lei Pei , Chengjun Liu , Zuochen Li , Shaowei Zhao , Feng Gao

The Bikou Group, situated in the southern part of the Bikou microblock along the northwestern Yangtze Block, preserves extensive remnants of Tonian volcanic magmatism. However, the timing of its formation and its tectonic setting remain debated. In this study, we report a newly identified geological record of subduction initiation from the Heimulin forearc ophiolite in the Bikou microblock. The Heimulin ophiolite comprises Tonian forearc peridotites, forearc basalts (diabases), boninites, high-Mg andesites and dacites, resembling the forearc igneous sequences observed in the Izu-Bonin-Mariana (IBM) subduction zone. Forearc basalts (diabase) with zircon U-Pb ages of 841 Ma exhibit geochemical signatures similar to normal mid-ocean ridge basalts (N-MORB) but lower Ti/V ratios indicate slightly higher concentrations of fluid-mobile elements than N-MORB. In contrast, the ∼ 834 Ma boninite displays more pronounced depletion in high field strength elements (HFSEs) and Heavy rare earth elements (HREEs) compared to the FABs. The high-Mg andesites (HMAs) and dacites yield zircon U-Pb ages of 833 Ma and 825 Ma, respectively. The HMAs were derived from partial melting of a mantle wedge metasomatized by melts/fluids released from a subducting oceanic slab, whereas the dacites were produced in a mature intra-oceanic arc setting through dehydration melting of mafic rocks in the middle to lower crust. The Heimulin forearc ophiolites record a magmatic evolution from less to more HFSE-depleted and LILE-enriched, similar to the magmatic evolution of the IBM forearc, reflecting progressive subduction of the oceanic slab. Inherited zircons and negative Hf isotopes indicate the presence of ribbon-like continental fragments in the Heimulin intra-oceanic arc, which may have facilitated the initiation of Tonian intra-oceanic subduction in the Heimulin Ocean. Integrated with previously published reliable data, our study provides further evidence that the northwestern Yangtze Block experienced continuous subduction-accretion processes during the Tonian, with the Yangtze Block (South China Block) likely situated on the margin of the Rodinia supercontinent.

碧口群位于扬子地块西北部碧口微地块的南部，保留了大量的东系火山岩浆活动遗迹。然而，它的形成时间和构造环境仍有争议。本文报道了碧口微块黑木林弧前蛇绿岩俯冲起始的新地质记录。黑木林蛇绿岩由东系弧前橄榄岩、弧前玄武岩（辉绿岩）、博长岩、高镁安山岩和英安岩组成，与伊豆-博宁-马里亚纳（IBM）俯冲带的弧前火成岩序列相似。锆石U-Pb年龄为841 Ma的前弧玄武岩（辉绿岩）具有与正常洋中脊玄武岩（N-MORB）相似的地球化学特征，但较低的Ti/V比值表明其流体流动元素浓度略高于N-MORB。相反，与fab相比，~ 834 Ma boninite在高场强元素（hfse）和重稀土元素（hree）中表现出更明显的耗损。高镁安山岩和英安岩的锆石U-Pb年龄分别为833 Ma和825 Ma。hma来源于俯冲洋板释放的熔体/流体交代的地幔楔的部分熔融，而英安岩则是在成熟的洋内弧环境中通过中下地壳基性岩的脱水熔融而产生的。黑木林弧前蛇绿岩的岩浆演化过程与IBM弧前相似，经历了由少到多的hfse -贫和lile -富的岩浆演化过程，反映了洋板的递进俯冲。继承的锆石和负Hf同位素表明，黑木林洋内弧中存在带状大陆碎片，这可能促进了黑木林洋内托宁期洋内俯冲的开始。结合前人已发表的可靠资料，进一步证明了扬子地块西北部在冬期经历了连续的俯冲-增生过程，扬子地块（华南地块）可能位于罗迪尼亚超大陆的边缘。

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引用次数: 0