Earth and Planetary Science Letters最新文献_第7页

Sediment provenance and transport pathways along the Atlantic Iberian Margin 大西洋伊比利亚边缘沉积物的来源和运输路径

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-18 DOI: 10.1016/j.epsl.2025.119788

Sara Campderrós , Leopoldo D. Pena , Ester Garcia-Solsona , Eduardo Paredes-Paredes , Albert Català , Jaime Frigola , Negar Haghipour , Isabel Cacho

The Atlantic Iberian margin is a dynamic region where oceanographic processes interact with continental sediment, influencing transport and deposition. To identify sediment sources and dominant transport dynamics we combine ⁸⁷Sr/⁸⁶Sr and Ɛ_Nd measurements on terrigenous sediments and ¹⁴C dating of planktonic foraminifera from core-tops along the margin. We present a new dataset of Sr-Nd isotope data from the Iberian Peninsula to characterize the isotopic composition of main river basins, considered potential sediment sources alongside African dust. By solving a ternary isotope mixing system, combined with a new statistical method to account for endmember isotopic distributions, we quantify the relative contribution of source areas to our samples. Our results reveal: 1) the margin is characterized by three isotopically distinct regions, 2) African dust is an important component of the terrigenous sediment (∼60 %), 3) regional differences in isotopic values reflect the influence of major river discharges: Guadalquivir in the south, Tagus in the centre, and Douro in the north, and 4) sediment transport follows a net northward direction along-slope. This sediment transport is attributed to the northward-flowing Mediterranean Outflow Water (MOW), which entrains and redistributes sediments along-slope. This is further supported by foraminifera ¹⁴C results, showing older radiocarbon ages along the MOW path, indicating sediment erosion. In contrast, younger radiocarbon ages are consistently found below MOW depths. The combined ⁸⁷Sr/⁸⁶Sr, Ɛ_Nd and ¹⁴C data suggest that MOW flow reduces sediment deposition along its path, transporting sediments northward, where it predominantly settles below the interface between MOW and the underlying North East Atlantic Deep Water.

大西洋伊比利亚边缘是一个海洋过程与大陆沉积物相互作用的动态区域，影响着运输和沉积。为了确定沉积物的来源和主要的输运动力学，我们结合了陆源沉积物的87Sr/86Sr和ƐNd测量以及沿边缘岩心顶部浮游有孔虫的14C测年。我们提出了一个新的来自伊比利亚半岛的Sr-Nd同位素数据集，以表征主要河流流域的同位素组成，这些流域被认为是非洲沙尘的潜在沉积物来源。通过求解三元同位素混合系统，结合一种新的统计方法来解释端元同位素分布，我们量化了源区对样品的相对贡献。结果表明：1)陆源沉积物主要由3个不同的区域组成；2)非洲沙尘是陆源沉积物的重要组成部分（约60%）；3)同位素值的区域差异反映了主要河流流量的影响：南部为瓜达尔基维尔，中部为塔古斯，北部为杜罗；4)沉积物沿坡向净北输。这种泥沙运移归因于向北流动的地中海流出水（MOW），它沿着斜坡携带和重新分配沉积物。有孔虫14C的结果进一步支持了这一点，显示出沿着MOW路径的更古老的放射性碳年龄，表明沉积物侵蚀。相比之下，更年轻的放射性碳年龄一直在MOW深度以下被发现。87Sr/86Sr、ƐNd和14C的综合数据表明，MOW流减少了其路径沿线的沉积物沉积，将沉积物向北输送，沉积物主要沉积在MOW流与下伏的东北大西洋深水界面下方。

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引用次数: 0

Isotope effects (Cl, O, C) of heterogeneous electrochemistry induced by Martian dust activities 火星尘埃活动诱导的非均相电化学同位素效应（Cl， O， C）

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-18 DOI: 10.1016/j.epsl.2025.119784

Neil C. Sturchio , Hao Yan , Alian Wang , W. Andrew Jackson , Huiming Bao , Chuck Y.C. Yan , Linnea J. Heraty , Yu Wei , Quincy H.K. Qu , Kevin S. Olsen

Some oxidized compounds in Martian soils may form through heterogeneous electrochemistry (HEC) stimulated by electrostatic discharge (ESD) during dust storms and dust devils. To test this hypothesis, we conducted medium-strength ESD experiments in a Mars simulation chamber and analyzed the Cl, O, and C isotopic compositions of the resulting chloride, (per)chlorate, and carbonate products. These ESD products exhibit substantial mass-dependent depletions in heavy isotopes relative to the reactants: ε³⁷Cl from -11.3 ‰ to +2.0 ‰, ε¹⁸O from -34.5 ‰ to -12.9 ‰, and ε¹³C around -11.4 ‰. These results, when compared with isotopic measurements from recent Mars missions (ESA’s ExoMars Trace Gas Orbiter and the Sample Analysis at Mars (SAM) instrument package aboard NASA’s Curiosity rover) and Martian meteorites, indicate that HEC induced by Martian dust activities can account for a substantial portion of the (per)chlorates and carbonates identified at the surface of Mars and the HCl in its atmosphere.

火星土壤中的一些氧化化合物可能是在沙尘暴和尘暴期间静电放电（ESD）刺激下形成的非均质电化学（HEC）。为了验证这一假设，我们在火星模拟室内进行了中等强度的ESD实验，并分析了氯、氯酸盐和碳酸盐产物的Cl、O和C同位素组成。这些ESD产物的重同位素相对于反应物表现出明显的质量依赖性损耗：ε37Cl从-11.3‰到+2.0‰，ε18O从-34.5‰到-12.9‰，ε13C在-11.4‰左右。这些结果，当与最近的火星任务（ESA的ExoMars痕量气体轨道器和NASA的好奇号火星车上的火星样本分析（SAM）仪器包）和火星陨石的同位素测量结果进行比较时，表明由火星尘埃活动引起的HEC可以解释在火星表面发现的氯酸盐和碳酸盐以及大气中的HCl的很大一部分。

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引用次数: 0

Changing volatile emissions and sources along the Ethiopian Rift 沿着埃塞俄比亚裂谷变化的挥发性排放物和来源

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-18 DOI: 10.1016/j.epsl.2025.119782

Abate A. Melaku , Gemechu B. Teferi , Takele Mihretie , Snorri Gudbrandsson , Yared Sinetebeb , Peter H. Barry , Tobias P. Fischer , Finlay M. Stuart , Ugur Balci , Sæmundur A. Halldórsson , Chris J. Ballentine , Darren J. Hillegonds , Emma L. Chambers , Derek Keir , Richard Bates , William Hutchison

Rift volcanoes are sites of intense volatile emissions. However, major uncertainties remain about the magnitude of rift volatile fluxes, particularly for greenhouse gases (e.g. CO₂) and whether along-rift variations in degassing relate to changing mantle sources and/or rifting processes (i.e. melt production and lithospheric thinning). Here, we investigate CO₂ flux and gas isotopes in Ethiopia; a mature, plume-influenced continental rift. We focus on one of the largest caldera volcanoes, Bora-Baricha-Tulu Moye (BBTM), which is situated in a region of high mantle melt production in the Central Main Ethiopian rift (∼500 km south-west the putative plume head). BBTM gases are characterized by plume-like ³He/⁴He values up to 17 R_a (the highest ever observed in Ethiopian Rift fumaroles) and we calculate total magmatic CO₂ flux of 757–901 t d^-1 (making BBTM the largest volcanic CO₂ emitter in the Ethiopian Rift). Using our CO₂ flux measurements, we estimate total CO₂ emissions from Ethiopia’s volcanic systems to be 2500–9200 kt yr^-1 and reveal important along-rift variation in CO₂ flux. High CO₂ flux sectors are found in Central Afar, as well as the Northern and Central Main Ethiopian Rift. These sectors are all regions of high partial melt content (evidenced by low seismic velocity in the underlying mantle) and also show the greatest ³He/⁴He values (>14 R_a). Cooccurrence of high mantle melt production, elevated CO₂ emissions and high ³He/⁴He demonstrates that in mature continental rifts carbon emissions and plume volatile contributions are particularly elevated in regions of greatest lithospheric thinning and mantle melting.

裂谷火山是释放大量挥发性物质的地方。然而，裂谷挥发性通量的大小，特别是温室气体（如二氧化碳）的大小，以及沿裂谷脱气的变化是否与变化的地幔源和/或裂谷过程（即熔体产生和岩石圈变薄）有关，仍然存在重大的不确定性。在这里，我们研究了埃塞俄比亚的二氧化碳通量和气体同位素；一个成熟的、受羽状物影响的大陆裂谷。我们的重点是最大的火山口火山之一，Bora-Baricha-Tulu Moye (BBTM)，它位于埃塞俄比亚中部裂谷的高地幔熔体生产区域（假定的羽头西南约500公里）。BBTM气体以羽状的3He/4He值为特征，高达17 Ra（埃塞俄比亚裂谷喷气孔中观测到的最高值），我们计算出总岩浆CO2通量为757-901 t d-1（使BBTM成为埃塞俄比亚裂谷中最大的火山CO2排放者）。利用我们的二氧化碳通量测量，我们估计埃塞俄比亚火山系统的二氧化碳总排放量为2500 - 9200kt年-1，并揭示了二氧化碳通量沿裂谷的重要变化。高二氧化碳通量区位于阿法尔中部以及埃塞俄比亚北部和中部裂谷。这些扇区都是部分熔体含量高的区域（下伏地幔地震速度低），也显示出最大的3He/4He值（>14 Ra）。高地幔熔体产量、高CO2排放和高3He/4He的同时发生表明，在成熟大陆裂谷中，岩石圈减薄和地幔融化最严重的地区，碳排放和地幔柱挥发贡献特别高。

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引用次数: 0

Isotopic constraints on the Barium subduction cycle 钡俯冲旋回的同位素约束

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-17 DOI: 10.1016/j.epsl.2025.119789

Qasid Ahmad , Martin Wille , Carolina Rosca , Thomas Pettke , Jörg Hermann , Stephan König

Subduction processes regulate elemental cycling and consequently the composition of Earth’s geochemical reservoirs - mantle, crust, atmosphere, and hydrosphere, exerting far-reaching effects for the evolution of life. Barium (Ba) is essential for understanding crust-mantle recycling, especially since over 90 % of Ba in arc lavas originates from subducted materials. While Ba enrichments in arc lavas have long been attributed to contributions from oceanic crust derived aqueous fluids, recent studies highlight hydrous sediment melts as a key carrier. Here, we present high-precision Ba isotope data (δ^138/134Ba) of input and output from the Tongan subduction zone. The results show that Ba is not predominantly supplied by the subducting oceanic crust. Instead, most Ba can be traced back to subducting sediments from which it is released in two stages. During early subduction, sedimentary barite dissolves and releases isotopically heavy Ba via aqueous fluids into the serpentinized mantle wedge, where this Ba is later remobilized during subsequent breakdown. With continued slab descent, remaining lithogenic phengite releases isotopically lighter Ba, which is recycled at subarc depths by hydrous melting. Both mechanisms can explain the entire range of Ba/Th and δ^138/134Ba in Tongan arc lavas without requiring Ba isotope fractionation between fluids and solids. These results from the endmember setting of Tonga, with minimal subducting sediments, imply higher proportion of sediment-derived Ba in other arcs worldwide. The Forearc Serpentinite Signature (FSS), which is created by the interaction of the mantle wedge with sediment-derived fluids at low temperatures (<600 °C), represents an additional fluid endmember that must be considered in the genesis of arc lavas. Lithogenic Ba that is not completely released at subarc depths can be further subducted into the deeper mantle, where it may later enrich mantle domains that source mid-ocean ridge and hotspot lavas. The relative proportions of sedimentary components in subducted slabs have changed over Earth’s history, highlighting the link between arc magma and mantle compositions and long-term shifts in Earth’s surface (bio)geochemical cycles.

俯冲过程调节了元素循环，从而调节了地球地球化学储层——地幔、地壳、大气和水圈的组成，对生命的进化产生了深远的影响。钡（Ba）对于理解壳幔再循环至关重要，特别是因为弧熔岩中超过90%的Ba来自俯冲物质。虽然弧熔岩中的Ba富集一直被认为是来自海洋地壳的含水流体的贡献，但最近的研究强调含水沉积物熔体是一个关键的载体。在此基础上，我们获得了铜安俯冲带输入和输出的高精度Ba同位素（δ138/134Ba）数据。结果表明，Ba主要不是由俯冲洋壳供给的。相反，大多数钡元素可以追溯到俯冲沉积物中，并分两个阶段释放出来。在早期俯冲过程中，沉积重晶石溶解，并通过水溶液将同位素重钡释放到蛇纹岩化的地幔楔中，在随后的破裂过程中，这些钡被重新活化。随着板块继续下降，剩余的成岩辉长岩释放出同位素较轻的Ba，在亚弧深度通过水熔融再循环。这两种机制都可以解释汤加弧熔岩中Ba/Th和δ138/134Ba的整个范围，而不需要流体和固体之间的Ba同位素分馏。这些结果来自汤加的端元环境，俯冲沉积物最少，意味着世界上其他弧中沉积源钡的比例更高。弧前蛇纹岩特征（FSS）是由地幔楔与低温（<600°C）下的沉积流体相互作用形成的，它代表了弧熔岩成因中必须考虑的另一个流体端元。在次弧深度未完全释放的造岩钡可以进一步俯冲到更深的地幔中，在那里它可能后来丰富了形成洋中脊和热点熔岩的地幔域。俯冲板块中沉积成分的相对比例在地球历史上发生了变化，突出了弧岩浆和地幔成分之间的联系以及地球表面（生物）地球化学循环的长期变化。

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引用次数: 0

Melting phase relations in Fe-FeS under Martian core pressures: Crystallization of Fe12S7 at the inner core? 火星核压力下Fe-FeS的熔融相关系：Fe12S7在内核的结晶？

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-17 DOI: 10.1016/j.epsl.2025.119785

Fumiya Sakai , Kei Hirose

Sulphur is believed to be a major light element in the Martian core, and if it is the single light element, 15 wt% to 34 wt% S is required to explain the mean core density deduced from the recent InSight observations. The existing Fe-FeS phase diagram at 21 GPa suggests the crystallization of Fe₃₊_xS₂ from such sulphur-rich core liquids, but melting phase relations at ∼40 GPa corresponding to Mars’ centre pressure are not known yet. Here we performed both subsolidus and melting experiments on Fe + 22.3–27.5 wt% S samples between 26 and 175 GPa to constrain the S-rich portion of the Fe-FeS phase diagram. Present experiments were conducted up to a pressure range much higher than that for the Mars’ core in order to constrain the melting curve and compression behaviour of Fe₁₂S₇. Synchrotron X-ray diffraction measurements demonstrated that Fe₁₂S₇ is formed above 27 GPa and Fe_3.2S₂ decomposes into Fe₁₂S₇ + FeS at least above 29 GPa. We also found that Fe₂S incongruently melts to liquid + Fe₁₂S₇, showing that Fe₁₂S₇ crystallizes from liquid Fe containing 20 to 25 wt% S under the proposed pressure and temperature at the Mars’ centre. Fe₁₂S₇ forms also from S-rich Fe-S-C/Fe-S-O core liquids following the crystallization of Fe₃C/FeO. Furthermore, the equation of state of Fe₁₂S₇ indicates its density is higher than the range of observed Martian mean core density. These suggest that the Martian inner core, if it exists, likely includes Fe₁₂S₇, even when considering the presence of other light elements.

硫被认为是火星核心的主要轻元素，如果它是唯一的轻元素，则需要15 wt%至34 wt%的硫来解释最近洞察号观测得出的平均核心密度。现有的21 GPa的Fe-FeS相图表明，Fe3+xS2是从这种富硫核心液体中结晶出来的，但与火星中心压力对应的~ 40 GPa的熔化相关系尚不清楚。在这里，我们对Fe + 22.3 - 27.5% wt% S样品在26 - 175 GPa之间进行了亚固态和熔融实验，以约束Fe- fes相图中富S部分。为了限制Fe12S7的熔化曲线和压缩行为，本实验在远高于火星核心的压力范围内进行。同步x射线衍射测量表明，Fe12S7在27gpa以上形成，Fe3.2S2在29gpa以上分解为Fe12S7 + FeS。我们还发现Fe2S不一致地熔化为液态+ Fe12S7，这表明Fe12S7是在火星中心所提出的压力和温度下由含20 - 25wt % S的液态Fe结晶而成的。Fe12S7也由富s的Fe-S-C/Fe-S-O核心液体在Fe3C/FeO结晶后形成。此外，Fe12S7的状态方程表明其密度高于观测到的火星平均核密度范围。这表明，即使考虑到其他轻元素的存在，火星内核（如果存在的话）也可能包含Fe12S7。

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引用次数: 0

Using rate-and-state friction constitutive laws to predict seismicity rates for ice rifts on the Ross Ice Shelf in Antarctica 利用速率和状态摩擦本构定律预测南极洲罗斯冰架冰裂缝的地震活动率

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-17 DOI: 10.1016/j.epsl.2025.119790

Kathrine Udell-Lopez, Mong-Han Huang, Vedran Lekić

Determining what fault characteristics and applied stress conditions modulate the occurrence of seismicity is a key question in the field of seismology. Here we analyze the seismicity measured at two ice shelf rift zones of different maturity in the Ross Ice Shelf, which are subjected to long-term dilatational stress modulated by tidal stress variations. We analyze the periodicity of the seismicity and its relationship to tidal stress variations and find that the seismicity rate at both rifts is controlled by tidal stress rate variations. We compare the observed icequake occurrence times with analytical predictions from rate-and-state friction constitutive laws that have been used to model frictional behavior on terrestrial faults. We find that seismicity rate is predicted well by an analytical model based on rate-and-state friction, confirming that it can be used to understand ice rift seismicity. We constrain for the first time the characteristic time of seismicity rate,

t_{a}

, for both rifts, and find that ice rifts have a faster recovery time than continental faults, and that their responses to stress and characteristic times are age dependent. This implies that the strength of the rift changes with time and determines the amount of stress or stress rate dependency of the system. Our results can be used to understand seismicity occurrence across other ice rifts in Antarctica and Greenland and holds implications for seismicity on icy satellites.

确定什么样的断层特征和外加应力条件调节地震活动性的发生是地震学领域的一个关键问题。本文分析了罗斯冰架两个不同成熟度冰架裂谷带的地震活动性，这些裂谷带受到潮汐应力变化调制的长期膨胀应力的影响。分析了地震活动性的周期性及其与潮汐应力变化的关系，发现两个裂谷的地震活动性受潮汐应力变化的控制。我们将观测到的地震发生时间与基于速率和状态摩擦本构定律的分析预测进行了比较，这些本构定律已被用于模拟陆地断层的摩擦行为。我们发现基于速率-状态摩擦的解析模型可以很好地预测地震活动性，证实了它可以用来理解冰裂谷地震活动性。我们首次约束了两个裂谷的地震活动性特征时间，发现冰裂谷比大陆断层有更快的恢复时间，并且它们对应力和特征时间的响应依赖于年龄。这意味着裂缝的强度随时间而变化，并决定了系统的应力量或应力速率依赖性。我们的结果可以用来了解南极洲和格陵兰岛其他冰裂谷的地震活动，并对冰冻卫星的地震活动产生影响。

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引用次数: 0

Fixation of atmospheric nitrogen on present-day Mars during dust events 沙尘事件期间火星大气氮的固定

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-17 DOI: 10.1016/j.epsl.2025.119786

Wenshuo Mao , Xiaohui Fu , Zhongchen Wu , Jiang Zhang , Zongcheng Ling , Yang Liu , Yu-Yan Sara Zhao , Jiacheng Liu , He Cui , Hitesh G. Changela , Yuheng Ni , Lifang Li , Joseph R. Michalski

N₂ is the second most abundant gas in the present-day Martian atmosphere and hosts the essential biochemical element N. Nitrate and (per)chlorate have been detected in numerous aeolian sediments in Gale crater. Thus, a potential nitrogen fixation may be active on present-day Mars. Interactions between Martian atmosphere and surface during dust events can trigger electrostatic discharge (ESD) and complex electrochemical reactions. By simulating this process in a Mars chamber, nitrate and (per)chlorate were produced under present-day Martian atmospheric conditions. Notably, the obtained nitrate/(per)chlorate abundance ratio is in agreement with Gale crater observations (< 1.0), but much lower than those in terrestrial Mars analogues and the products of other pathways proposed for Mars. The results strongly indicate that electrochemical reactions during Mars dust events represents a new nitrogen fixation mechanism on present-day Mars. It is different from other fixation processes on Earth and early Mars, expanding the knowledge of nitrogen cycle and nitrogen fixation in solar system. Electrochemical reactions may also play crucial roles in global nitrogen cycling throughout the Amazonian period. These nitrate salts in Martian dusts potentially provide an accessible source of nitrogen for possible organic molecule formation on present-day Mars.

氮气是现今火星大气中含量第二丰富的气体，含有必要的生物化学元素n。在盖尔陨石坑的大量风成沉积物中发现了硝酸盐和氯酸盐。因此，在今天的火星上可能存在潜在的固氮作用。尘埃事件发生时火星大气与地表的相互作用会引发静电放电和复杂的电化学反应。通过在火星室内模拟这一过程，硝酸盐和氯酸盐（per）在今天的火星大气条件下产生。值得注意的是，获得的硝酸盐/氯酸盐丰度比与Gale陨石坑观测值一致（< 1.0），但远低于陆地火星类似物和其他途径提出的火星产物。结果有力地表明，火星尘埃事件中的电化学反应代表了一种新的火星固氮机制。它不同于地球和早期火星上的其他固定过程，扩展了对太阳系氮循环和氮固定的认识。电化学反应也可能在整个亚马逊时期的全球氮循环中发挥关键作用。火星尘埃中的这些硝酸盐可能为今天火星上可能形成的有机分子提供了一种可行的氮源。

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引用次数: 0

Friction heterogeneity constrains rupture dynamics across a narrow seismogenic zone: The 2021 Mw 7.4 Maduo Earthquake (Eastern Tibet) 摩擦非均质性限制了狭窄发震带的破裂动力学：2021 Mw 7。

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-16 DOI: 10.1016/j.epsl.2025.119769

Kuilin Xiao , Qiang Qiu

Slip magnitude and rupture extent are crucial for understanding fault mechanics and seismic hazard but remain poorly resolved at depth. Here, we integrate GNSS and remote sensing observations with a resolution-optimized slip inversion technique to determine the coseismic slip distribution due to the 2021 Mw 7.4 Maduo earthquake (Tibet). Our high-resolution model reveals three key aspects unresolved in prior studies: a larger maximum slip of ∼9 m on the eastern fault, a moderate shallow slip deficit (SSD) of ∼40% above ∼2 km depth, and a narrower seismogenic layer confined to depths of 2–8 km. Further, we conduct physics-based 2D earthquake-cycle models, constrained by InSAR data and geological information, which reconcile these observations and indicate a transition from rate-weakening (seismogenic depths) to rate-strengthening (shallow depths), explaining both the SSD and along-strike variations in seismogenic zone width. Coulomb stress transfer calculation from our model successfully forecasts aftershocks over days to years, providing a benchmark for future seismic hazard assessment. These findings imply heightened seismic risk in the eastern Bayan Har Block, necessitating focused monitoring.

滑移震级和破裂程度对于了解断层力学和地震危险性至关重要，但在深部仍未得到很好的解决。在这里，我们将GNSS和遥感观测与分辨率优化的滑动反演技术相结合，以确定2021 Mw 7的同震滑动分布。我们的高分辨率模型揭示了之前研究未解决的三个关键方面：东部断层的最大滑移量为~ 9 m，在~ 2 km深度以上的中度浅滑动亏损（SSD）为~ 40%，以及局限于2 - 8 km深度的较窄的孕震层。此外，在InSAR数据和地质信息的约束下，我们进行了基于物理的二维地震周期模型，该模型与这些观测结果相吻合，并表明从速率减弱（孕震深度）到速率增强（浅层深度）的转变，解释了SSD和孕震带宽度的沿走向变化。基于该模型的库仑应力传递计算成功地预测了数天至数年的余震，为未来的地震危险性评估提供了基准。这些发现表明，巴颜喀尔地块东部地震风险较高，有必要进行重点监测。

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引用次数: 0

Enhanced marine primary productivity during the long-term Ordovician cooling: A barium isotope perspective from South China 奥陶系长期降温过程中海洋初级生产力的增强：来自华南的钡同位素视角

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-15 DOI: 10.1016/j.epsl.2025.119783

Shengchao Yang , Junxuan Fan , Chao Li , Yi-Bo Lin , Yiying Deng , Zongyuan Sun , Jian Cao , Shu-zhong Shen

Global cooling has been strongly associated with the Great Ordovician Biodiversification Event (GOBE), but the underlying mechanisms remain unexplored. To assess whether enhanced biological pump contributed to global cooling during the GOBE, we performed δ¹³⁸Ba_carb-δ¹³C_carb analyses on an Ordovician shallow marine limestone section from South China. Our results show that δ¹³⁸Ba_carb in the Ordovician (median 0.73‰) is significantly higher than in other geological periods and reservoirs (median values ranging from –0.18‰ to 0.29‰), indicating exceptionally high δ¹³⁸Ba values in the surface ocean in South China, possibly due to plankton radiation, which increased the removal of Ba during the GOBE. Furthermore, shifts in δ¹³⁸Ba_carb correlated with long-term increases in δ¹³C_carb, with positive correlation during the early Tremadocian (Stage 1), followed by negative correlation during the late Tremadocian to Dapingian (Stage 2), and positive correlation from the Darriwilian to Katian (Stage 3). These δ¹³⁸Ba_carb-δ¹³C_carb covariations suggest that marine primary productivity was enhanced during the Ordovician in South China. Additionally, the gradual increase in δ¹³C_carb is strongly correlated with global cooling and an increase in marine biodiversity, suggesting that plankton radiation during the GOBE may be an important cause of the increased marine primary productivity, thus enhancing organic carbon burial, contributing to the long-term Ordovician cooling, and linking the GOBE and contemporaneous environmental changes.

全球变冷与奥陶纪生物大多样化事件（GOBE）密切相关，但其潜在机制尚未探索。为了评估增强的生物泵是否对GOBE期间的全球降温做出了贡献，我们对中国南方奥陶系浅海灰岩剖面进行了δ 13bacarb -δ13Ccarb分析。结果表明，奥陶纪δ138Bacarb值（中值0.73‰）显著高于其他地质时期和储层（中值范围为-0.18‰~ 0.29‰），表明华南表层海洋δ138Ba值异常高，可能是浮游生物辐射导致的，在GOBE时期增加了Ba的去除。δ13Ccarb的变化与δ13Ccarb的长期升高相关，在Tremadocian早期（第1阶段）呈正相关，在Tremadocian晚期至大坪期（第2阶段）呈负相关，在Darriwilian至Katian阶段呈正相关（第3阶段）。这些δ138Bacarb-δ13Ccarb共变表明中国南方奥陶纪海相初级生产力增强。δ13Ccarb的逐渐增加与全球变冷和海洋生物多样性的增加密切相关，表明GOBE时期的浮游生物辐射可能是海洋初级生产力增加的重要原因，从而增强了有机碳埋藏，促进了奥陶纪的长期降温，并将GOBE与同期环境变化联系起来。

{"title":"Enhanced marine primary productivity during the long-term Ordovician cooling: A barium isotope perspective from South China","authors":"Shengchao Yang , Junxuan Fan , Chao Li , Yi-Bo Lin , Yiying Deng , Zongyuan Sun , Jian Cao , Shu-zhong Shen","doi":"10.1016/j.epsl.2025.119783","DOIUrl":"10.1016/j.epsl.2025.119783","url":null,"abstract":"<div><div>Global cooling has been strongly associated with the Great Ordovician Biodiversification Event (GOBE), but the underlying mechanisms remain unexplored. To assess whether enhanced biological pump contributed to global cooling during the GOBE, we performed δ<sup>138</sup>Ba<sub>carb</sub>-δ<sup>13</sup>C<sub>carb</sub> analyses on an Ordovician shallow marine limestone section from South China. Our results show that δ<sup>138</sup>Ba<sub>carb</sub> in the Ordovician (median 0.73‰) is significantly higher than in other geological periods and reservoirs (median values ranging from –0.18‰ to 0.29‰), indicating exceptionally high δ<sup>138</sup>Ba values in the surface ocean in South China, possibly due to plankton radiation, which increased the removal of Ba during the GOBE. Furthermore, shifts in δ<sup>138</sup>Ba<sub>carb</sub> correlated with long-term increases in δ<sup>13</sup>C<sub>carb</sub>, with positive correlation during the early Tremadocian (Stage 1), followed by negative correlation during the late Tremadocian to Dapingian (Stage 2), and positive correlation from the Darriwilian to Katian (Stage 3). These δ<sup>138</sup>Ba<sub>carb</sub>-δ<sup>13</sup>C<sub>carb</sub> covariations suggest that marine primary productivity was enhanced during the Ordovician in South China. Additionally, the gradual increase in δ<sup>13</sup>C<sub>carb</sub> is strongly correlated with global cooling and an increase in marine biodiversity, suggesting that plankton radiation during the GOBE may be an important cause of the increased marine primary productivity, thus enhancing organic carbon burial, contributing to the long-term Ordovician cooling, and linking the GOBE and contemporaneous environmental changes.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119783"},"PeriodicalIF":4.8,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797726","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}

引用次数: 0

Tectonic structures and stress state associated with seamount subduction in accretionary prism. Implications for slip behavior 与海山俯冲有关的增生棱柱构造与应力状态。滑移行为的含义

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-11 DOI: 10.1016/j.epsl.2025.119767

Alexis Gauthier , Nadaya Cubas , Laetitia Le Pourhiet

Seamounts on oceanic plates are thought to affect the dynamics of accretionary prism at subduction zones, particularly the slip behavior. Geophysical studies show that pore fluid overpressure is associated with the nucleation of shallow slow slip events (SSEs). We use numerical simulations in which the subducting plate bends in response to tectonic, gravitational collapse and surface processes to capture structural complexities arising from the subduction of buried seamounts and compute the resulting stress state. We show that tectonic slices of undeformed sediments develop on both sides of the seamount and that a basin forms atop the seaward slice. These structures, recognizable in seismic data, represent the long-term tectonic signature of seamount subduction.

Gravitational collapse only occurs when a critical lengthscale, we quantified, of perturbed accretionary prism is reached. Seamounts that are small enough, instead get decapitated and do not perturb the prism over a sufficient lengthscale to trigger gravitational collapse.

Stress analysis reveals that the seaward side of the seamount is under an extensional regime, whereas its landward side is in a compressive state. We thus propose that sustained pore fluid overpressure can only develop on the landward side. This mechanism supports observations along Hikurangi, where a highly reflective zone, interpreted as a zone of pore fluid overpressure, has been imaged downdip of the Papaku seamount. Since this zone coincides with the largest slip magnitudes of shallow SSEs, we propose that the landward slice of undeformed sediments presents favorable conditions for SSEs nucleation.

海洋板块上的海山被认为影响了俯冲带的增生棱镜动力学，特别是滑动行为。地球物理研究表明，孔隙流体超压与浅层慢滑事件成核有关。我们使用数值模拟，其中俯冲板块弯曲以响应构造，重力塌陷和地表过程，以捕捉埋藏海山俯冲引起的结构复杂性，并计算由此产生的应力状态。研究表明，海山两侧发育未变形沉积构造片，海山向海构造片上形成盆地。这些构造在地震资料中可识别，代表了海山俯冲的长期构造特征。引力坍缩只有在扰动吸积棱镜达到临界长度尺度时才会发生。而那些足够小的海山则会被砍断，不会在足够长的尺度上扰动棱镜，从而引发引力坍缩。应力分析表明，海山向海侧处于张拉状态，向海侧处于挤压状态。因此，我们认为持续的孔隙流体超压只能在陆地一侧发展。这一机制支持了沿Hikurangi的观测，在那里，一个高反射区被解释为孔隙流体超压区，已经被成像为Papaku海山的下坡。由于该带与浅层碳酸盐岩最大滑动震级重合，我们认为未变形沉积物的向陆切片为碳酸盐岩成核提供了有利条件。

{"title":"Tectonic structures and stress state associated with seamount subduction in accretionary prism. Implications for slip behavior","authors":"Alexis Gauthier , Nadaya Cubas , Laetitia Le Pourhiet","doi":"10.1016/j.epsl.2025.119767","DOIUrl":"10.1016/j.epsl.2025.119767","url":null,"abstract":"<div><div>Seamounts on oceanic plates are thought to affect the dynamics of accretionary prism at subduction zones, particularly the slip behavior. Geophysical studies show that pore fluid overpressure is associated with the nucleation of shallow slow slip events (SSEs). We use numerical simulations in which the subducting plate bends in response to tectonic, gravitational collapse and surface processes to capture structural complexities arising from the subduction of buried seamounts and compute the resulting stress state. We show that tectonic slices of undeformed sediments develop on both sides of the seamount and that a basin forms atop the seaward slice. These structures, recognizable in seismic data, represent the long-term tectonic signature of seamount subduction.</div><div>Gravitational collapse only occurs when a critical lengthscale, we quantified, of perturbed accretionary prism is reached. Seamounts that are small enough, instead get decapitated and do not perturb the prism over a sufficient lengthscale to trigger gravitational collapse.</div><div>Stress analysis reveals that the seaward side of the seamount is under an extensional regime, whereas its landward side is in a compressive state. We thus propose that sustained pore fluid overpressure can only develop on the landward side. This mechanism supports observations along Hikurangi, where a highly reflective zone, interpreted as a zone of pore fluid overpressure, has been imaged downdip of the Papaku seamount. Since this zone coincides with the largest slip magnitudes of shallow SSEs, we propose that the landward slice of undeformed sediments presents favorable conditions for SSEs nucleation.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119767"},"PeriodicalIF":4.8,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734591","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}

引用次数: 0