Earth and Planetary Science Letters最新文献_第4页

Seasonal diversity & behaviour of internal tidal bores revealed by year-long direct monitoring within a submarine canyon: Implications for particulate transport 海底峡谷内一年的直接监测揭示的内部潮汐孔的季节性多样性和行为：对颗粒运输的影响

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-16 DOI: 10.1016/j.epsl.2026.119835

Morgan T. Wolfe , Michael A. Clare , Esther J. Sumner , Veerle A.I. Huvenne , Rob A. Hall , Ian A. Kane

Submarine canyons are the primary conduits for particulate transport from the continents to the deep sea, including sediments, organic carbon, and pollutants. Previously, focus has primarily been on transport due to downslope gravity currents. There is increasing recognition of the role internal tides may play, however, a lack of long-term seabed monitoring limits understanding of their significance. Here, we present novel near-seafloor monitoring data of breaking internal tides (‘bores’), spanning one year within Whittard Canyon, a land-detached submarine canyon on the NE Atlantic margin. Throughout the year, these bores are energetic, with flow speeds regularly exceeding 0.5 m/s, and capable of resuspending seafloor sediments. Bores were observed for ∼80 % of tidal cycles during the deployment. The shape and structure of bores varies throughout the year, in relation to spring-neap tidal cycles and longer-term seasonal changes. During the period of November-March, these bores generally attain higher speeds, show more abrupt changes in flow speed, and hold the greatest potential for up-canyon sediment transport. While fine-grained material may be moved throughout the year, this stronger winter activity has the greatest capacity to mobilize larger grains up-canyon. We show that bores, driven by internal tides, are an important, but previously poorly-observed agent for particulate transport. Bores occur frequently, yet exhibit variability at both seasonal and shorter time scales that may shape particulate transport within submarine canyons. These findings change our view of the general significance of internal tides in submarine canyons, with wide implications for hazards, tempo and fluxes of particulate transport.

海底峡谷是微粒从大陆输送到深海的主要通道，这些微粒包括沉积物、有机碳和污染物。在此之前，主要关注的是下坡重力流造成的输送。人们越来越认识到内部潮汐可能发挥的作用，然而，缺乏长期海底监测限制了对其重要性的了解。在这里，我们提出了新的近海底监测数据，打破内部潮汐（“钻”），跨越一年在惠塔德峡谷，一个陆地分离的海底峡谷在东北大西洋边缘。全年，这些钻孔充满活力，流速经常超过0.5米/秒，能够重新悬浮海底沉积物。在部署期间，约80%的潮汐周期观测到钻孔。孔的形状和结构在一年中随春季-小潮周期和较长期的季节变化而变化。在11月至3月期间，这些钻孔的流速普遍较高，流速变化更为突然，并且具有最大的向峡谷上游输送沉积物的潜力。虽然细颗粒的物质可能全年都在移动，但这种更强烈的冬季活动有最大的能力将较大的颗粒动员到峡谷上方。我们表明，由内部潮汐驱动的钻孔是一个重要的，但以前很少观察到的颗粒输送剂。钻孔经常发生，但在季节性和较短的时间尺度上都表现出可变性，这可能影响海底峡谷内的颗粒运输。这些发现改变了我们对海底峡谷内部潮汐的一般意义的看法，对颗粒运输的危害、速度和通量具有广泛的影响。

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引用次数: 0

A mid‐Proterozoic coupled Sr and Li isotope excursion and its potential connection to enhanced weathering and ocean oxygenation at 1.57 Ga 中元古代Sr和Li同位素偏移及其与1.57 Ga增强风化和海洋氧合的潜在联系

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-16 DOI: 10.1016/j.epsl.2026.119848

Xi Chen , Ying Zhou , Simon W. Poulton , Fred T. Bowyer , Colin Mettam , Shihong Zhang , Maoyan Zhu , Da Li , Philip A.E. Pogge von Strandmann , Benjamin J.W. Mills , Graham A. Shields

Chemical weathering is a critical Earth system process that regulates climate, ocean chemistry and the long-term carbon cycle. However, the intensity and variability of chemical weathering remain insufficiently constrained for the mid-Proterozoic (∼1.8‒0.8 Ga), greatly limiting our understanding of the environmental context to early eukaryotic evolution. Here, we report the first coupled positive seawater ⁸⁷Sr/⁸⁶Sr (∼0.0007) and δ⁷Li (∼5‰) isotope excursions of the Mesoproterozoic Era (1.6‒1.0 Ga), which we argue signifies a substantial weathering event at ∼1.57 Ga, characterised by increased silicate weathering rates and decreased weathering congruency. Drawing on independent geological evidence, we posit that enhanced volcanic CO₂ degassing, possibly alongside accretional orogenesis, increased denudation rates and invigorated the hydrological cycle, amplifying silicate weathering and secondary clay formation. This weathering pulse broadly coincided with coeval ocean oxygenation and carbon cycle disruption, implicating it in the appearance of the earliest known decimetre-scale, multicellular eukaryotic fossils.

化学风化是调节气候、海洋化学和长期碳循环的关键地球系统过程。然而，化学风化的强度和变异性在中元古代（~ 1.8-0.8 Ga）仍然没有得到足够的限制，这极大地限制了我们对早期真核生物进化的环境背景的理解。本文首次报道了中元古代（1.6 ~ 1.0 Ga）海水87Sr/86Sr（~ 0.0007）和δ7Li（~ 5‰）同位素的耦合偏移，认为这表明在~ 1.57 Ga发生了大量的风化事件，其特征是硅酸盐风化速率增加，风化一致性降低。根据独立的地质证据，我们假设火山二氧化碳脱气的增强，可能伴随着增生造山作用，增加了剥蚀速率，激活了水文循环，放大了硅酸盐风化和次生粘土的形成。这种风化脉冲大致与同时期的海洋氧合作用和碳循环中断相吻合，表明它与已知最早的分米尺度、多细胞真核生物化石的出现有关。

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引用次数: 0

Immiscibility between hydrogen and molten iron in planetary cores 行星核心中氢和熔融铁的不混溶性

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-16 DOI: 10.1016/j.epsl.2026.119851

Emma R. Stoutenburg , Razvan Caracas , Andrew J. Campbell

Hydrogen is a likely light element candidate in planetary cores. A hydrogen solubility limit in molten iron could determine the maximum amount of hydrogen possible in the core of a rocky planet. Here, we use ab initio molecular dynamics to investigate the liquid iron-hydrogen system at 10, 50, and 136 GPa and at high temperatures where iron is molten. We calculate Gibbs free energy of mixing at several compositions, from pure iron to hydrogen, using thermodynamic integration. We find that at 10 GPa and 3000 K, there is a liquid-liquid miscibility gap; iron and hydrogen unmix to form Fe_0.34H_0.66 and H₂. At 50 GPa, >2500 K and at 136 GPa, >3500 K, the melts are fully miscible. We extrapolate the Gibbs free energy of mixing to estimate the iron-hydrogen phase diagram down to 1 GPa and in the 1500–6000 K temperature range. As pressure increases, the liquid-liquid miscibility gap shrinks: the solubility limit of hydrogen in liquid iron increases and the closure temperature decreases. At 1 GPa, we estimate the solubility is 18 at% (0.38 wt%) hydrogen at 1500 K. The gap has completely closed by 38 GPa and 3000 K, 69 GPa and 2000 K, and 94 GPa and 1500 K. Thus, small bodies like moons, planetesimals, Mercury, and Mars, which have core-mantle boundary pressures under 30 GPa, are the most limited in the amount of hydrogen their cores can accommodate. On the other hand, iron and hydrogen are fully miscible at the core conditions of larger planets like Earth, Venus, super-Earths, and sub-Neptunes, so their hydrogen concentrations will be limited by sources during formation rather than a thermodynamic limit.

氢可能是行星核心的候选轻元素。氢在熔融铁中的溶解度极限可以决定岩石行星核心可能存在的最大氢量。在这里，我们使用从头算分子动力学研究了在10、50和136 GPa以及铁熔融的高温下的铁氢液态水系统。我们用热力学积分计算了从纯铁到氢的几种成分的混合吉布斯自由能。结果表明，在10gpa和3000k条件下，存在液-液混相间隙；铁和氢分解生成Fe0.34H0.66和H2。在50gpa， 2500k和136gpa， 3500k时，熔体完全混相。在1500-6000 K的温度范围内，我们用吉布斯混合自由能来估计铁氢相图。随着压力的增大，液液混相间隙缩小，氢在铁液中的溶解度极限增大，闭合温度降低。在1 GPa时，我们估计在1500 K时溶解度为18% （0.38 wt%）。38 GPa和3000 K、69 GPa和2000 K、94 GPa和1500 K的差距已经完全缩小。因此，像卫星、星子、水星和火星这样的小天体，其核心-地幔边界压力低于30gpa，其核心所能容纳的氢量是最有限的。另一方面，在地球、金星、超级地球和次海王星等大行星的核心条件下，铁和氢是完全可混溶的，因此它们的氢浓度将受到形成过程中来源的限制，而不是热力学极限。

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引用次数: 0

Unraveling the marine biogeochemical changes during the Neoproterozoic Snowball Earth collapse 揭示新元古代雪球地球崩塌期间的海洋生物地球化学变化

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-16 DOI: 10.1016/j.epsl.2026.119854

Shengxian Zhu , Xianguo Lang , Peter W. Crockford , Bolin Zhang , Chengguo Guan , Chaochao Xing , Zongyuan Sun , Mingcai Hou

Understanding the collapse of the Neoproterozoic Snowball Earth is crucial for unraveling microbial responses to extreme climate change. However, the contrasting lithostratigraphic architecture of the glacial deposits and post-glacial sedimentary facies makes it challenging to identify clear global patterns of marine biogeochemical change across the two ice-house-hot-house transitions. To address this, we conducted a basin-scale mineralogical and geochemical analysis of pyrite in the terminal Sturtian glacial units of South China. Sedimentary-diagenetic pyrite occurs as nodules, laminae, and disseminated forms, with the latter type dominating most strata. Disseminated pyrite comprises euhedral/anhedral crystals and framboids. In the slope facies, laser-ablation δ³⁴S_py of the euhedral/anhedral crystals is uniform at 58.9±3.0‰. Framboids within almost all samples constitute 1-63% of total pyrite, and their proportion negatively correlates with bulk-sample δ³⁴S_py values. This morphology-isotope correlation appears to be a persistent feature across the basin. Specifically, the shelf facies lacks framboids and shows bulk-sample δ³⁴S_py values of 38.3±2.9‰ and the basin facies is enriched in ∼100% framboids and yields bulk-sample δ³⁴S_py values of 12.7±6.9‰. Pyrite content increases seaward from 0.2±0.2 wt.% to 0.8±2.0 wt.% but peaks at 5.6±2.7 wt.% in the slope facies. Across these sulfur isotope trends samples have TOC contents of 0.4±0.5 wt.% and δ¹³C_org values of -30.5±1.7‰ and display a negative correlation within the slope facies. We simulated the geochemical data through one-dimensional diffusion-advection-reaction and two-component organic carbon degradation models. While the former does not reproduce the sulfur abundance and isotope data, the latter suggests that the primary carbon is ∼30 times that of detrital carbon. These results define a seaward-thinning euxinic wedge with a δ³⁴S gradient during the transition out of the Sturtian Snowball Earth, providing a window into this critical event.

了解新元古代雪球地球的崩溃对于揭示微生物对极端气候变化的反应至关重要。然而，由于冰川沉积和冰后沉积相的岩石地层结构的差异，确定这两个冰-热过渡期间海洋生物地球化学变化的清晰全球模式具有挑战性。为了解决这一问题，我们对华南末斯图特冰川单元的黄铁矿进行了盆地尺度的矿物学和地球化学分析。沉积成岩黄铁矿以结核状、纹状和浸染状三种形式赋存，其中浸染状黄铁矿占多数地层的主导地位。浸染型黄铁矿包括自面体/自面体晶体和草莓状。在斜坡相中，自面体/反面体晶体的激光烧蚀δ34Spy均匀分布在58.9±3.0‰。几乎所有样品中的树状体占总黄铁矿的1 ~ 63%，其比例与样品的δ34Spy值呈负相关。这种形态-同位素对比似乎是整个盆地的一个持续特征。其中陆架相缺乏树状体，整体样品δ34Spy值为38.3±2.9‰；盆地相富含~ 100%树状体，整体样品δ34Spy值为12.7±6.9‰。黄铁矿含量向海方向增加，从0.2±0.2 wt.%增加到0.8±2.0 wt.%，但在斜坡相中最高为5.6±2.7 wt.%。在这些硫同位素趋势中，样品的TOC含量为0.4±0.5 wt.%， δ13Corg值为-30.5±1.7‰，在斜坡相内呈负相关。通过一维扩散-平流-反应模型和双组分有机碳降解模型对地球化学数据进行了模拟。虽然前者不能重现硫丰度和同位素数据，但后者表明原生碳是碎屑碳的30倍。这些结果定义了一个从斯图亚特雪球地球向外转变的δ34S梯度的向海变薄的含氧楔块，为这一关键事件提供了一个窗口。

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引用次数: 0

Conservative behavior of radiogenic neodymium isotopes in the South Pacific interior 南太平洋内部放射性成因钕同位素的保守行为

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-15 DOI: 10.1016/j.epsl.2026.119850

Zhouling Zhang , Antao Xu , Xuegang Chen , Ed Hathorne , Marcus Gutjahr , Martin Frank

The radiogenic neodymium isotope composition (εNd) is widely used to reconstruct past water mass mixing based on the assumption of quasi-conservative behavior in the open ocean. While non-conservative influences from boundary exchange, benthic fluxes, or hydrothermal inputs have been recognized near ocean margins and mid ocean ridges, uncertainties remain regarding the extent to which these processes influence Nd isotope distributions in the Pacific interior, where sluggish circulation and widespread volcanic provinces may lead to the modification of isotopic signatures.

Here we present full-depth distributions of εNd and Nd concentrations ([Nd]) from GEOTRACES zonal section GP21 (26–32°S) across the entire South Pacific basin. Using fractional water mass contributions derived from an Optimum Multi-Parameter Analysis, we show that εNd and [Nd] behave conservatively across the oligotrophic South Pacific Gyre, with detectable modifications restricted to the eastern and western boundaries. Combining the GP21 data with other South Pacific zonal transects further demonstrates that intermediate and deep water compositions can be explained by essentially conservative behavior of Nd signatures from subpolar to subtropical latitudes, with minimal alteration (≤2 εNd units) along the major advective pathways. In particular, Lower Circumpolar Deep Water shows no measurable isotopic imprint from benthic fluxes during northward transport from the subpolar South Pacific to ∼20°S.

These findings demonstrate that water mass mixing dominates Nd distributions in the central South Pacific, supporting the use of εNd as a robust tracer of past ocean circulation in the basin interior, while highlighting boundary regions as hotspots of isotopic exchange.

放射性成因的钕同位素组成（εNd）被广泛地用于重建过去公海中基于准保守行为假设的水团混合。虽然在海洋边缘和洋中脊附近已经认识到来自边界交换、底栖生物通量或热液输入的非保守影响，但这些过程对太平洋内部Nd同位素分布的影响程度仍然不确定，在太平洋内部，缓慢的环流和广泛的火山省可能导致同位素特征的改变。本文给出了GEOTRACES纬向剖面GP21（26-32°S）在整个南太平洋盆地的εNd和Nd浓度（[Nd]）的全深度分布。利用最优多参数分析得出的分数水质量贡献，我们发现εNd和[Nd]在南太平洋少营养环流中表现保守，仅在东、西边界有可检测到的变化。GP21数据与其他南太平洋纬向样带的结合进一步表明，中深水组成可以用从亚极到副热带纬度的Nd特征基本保守的行为来解释，沿主要平流路径变化最小（≤2 εNd单位）。特别是，在从南太平洋次极地向北输送到~ 20°S的过程中，环极深水下部没有显示底栖生物通量的可测量同位素印记。这些发现表明，在南太平洋中部，水团混合主导着Nd的分布，这支持了εNd作为盆地内部过去海洋环流的强大示踪剂的使用，同时突出了边界区域是同位素交换的热点。

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引用次数: 0

The influence of crustal recycling on the zirconium isotope composition of ocean island lavas 地壳再循环对洋岛熔岩锆同位素组成的影响

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-15 DOI: 10.1016/j.epsl.2025.119817

Shengyu Tian , Frédéric Moynier , Matthew G. Jackson , Edward C. Inglis , James M.D. Day

Crustal recycling into Earth’s mantle influences mantle composition and contributes to chemical heterogeneities in Earth’s interior. Zirconium is a refractory and immobile element in fluids and its stable isotopes are fractionated during magmatic differentiation. Therefore, Zr isotopes have the potential to be used to trace crustal recycling into the mantle. Here, we provide a survey of Zr isotopic systematics in some oceanic island lavas erupted at intraplate volcanic hotspots, collected from geochemically and geologically diverse mantle end members. These samples document either extremely high-³He/⁴He ratios, HIMU (high ‘μ’, or high ²³⁸U/²⁰⁴Pb), EM1 (enriched mantle I) or EM2 (enriched mantle II) mantle sources. Most ocean island lavas display homogeneous δ^94/90Zr (permil deviation of the ⁹⁴Zr/⁹⁰Zr ratio from the IPGP-Zr standard) values, especially for high-³He/⁴He, HIMU and EM1, with δ^94/90Zr indistinguishable within error relative to the bulk silicate Earth estimate (i.e., 0.041 ± 0.041‰). In contrast, Samoan EM2 lavas display higher δ^94/90Zr (up to 0.194 ± 0.019‰). Additionally, the δ^94/90Zr values of the Samoan EM2 lavas show co-variation with radiogenic ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd ratios. The elevated δ^94/90Zr signatures are not the result of zircon saturation, mantle melting or shallow assimilation. Instead, the Samoan δ^94/90Zr-⁸⁷Sr/⁸⁶Sr and δ^94/90Zr-¹⁴³Nd/¹⁴⁴Nd trends are consistent with binary mixing between a depleted mantle source with lower δ^94/90Zr and a recycled component originating from the upper continental crust (UCC) (∼6%) with higher δ^94/90Zr. The δ^94/90Zr of the recycled UCC material in the Samoan mantle source is calculated to be 0.363‰, falling within the δ^94/90Zr range of intermediate-felsic continental rocks. Based on the δ^94/90Zr-⁸⁷Sr/⁸⁶Sr array formed by EM2 lavas, a felsic continental protolith from UCC is the most likely origin for the incompatible element isotopic composition of the Samoan EM2 mantle.

地壳再循环进入地幔影响地幔组成，并导致地球内部的化学不均匀性。锆是流体中一种难熔、不动的元素，其稳定同位素在岩浆分异过程中分出。因此，Zr同位素有可能用于追踪地壳再循环进入地幔。本文对板块内火山热点喷发的一些海洋岛屿熔岩进行了地球化学和地质特征不同的地幔端段锆石同位素系统研究。这些样品记录了极高的3he /4He比率，HIMU（高μ）或高238U/204Pb), EM1（富集地幔I）或EM2（富集地幔II）地幔源。大部分海岛熔岩的δ94/90Zr （94Zr/90Zr比值与IPGP-Zr标准的peril偏差）均为均匀值，特别是高3he /4He、HIMU和EM1， δ94/90Zr与硅酸盐地球整体估算值（0.041±0.041‰）的误差范围内难以区分。萨摩亚EM2熔岩δ94/90Zr较高，可达0.194±0.019‰。Samoan EM2熔岩的δ94/90Zr值与放射性成因87Sr/86Sr和143Nd/144Nd比值呈共变关系。较高的δ94/90Zr特征不是锆石饱和、地幔熔融或浅层同化的结果。相反，萨摩亚δ94/90Zr- 87sr /86Sr和δ94/90Zr- 143nd /144Nd趋势符合低δ94/90Zr的枯竭地幔源和高δ94/90Zr的上大陆地壳（UCC）再循环组分（~ 6%）的二元混合。萨摩亚地幔源区循环UCC物质的δ94/90Zr为0.363‰，属于中长英质陆相岩石的δ94/90Zr范围。根据EM2熔岩形成的δ94/90Zr-87Sr/86Sr阵列，UCC的长英质大陆原岩是萨摩亚EM2地幔不相容元素同位素组成的最可能来源。

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引用次数: 0

Evidence of shallow subsurface ice at Tianwen-1 landing site “天文一号”着陆点存在浅层地下冰的证据

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-15 DOI: 10.1016/j.epsl.2026.119832

Xindong Meng , Ling Zhang , Yi Xu , Giannakis Iraklis , Roberto Bugiolacchi , Jiannan Zhao , Xiaoping Zhang , Qiquan Yang , Rui Chen , Renrui Liu , Xiaoting Xu , Huaqing Cao , Zhijun Huo , Long Xiao , Jialong Lai , Rui Gao

Surface and shallow subsurface water ice has been identified in both polar and mid-to-high latitude regions of Mars. However, its distribution at low-to-mid latitudes remains under investigation. China’s first Mars mission, Tianwen-1, landed in southern Utopia Planitia, a region that shows geological evidence of an active hydrological past, making it an ideal site for the search for subsurface water ice. The Mars Rover Penetrating Radar (RoPeR) onboard the Zhurong Rover can reveal subsurface stratigraphy and material properties. It detected a ∼7 m thick layer of low-loss material sandwiched by two high-loss layers. The estimated loss tangent value (0.0030 ± 0.0018) and dielectric constant (∼3.86) are consistent with water ice, suggesting its possible presence at the depth of

15_{- 5}^{+ 7}

m. We conducted simulations exploring a range of scenarios that varied in loss materials, stone distribution, and density within the layer. The results indicate that a model incorporating dirty ice mixed with stones aligns most closely with the RoPeR observations. The presence of a shallow subsurface ice-bearing layer at low-to-mid latitudes would represent a valuable and readily accessible resource for future human exploration.

在火星的极地和中高纬度地区都发现了地表和浅层地下水冰。然而，它在中低纬度地区的分布仍在调查中。中国的首个火星任务“天文一号”在乌托邦平原南部着陆，该地区显示出过去活跃水文的地质证据，使其成为寻找地下水冰的理想地点。朱荣火星车上的火星探测车穿透雷达（RoPeR）可以揭示地下地层和物质特性。它检测到一个约7米厚的低损耗材料层夹在两个高损耗层之间。估计的损耗正切值（0.0030±0.0018）和介电常数（~ 3.86）与水冰一致，表明水冰可能存在于15−5+7 m的深度。我们进行了一系列模拟，探索了不同的损失材料、石头分布和层内密度的情况。结果表明，将脏冰与石头混合在一起的模型与RoPeR的观测结果最为吻合。在中低纬度地区存在的浅层地下含冰层将为未来的人类勘探提供宝贵且易于获取的资源。

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引用次数: 0

Limited crustal contamination in large igneous province basalts: Sr-Nd-Pb-Os isotope evidence from the Western Ghats, Deccan Traps 大火成岩省玄武岩的有限地壳污染：德干圈闭西高止山脉Sr-Nd-Pb-Os同位素证据

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-14 DOI: 10.1016/j.epsl.2026.119847

A. Marzoli , L. Reisberg , M. Capriolo , S. Callegaro , P.R. Renne , M. Chiaradia , C.M. Meyzen , S. Self , L. Vanderkluysen , A. Boscaini

The origin of basalts from the Western Ghats lava sequences of the Deccan large igneous province (LIP) was investigated through combined major and trace element and isotopic analysis. Sr-Nd-Pb isotopic compositions are strongly variable and show a time-related shift from enriched, crustal-like values for the late Cretaceous Kalsubai and Lonavala Subgroup basalts to more depleted mantle-like values for the early Paleogene Wai Subgroup basalts. By contrast, Os isotopic data are relatively uniform from base to top of the Western Ghats (initial ¹⁸⁷Os/¹⁸⁸Os_i at 66 Ma: 0.12-0.21) and generally similar to those of the present-day Réunion mantle plume. The basalts from the Wai Subgroup Ambenali Formation (¹⁸⁷Os/¹⁸⁸Os_i 0.120) may show a moderate contribution from the sub-continental lithospheric mantle. In general, the combined isotopic and trace element compositions, and ¹⁸⁷Os/¹⁸⁸Os_i in particular, show that assimilation of the Proterozoic to Archean Indian crust was generally low (<3 wt.% of starting magma) and did not exceed 8 wt.% in any of the studied lavas. Similar results have been previously reported for other Phanerozoic LIPs. Therefore, we suggest that the emplacement of LIPs as short-lived eruptive pulses interrupted by relatively longer hiatus periods possibly hindered effective and prolonged heating of the basement rocks above their solidus temperature. Most likely, this obstacle to crustal contamination was particularly effective for the Wai basalts, which are interlayered with numerous sedimentary or paleosol layers probably formed during periods of volcanic quiescence when the crustal basement may have returned to low sub-solidus temperatures.

采用主微量元素和同位素分析相结合的方法，研究了德干大火成岩省西高止熔岩层序中玄武岩的成因。Sr-Nd-Pb同位素组成变化剧烈，呈现出从晚白垩世Kalsubai和Lonavala亚群富集的类地壳值到早古近纪Wai亚群富集的类地幔值的时间相关转变。相比之下，西高止山脉的Os同位素数据从底部到顶部相对一致（187Os/188Osi在66 Ma时初始值：0.12-0.21），与现今的r联合地幔柱大致相似。Wai亚群Ambenali组（187Os/188Osi 0.120）的玄武岩可能有来自次大陆岩石圈地幔的中等贡献。总的来说，同位素和微量元素组合，特别是187Os/188Osi，表明元古代对太古代印度地壳的同化作用一般较低（占起始岩浆的3 wt.%），在任何研究的熔岩中都不超过8 wt.%。其他显生宙唇部也有类似的结果。因此，我们认为lip作为短暂的喷发脉冲的位置被相对较长的间歇期打断，可能阻碍了基底岩石在固体温度以上的有效和长期加热。最有可能的是，这种地壳污染的障碍对Wai玄武岩特别有效，这些玄武岩与许多沉积层或古土壤层相互作用，这些沉积层或古土壤层可能是在火山静止时期形成的，当时地壳基底可能已经恢复到低的亚固体温度。

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引用次数: 0

An equation of motion for unsteady frictional slip pulses 非定常摩擦滑移脉冲的运动方程

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-13 DOI: 10.1016/j.epsl.2026.119831

Eran Bouchbinder

Frictional sliding, e.g., earthquakes along geological faults, are mediated either by frictional crack-like ruptures, where interfacial (fault) slip is accumulated during the entire sliding event, or by frictional pulse-like ruptures, featuring a finite length over which slip is accumulated. Our basic understanding of slip pulses, which are believed to dominate most crustal earthquakes, is still incomplete. Here, building on recent progress, we present an analytic equation of motion for rate-and-state frictional slip pulses, which are intrinsically unstable spatiotemporal objects, in terms of a single degree of freedom. The predictions of the equation are supported by large-scale simulations of growing pulses and reveal the origin of the slow development of their instability, which explains the dynamic relevance of pulses in a broad range of natural and manmade frictional systems. These results may pave the way for an improved estimation of the properties of crustal and laboratory pulse-like earthquakes, and for understanding the emergence of fault slip complexity.

摩擦滑动，例如沿地质断层的地震，要么是由摩擦裂缝状破裂介导的，在整个滑动事件中，界面（断层）滑动累积，要么是由摩擦脉冲状破裂介导的，滑动累积的长度有限。我们对滑动脉冲的基本了解，被认为是主导大多数地壳地震，仍然是不完整的。在这里，基于最近的进展，我们提出了速率和状态摩擦滑移脉冲的解析运动方程，这是本质上不稳定的时空物体，在单一自由度方面。该方程的预测得到了生长脉冲的大规模模拟的支持，并揭示了其不稳定性缓慢发展的起源，这解释了脉冲在广泛的自然和人造摩擦系统中的动态相关性。这些结果可能为改进对地壳和实验室脉冲地震性质的估计铺平道路，并为理解断层滑动复杂性的出现铺平道路。

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Seismic evidence for slab breakup triggering deep mantle upwelling beneath Central America 板块破裂引发中美洲深部地幔上涌的地震证据

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-01-13 DOI: 10.1016/j.epsl.2026.119836

Maoshan Yuan , Chunquan Yu , Zhicheng Jing

Understanding the interaction between subducted slabs and the lowermost mantle is fundamental to unraveling Earth’s thermochemical evolution. Here, we present seismic evidence of slab breakup triggering deep mantle upwelling. By analyzing pre-critical shear wave reflections off the D'' discontinuity (SdS) using advanced array-based processing, we enhance the resolution of arrival-time and amplitude measurements to constrain the height and elastic properties of the D'' discontinuity beneath Central America. In most regions, the D'' discontinuity lies 180 to 240 km above the core-mantle boundary, consistent with the accumulation of cold slab remnants. Lateral variations in shear-wave velocity contrasts suggest compositional heterogeneity, potentially reflecting separation of basaltic crust from the harzburgitic slab mantle. In contrast, a pronounced ∼80 km depression of the D'' discontinuity, spatially coinciding with tomographic low-velocity anomalies, indicates localized mantle upwelling. We interpret this upwelling to be dynamically linked to slab breakup, driven by thermal insulation beneath stagnant slabs and may be influenced by hot material from the Pacific Large Low Velocity Province. Our findings provide new constraints on the coupling between slab dynamics and deep mantle processes, emphasizing the role of slab breakup in triggering localized upwellings and contributing to the thermochemical evolution of Earth’s deep interior.

了解俯冲板块和最下层地幔之间的相互作用是解开地球热化学演化的基础。在这里，我们提出了板块破裂引发深部地幔上涌的地震证据。通过使用先进的阵列处理技术分析D‘’不连续面（SdS）的前临界横波反射，我们提高了到达时间和振幅测量的分辨率，从而约束了中美洲D‘’不连续面的高度和弹性特性。在大部分地区，D”不连续位于核幔边界上方180 ~ 240 km处，与冷板块残余物的堆积相一致。横波速度对比的横向变化表明了成分的非均质性，可能反映了玄武岩地壳与哈兹伯尔质板块地幔的分离。相反，一个明显的~ 80 km的D”不连续凹陷，在空间上与层析低速异常一致，表明局部地幔上涌。我们解释说，这种上升流与板块破裂动态相关，由停滞板块下方的绝热驱动，并可能受到来自太平洋大低速省的热物质的影响。我们的发现为板块动力学与深部地幔过程之间的耦合提供了新的约束，强调了板块破裂在触发局部上升流和促进地球深部内部热化学演化中的作用。

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引用次数: 0