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

Coupled trace element and Hf-isotope measurements of Hadean through Paleoarchean zircons from the Singhbhum Craton indicate derivation from a long-lived, mantle-derived protocrust singhbham克拉通古宙至古太古代锆石的微量元素和hf同位素耦合测量表明，它起源于一个长寿命的幔源原地壳

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-03-01 Epub Date: 2025-12-31 DOI: 10.1016/j.epsl.2025.119813

Heather Kirkpatrick , Emily Stoll , Nadja Drabon

Due to the dearth of rock records during the Hadean, little is known about early crustal chemistry and geodynamics. Here, we present zircon trace and rare earth element and Lu-Hf measurements of zircons ∼ 3.3 Ga to ∼ 4.2 Ga from the Older Metamorphic Tonalitic Gneiss in the Singhbhum Craton to better understand geodynamic changes during the Hadean and Archean. We find decreasing, subchondritic zircon ε_HfT among zircons > 3.7 Ga and no indication of addition of new crustal material during the Hadean after initial formation of this protocrust. Trace and rare earth element analyses of > 3.7 Ga grains indicate derivation from a source heavily influenced by the enriched mantle with little evidence for flux melting, and no clear evidence for deep melting. At ∼ 3.7 Ga, we observe an average ε_HfT increase indicating new additions of juvenile felsic material. These zircons still show predominantly mantle-like trace elements, but with the appearance of some arc-like signatures and evidence for crustal thickening. This period of crustal reorganization speaks towards a shift in geodynamic regime characterized by the onset of communication between the mantle and the crust from which the zircons formed at this location. The presence of long-lived, mantle-derived protocrust in both India and South Africa appears to suggest the possibility of a local stagnant lid, albeit more data is necessary to confirm this. The presence of a transition of ε_HfT data globally may point towards an important, diachronous period of crustal reorganization 3.9 – 3.6 Ga ago.

由于冥古宙时期岩石记录的缺乏，人们对早期地壳化学和地球动力学知之甚少。为了更好地了解冥古宙和太古宙的地球动力学变化，我们对兴兴克拉通古变质调性片麻岩~ 3.3 ~ 4.2 Ga锆石进行了锆石痕量锆石、稀土元素和Lu-Hf测量。在3.7 Ga的锆石中，我们发现亚球粒锆石εHfT呈下降趋势，在该原地壳初始形成后的冥古宙没有新的地壳物质加入的迹象。对>； 3.7 Ga颗粒的痕量和稀土元素分析表明，其来源受到富集地幔的严重影响，几乎没有通量熔融的证据，也没有深部熔融的明确证据。在~ 3.7 Ga，我们观察到平均εHfT增加，表明新添加了幼长英质物质。这些锆石仍主要显示出地幔样的微量元素，但出现了一些弧状特征和地壳增厚的证据。这一时期的地壳重组预示着地球动力学机制的转变，其特征是地幔和地壳之间开始交流，锆石由此形成。印度和南非存在着寿命较长的、源自地幔的原地壳，这似乎表明当地可能存在一个停滞的地壳盖，尽管需要更多的数据来证实这一点。全球范围内εHfT数据的转变可能指向3.9 ~ 3.6 Ga前一个重要的地壳重组历时期。

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引用次数: 0

Dual controls on lithospheric dripping: The role of mantle flow and orogen scale 岩石圈滴水的双重控制：地幔流和造山带尺度的作用

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-03-01 Epub Date: 2025-12-31 DOI: 10.1016/j.epsl.2025.119795

Qiuling Wang , Huilin Wang , Zhuang Li

Lithospheric dripping is a fundamental mechanism for recycling thickened lithosphere in orogens, but its dynamic controls remain incompletely understood. Classical models emphasizing intra-lithospheric dynamics predict symmetric lithosphere downwelling with coupled surface subsidence/uplift and volcanic activities, consistent with observations in small orogens. However, these models cannot explain the asymmetric dripping geometries and spatially decoupled magmatic-topographic signals observed in some large orogens. In this study, we use numerical models to investigate how mantle flow interacts with different orogenic architectures to modulate dripping styles. Our results show that thin and cold orogens maintain strong intra-lithospheric coupling that restricts mantle flow influence, producing classical dripping behavior characterized by localized, near-vertical instability descent and symmetric surface responses. In contrast, thick, hot, and moderately wide orogens with weak intra-lithospheric viscous coupling enable mantle flow to entrain and amplify lithospheric drips, resulting in extensive lithospheric thinning and laterally offset topographic and magmatic responses. Orogen width influences the amount and extent of lithospheric thinning. Broad orogens that maintain a high lithospheric viscosity result in more localized removal. Lithosphere thinning is restricted to drip-adjacent zones. These results can reconcile the diverse dripping styles and surface responses observed in various orogens, demonstrating that lithospheric dripping is a tiered process governed by the interplay of mantle flow and orogen-scale properties, where orogenic thermal-mechanical characteristics control sensitivity to basal flow. The results offer new insights into understanding mantle-lithosphere interactions and scale-dependent orogenic evolution.

岩石圈滴落是造山带岩石圈增厚再循环的基本机制，但其动力学控制机制尚不完全清楚。强调岩石圈内动力学的经典模型预测岩石圈的对称下移与地表沉降/隆升和火山活动的耦合，与小造山带的观测结果一致。然而，这些模型不能解释在一些大型造山带观测到的不对称滴状几何和空间解耦的岩浆地形信号。在这项研究中，我们使用数值模型来研究地幔流动如何与不同的造山带结构相互作用以调节滴水方式。研究结果表明，薄造山带和冷造山带保持着强烈的岩石圈内耦合，限制了地幔流的影响，形成了以局部、近垂直不稳定下降和对称地表响应为特征的经典滴水行为。相比之下，厚、热、宽适中的造山带与较弱的岩石圈内黏性耦合使地幔流动夹带并放大岩石圈滴液，导致岩石圈广泛变薄和横向偏移的地形和岩浆响应。造山带宽度影响岩石圈减薄的数量和程度。维持高岩石圈粘度的宽造山带导致更局部的去除。岩石圈减薄仅限于与水滴相邻的区域。这些结果与在不同造山带观测到的不同滴注样式和地表响应相一致，表明岩石圈滴注是一个受地幔流和造山带尺度性质相互作用支配的分层过程，造山带热力学特征控制着对基流的敏感性。研究结果为理解地幔-岩石圈相互作用和规模依赖性造山演化提供了新的见解。

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引用次数: 0

Global evidence for the contribution of Earth’s surface topography to seismic PP precursor waves 地球表面地形对地震PP前驱波贡献的全球证据

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-03-01 Epub Date: 2026-01-08 DOI: 10.1016/j.epsl.2025.119814

Tuo Zhang , Christoph Sens-Schönfelder , Ye Yuan

Seismic precursors to the PP phase have long been attributed to scattering from mid-mantle heterogeneities, often interpreted as signatures of subducted slab remnants. However, using a global dataset of high-quality records from shallow earthquakes, we identify a signal of consistent, progressively increasing energy over time preceding PP arrivals, which strongly correlates with PP surface reflection points, particularly over continental regions. Beamforming analysis reveals two distinct slowness branches in the precursor energy that align with theoretical predictions for P waves deflected by topographic slopes. Monte Carlo simulations incorporating realistic surface topography accurately reproduce the observed arrival times and amplitudes of the precursors, whereas models based solely on mantle scattering fail to match the data. These results demonstrate that surface topography, rather than the mantle structures, dominates the generation of globally observed PP precursors. This reinterpretation calls for caution in using PP precursors to infer crust or mantle heterogeneity and highlights the critical role of surface effects in seismic waveform modelling.

PP期的地震前兆长期以来被认为是中地幔非均质散射所致，通常被解释为俯冲板块残余物的特征。然而，利用全球浅层地震的高质量记录数据集，我们发现在PP到达之前，有一个一致的、逐渐增加的能量信号，这与PP表面反射点密切相关，特别是在大陆地区。波束形成分析揭示了前驱能量中两个不同的慢度分支，这与地形坡度偏转的P波的理论预测相一致。结合真实地表地形的蒙特卡罗模拟准确地再现了观测到的前体到达时间和振幅，而仅基于地幔散射的模型无法匹配数据。这些结果表明，地表地形，而不是地幔结构，主导了全球观测到的PP前体的产生。这种重新解释要求谨慎使用PP前体来推断地壳或地幔的非均质性，并强调地表效应在地震波形建模中的关键作用。

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引用次数: 0

A model for Cenozoic seawater chemistry and carbon cycling 新生代海水化学与碳循环模式

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-03-01 Epub Date: 2025-12-31 DOI: 10.1016/j.epsl.2025.119811

Laurence A. Coogan, Stan E. Dosso

We present a model for the evolution of seawater chemistry and carbon cycling over the Cenozoic forced by changes in global mean temperature, continental weatherability, ocean crust accretion and solid Earth CO₂ degassing. The model tracks fluxes from continental silicate and carbonate weathering, seafloor weathering, marine silicate diagenesis, high-temperature hydrothermal circulation and carbonate sediment formation. The carbon system in the ocean is tracked through alkalinity (ALK) and dissolved inorganic carbon (DIC) fluxes allowing the entire carbon system to be calculated. The model has 48 parameters that are treated as unknowns, and we use a Bayesian inversion to determine the probable range of parameter values. Reasonable fits to reconstructions of Cenozoic seawater compositions (e.g., Mg, Ca, δ⁷Li, ⁸⁷Sr/⁸⁶Sr) and pCO₂ records are achieved. Consistent with other studies that consider the carbon system in seawater, the model results have limited change in seawater DIC and ALK over the Cenozoic. Key results include that the: (i) decrease in pCO₂ over the Cenozoic is driven by changing ocean chemistry (increased ratio of ALK to DIC) without a systematic change in the total carbon content of the ocean-atmosphere system, and (ii) CO₂ degassing rate and pCO₂ are decoupled. These results are inconsistent with commonly used geological carbon cycle models (e.g., GEOCARB, COPSE) but are readily understood in terms of seawater carbon chemistry and carbon cycling. Decreasing the Ca content of seawater at the same time as deepening the carbonate compensation depth requires increasing the carbonate ion concentration in the deep ocean; in the models this results from an increased ratio of ALK to DIC.

我们建立了一个受全球平均温度变化、大陆气候、海洋地壳增生和固体地球CO2脱气影响的新生代海水化学和碳循环演化模型。该模型跟踪了大陆硅酸盐和碳酸盐风化、海底风化、海相硅酸盐成岩作用、高温热液循环和碳酸盐沉积形成的通量。通过碱度（ALK）和溶解无机碳（DIC）通量来跟踪海洋中的碳系统，从而计算出整个碳系统。该模型有48个参数被视为未知数，我们使用贝叶斯反演来确定参数值的可能范围。对重建的新生代海水成分（如Mg、Ca、δ7Li、87Sr/86Sr）和pCO2记录进行了较好的拟合。与其他考虑海水碳系统的研究结果一致，该模式的结果显示新生代海水DIC和ALK的变化有限。主要结果包括：(1)新生代pCO2的减少是由海洋化学变化（ALK / DIC比值增加）驱动的，而海洋-大气系统总碳含量没有系统变化；(2)CO2脱气速率与pCO2解耦。这些结果与常用的地质碳循环模型（如GEOCARB、COPSE）不一致，但在海水碳化学和碳循环方面很容易理解。在加深碳酸盐补偿深度的同时降低海水中Ca含量，需要增加深海中的碳酸盐离子浓度；在模型中，这是由于ALK与DIC的比值增加。

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引用次数: 0

Generation of large transient porosity at the brittle to semi-ductile transition 在脆性向半韧性转变时产生大的瞬态孔隙

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-03-01 Epub Date: 2025-12-30 DOI: 10.1016/j.epsl.2025.119805

Erina Prastyani , Benoît Cordonnier , François Renard

Fluid circulation within Earth’s crust is contingent on the presence of connected porosity. Yet, at depths near the brittle to ductile transition regimes, where the base of the seismogenic zone is located, high pressure compacts the rock, reducing porosity and inhibiting fluid circulation. At greater depths, plastic mechanisms during ductile deformation further reduce the likelihood of porosity generation. In this study, we experimentally simulated the brittle to semi-ductile transition in Carrara marble by performing triaxial deformation experiments coupled with time-lapse 3D synchrotron X-ray microtomography at five confining pressures, ranging from 5 MPa to 70 MPa at room temperature and tracked the evolution of porosity over time. Contrary to the prevailing belief, our results show that porosity increases with increasing axial stress at stresses corresponding to the brittle to semi-ductile transition, where fluid circulation is thought to be impeded. In both the semi-brittle and semi-ductile regimes, the total porosity (averaged over the entire sample) exhibits similar values, close to 18%, increasing from an initial porosity of approximately 1% at equivalent axial strain. Although the porosity is comparable, the dominant deformation mechanisms differ: localized shear zones and distributed microcracking characterize the semi-brittle regime, whereas distributed microcracking, without localization, becomes more prominent in the semi-ductile regime. Our findings reveal the formation of high porosity within the semi-brittle and semi-ductile regimes and offer new insight into how this porosity, interpreted as transient within the crust, may enable fluid circulation at the base of the seismogenic zone in Earth’s crust.

地壳内的流体循环取决于连通孔隙的存在。然而，在靠近脆性到韧性过渡区的深度，也就是孕震带底部的位置，高压会压实岩石，降低孔隙度，抑制流体循环。在更深的深度，塑性变形过程中的塑性机制进一步降低了孔隙产生的可能性。在本研究中，我们通过实验模拟了Carrara大理岩在5 MPa至70 MPa的室温围压下的三轴变形实验，并结合延时3D同步加速器x射线微断层扫描技术，模拟了大理岩脆性向半韧性转变的过程，并跟踪了孔隙度随时间的演变。与普遍的看法相反，我们的研究结果表明，在脆性到半韧性转变的应力中，孔隙度随着轴向应力的增加而增加，流体循环被认为受到阻碍。在半脆性和半延性状态下，总孔隙度（整个样品的平均值）显示出相似的值，接近18%，在等效轴向应变下的初始孔隙度约为1%。虽然孔隙度相似，但主要的变形机制不同：局部剪切带和分布微裂纹是半脆性的特征，而分布微裂纹在半延性中更加突出，而非局部化。我们的发现揭示了高孔隙度在半脆性和半韧性体系内的形成，并提供了新的见解，解释了这种孔隙度在地壳内的短暂性，如何使地壳地震带底部的流体循环成为可能。

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引用次数: 0

Shifting carbonate burial between oceanic and continental crust across Earth history 在整个地球历史中，在海洋和大陆地壳之间转移碳酸盐埋藏

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-03-01 Epub Date: 2026-01-05 DOI: 10.1016/j.epsl.2025.119810

Jon M. Husson , Shanan E. Peters

Chemical weathering fluxes determine carbonate burial rates on geologic timescales, but the locus of carbonate burial is sensitive to tectonic and biologic boundary conditions that have changed across Earth history. Depositional setting is important because sediments on oceanic crust are readily recycled on the timescale of seafloor subduction, whereas sediments on continental crust can be sequestered over much longer durations. Here we present records of carbonate abundance in continental sediments for the past 3600 million years based on the North American components of the Macrostrat geologic column database and globally-distributed geological map units. Whether carbonate abundance is measured in absolute (area, volume) or in relative terms (carbonate normalized by total sediment), secular patterns emerge. In the Precambrian, carbonate abundance in continental crust is generally low. In the Phanerozoic, it climbs abruptly to a Paleozoic maximum and then declines towards the present. Decrease in shelf carbonate abundance across the Phanerozoic has been previously documented, driven in part by evolving paleogeography and the early Mesozoic evolution of pelagic calcifiers, which helped to shift carbonate burial from continental to oceanic crust. A Precambrian low in continental carbonate has received less attention. Here we propose that carbonate burial during much of the Precambrian was dominated by accumulation on (or within) oceanic crust and then shifted to continental crust in the early Paleozoic. Carbonate burial fluxes calibrated from the surviving rock record are an order of magnitude larger in the early Paleozoic than they appear to have been in the Proterozoic, with a step-wise increase occurring during the Ediacaran-Cambrian transition. This observation implies a large and relatively abrupt shift in the principal locus of CaCO₃ burial, from short-lived oceanic crust during much of the Proterozoic to longer-surviving continental crust in the early Paleozoic. Oceanic crust became, once again, a significant locus for carbonate accumulation during the Mesozoic and Cenozoic. The Paleozoic accommodation of most of the global carbon burial flux on the continents has many implications, including for secular changes in carbon cycling rates and the sensitivity of the surface environment to CO₂ injections.

化学风化通量决定了地质时间尺度上的碳酸盐埋藏速率，但碳酸盐埋藏的位置对地球历史上不断变化的构造和生物边界条件很敏感。沉积环境很重要，因为海洋地壳上的沉积物在海底俯冲的时间尺度上很容易再循环，而大陆地壳上的沉积物可以在更长的时间内被隔离。本文基于macrostrata地质柱数据库的北美成分和全球分布的地质图单元，给出了过去36亿年大陆沉积物中碳酸盐丰度的记录。无论碳酸盐丰度是以绝对（面积、体积）还是以相对（碳酸盐按总沉积物归一化）来衡量，都会出现长期模式。在前寒武纪，大陆地壳碳酸盐丰度普遍较低。在显生宙，它突然攀升到古生代的最大值，然后向现在下降。在显生宙，陆架碳酸盐丰度的减少已经有文献记载，部分原因是古地理的进化和中生代早期上层钙化物的进化，这有助于将碳酸盐埋藏从大陆地壳转移到海洋地壳。陆相碳酸盐岩的前寒武纪低沉积受到的关注较少。本文认为，在前寒武纪的大部分时间里，碳酸盐岩的埋藏主要是在海洋地壳上（或在海洋地壳内）聚集，然后在早古生代转移到大陆地壳。根据现存岩石记录校准的碳酸盐埋藏通量在早古生代比在元古代要大一个数量级，在埃迪卡拉纪-寒武纪过渡期间，碳酸盐埋藏通量逐步增加。这一观察结果表明，CaCO3埋藏的主要地点发生了一次较大且相对突然的转变，从元古代大部分时间的短暂海洋地壳到古生代早期存活时间较长的大陆地壳。在中生代和新生代，洋壳再次成为碳酸盐岩聚集的重要场所。古生代对大陆上大部分全球碳埋藏通量的调节具有许多意义，包括碳循环速率的长期变化和地表环境对二氧化碳注入的敏感性。

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引用次数: 0

Ancient, buoyant mantle under the Sierra Leone Ridge in the equatorial Atlantic 赤道大西洋塞拉利昂海岭下古老的浮力地幔

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-03-01 Epub Date: 2025-12-31 DOI: 10.1016/j.epsl.2025.119812

Camilla Sani , Alessio Sanfilippo , Felix Genske , Carlotta Ferrando , Daniele Brunelli , Anna Cipriani , Alexander Peyve , Sergey Skolotnev , Marco Ligi , Andreas Stracke

The Sierra Leone Ridge is the equatorial portion of the Mid-Atlantic Ridge (MAR) between the St. Paul (0–1°N) and Doldrums (7–9°N) Fracture Zones. At ∼80 Ma, a submarine plateau –the Sierra Leone Rise which is now located off-ridge on the African plate and the Céarà Rise on the South American plate– formed due to excess magma production. Incompatible element-enriched MORB with high Sr-Pb but low Nd isotope ratios suggests that the high magma production could result from the interaction of a mantle plume with the Sierra Leone Ridge, the so-called Sierra Leone mantle plume that may now be centered at ∼1.7°N along the MAR. In order to define the nature of the mantle source beneath the Sierra Leone Ridge, we present major-trace element concentrations and radiogenic isotope ratios from abyssal peridotites and MORB from 4 to 7°N along the MAR. High Hf isotope ratios are preserved in clinopyroxenes from abyssal peridotites (Ɛ_Hf = 12–54), indicating that the mantle beneath the Sierra Leone Ridge underwent extensive melting several 10⁸–10⁹ years before remelting under the present MAR. Most peridotites have high Ɛ_Hf, but low Ɛ_Nd similar to MORBs, although some extend to unusually low Ɛ_Nd of ∼-6. We argue that these peridotites not only melted, but were also re-enriched in compatible elements concurrent to melting in the past, and that such incompatible element re-enriched peridotites are now the main component of the sub-ridge mantle in the Sierra Leone area. Extensive remelting of ancient, incompatible element re-enriched peridotite that is compositionally buoyant, in addition to minor amounts of recycled crust, may therefore have caused the abundant magmatism that characterizes this portion of the MAR since formation of the Sierra Leone and Céarà Rise ∼80 Ma ago, and accounts for its elevated topography.

塞拉利昂海脊是中大西洋海脊（MAR）的赤道部分，位于圣保罗断裂带（0-1°N）和低潮断裂带（7-9°N）之间。在~ 80 Ma，海底高原——现在位于非洲板块的塞拉利昂隆起和南美洲板块的csamaracom隆起——由于过量的岩浆产生而形成。具有高Sr-Pb和低Nd同位素比率的不相容元素富集MORB表明，高岩浆产量可能是地幔柱与塞拉利昂山脊相互作用的结果，所谓的塞拉利昂地幔柱现在可能集中在沿mar的~ 1.7°N。我们从4 ~ 7°N的深海橄榄岩和MORB中获得了主要微量元素的浓度和放射性成因同位素比值。深海橄榄岩的斜斜辉石中保存了较高的Hf同位素比值（ƐHf = 12-54），表明塞拉利昂山脊下的地幔在10⁸-10⁹年的时间里经历了广泛的融化，然后在现在的mar下重新融化。大多数橄榄岩的ƐHf高，ƐNd低，与MORB相似，尽管有些橄榄岩的ƐNd低至~ -6。我们认为，这些橄榄岩在过去不仅熔融，而且在熔融的同时还被相容元素重新富集，并且这种不相容元素重新富集的橄榄岩现在是塞拉利昂地区次脊地幔的主要组成部分。古不相容元素再富集橄榄岩的大量重熔，以及少量的再循环地壳，可能导致了自塞拉利昂和csamuaros隆起形成以来的丰富岩浆活动，这些岩浆活动是MAR的这一部分的特征，并解释了其隆起的地形。

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引用次数: 0

Organic carbon burial and ocean redox modulated biotic recovery after the latest Ordovician crisis 最近一次奥陶纪危机后，有机碳埋藏和海洋氧化还原调节了生物恢复

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-02-15 Epub Date: 2025-12-24 DOI: 10.1016/j.epsl.2025.119794

Wei Tang , Mu Liu , Heng-Ye Wei , Li-Guang Wu , Kai Lu , Jian Wang , Xian-Hua Li

Widespread marine anoxia is considered a key impediment to recovery following the late Ordovician mass extinction (LOME), yet the spatiotemporal evolution of early Silurian ocean redox condition remains unresolved. Benthic ecosystem recovery on the South China inner shelf coincided with a global cooling trend during the Rhuddanian–Aeronian transition, but its drivers and links to redox dynamics remain poorly understood. Here we reconstruct redox conditions across a shelf transect in the Yangtze region using iron speciation, redox-sensitive trace elements (RSTEs), C_org/P ratios, and δ¹³C_org data from three sections spanning inner- to outer-shelf environments. Combined with a global compilation of 49 continental shelf sections and a new CA-ID-TIMS zircon U–Pb date of 439.51 ± 0.23 Ma, the data indicate that reducing conditions have persisted for ∼2.91 ± 0.39 million years on the inner shelf after the LOME, followed by progressive reoxygenation beginning in the late Rhuddanian and extending into the Aeronian. A sharp rise in global organic carbon burial rates—up to ∼23 times the Hirnantian baseline, together with coeval rises in ⁸⁷Sr/⁸⁶Sr ratios indicative of intensified continental silicate weathering, would have driven a drawdown of atmospheric CO₂ and global cooling. This climatic shift likely enhanced shelf ventilation and oxygen solubility, facilitating benthic metazoan recovery in shallow settings, while outer-shelf environments remained anoxic until the mid-Aeronian. These findings underscore the tight coupling among carbon cycling, climate regulation, redox evolution, and biotic recovery, highlighting continental shelves as key sites of carbon–climate feedback in the aftermath of mass extinction events.

广泛的海洋缺氧被认为是晚奥陶世大灭绝（LOME）后恢复的关键障碍，但早志留世海洋氧化还原条件的时空演变尚未解决。华南内陆陆架底栖生物生态系统的恢复与鲁达尼—aeronian过渡期间的全球降温趋势一致，但其驱动因素及其与氧化还原动力学的联系尚不清楚。本文利用铁形态、氧化还原敏感微量元素（RSTEs）、Corg/P比值和δ13Corg数据重建了长江地区陆架样带的氧化还原条件。结合49个大陆架剖面的全球汇编和新的CA-ID-TIMS锆石U-Pb测年（439.51±0.23 Ma），数据表明，LOME后，内大陆架的还原条件持续了~ 2.91±0.39万年，随后从晚鲁达尼世开始逐步再氧化，并延伸到Aeronian。全球有机碳埋藏率的急剧上升（达到希尔南提基线的23倍），以及87Sr/86Sr比值的同期上升（表明大陆硅酸盐风化加剧），将推动大气二氧化碳的减少和全球变冷。这种气候变化可能增强了大陆架的通风和氧的溶解度，促进了浅层环境中底栖后生动物的恢复，而大陆架外部环境直到aeronian中期仍处于缺氧状态。这些发现强调了碳循环、气候调节、氧化还原进化和生物恢复之间的紧密耦合，强调了大陆架是大规模灭绝事件后碳-气候反馈的关键场所。

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引用次数: 0

Coral reef terrace age deduced from retreating knickpoints 珊瑚礁阶地年龄由退缩的凿点推断

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-02-15 Epub Date: 2025-12-18 DOI: 10.1016/j.epsl.2025.119792

Yiran Wang , Aron J. Meltzner , Michael E. Oskin , Jennifer Quye-Sawyer , Lin Thu Aung , Noelynna Ramos

The accurate dating of Quaternary coral terraces has long been challenging due to recrystallization of aragonite corals. Here, we present an approach to infer terrace age based on (1) the linkage between sea-level drop and river knickpoint formation and (2) the history of sea-level rise and fall recorded by the elevation–age relationship of knickpoints. Our study in northwestern Luzon, Philippines, combines field surveys, sedimentological analysis, and topographic and river-profile analysis, through which we map the coral reef terrace extent and correlate terrace outer edges to the initiation location of major knickpoints in adjacent river profiles. Through χ transformation, the knickpoint retreat distance is equivalent to knickpoint/terrace age, and therefore the elevation–retreat distance relationship of the knickpoints can be used to determine the age of the correlated terrace. Using this method, we deduce that the lower coral reef terrace sequences (T1-T4) correspond to Marine Isotope Stages (MIS) 5a, 5c, 5e, and 7a, respectively. Furthermore, we suggest the coastal area is gently tilting seaward with an average uplift rate of ∼1 m/kyr, and the highest terrace surface (420–440 m) may be more than 400 kyr old. We propose that this technique offers a promising solution for dating coral reef terraces in uplifting coastal regions where absolute age-dating techniques fail due to diagenetic alteration, and for terraces associated with bedrock rivers that developed before the penultimate glacial period.

由于文石珊瑚的再结晶，第四纪珊瑚梯田的准确测年一直是一个挑战。在此，我们提出了一种基于(1)海平面下降与河流裂缝点形成之间的联系以及(2)裂缝点的高程-年龄关系记录的海平面上升和下降的历史来推断阶地年龄的方法。我们在菲律宾吕宋岛西北部的研究结合了实地调查、沉积学分析、地形和河流剖面分析，通过这些分析，我们绘制了珊瑚礁阶地的范围，并将阶地的外缘与邻近河流剖面中主要断裂点的起始位置相关联。通过χ变换，裂缝点的后退距离相当于裂缝点/阶地年龄，因此可以利用裂缝点的高程-后退距离关系来确定相关阶地的年龄。利用该方法，我们推断下部珊瑚礁阶地层序（T1-T4）分别对应于海洋同位素阶段（MIS） 5a、5c、5e和7a。此外，我们认为沿海地区缓慢向海倾斜，平均隆升速率为~ 1 m/kyr，最高阶地表面（420-440 m）可能超过400 kyr。我们提出，这项技术为隆升沿海地区的珊瑚礁阶地的定年提供了一种有希望的解决方案，在这些地区，绝对年龄测年技术由于成岩蚀变而失败，以及与第二次冰期之前发育的基岩河流相关的阶地。

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引用次数: 0

Strain rate concentration along the Niigata-Kobe tectonic zone, central Japan as explained by 2D collision numerical models with visco-elasto-plastic rheology 用粘弹塑性流变学的二维碰撞数值模型解释了日本中部新潟-神户构造带的应变率集中

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2026-02-15 Epub Date: 2025-12-26 DOI: 10.1016/j.epsl.2025.119806

Erika J. Moreno , Shoichi Yoshioka , Vlad C. Manea , Marina Manea , Nobuaki Suenaga

Unusual high strain rate concentration and WNW-ESE shortening along the Niigata-Kobe tectonic zone (NKTZ) are reported by GEONET (GNSS Earth observation network). The highest concentration of strain rate has been observed in the Niigata Prefecture, NE Japan, where earthquakes with magnitude M_j > 6 have been recorded. In order to explain the shortening along the NKTZ, different hypotheses are put forward. One of them relates the strain rate concentration near the Earth's surface to weakening of the lower crust caused by the interaction between the continental Amurian plate and the continental North American plate, or the oceanic PHS (Philippine Sea) plate/NA (North American) plate and the oceanic PAC (Pacific) plate/NA plate. Other studies suggest the existence of low-viscosity weak zones beneath the upper continental crust caused by upwelling dehydrated fluids, melts from the PHS and PAC plates, and presence of soft sediments. In this study, we employ two-dimensional high-resolution thermomechanical numerical models with visco-elasto-plastic rheology subject to simple horizontal compression, as well as a combination of horizontal extension and compression. We select three profiles across the SW, central, and NE parts of the NKTZ aligned with the direction of maximum contraction of the principal strain. Numerical models that incorporate hydrated lower crust, magmatic intrusions, and soft sediments are tested against the observations along these three profiles. Our numerical results indicate that significant surface strain concentration develops where low-viscosity weak zones, represented by fluids, magmatism, and soft sediments, are localized at different crustal levels. These weak zones consequently play a key role in fault development and in the Earth’s surface strain concentration along the NKTZ.

GEONET （GNSS地球观测网）报道了沿新潟-神户构造带（NKTZ）异常的高应变速率集中和WNW-ESE缩短。应变率的最高集中在日本东北部的新泻县，那里记录了6级地震。为了解释沿NKTZ的缩短，提出了不同的假设。其中一种理论认为，近地表应变速率的集中与阿姆里亚大陆板块与北美大陆板块或菲律宾海（PHS）板块/北美（NA）板块与太平洋（PAC）板块/北美（NA）板块相互作用引起的下地壳弱化有关。其他研究表明，由于上涌的脱水流体、PHS和PAC板块的熔体以及软沉积物的存在，在上大陆地壳下存在低粘度弱带。在这项研究中，我们采用二维高分辨率的热力学数值模型，包括简单水平压缩下的粘弹塑性流变，以及水平拉伸和压缩的组合。我们选择了与主应变最大收缩方向一致的NKTZ的SW、central和NE部分的三个剖面。结合水合下地壳、岩浆侵入和软沉积物的数值模型根据这三条剖面的观测结果进行了测试。数值结果表明，以流体、岩浆活动和软沉积物为代表的低黏度弱带在不同的地壳水平上具有显著的地表应变集中。因此，这些弱带在断层发育和地球表面应变沿NKTZ集中中起关键作用。

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引用次数: 0