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

From seal to pathway: carbonate veins reveal fluid flow in the clay-rich strike-slip Yangsan Fault, South Korea 从封闭到通道：碳酸盐岩脉体揭示了韩国梁山富泥走滑断层的流体流动

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-27 DOI: 10.1016/j.epsl.2025.119807

Luca Smeraglia , Youngbeom Cheon , Chang-Min Kim , Andrea Billi , Chiara Boschi , Ilaria Baneschi , Stefano M. Bernasconi , Andrea Fiorini , Eugenio Carminati

Clay-rich fault cores are commonly considered low-permeability barriers to across-fault fluid flow. However, increasing field-based evidence revealed syn-tectonic mineralizations within such fault cores, raising questions about their long-term hydraulic behavior, particularly during seismic events. This study investigates calcite veins and slickenfibres from the clay-rich fault core and damage zone of the 200-km-long strike-slip Yangsan Fault in South Korea, the major intraplate active fault in this region, by integrating structural and microstructural analyses with stable and clumped isotope geochemistry. Our data reveal that meteoric fluids downward infiltrated the fault damage zone over long time periods (possibly since late Cretaceous time), heated with depth according to the geothermal gradient, mixed with local formation water, and laterally infiltrated (i.e. across-fault) through a network of foliation planes into the clay-rich fault core, possibly affecting fault strength. We also propose meteoric water mixing with hydrothermal fluids derived by Late Cretaceous and Paleogene granite emplacement. We infer that mineralizations precipitated during different stages of the seismic cycle. Slickenfibres along fault-parallel foliation and shear planes probably precipitated during post-seismic to interseismic creep. Precipitation of foliation parallel extensional veins and stockwork veins probably occurred during the co-seismic phase due to earthquake fracturing. We speculate that transient pressurized fluid release may have occurred during the co-seismic phase. These findings challenge the prevailing view of clay-rich fault cores as static fluid barriers, instead pointing to a dynamic sealing behavior that evolves with the seismic cycles and over long-term geological timescales. Both slow, long-term interseismic fluid infiltration and rapid, short-term co-seismic fluid flow must be accounted for modeling the permeability of clay-rich faults in risk assessments for CO₂ and H₂ storage sites or for resource (hydrocarbons, geothermal fluids) exploration, especially in seismically active areas.

富粘土断层岩心通常被认为是阻碍断层间流体流动的低渗透屏障。然而，越来越多的现场证据显示，在这些断层核心中存在同构造矿化，这就提出了关于它们长期水力行为的问题，特别是在地震事件期间。通过构造和微观构造分析，结合稳定和团块同位素地球化学，研究了该地区主要板内活动断裂——韩国梁山走滑断裂200 km长富粘土断裂核和损伤带的方解石脉和滑脱纤维。我们的数据表明，在很长一段时间内（可能从晚白垩世开始），大气流体向下渗透断层破坏带，根据地温梯度随深度加热，与当地地层水混合，并通过片理面网络横向渗透（即跨断层）进入富含粘土的断层核心，可能影响断层强度。我们还认为大气水与晚白垩世和古近纪花岗岩侵位形成的热液混合。我们推断矿化沉淀发生在地震旋回的不同阶段。顺滑纤维可能在震后至震间蠕变过程中沿断层平行片理面和剪切面沉积。片理平行张脉和网状脉可能在同震阶段由于地震破裂而形成。我们推测瞬态加压流体释放可能发生在同震阶段。这些发现挑战了富粘土断层核是静态流体屏障的主流观点，而是指出了一种随地震周期和长期地质时间尺度演变的动态密封行为。在对CO2和H2储存地点或资源（碳氢化合物、地热流体）勘探进行风险评估时，特别是在地震活跃地区，必须考虑到缓慢的、长期的地震间流体渗透和快速的、短期的同震流体流动，以模拟富粘土断层的渗透率。

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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 : 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

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 : 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

Eoarchean TTG formation via melt-solid interaction at the base of the Tanzania Craton inferred from multi-proxy detrital zircon data 根据多代碎屑锆石资料推断坦桑尼亚克拉通底部始太古代融固相互作用形成的TTG

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-22 DOI: 10.1016/j.epsl.2025.119701

Robert Bolhar , Axel Hofmann , Balz S. Kamber , Martin J. Whitehouse , Roland Maas , Jeffrey D. Vervoort , Heejin Jeon , Manuela Botero , Joas Kabete

Detrital zircon grains with U-Pb ages >3.8 Ga from the Tanzania Craton represent a rare, and so far understudied, record of early crust formation in Africa. Here we report microbeam-based isotopic (U-Th-Pb, Lu-Hf, O) and trace element (REE, U, Th, Ti) compositions for Eoarchean to Hadean grains from Tanzania and discuss this record in the context of early crust formation. Zircon, extracted from a pre-3.2 Ga quartzite sequence in the Simba-Nguru Hills of the Dodoma Basement Complex, has ²⁰⁷Pb/²⁰⁶Pb ages of 4013 to 3482 Ma. The most concordant analyses are spread between 4.0 and 3.6 Ga. Oscillatory-zoned zircons preserve magmatic REE patterns, and Ti-in-zircon model temperatures of 818 ± 33 °C suggest crystallisation from TTG-like magmas. Estimates of oxygen fugacity (fO₂) derived from zircon REE systematics (-3.4 to +1.8 ΔFMQ) match both modern and Archean mantle values. Zircon δ¹⁸O largely overlaps the ‘mantle’ range through the entire 400 Ma age span and initial ε_Hf values are near-chondritic, becoming slightly more juvenile with time. These signatures are difficult to reconcile with zircon parent rocks derived from strongly depleted (high-ε_Hf) mantle-like sources, from old and evolved continental crust, or from strongly hydrated sources with a low-temperature, high-δ¹⁸O signature. Thus, the data add to a growing body of evidence that the early Earth crust was formed from chondritic mantle. We propose zircon to have crystallised in TTG magmas that formed through reaction of underplated basalt with mafic granulite at the Moho of the proto-continental crust, likely in an intraplate setting.

来自坦桑尼亚克拉通的U-Pb年龄为>；3.8 Ga的碎屑锆石颗粒代表了非洲早期地壳形成的一种罕见的、迄今尚未得到充分研究的记录。本文报道了坦桑尼亚太古宙至古宙颗粒的微束同位素（U-Th- pb, Lu-Hf， O）和微量元素（REE， U, Th, Ti）组成，并在早期地壳形成的背景下讨论了这一记录。锆石提取自Dodoma基底杂岩Simba-Nguru山前3.2 Ga石英岩层序，其207Pb/206Pb年龄为4013 ~ 3482 Ma。最一致的分析分布在4.0和3.6 Ga之间。振荡带锆石保留了岩浆的REE模式，锆石中的ti -in模式温度为818±33℃，表明结晶来自ttg类岩浆。锆石REE系统估算的氧逸度（fO2）（-3.4 ~ +1.8 ΔFMQ）与现代和太古宙地幔值吻合。锆石δ18O在整个400 Ma年龄跨度内大部分重叠于“地幔”范围，初始εHf值接近球粒质，随着时间的推移略显年轻。这些特征很难与来自强烈衰竭（高ε hf）的幔状源、来自古老演化的大陆地壳或来自低温、高δ 18o特征的强水合源的锆石母岩相协调。因此，这些数据进一步证明了早期地壳是由球粒质地幔形成的。我们认为锆石在TTG岩浆中结晶，TTG岩浆是由下镀玄武岩与原大陆地壳莫霍处的基性麻粒岩反应形成的，可能是在板内环境中形成的。

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引用次数: 0

Mantle flow and deformation of the eastern Adria subduction: New insights from AdriaArray seismic anisotropy 东亚德里亚俯冲的地幔流动和变形：来自AdriaArray地震各向异性的新认识

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-22 DOI: 10.1016/j.epsl.2025.119793

Laura Petrescu , Felix Borleanu , Samuel Celis , Dániel Kalmár , the AdriaArray Seismology Group

The Adriatic slab beneath the Dinarides-Albanides-Hellenides represents a uniquely segmented and dynamically complex subduction system, where slab tears and edges significantly influence mantle flow patterns. Benefiting from unprecedented dense seismic data from the 2022–2025 AdriaArray deployment, we reveal sharp lateral variations in SKS anisotropy that directly image the mantle’s deformation response to slab fragmentation and subduction processes. Our SKS splitting analysis uncovers a striking spatial dichotomy: near-coastal stations record weak, slab strike-perpendicular anisotropy consistent with focused sub-slab mantle inflow, while inland stations above the subducted plate display robust, slab strike-parallel anisotropy reflecting organized mantle wedge deformation. Interpreted in the context of seismic tomography, our results provide evidence of two distinct slab tears at ∼45°N and ∼42°N. Here, toroidal mantle flow facilitates mantle wedge replenishment, reshaping mantle convection around the subduction system. Moreover, the slab’s north-south geometry varies significantly, influencing observed anisotropy patterns: the northern, thinner slab segment beneath the Dinarides is predominantly characterized by strike-parallel flow, likely occurring in the mantle wedge. The stations above the thicker, deeper southern segment beneath the Albanides-Hellenides exhibit more complex, multi-layered mantle flow, possibly integrating sub-slab, wedge, and slab-internal deformation components. These observations provide unprecedented direct evidence for how tear-induced mantle circulation and segmented subduction modulate mantle dynamics beneath a complex subduction zone.

Dinarides-Albanides-Hellenides下的亚得里亚海板块代表了一个独特的、动态复杂的俯冲系统，其中板块撕裂和边缘显著影响着地幔的流动模式。得益于2022-2025年AdriaArray部署的前所未有的密集地震数据，我们揭示了SKS各向异性的急剧横向变化，直接描绘了地幔对板块破碎和俯冲过程的变形响应。我们的SKS分裂分析揭示了一个引人注目的空间二元性：近海岸台站记录了弱的、板块走向垂直的各向异性，与集中的板块下地幔流入相一致，而俯冲板块上方的内陆台站显示了强的、板块走向平行的各向异性，反映了有组织的地幔楔变形。在地震层析成像的背景下解释，我们的结果提供了在~ 45°N和~ 42°N两个不同的板撕裂的证据。在这里，环形地幔流动促进了地幔楔的补充，重塑了俯冲系统周围的地幔对流。此外，板块的南北几何形状差异很大，影响了观测到的各向异性模式：迪纳里德板块下方的北部较薄板块主要以走向平行流动为特征，可能发生在地幔楔中。位于Albanides-Hellenides下方较厚、较深的南段之上的站点显示出更复杂的多层地幔流动，可能整合了亚板块、楔块和板块内部变形分量。这些观测结果提供了前所未有的直接证据，说明在复杂俯冲带下，撕裂诱发的地幔循环和分段俯冲如何调节地幔动力学。

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引用次数: 0

Axial-valley floor faults tell a different story than faults outside the axial valley: the role of dike-induced deformation 轴谷底断层与轴谷外的断层讲述了一个不同的故事：岩脉引起的变形的作用

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-22 DOI: 10.1016/j.epsl.2025.119796

Jie Chen , Masako Tominaga , Javier Escartín

Slow-spreading ridges are highly segmented divergent plate boundaries with various modes of magma supply and faulting. Conventionally, magmatism and faulting that accommodate the plate divergence are thought to have an inverse relationship. However, our observations on fine-scale faulting, using high-resolution Autonomous Underwater Vehicle (AUV) bathymetry data along the axial-valley floor of the 14°N segment of the Mid-Atlantic Ridge, challenge this hypothesis. We show that axial faulting decreases from the segment center to the segment end as the rate of magma supply decreases and the lithosphere cools. This general pattern is also observed on several other slow-spreading ridge segments. We propose that this pattern relates to the link between fine-scale, newly-created axial faults and fissures and modes of magma supply. At segment centers, diking is frequent and centralized to the ridge axis, yielding strain localization and creating closely-spaced faults, whereas at segment ends, diking is less frequent and more widely distributed, yielding strain delocalization with faults distributed throughout the axial valley floor.

缓展脊是高度分段的发散型板块边界，岩浆供给和断裂方式各异。传统上，岩浆活动和容纳板块发散的断层作用被认为是反比关系。然而，我们利用高分辨率自主水下航行器（AUV）测深数据，沿着大西洋中脊14°N段的轴向谷底对精细断层进行了观察，挑战了这一假设。研究表明，随着岩浆供给速率的降低和岩石圈的冷却，轴向断裂从岩石圈中心到岩石圈末端逐渐减小。在其他几个缓慢扩展的脊段上也观察到这种一般模式。我们认为这种模式与精细的、新形成的轴向断裂和裂缝与岩浆供应方式之间的联系有关。在分段中心，岩脉频繁且集中于脊轴，导致屈服应变局部化，形成紧密断层；而在分段末端，岩脉频率较低且分布较广，导致屈服应变局部化，断层分布于整个轴向谷底。

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引用次数: 0

Residual mass-independently fractionated oxygen present in solids accreted during planetesimal formation in the early Solar System: potential evidence from main group pallasites 早期太阳系中星子形成过程中固体中存在的与质量无关的残余分馏氧：来自主要类群的潜在证据

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters

Pub Date : 2025-12-20 DOI: 10.1016/j.epsl.2025.119717

Martin F. Miller

Refractory Ca-Al-rich inclusions (CAIs) in chondritic meteorites, the oldest known solids in the Solar System, are characterised by ‘mass-independently fractionated’ (MIF) oxygen isotopic compositions, with δ¹⁷O variations approximately equal to those of δ¹⁸O. The apparent absence of this characteristic from nearly all other oxygen-bearing constituents of early-formed asteroids, together with the brief formation interval for CAIs, indicates that the process responsible was localised and of short duration in the context of Solar System evolution. From reassessing a recent study of main group pallasite meteorites, it is argued that the oxygen isotopic compositions of their coexisting olivine and chromite potentially provide evidence that a minor component of solids containing MIF oxygen was accreted during formation of the parent planetesimal, or its precursors, shortly after CAI formation. Modelling indicates that a contribution of ∼1.6 ± 0.3 % conforming to δ¹⁷O ∼ δ¹⁸O – γ, for γ assigned as –1.21 or –3.45 (from literature data) is consistent with the reported measurements. If true, and the pallasite olivine and chromite derived from the mantle of an impacted planetesimal and the IIIAB parent body respectively, as proposed elsewhere, then a ‘residual’ MIF oxygen component must have been present in solids accreted by those early planetesimals, probably in the same feeder zone. A testable prediction is that such residual MIF oxygen may similarly have been accreted in more early-formed planetesimals than recognised hitherto. If so, its presence should be detectable from comparable measurements of coexisting oxygen-bearing minerals in the associated meteorites, subject to the δ¹⁸O range being of sufficient magnitude.

球粒陨石中的难熔富钙铝包裹体（CAIs）是太阳系已知最古老的固体，其特征是“质量无关分异”（MIF）氧同位素组成，δ17O的变化近似等于δ18O的变化。在早期形成的小行星中，几乎所有其他含氧成分都明显缺乏这一特征，再加上cai的形成间隔很短，这表明在太阳系演化的背景下，这一过程是局部的，持续时间很短。通过重新评估最近对主要类群pallasite陨石的研究，认为它们共存的橄榄石和铬铁矿的氧同位素组成可能提供了证据，表明在母星子或其前体形成后不久，在母星子或其前体形成期间，含有少量MIF氧的固体成分被吸积。建模表明，δ17O ~ δ18O - γ的贡献为~ 1.6±0.3%，γ的分配为- 1.21或- 3.45（来自文献数据）与报道的测量结果一致。如果这是真的，并且像其他地方提出的那样，pallasite橄榄石和铬铁矿分别来自受影响的星子和IIIAB母体的地幔，那么“残余”的MIF氧成分一定存在于这些早期星子吸积的固体中，可能在同一个喂养区。一个可验证的预测是，这种残余的MIF氧可能在更多的早期形成的星子中被吸积，而不是迄今为止所认识到的。如果是这样，在δ18O值范围足够大的情况下，通过对伴生陨石中共存的含氧矿物的可比测量，应该可以探测到它的存在。

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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 : 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

In-situ U-Pb dating of early marine carbonate cements constrains the age of the late Ediacaran lower Nama Group, Namibia 早期海相碳酸盐胶结物的原位U-Pb定年限制了纳米比亚晚埃迪卡拉世下Nama群的年龄

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.2025.119787

Mariana A. Yilales , Nick MW Roberts , Collen-Issia Uahengo , Nathan Rochelle-Bates , Fred Bowyer , Rachel Wood

The middle-late Ediacaran (∼580 to >533 Ma) saw the emergence and early diversification of animals (metazoans), but the tempo of this event is obscured by a paucity of datable ash beds and uncertainties in global stratigraphic correlation through specific intervals. The Nama Group, Namibia, is of fundamental importance as this succession preserves a diverse terminal Ediacaran fossil assemblage that includes the first appearance of metazoan biomineralization, a key evolutionary innovation. The precise age of the lowermost Nama Group is unknown, however, with best estimates based on global chemostratigraphic correlation and inferred depositional rates suggesting that the onset of deposition was between ca. 555 and 551 Ma. Here we use uranium-lead (U-Pb) radioisotopic dating by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), to date early marine pseudomorphed calcite cements from the lower Nama Group. The analyses yield an absolute age of 549.3 ± 9.8 Ma and constitute the first independent time constraint for the lowermost Nama Group. The result is consistent with current chemostratigraphic age models and validates the use of in-situ U-Pb dating of early marine carbonate cements to constrain depositional ages.

埃迪卡拉纪中晚期（~ 580 ~ >533 Ma）出现了动物（后生动物）的出现和早期多样化，但这一事件的速度由于缺乏可测定的火山灰床和通过特定间隔的全球地层对比的不确定性而模糊不清。纳米比亚的Nama群具有根本性的重要性，因为这一演替保留了多样化的埃迪卡拉末期化石组合，其中包括后生动物生物矿化的首次出现，这是一个关键的进化创新。然而，最底下的Nama群的确切年龄尚不清楚，根据全球化学地层对比和推断的沉积速率，最好的估计表明，沉积开始于约555至551 Ma之间。在这里，我们使用激光烧蚀电感耦合等离子体质谱（LA-ICP-MS）的铀铅（U-Pb）放射性同位素定年，确定了Nama群下部早期海洋伪晶方解石胶结物的年代。分析得出的绝对年龄为549.3±9.8 Ma，是最底的Nama群的第一个独立的时间约束。该结果与目前的化学地层年龄模型一致，并验证了早期海相碳酸盐胶结物原位U-Pb定年对沉积年龄的约束。

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引用次数: 0

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