Pub Date : 2026-03-15Epub Date: 2026-01-12DOI: 10.1016/j.epsl.2026.119825
Christopher A. Parendo , Stein B. Jacobsen , Michail I. Petaev
Calcium-aluminum-rich inclusions (CAIs), the oldest dated solids in the Solar System, preserve elemental and isotopic records of the thermal evolution of the early solar nebula—but some aspects, such as the processes driving large Ca-isotope variations, remain ambiguous. Previous studies observed isotopically light Ca in some CAIs, but whether these signatures arose from evaporation or condensation remains unresolved. We report new Ca-isotope and elemental data for 19 CAIs and 2 AOAs from the Allende meteorite and apply kinetic modeling to evaluate whether evaporation or condensation can account for the observed signatures. Our data confirm that CAIs exhibiting volatility-related REE fractionation have lighter Ca-isotope compositions than those with unfractionated REEs. Modeling demonstrates that evaporation cannot produce materials with both isotopically light Ca and near-chondritic Al/Ca ratios, requiring condensation as the cause of the observed Ca-isotope variations. Notably, modeled rates indicate that condensation occurred rapidly, over ∼10-1000 days, much faster than secular cooling of the solar nebula. These results constrain CAI thermal histories and offer insight into high-temperature processes in the early Solar System.
{"title":"Calcium isotopes support rapid condensation of CAIs in the early solar nebula","authors":"Christopher A. Parendo , Stein B. Jacobsen , Michail I. Petaev","doi":"10.1016/j.epsl.2026.119825","DOIUrl":"10.1016/j.epsl.2026.119825","url":null,"abstract":"<div><div>Calcium-aluminum-rich inclusions (CAIs), the oldest dated solids in the Solar System, preserve elemental and isotopic records of the thermal evolution of the early solar nebula—but some aspects, such as the processes driving large Ca-isotope variations, remain ambiguous. Previous studies observed isotopically light Ca in some CAIs, but whether these signatures arose from evaporation or condensation remains unresolved. We report new Ca-isotope and elemental data for 19 CAIs and 2 AOAs from the Allende meteorite and apply kinetic modeling to evaluate whether evaporation or condensation can account for the observed signatures. Our data confirm that CAIs exhibiting volatility-related REE fractionation have lighter Ca-isotope compositions than those with unfractionated REEs. Modeling demonstrates that evaporation cannot produce materials with both isotopically light Ca and near-chondritic Al/Ca ratios, requiring condensation as the cause of the observed Ca-isotope variations. Notably, modeled rates indicate that condensation occurred rapidly, over ∼10-1000 days, much faster than secular cooling of the solar nebula. These results constrain CAI thermal histories and offer insight into high-temperature processes in the early Solar System.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119825"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975732","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}
Pub Date : 2026-03-15Epub Date: 2026-01-20DOI: 10.1016/j.epsl.2026.119855
Yong Xu , Qing Xiong , Bin Qin , Ruohan Gao , Xiaohan Gong , Degao Zhai , D. Graham Pearson , Jingao Liu
The strongly compatible 190Pt-187Re-186, 187Os systematics are relatively resistant to post-magmatic alteration and potentially preserve snapshots of deep mantle processes, making them valuable for tracing the origins of ultramafic-mafic rocks. To compare high-Cr and low-Cr podiform chromitites within ophiolite suites and uncover their formation mechanisms and related mantle evolution, we conducted the first combined high-precision 186Os-187Os and platinum group elemental (PGE: Os, Ir, Ru, Pt, and Pd) investigation of the Luobusa (mean Cr#=78) and Zedang (mean Cr#= 61) ophiolitic chromitites from south Tibet, China. The contrasting 187Os/188Os ratios between the Luobusa high-Cr (0.1271 ± 0.0002) and Zedang low-Cr (0.1292 ± 0.0004) chromitites correlate with their different degrees of fractionation between palladium-group (PPGE) and iridium-group (IPGE) PGE. This relationship follows a global trend and largely reflects the distinct natures of their parental magmas (boninitic vs. MORB-like). Importantly, both chromitites exhibit relatively homogeneous unradiogenic 186Os/188Os ratios (Luobusa: 0.1198359±0.0000026; Zedang: 0.1198355±0.0000005), which are independent of indices of magmatic differentiation such as Cr# and PGE fractionation. These values are comparable, within analytical uncertainties, to the averages of global abyssal peridotites and Phanerozoic Os-rich alloys, and are slightly lower than the primitive mantle and H ordinary chondrites. The 186Os similarity between the Luobusa chromitites and abyssal peridotites is consistent with their known 187Os similarity that features an unradiogenic 187Os/188Os peak at ∼0.126. The combined unradiogenic 186Os-187Os systematics also show no resolvable genetic linkage to plume-related magmatism or recycled crustal materials. Instead, their parental magmas appear to originate from a depleted mantle source.
强相容的190Pt-187Re-186、187Os系统相对不受岩浆后蚀变的影响，并可能保存深部地幔过程的快照，使其对追踪超基性-基性岩石的起源具有价值。为了比较蛇绿岩组中高铬和低铬脚状铬铁矿，揭示其形成机制和相关的地幔演化，我们首次对藏南罗布沙（平均Cr#=78）和泽当（平均Cr#= 61）蛇绿岩铬铁矿进行了高精度186Os-187Os和铂族元素（PGE: Os, Ir, Ru， Pt和Pd）的组合研究。罗布萨高铬（0.1271±0.0002）和泽当低铬（0.1292±0.0004）铬铁矿的187Os/188Os比值差异与钯基（PPGE）和铱基（IPGE）的PGE分馏程度不同有关。这种关系遵循全球趋势，并在很大程度上反映了它们的母岩浆的不同性质（博尼岩型与morb型）。重要的是，两种铬铁矿均表现出相对均匀的非放射性成因的186Os/188Os比值（罗布萨∶0.1198359±0.0000026；泽当∶0.1198355±0.0000005），与Cr#和PGE分选等岩浆分异指标无关。在分析不确定度范围内，这些值与全球深海橄榄岩和显生宙富os合金的平均值相当，略低于原始地幔和H普通球粒陨石。罗布萨铬铁矿与深海橄榄岩之间的186Os相似性与已知的187Os相似性一致，其中187Os/188Os峰值为~ 0.126。1860s - 1870s的非放射性成因系统也显示出与羽状岩浆活动或再循环地壳物质没有可解决的遗传联系。相反，它们的母岩浆似乎来自枯竭的地幔源。
{"title":"Inheritance of depleted mantle 186Os signatures in Tibetan ophiolitic chromitites","authors":"Yong Xu , Qing Xiong , Bin Qin , Ruohan Gao , Xiaohan Gong , Degao Zhai , D. Graham Pearson , Jingao Liu","doi":"10.1016/j.epsl.2026.119855","DOIUrl":"10.1016/j.epsl.2026.119855","url":null,"abstract":"<div><div>The strongly compatible <sup>190</sup>Pt-<sup>187</sup>Re-<sup>186, 187</sup>Os systematics are relatively resistant to post-magmatic alteration and potentially preserve snapshots of deep mantle processes, making them valuable for tracing the origins of ultramafic-mafic rocks. To compare high-Cr and low-Cr podiform chromitites within ophiolite suites and uncover their formation mechanisms and related mantle evolution, we conducted the first combined high-precision <sup>186</sup>Os-<sup>187</sup>Os and platinum group elemental (PGE: Os, Ir, Ru, Pt, and Pd) investigation of the Luobusa (mean Cr#=78) and Zedang (mean Cr#= 61) ophiolitic chromitites from south Tibet, China. The contrasting <sup>187</sup>Os/<sup>188</sup>Os ratios between the Luobusa high-Cr (0.1271 ± 0.0002) and Zedang low-Cr (0.1292 ± 0.0004) chromitites correlate with their different degrees of fractionation between palladium-group (PPGE) and iridium-group (IPGE) PGE. This relationship follows a global trend and largely reflects the distinct natures of their parental magmas (boninitic vs. MORB-like). Importantly, both chromitites exhibit relatively homogeneous unradiogenic <sup>186</sup>Os/<sup>188</sup>Os ratios (Luobusa: 0.1198359±0.0000026; Zedang: 0.1198355±0.0000005), which are independent of indices of magmatic differentiation such as Cr# and PGE fractionation. These values are comparable, within analytical uncertainties, to the averages of global abyssal peridotites and Phanerozoic Os-rich alloys, and are slightly lower than the primitive mantle and H ordinary chondrites. The <sup>186</sup>Os similarity between the Luobusa chromitites and abyssal peridotites is consistent with their known <sup>187</sup>Os similarity that features an unradiogenic <sup>187</sup>Os/<sup>188</sup>Os peak at ∼0.126. The combined unradiogenic <sup>186</sup>Os-<sup>187</sup>Os systematics also show no resolvable genetic linkage to plume-related magmatism or recycled crustal materials. Instead, their parental magmas appear to originate from a depleted mantle source.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119855"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035311","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}
Pub Date : 2026-03-15Epub Date: 2026-01-13DOI: 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.
{"title":"An equation of motion for unsteady frictional slip pulses","authors":"Eran Bouchbinder","doi":"10.1016/j.epsl.2026.119831","DOIUrl":"10.1016/j.epsl.2026.119831","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119831"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975725","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}
Pub Date : 2026-03-15Epub Date: 2026-01-13DOI: 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.
{"title":"Seismic evidence for slab breakup triggering deep mantle upwelling beneath Central America","authors":"Maoshan Yuan , Chunquan Yu , Zhicheng Jing","doi":"10.1016/j.epsl.2026.119836","DOIUrl":"10.1016/j.epsl.2026.119836","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119836"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975726","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}
Pub Date : 2026-03-15Epub Date: 2026-01-09DOI: 10.1016/j.epsl.2025.119809
Kyle Michael James Mayers , Nele Manon Vollmar , Tristan Cordier , Agnes Katharina Maria Weiner , Juliane Müller , Aud Larsen , Stijn De Schepper
{"title":"First-year sea ice history in the Arctic Ocean inferred from ancient DNA of Polerella glacialis over the past 50,000 years","authors":"Kyle Michael James Mayers , Nele Manon Vollmar , Tristan Cordier , Agnes Katharina Maria Weiner , Juliane Müller , Aud Larsen , Stijn De Schepper","doi":"10.1016/j.epsl.2025.119809","DOIUrl":"10.1016/j.epsl.2025.119809","url":null,"abstract":"","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119809"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145938706","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}
Pub Date : 2026-03-15Epub Date: 2026-01-13DOI: 10.1016/j.epsl.2026.119834
A. Binnie , S.A. Binnie , P. Victor , J-L. García , S. Heinze , T.J. Dunai
How major shifts in climate over the Quaternary have affected topography is unclear, especially in tectonically active regions. This shortcoming is largely due to a lack of robust chronologies of landscape evolution over the last few million years. Here we document a rare case, where a fluvial landscape has been preserved well enough to record its responses to tectonic and climatic shifts throughout the Quaternary. Our results show that aggradation of sediment fill near the Huasco River mouth in the semi-arid Central Andes at the beginning of the Quaternary corresponds to an increased upstream erosion rate and we propose that this was due to glacial expansion. At 1.3 Ma, the river began to incise into these sediments, and at 1.0 Ma the rate of downcutting increased notably. The fluvial incision coincides with the Early-Middle Pleistocene Transition, when the periodicity of global climate cycles lengthened. We integrate these findings with marine terrace dating in the same region and find that, although fundamental changes of aggradation and incision were coeval with global climate change, the average rates of fluvial incision over million-year timescales are comparable to rates of uplift. Our findings imply that the Central Andean landscape has responded to major shifts in the frequency of orbitally-driven climatic cycles, impacting topography that is governed by tectonic uplift over longer timescales. As the supply of sediments offshore to subduction zones is considered to exert a control on uplift, our results have broader implications for feedbacks between climatic and tectonic processes.
{"title":"Fluvial responses to climate and tectonics throughout the Quaternary in the semi-arid Andes","authors":"A. Binnie , S.A. Binnie , P. Victor , J-L. García , S. Heinze , T.J. Dunai","doi":"10.1016/j.epsl.2026.119834","DOIUrl":"10.1016/j.epsl.2026.119834","url":null,"abstract":"<div><div>How major shifts in climate over the Quaternary have affected topography is unclear, especially in tectonically active regions. This shortcoming is largely due to a lack of robust chronologies of landscape evolution over the last few million years. Here we document a rare case, where a fluvial landscape has been preserved well enough to record its responses to tectonic and climatic shifts throughout the Quaternary. Our results show that aggradation of sediment fill near the Huasco River mouth in the semi-arid Central Andes at the beginning of the Quaternary corresponds to an increased upstream erosion rate and we propose that this was due to glacial expansion. At 1.3 Ma, the river began to incise into these sediments, and at 1.0 Ma the rate of downcutting increased notably. The fluvial incision coincides with the Early-Middle Pleistocene Transition, when the periodicity of global climate cycles lengthened. We integrate these findings with marine terrace dating in the same region and find that, although fundamental changes of aggradation and incision were coeval with global climate change, the average rates of fluvial incision over million-year timescales are comparable to rates of uplift. Our findings imply that the Central Andean landscape has responded to major shifts in the frequency of orbitally-driven climatic cycles, impacting topography that is governed by tectonic uplift over longer timescales. As the supply of sediments offshore to subduction zones is considered to exert a control on uplift, our results have broader implications for feedbacks between climatic and tectonic processes.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119834"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975723","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}
Pub Date : 2026-03-15Epub Date: 2026-01-16DOI: 10.1016/j.epsl.2025.119816
Francesco Mosconi , Elisa Tinti , Mariano Supino , Alice-Agnes Gabriel , Emanuele Casarotti , Men-Andrin Meier , Antonio Pio Rinaldi , Domenico Giardini , Massimo Cocco
Determining the maximum possible magnitude of fluid-induced earthquakes requires to understand rupture arrest within or outside a fluid-pressurized patch. Recent studies have highlighted the importance of incorporating rupture physics into the study of injection-induced earthquakes. We perform 3D dynamic simulations of spontaneous ruptures propagating across a pressurized fault, stimulated by fluid injection within the nucleation zone. Our simulations unveil two end-member models describing a fluid-induced micro-earthquake: a self-arresting rupture that decelerates spontaneously and a run-away rupture that terminates abruptly at the fault edge. We compute synthetic waveforms radiated from both models and invert them using a probabilistic spectral inversion approach to identify characteristics that distinguish between the two rupture types. We find that self-arresting ruptures radiate less high-frequency waves (with γ > 3) and lack the typical P/S corner frequency shift. In contrast, run-away ruptures conform to the ω2 model (γ ∼ 2, ). We interpret these differences as primarily arising from the rupture arrest mechanism, smooth arrest results in gradual variations in the moment-rate function, whereas abrupt arrest at a barrier causes a sharp changes in the moment-rate function. This abrupt arrest generates high-frequency radiation and a back-propagating stopping phase, playing a critical role in controlling the rupture duration and the radiated seismic waves. Our results demonstrate that spectral features such as high-frequency decay and P/S corner frequency shift may provide observational diagnostics to distinguish rupture arrest mechanisms, even in the absence of direct evidence from rupture kinematics.
{"title":"Discriminating dynamic rupture arrest in fluid-induced microearthquakes using spectral inversion","authors":"Francesco Mosconi , Elisa Tinti , Mariano Supino , Alice-Agnes Gabriel , Emanuele Casarotti , Men-Andrin Meier , Antonio Pio Rinaldi , Domenico Giardini , Massimo Cocco","doi":"10.1016/j.epsl.2025.119816","DOIUrl":"10.1016/j.epsl.2025.119816","url":null,"abstract":"<div><div>Determining the maximum possible magnitude of fluid-induced earthquakes requires to understand rupture arrest within or outside a fluid-pressurized patch. Recent studies have highlighted the importance of incorporating rupture physics into the study of injection-induced earthquakes. We perform 3D dynamic simulations of spontaneous ruptures propagating across a pressurized fault, stimulated by fluid injection within the nucleation zone. Our simulations unveil two end-member models describing a fluid-induced micro-earthquake: a self-arresting rupture that decelerates spontaneously and a run-away rupture that terminates abruptly at the fault edge. We compute synthetic waveforms radiated from both models and invert them using a probabilistic spectral inversion approach to identify characteristics that distinguish between the two rupture types. We find that self-arresting ruptures radiate less high-frequency waves (with <em>γ</em> > 3) and lack the typical P/S corner frequency shift. In contrast, run-away ruptures conform to the <em>ω</em><sup>2</sup> model (<em>γ</em> ∼ 2, <span><math><mrow><msubsup><mi>f</mi><mi>c</mi><mi>P</mi></msubsup><mo>/</mo><msubsup><mi>f</mi><mi>c</mi><mi>S</mi></msubsup><mo>∼</mo><mn>1.3</mn></mrow></math></span>). We interpret these differences as primarily arising from the rupture arrest mechanism, smooth arrest results in gradual variations in the moment-rate function, whereas abrupt arrest at a barrier causes a sharp changes in the moment-rate function. This abrupt arrest generates high-frequency radiation and a back-propagating stopping phase, playing a critical role in controlling the rupture duration and the radiated seismic waves. Our results demonstrate that spectral features such as high-frequency decay and P/S corner frequency shift may provide observational diagnostics to distinguish rupture arrest mechanisms, even in the absence of direct evidence from rupture kinematics.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119816"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975724","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}
Pub Date : 2026-03-15Epub Date: 2026-01-15DOI: 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.
{"title":"Conservative behavior of radiogenic neodymium isotopes in the South Pacific interior","authors":"Zhouling Zhang , Antao Xu , Xuegang Chen , Ed Hathorne , Marcus Gutjahr , Martin Frank","doi":"10.1016/j.epsl.2026.119850","DOIUrl":"10.1016/j.epsl.2026.119850","url":null,"abstract":"<div><div>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.</div><div>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.</div><div>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.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119850"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975728","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}
Pub Date : 2026-03-15Epub Date: 2026-01-16DOI: 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.
{"title":"Seasonal diversity & behaviour of internal tidal bores revealed by year-long direct monitoring within a submarine canyon: Implications for particulate transport","authors":"Morgan T. Wolfe , Michael A. Clare , Esther J. Sumner , Veerle A.I. Huvenne , Rob A. Hall , Ian A. Kane","doi":"10.1016/j.epsl.2026.119835","DOIUrl":"10.1016/j.epsl.2026.119835","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119835"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975718","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}
Pub Date : 2026-03-15Epub Date: 2026-01-12DOI: 10.1016/j.epsl.2026.119833
Zhiming Liang , Zhenyu Zhang , Beata Orlecka-Sikora , Shengpeng Hao , Kun Long
Pore pressure complicates the stress field in seismogenic zones and is an important factor controlling fault slip stability in injection-induced seismicity. However, the coupling effect of pore pressure and unequal horizontal stresses on the mechanics of earthquakes is constrained. Therefore, we perform velocity-stepping experiments under true triaxial stress conditions to investigate the influence of pore pressure on the frictional properties and fault stability. Our results show that pore pressure has two different effects on fault stability with the change of stress conditions. Potentially unstable behavior, which is characterized by a decrease in velocity dependence (a-b), is observed with increasing pore pressure under the constant horizontal stress condition. In contrast, pore pressure development promotes a more velocity-strengthening behavior under the constant effective horizontal stress condition, favoring stable slip. The different response in frictional stability of faults with elevated pore pressure is caused by the evolution of the rate-and-state parameter b, relating to the contact area. The strengthening stabilizing effect under the constant effective horizontal stress condition can be explained by the micro-morphology evolution of the bare fault surface, from discrete particle contact to powder distributed contact due to the asperity weakening with elevating pore pressure. Under the constant horizontal stress condition, the direct effect of increasing pore pressure reducing the effective normal stress promotes dilation, dominating the velocity dependence evolutionary tendency. These results have important implications for understanding the coupling effect of the stress field and pore pressure on controlling the fault stability.
{"title":"Frictional properties of Longmenshan sandstone under varying true triaxial stress and pore pressure conditions","authors":"Zhiming Liang , Zhenyu Zhang , Beata Orlecka-Sikora , Shengpeng Hao , Kun Long","doi":"10.1016/j.epsl.2026.119833","DOIUrl":"10.1016/j.epsl.2026.119833","url":null,"abstract":"<div><div>Pore pressure complicates the stress field in seismogenic zones and is an important factor controlling fault slip stability in injection-induced seismicity. However, the coupling effect of pore pressure and unequal horizontal stresses on the mechanics of earthquakes is constrained. Therefore, we perform velocity-stepping experiments under true triaxial stress conditions to investigate the influence of pore pressure on the frictional properties and fault stability. Our results show that pore pressure has two different effects on fault stability with the change of stress conditions. Potentially unstable behavior, which is characterized by a decrease in velocity dependence (<em>a</em>-<em>b</em>), is observed with increasing pore pressure under the constant horizontal stress condition. In contrast, pore pressure development promotes a more velocity-strengthening behavior under the constant effective horizontal stress condition, favoring stable slip. The different response in frictional stability of faults with elevated pore pressure is caused by the evolution of the rate-and-state parameter <em>b</em>, relating to the contact area. The strengthening stabilizing effect under the constant effective horizontal stress condition can be explained by the micro-morphology evolution of the bare fault surface, from discrete particle contact to powder distributed contact due to the asperity weakening with elevating pore pressure. Under the constant horizontal stress condition, the direct effect of increasing pore pressure reducing the effective normal stress promotes dilation, dominating the velocity dependence evolutionary tendency. These results have important implications for understanding the coupling effect of the stress field and pore pressure on controlling the fault stability.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119833"},"PeriodicalIF":4.8,"publicationDate":"2026-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145975731","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}
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