Determining what fault characteristics and applied stress conditions modulate the occurrence of seismicity is a key question in the field of seismology. Here we analyze the seismicity measured at two ice shelf rift zones of different maturity in the Ross Ice Shelf, which are subjected to long-term dilatational stress modulated by tidal stress variations. We analyze the periodicity of the seismicity and its relationship to tidal stress variations and find that the seismicity rate at both rifts is controlled by tidal stress rate variations. We compare the observed icequake occurrence times with analytical predictions from rate-and-state friction constitutive laws that have been used to model frictional behavior on terrestrial faults. We find that seismicity rate is predicted well by an analytical model based on rate-and-state friction, confirming that it can be used to understand ice rift seismicity. We constrain for the first time the characteristic time of seismicity rate, , for both rifts, and find that ice rifts have a faster recovery time than continental faults, and that their responses to stress and characteristic times are age dependent. This implies that the strength of the rift changes with time and determines the amount of stress or stress rate dependency of the system. Our results can be used to understand seismicity occurrence across other ice rifts in Antarctica and Greenland and holds implications for seismicity on icy satellites.
{"title":"Using rate-and-state friction constitutive laws to predict seismicity rates for ice rifts on the Ross Ice Shelf in Antarctica","authors":"Kathrine Udell-Lopez, Mong-Han Huang, Vedran Lekić","doi":"10.1016/j.epsl.2025.119790","DOIUrl":"10.1016/j.epsl.2025.119790","url":null,"abstract":"<div><div>Determining what fault characteristics and applied stress conditions modulate the occurrence of seismicity is a key question in the field of seismology. Here we analyze the seismicity measured at two ice shelf rift zones of different maturity in the Ross Ice Shelf, which are subjected to long-term dilatational stress modulated by tidal stress variations. We analyze the periodicity of the seismicity and its relationship to tidal stress variations and find that the seismicity rate at both rifts is controlled by tidal stress rate variations. We compare the observed icequake occurrence times with analytical predictions from rate-and-state friction constitutive laws that have been used to model frictional behavior on terrestrial faults. We find that seismicity rate is predicted well by an analytical model based on rate-and-state friction, confirming that it can be used to understand ice rift seismicity. We constrain for the first time the characteristic time of seismicity rate, <span><math><msub><mi>t</mi><mi>a</mi></msub></math></span>, for both rifts, and find that ice rifts have a faster recovery time than continental faults, and that their responses to stress and characteristic times are age dependent. This implies that the strength of the rift changes with time and determines the amount of stress or stress rate dependency of the system. Our results can be used to understand seismicity occurrence across other ice rifts in Antarctica and Greenland and holds implications for seismicity on icy satellites.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119790"},"PeriodicalIF":4.8,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797771","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 : 2025-12-17DOI: 10.1016/j.epsl.2025.119786
Wenshuo Mao , Xiaohui Fu , Zhongchen Wu , Jiang Zhang , Zongcheng Ling , Yang Liu , Yu-Yan Sara Zhao , Jiacheng Liu , He Cui , Hitesh G. Changela , Yuheng Ni , Lifang Li , Joseph R. Michalski
N2 is the second most abundant gas in the present-day Martian atmosphere and hosts the essential biochemical element N. Nitrate and (per)chlorate have been detected in numerous aeolian sediments in Gale crater. Thus, a potential nitrogen fixation may be active on present-day Mars. Interactions between Martian atmosphere and surface during dust events can trigger electrostatic discharge (ESD) and complex electrochemical reactions. By simulating this process in a Mars chamber, nitrate and (per)chlorate were produced under present-day Martian atmospheric conditions. Notably, the obtained nitrate/(per)chlorate abundance ratio is in agreement with Gale crater observations (< 1.0), but much lower than those in terrestrial Mars analogues and the products of other pathways proposed for Mars. The results strongly indicate that electrochemical reactions during Mars dust events represents a new nitrogen fixation mechanism on present-day Mars. It is different from other fixation processes on Earth and early Mars, expanding the knowledge of nitrogen cycle and nitrogen fixation in solar system. Electrochemical reactions may also play crucial roles in global nitrogen cycling throughout the Amazonian period. These nitrate salts in Martian dusts potentially provide an accessible source of nitrogen for possible organic molecule formation on present-day Mars.
{"title":"Fixation of atmospheric nitrogen on present-day Mars during dust events","authors":"Wenshuo Mao , Xiaohui Fu , Zhongchen Wu , Jiang Zhang , Zongcheng Ling , Yang Liu , Yu-Yan Sara Zhao , Jiacheng Liu , He Cui , Hitesh G. Changela , Yuheng Ni , Lifang Li , Joseph R. Michalski","doi":"10.1016/j.epsl.2025.119786","DOIUrl":"10.1016/j.epsl.2025.119786","url":null,"abstract":"<div><div>N<sub>2</sub> is the second most abundant gas in the present-day Martian atmosphere and hosts the essential biochemical element N. Nitrate and (per)chlorate have been detected in numerous aeolian sediments in Gale crater. Thus, a potential nitrogen fixation may be active on present-day Mars. Interactions between Martian atmosphere and surface during dust events can trigger electrostatic discharge (ESD) and complex electrochemical reactions. By simulating this process in a Mars chamber, nitrate and (per)chlorate were produced under present-day Martian atmospheric conditions. Notably, the obtained nitrate/(per)chlorate abundance ratio is in agreement with Gale crater observations (< 1.0), but much lower than those in terrestrial Mars analogues and the products of other pathways proposed for Mars. The results strongly indicate that electrochemical reactions during Mars dust events represents a new nitrogen fixation mechanism on present-day Mars. It is different from other fixation processes on Earth and early Mars, expanding the knowledge of nitrogen cycle and nitrogen fixation in solar system. Electrochemical reactions may also play crucial roles in global nitrogen cycling throughout the Amazonian period. These nitrate salts in Martian dusts potentially provide an accessible source of nitrogen for possible organic molecule formation on present-day Mars.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119786"},"PeriodicalIF":4.8,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797772","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 : 2025-12-16DOI: 10.1016/j.epsl.2025.119769
Kuilin Xiao , Qiang Qiu
Slip magnitude and rupture extent are crucial for understanding fault mechanics and seismic hazard but remain poorly resolved at depth. Here, we integrate GNSS and remote sensing observations with a resolution-optimized slip inversion technique to determine the coseismic slip distribution due to the 2021 Mw 7.4 Maduo earthquake (Tibet). Our high-resolution model reveals three key aspects unresolved in prior studies: a larger maximum slip of ∼9 m on the eastern fault, a moderate shallow slip deficit (SSD) of ∼40% above ∼2 km depth, and a narrower seismogenic layer confined to depths of 2–8 km. Further, we conduct physics-based 2D earthquake-cycle models, constrained by InSAR data and geological information, which reconcile these observations and indicate a transition from rate-weakening (seismogenic depths) to rate-strengthening (shallow depths), explaining both the SSD and along-strike variations in seismogenic zone width. Coulomb stress transfer calculation from our model successfully forecasts aftershocks over days to years, providing a benchmark for future seismic hazard assessment. These findings imply heightened seismic risk in the eastern Bayan Har Block, necessitating focused monitoring.
{"title":"Friction heterogeneity constrains rupture dynamics across a narrow seismogenic zone: The 2021 Mw 7.4 Maduo Earthquake (Eastern Tibet)","authors":"Kuilin Xiao , Qiang Qiu","doi":"10.1016/j.epsl.2025.119769","DOIUrl":"10.1016/j.epsl.2025.119769","url":null,"abstract":"<div><div>Slip magnitude and rupture extent are crucial for understanding fault mechanics and seismic hazard but remain poorly resolved at depth. Here, we integrate GNSS and remote sensing observations with a resolution-optimized slip inversion technique to determine the coseismic slip distribution due to the 2021 Mw 7.4 Maduo earthquake (Tibet). Our high-resolution model reveals three key aspects unresolved in prior studies: a larger maximum slip of ∼9 m on the eastern fault, a moderate shallow slip deficit (SSD) of ∼40% above ∼2 km depth, and a narrower seismogenic layer confined to depths of 2–8 km. Further, we conduct physics-based 2D earthquake-cycle models, constrained by InSAR data and geological information, which reconcile these observations and indicate a transition from rate-weakening (seismogenic depths) to rate-strengthening (shallow depths), explaining both the SSD and along-strike variations in seismogenic zone width. Coulomb stress transfer calculation from our model successfully forecasts aftershocks over days to years, providing a benchmark for future seismic hazard assessment. These findings imply heightened seismic risk in the eastern Bayan Har Block, necessitating focused monitoring.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119769"},"PeriodicalIF":4.8,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797727","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 : 2025-12-15DOI: 10.1016/j.epsl.2025.119783
Shengchao Yang , Junxuan Fan , Chao Li , Yi-Bo Lin , Yiying Deng , Zongyuan Sun , Jian Cao , Shu-zhong Shen
Global cooling has been strongly associated with the Great Ordovician Biodiversification Event (GOBE), but the underlying mechanisms remain unexplored. To assess whether enhanced biological pump contributed to global cooling during the GOBE, we performed δ138Bacarb-δ13Ccarb analyses on an Ordovician shallow marine limestone section from South China. Our results show that δ138Bacarb in the Ordovician (median 0.73‰) is significantly higher than in other geological periods and reservoirs (median values ranging from –0.18‰ to 0.29‰), indicating exceptionally high δ138Ba values in the surface ocean in South China, possibly due to plankton radiation, which increased the removal of Ba during the GOBE. Furthermore, shifts in δ138Bacarb correlated with long-term increases in δ13Ccarb, with positive correlation during the early Tremadocian (Stage 1), followed by negative correlation during the late Tremadocian to Dapingian (Stage 2), and positive correlation from the Darriwilian to Katian (Stage 3). These δ138Bacarb-δ13Ccarb covariations suggest that marine primary productivity was enhanced during the Ordovician in South China. Additionally, the gradual increase in δ13Ccarb is strongly correlated with global cooling and an increase in marine biodiversity, suggesting that plankton radiation during the GOBE may be an important cause of the increased marine primary productivity, thus enhancing organic carbon burial, contributing to the long-term Ordovician cooling, and linking the GOBE and contemporaneous environmental changes.
{"title":"Enhanced marine primary productivity during the long-term Ordovician cooling: A barium isotope perspective from South China","authors":"Shengchao Yang , Junxuan Fan , Chao Li , Yi-Bo Lin , Yiying Deng , Zongyuan Sun , Jian Cao , Shu-zhong Shen","doi":"10.1016/j.epsl.2025.119783","DOIUrl":"10.1016/j.epsl.2025.119783","url":null,"abstract":"<div><div>Global cooling has been strongly associated with the Great Ordovician Biodiversification Event (GOBE), but the underlying mechanisms remain unexplored. To assess whether enhanced biological pump contributed to global cooling during the GOBE, we performed δ<sup>138</sup>Ba<sub>carb</sub>-δ<sup>13</sup>C<sub>carb</sub> analyses on an Ordovician shallow marine limestone section from South China. Our results show that δ<sup>138</sup>Ba<sub>carb</sub> in the Ordovician (median 0.73‰) is significantly higher than in other geological periods and reservoirs (median values ranging from –0.18‰ to 0.29‰), indicating exceptionally high δ<sup>138</sup>Ba values in the surface ocean in South China, possibly due to plankton radiation, which increased the removal of Ba during the GOBE. Furthermore, shifts in δ<sup>138</sup>Ba<sub>carb</sub> correlated with long-term increases in δ<sup>13</sup>C<sub>carb</sub>, with positive correlation during the early Tremadocian (Stage 1), followed by negative correlation during the late Tremadocian to Dapingian (Stage 2), and positive correlation from the Darriwilian to Katian (Stage 3). These δ<sup>138</sup>Ba<sub>carb</sub>-δ<sup>13</sup>C<sub>carb</sub> covariations suggest that marine primary productivity was enhanced during the Ordovician in South China. Additionally, the gradual increase in δ<sup>13</sup>C<sub>carb</sub> is strongly correlated with global cooling and an increase in marine biodiversity, suggesting that plankton radiation during the GOBE may be an important cause of the increased marine primary productivity, thus enhancing organic carbon burial, contributing to the long-term Ordovician cooling, and linking the GOBE and contemporaneous environmental changes.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119783"},"PeriodicalIF":4.8,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-11DOI: 10.1016/j.epsl.2025.119767
Alexis Gauthier , Nadaya Cubas , Laetitia Le Pourhiet
Seamounts on oceanic plates are thought to affect the dynamics of accretionary prism at subduction zones, particularly the slip behavior. Geophysical studies show that pore fluid overpressure is associated with the nucleation of shallow slow slip events (SSEs). We use numerical simulations in which the subducting plate bends in response to tectonic, gravitational collapse and surface processes to capture structural complexities arising from the subduction of buried seamounts and compute the resulting stress state. We show that tectonic slices of undeformed sediments develop on both sides of the seamount and that a basin forms atop the seaward slice. These structures, recognizable in seismic data, represent the long-term tectonic signature of seamount subduction.
Gravitational collapse only occurs when a critical lengthscale, we quantified, of perturbed accretionary prism is reached. Seamounts that are small enough, instead get decapitated and do not perturb the prism over a sufficient lengthscale to trigger gravitational collapse.
Stress analysis reveals that the seaward side of the seamount is under an extensional regime, whereas its landward side is in a compressive state. We thus propose that sustained pore fluid overpressure can only develop on the landward side. This mechanism supports observations along Hikurangi, where a highly reflective zone, interpreted as a zone of pore fluid overpressure, has been imaged downdip of the Papaku seamount. Since this zone coincides with the largest slip magnitudes of shallow SSEs, we propose that the landward slice of undeformed sediments presents favorable conditions for SSEs nucleation.
{"title":"Tectonic structures and stress state associated with seamount subduction in accretionary prism. Implications for slip behavior","authors":"Alexis Gauthier , Nadaya Cubas , Laetitia Le Pourhiet","doi":"10.1016/j.epsl.2025.119767","DOIUrl":"10.1016/j.epsl.2025.119767","url":null,"abstract":"<div><div>Seamounts on oceanic plates are thought to affect the dynamics of accretionary prism at subduction zones, particularly the slip behavior. Geophysical studies show that pore fluid overpressure is associated with the nucleation of shallow slow slip events (SSEs). We use numerical simulations in which the subducting plate bends in response to tectonic, gravitational collapse and surface processes to capture structural complexities arising from the subduction of buried seamounts and compute the resulting stress state. We show that tectonic slices of undeformed sediments develop on both sides of the seamount and that a basin forms atop the seaward slice. These structures, recognizable in seismic data, represent the long-term tectonic signature of seamount subduction.</div><div>Gravitational collapse only occurs when a critical lengthscale, we quantified, of perturbed accretionary prism is reached. Seamounts that are small enough, instead get decapitated and do not perturb the prism over a sufficient lengthscale to trigger gravitational collapse.</div><div>Stress analysis reveals that the seaward side of the seamount is under an extensional regime, whereas its landward side is in a compressive state. We thus propose that sustained pore fluid overpressure can only develop on the landward side. This mechanism supports observations along Hikurangi, where a highly reflective zone, interpreted as a zone of pore fluid overpressure, has been imaged downdip of the Papaku seamount. Since this zone coincides with the largest slip magnitudes of shallow SSEs, we propose that the landward slice of undeformed sediments presents favorable conditions for SSEs nucleation.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119767"},"PeriodicalIF":4.8,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-11DOI: 10.1016/j.epsl.2025.119779
Eirini M. Poulaki , Cailey B. Condit , Margaret L. Odlum , Jason N. Ott , Megan E. Ferrell
The subduction plate interface accommodates deformation between the downgoing and overriding plates and features a range of mechanical and chemical processes that influence the strength and slip behavior of this zone. Apatite, a calcium phosphate accessory mineral, records these subduction processes including metamorphism, metasomatism, and deformation. It can deform, recrystallize, and archive chemical processes through its trace elements across the pressure and temperatures conditions that span the depths at the bottom of the subduction seismogenic zone. We leverage these apatite characteristics in a metabasite within an exhumed subduction complex on Andros Island, Greece to demonstrate that apatite grains show multiple deformation mechanisms and inform on fluid’s composition and role in deformation processes. Apatite deformation mechanisms are dependent on the surrounding mineral phases, with grains within the chlorite matrix exhibiting evidence of dissolution-precipitation while grains in contact with strong mineral phases (e.g., clinozoisite, albite) deform by dislocation-accommodated deformation. Dislocations formed by prism 〈c〉 slip in apatite act as pathways for fluid mobile elements during deformation while dislocations formed by basal 〈a〉 slip did not facilitate trace element diffusivity, likely due to a crystallographic control. We also show that apatite is a powerful geochemical archive recording infiltration of aqueous sedimentary fluids with small amounts of CO2 during metasomatism. We highlight the utility of in-situ apatite geochemistry in polymetamorphic and polydeformed rocks. We show that even at the grain scale, lattice impurities will control the geochemical signatures.
俯冲板块界面容纳了下行板块和上覆板块之间的变形，并具有一系列影响该带强度和滑移行为的机械和化学过程。磷灰石是一种磷酸钙辅助矿物，记录了这些俯冲过程，包括变质作用、交代作用和变形作用。它可以变形、再结晶，并通过其微量元素在压力和温度条件下记录化学过程，这些条件跨越了俯冲发震带底部的深度。我们利用这些磷灰石特征在希腊安德罗斯岛的一个潜没杂岩中发现的变质岩中，证明磷灰石颗粒具有多种变形机制，并为流体成分和变形过程中的作用提供了信息。磷灰石的变形机制取决于周围的矿物相，绿泥石基质中的颗粒表现出溶解沉淀的证据，而与强矿物相（如斜沸石、钠长石）接触的颗粒则通过位错调节变形而变形。磷灰石中棱柱状< c >滑移形成的位错是变形过程中流体流动元素的通道，而基底< a >滑移形成的位错可能受晶体学控制，不能促进微量元素的扩散。我们还表明，磷灰石是一个强大的地球化学档案，记录了在交代过程中含有少量CO2的含水沉积流体的渗透。我们强调了原位磷灰石地球化学在多变质和多变形岩石中的应用。我们发现，即使在晶粒尺度上，晶格杂质也会控制地球化学特征。
{"title":"Apatite records mechanical and chemical processes over the lifetime of a subduction interface, Andros Island, Greece","authors":"Eirini M. Poulaki , Cailey B. Condit , Margaret L. Odlum , Jason N. Ott , Megan E. Ferrell","doi":"10.1016/j.epsl.2025.119779","DOIUrl":"10.1016/j.epsl.2025.119779","url":null,"abstract":"<div><div>The subduction plate interface accommodates deformation between the downgoing and overriding plates and features a range of mechanical and chemical processes that influence the strength and slip behavior of this zone. Apatite, a calcium phosphate accessory mineral, records these subduction processes including metamorphism, metasomatism, and deformation. It can deform, recrystallize, and archive chemical processes through its trace elements across the pressure and temperatures conditions that span the depths at the bottom of the subduction seismogenic zone. We leverage these apatite characteristics in a metabasite within an exhumed subduction complex on Andros Island, Greece to demonstrate that apatite grains show multiple deformation mechanisms and inform on fluid’s composition and role in deformation processes. Apatite deformation mechanisms are dependent on the surrounding mineral phases, with grains within the chlorite matrix exhibiting evidence of dissolution-precipitation while grains in contact with strong mineral phases (e.g., clinozoisite, albite) deform by dislocation-accommodated deformation. Dislocations formed by prism 〈c〉 slip in apatite act as pathways for fluid mobile elements during deformation while dislocations formed by basal 〈a〉 slip did not facilitate trace element diffusivity, likely due to a crystallographic control. We also show that apatite is a powerful geochemical archive recording infiltration of aqueous sedimentary fluids with small amounts of CO<sub>2</sub> during metasomatism. We highlight the utility of in-situ apatite geochemistry in polymetamorphic and polydeformed rocks. We show that even at the grain scale, lattice impurities will control the geochemical signatures.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119779"},"PeriodicalIF":4.8,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734590","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}
Marius Hills, located in the central Oceanus Procellarum on the nearside of the Moon, is a significant volcanic complex, characterized by hundreds of domes and cones. Understanding its subsurface density structure is essential for enhancing our knowledge of lunar volcanic activity and its evolutionary history, yet it remains controversial. To investigate the density structure underneath Marius Hills, we developed a gravity inversion method based on the L1 norm and total variation regularization in spherical coordinates. We validated the method through a synthetic model test. We then applied it to the inversion of gravity data derived from the GRAIL mission in Marius Hills. Our results reveal two distinct high-density anomalies in the northern and southern segments of Marius Hills. The northern anomaly is located at 14–29 km depth directly beneath the shield volcano of Marius Hills, with a density contrast of ∼620 kg/m³ and a volume of about 60 × 60 × 15 km³. The southern anomaly exhibits a density contrast of ∼440 kg/m³ and a size of 75 × 75 × 15 km³ at depths of 18–33 km. These two dense anomalies are likely solidified basaltic magma chambers situated near the crust-mantle boundary, that served as magma sources for the volcanic activities in Marius Hills.
{"title":"Three-dimensional density structure underneath the Marius Hills volcanic complex on the Moon","authors":"Shiyu Zhang , Bo Chen , Qian Huang , Changyi Xu , Xiaolong Wei","doi":"10.1016/j.epsl.2025.119770","DOIUrl":"10.1016/j.epsl.2025.119770","url":null,"abstract":"<div><div>Marius Hills, located in the central Oceanus Procellarum on the nearside of the Moon, is a significant volcanic complex, characterized by hundreds of domes and cones. Understanding its subsurface density structure is essential for enhancing our knowledge of lunar volcanic activity and its evolutionary history, yet it remains controversial. To investigate the density structure underneath Marius Hills, we developed a gravity inversion method based on the L1 norm and total variation regularization in spherical coordinates. We validated the method through a synthetic model test. We then applied it to the inversion of gravity data derived from the GRAIL mission in Marius Hills. Our results reveal two distinct high-density anomalies in the northern and southern segments of Marius Hills. The northern anomaly is located at 14–29 km depth directly beneath the shield volcano of Marius Hills, with a density contrast of ∼620 kg/m³ and a volume of about 60 × 60 × 15 km³. The southern anomaly exhibits a density contrast of ∼440 kg/m³ and a size of 75 × 75 × 15 km³ at depths of 18–33 km. These two dense anomalies are likely solidified basaltic magma chambers situated near the crust-mantle boundary, that served as magma sources for the volcanic activities in Marius Hills.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119770"},"PeriodicalIF":4.8,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734592","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 : 2025-12-08DOI: 10.1016/j.epsl.2025.119771
Fabio Arzilli , Giuseppe La Spina , Emily C. Bamber , Daniele Morgavi , Lorenzo Fedele , Lucia Mancini , Marko Prašek , Ileana Santangelo , Giulia Chiominto , Annamaria Perrotta , Thomas Lemaire , Hélène Balcone-Boissard , Daniele Giordano , Claudio Scarpati
Intermediate to evolved alkaline magmas (phono-tephritic, tephri-phonolitic and phonolitic) exhibit a wide range in eruptive style and have produced some of the most catastrophic eruptions in human history, such as the 79 AD Plinian eruption of Vesuvius (Italy). However, eruptive dynamics are driven by complex, non-linear conduit processes during magma ascent, requiring a holistic approach to investigate their influence on explosivity. This study integrates synchrotron radiation X-ray computed microtomography (SRµCT) with a 1D steady-state conduit model, to investigate how crystal-bubble interactions, pre-eruptive conditions, outgassing, and magma composition affect eruptive style at alkaline volcanic systems, using Vesuvius as a case study.
We analyse pyroclasts from the 79 AD Plinian and 1944 lava-fountaining eruptions using SRμCT. Our SRµCT results reveal that heterogeneous bubble nucleation can be promoted further by leucite crystals, contributing to the high bubble number densities (>10⁴ mm⁻³) observed in Plinian products. Despite high bubble connectivity, low throat-pore size ratios (the ratio between the radii of the throat and connected vesicles) and elevated tortuosity restrict gas–melt separation during fast magma ascent, promoting fragmentation. Numerical simulations reveal tephri-phonolitic and phonolitic magmas are prone to fragmentation across diverse conditions, producing highly explosive eruptions. Only relatively high temperatures (>1050 °C) and low bubble number densities (102 to 103 mm-3) can promote lava flow and fountaining activity. Instead, phono-tephritic magmas exhibit highly explosive eruptions at considerably lower temperatures (<950 °C). Temperature controls magma viscosity, influencing the ascent rate and the outgassing efficiency, which, in turn, affects conduit dynamics and the eruptive behaviour.
Our findings highlight that for alkaline systems, the parameter space which is conducive to highly explosive eruptions expands as the magma composition evolves and its viscosity increases. These insights enhance our understanding of eruption mechanisms, providing critical insights for assessing volcanic hazard and emergency planning at alkaline volcanic systems.
{"title":"The role of crystal-bubble interactions, outgassing and magma composition in the ascent dynamics of alkaline magmas: Implications for eruptions at Vesuvius","authors":"Fabio Arzilli , Giuseppe La Spina , Emily C. Bamber , Daniele Morgavi , Lorenzo Fedele , Lucia Mancini , Marko Prašek , Ileana Santangelo , Giulia Chiominto , Annamaria Perrotta , Thomas Lemaire , Hélène Balcone-Boissard , Daniele Giordano , Claudio Scarpati","doi":"10.1016/j.epsl.2025.119771","DOIUrl":"10.1016/j.epsl.2025.119771","url":null,"abstract":"<div><div>Intermediate to evolved alkaline magmas (phono-tephritic, tephri-phonolitic and phonolitic) exhibit a wide range in eruptive style and have produced some of the most catastrophic eruptions in human history, such as the 79 AD Plinian eruption of Vesuvius (Italy). However, eruptive dynamics are driven by complex, non-linear conduit processes during magma ascent, requiring a holistic approach to investigate their influence on explosivity. This study integrates synchrotron radiation X-ray computed microtomography (SRµCT) with a 1D steady-state conduit model, to investigate how crystal-bubble interactions, pre-eruptive conditions, outgassing, and magma composition affect eruptive style at alkaline volcanic systems, using Vesuvius as a case study.</div><div>We analyse pyroclasts from the 79 AD Plinian and 1944 lava-fountaining eruptions using SRμCT. Our SRµCT results reveal that heterogeneous bubble nucleation can be promoted further by leucite crystals, contributing to the high bubble number densities (>10⁴ mm⁻³) observed in Plinian products. Despite high bubble connectivity, low throat-pore size ratios (the ratio between the radii of the throat and connected vesicles) and elevated tortuosity restrict gas–melt separation during fast magma ascent, promoting fragmentation. Numerical simulations reveal tephri-phonolitic and phonolitic magmas are prone to fragmentation across diverse conditions, producing highly explosive eruptions. Only relatively high temperatures (>1050 °C) and low bubble number densities (10<sup>2</sup> to 10<sup>3</sup> mm<sup>-3</sup>) can promote lava flow and fountaining activity. Instead, phono-tephritic magmas exhibit highly explosive eruptions at considerably lower temperatures (<950 °C). Temperature controls magma viscosity, influencing the ascent rate and the outgassing efficiency, which, in turn, affects conduit dynamics and the eruptive behaviour.</div><div>Our findings highlight that for alkaline systems, the parameter space which is conducive to highly explosive eruptions expands as the magma composition evolves and its viscosity increases. These insights enhance our understanding of eruption mechanisms, providing critical insights for assessing volcanic hazard and emergency planning at alkaline volcanic systems.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119771"},"PeriodicalIF":4.8,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145734589","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 : 2025-12-06DOI: 10.1016/j.epsl.2025.119765
Mingqi Liu, Sylvain Barbot
The generation of earthquakes is primarily governed by the thermo-mechanical and structural properties of fault zones. However, the influence of lithological and hydrothermal factors on the rupture style, size, and recurrence patterns of seismic activity remains poorly understood. Here, we explore the role of hydrothermal alteration on the spatial distribution and source characteristics of earthquakes along oceanic transform faults. We perform three-dimensional seismic cycle simulations calibrated with thermal profiles from thermo-mechanical geodynamic models and laboratory-derived frictional properties of crust and mantle rocks to elucidate the seismic patterns of oceanic transform faults. The thermally activated healing of antigorite in serpentinized mantle pockets may facilitate the spontaneous generation of seismic swarms, depending on the intensity of shear heating and the activation energy of the healing process. Fluid circulation influences seismic behavior by driving local alteration, affecting fault frictional properties. The unstable nature of gabbro friction over a finite range of temperature supports a narrow seismogenic zone within the oceanic crust, with a lateral extent of seismic ruptures limited by patches of hydrothermal alteration products (e.g., talc and chlorite) within the fault zone. Abundant microseismicity may occur within partially altered, heterogeneous barrier zones. These findings highlight the critical interplay between lithology, hydrothermal processes, and fault mechanics, providing new insights into the tectonic framework of seismicity along oceanic transform faults.
{"title":"Role of hydrothermal alteration and thermally activated healing on earthquake dynamics along oceanic transform faults","authors":"Mingqi Liu, Sylvain Barbot","doi":"10.1016/j.epsl.2025.119765","DOIUrl":"10.1016/j.epsl.2025.119765","url":null,"abstract":"<div><div>The generation of earthquakes is primarily governed by the thermo-mechanical and structural properties of fault zones. However, the influence of lithological and hydrothermal factors on the rupture style, size, and recurrence patterns of seismic activity remains poorly understood. Here, we explore the role of hydrothermal alteration on the spatial distribution and source characteristics of earthquakes along oceanic transform faults. We perform three-dimensional seismic cycle simulations calibrated with thermal profiles from thermo-mechanical geodynamic models and laboratory-derived frictional properties of crust and mantle rocks to elucidate the seismic patterns of oceanic transform faults. The thermally activated healing of antigorite in serpentinized mantle pockets may facilitate the spontaneous generation of seismic swarms, depending on the intensity of shear heating and the activation energy of the healing process. Fluid circulation influences seismic behavior by driving local alteration, affecting fault frictional properties. The unstable nature of gabbro friction over a finite range of temperature supports a narrow seismogenic zone within the oceanic crust, with a lateral extent of seismic ruptures limited by patches of hydrothermal alteration products (e.g., talc and chlorite) within the fault zone. Abundant microseismicity may occur within partially altered, heterogeneous barrier zones. These findings highlight the critical interplay between lithology, hydrothermal processes, and fault mechanics, providing new insights into the tectonic framework of seismicity along oceanic transform faults.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119765"},"PeriodicalIF":4.8,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145693386","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 : 2025-12-04DOI: 10.1016/j.epsl.2025.119746
O. Beyssac , E. Clavé , O. Forni , A. Udry , A.C. Pascuzzo , E. Dehouck , P. Beck , L. Mandon , C. Quantin-Nataf , N. Mangold , G. Lopez-Reyes , C. Royer , O. Gasnault , T.S.J. Gabriel , L. Kah , S. Schröder , J.R. Johnson , T. Bertrand , B. Chide , T. Fouchet , A. Cousin
Based on observation and data from meteorites and in situ scientific missions, experiments as well as models, the Martian mantle is assumed to share some compositional and mineralogical affinity with the terrestrial mantle. However, there might be subtle differences like the Martian mantle being more ferroan. Yet, we do not have any direct analysis of a Martian mantle rock to confirm this assumption. NASA’s Perseverance rover found olivine-rich boulder-sized float rocks on the upper Jezero fan (Mars). These boulders have an ultramafic composition and their mineralogy is dominantly composed of Fo73±3 olivine with high-Mg orthopyroxene, Cr-rich Ti-Fe oxides and minor plagioclase and high-Ca pyroxene. Microtextural and petrological analysis reveals that these minerals crystallized at equilibrium. In addition, these boulders are different from all the bedrocks analyzed by Perseverance along its traverse which are crustal igneous rocks and sediments. Comparing our data to Martian meteorites and available Mars bulk silicate models (BSM), we discuss that these boulders could represent primitive melts and/or lower crustal material, and we specifically hypothesize that they could be mantle peridotites. We propose that these putative mantle rocks could have been excavated by the succession of impacts from the shallow mantle or lower crust in the Isidis region where Jezero crater is located. These olivine-rich boulders could thereby constitute the first direct analysis of a Martian mantle rock.
{"title":"Ultramafic float rocks at Jezero crater (Mars): excavation of lower crustal rocks or mantle peridotites by impact cratering?","authors":"O. Beyssac , E. Clavé , O. Forni , A. Udry , A.C. Pascuzzo , E. Dehouck , P. Beck , L. Mandon , C. Quantin-Nataf , N. Mangold , G. Lopez-Reyes , C. Royer , O. Gasnault , T.S.J. Gabriel , L. Kah , S. Schröder , J.R. Johnson , T. Bertrand , B. Chide , T. Fouchet , A. Cousin","doi":"10.1016/j.epsl.2025.119746","DOIUrl":"10.1016/j.epsl.2025.119746","url":null,"abstract":"<div><div>Based on observation and data from meteorites and in situ scientific missions, experiments as well as models, the Martian mantle is assumed to share some compositional and mineralogical affinity with the terrestrial mantle. However, there might be subtle differences like the Martian mantle being more ferroan. Yet, we do not have any direct analysis of a Martian mantle rock to confirm this assumption. NASA’s <em>Perseverance</em> rover found olivine-rich boulder-sized float rocks on the upper Jezero fan (Mars). These boulders have an ultramafic composition and their mineralogy is dominantly composed of Fo<sub>73±3</sub> olivine with high-Mg orthopyroxene, Cr-rich Ti-Fe oxides and minor plagioclase and high-Ca pyroxene. Microtextural and petrological analysis reveals that these minerals crystallized at equilibrium. In addition, these boulders are different from all the bedrocks analyzed by <em>Perseverance</em> along its traverse which are crustal igneous rocks and sediments. Comparing our data to Martian meteorites and available Mars bulk silicate models (BSM), we discuss that these boulders could represent primitive melts and/or lower crustal material, and we specifically hypothesize that they could be mantle peridotites. We propose that these putative mantle rocks could have been excavated by the succession of impacts from the shallow mantle or lower crust in the Isidis region where Jezero crater is located. These olivine-rich boulders could thereby constitute the first direct analysis of a Martian mantle rock.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"675 ","pages":"Article 119746"},"PeriodicalIF":4.8,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145693279","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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