P. Vitouš, M. S. Petronis, M. S. Foucher, F. Tomek
Characteristic remanent magnetizations isolated from the late Variscan Altenberg–Teplice Caldera exhibit paleomagnetic directions, ranging from those consistent with the expected primary Late Carboniferous geomagnetic field to intermediate directions that significantly diverge from the dipole states. Most of the examined samples of the syn-caldera rhyolite dike swarm, portions of the intra-caldera ignimbrite fill, the outflow ignimbrite, and the syn- to post-caldera ring dike system appear to retain a primary thermoremanent magnetization, as supported by rock-magnetic data. Certain parts of the intra-caldera ignimbrites and younger syn- to post-collapse ring dikes record intermediate directions, which we interpret as unrecognized field behavior intervals during the Late Carboniferous, within the Kiaman Reversed Polarity Superchron. Based on our new paleomagnetic results supported by cross-cutting relationships, we propose the identification of previously unrecognized excursions within the Kiaman Superchron. These events are constrained by geochronology and occurred between approximately 314.7 and 312.6 million years ago during Chron PE5r. This study provides new paleomagnetic evidence that challenges the long-standing assumption of generally reversed polarity over the ∼55-million-year duration of the Kiaman Superchron and offers new insights into the variability of geomagnetic behavior during this interval in Earth's history.
{"title":"Late Carboniferous Geomagnetic Field Events Recorded in Post-Collisional Altenberg–Teplice Caldera, Variscan Belt","authors":"P. Vitouš, M. S. Petronis, M. S. Foucher, F. Tomek","doi":"10.1029/2025jb031983","DOIUrl":"https://doi.org/10.1029/2025jb031983","url":null,"abstract":"Characteristic remanent magnetizations isolated from the late Variscan Altenberg–Teplice Caldera exhibit paleomagnetic directions, ranging from those consistent with the expected primary Late Carboniferous geomagnetic field to intermediate directions that significantly diverge from the dipole states. Most of the examined samples of the syn-caldera rhyolite dike swarm, portions of the intra-caldera ignimbrite fill, the outflow ignimbrite, and the syn- to post-caldera ring dike system appear to retain a primary thermoremanent magnetization, as supported by rock-magnetic data. Certain parts of the intra-caldera ignimbrites and younger syn- to post-collapse ring dikes record intermediate directions, which we interpret as unrecognized field behavior intervals during the Late Carboniferous, within the Kiaman Reversed Polarity Superchron. Based on our new paleomagnetic results supported by cross-cutting relationships, we propose the identification of previously unrecognized excursions within the Kiaman Superchron. These events are constrained by geochronology and occurred between approximately 314.7 and 312.6 million years ago during Chron PE5r. This study provides new paleomagnetic evidence that challenges the long-standing assumption of generally reversed polarity over the ∼55-million-year duration of the Kiaman Superchron and offers new insights into the variability of geomagnetic behavior during this interval in Earth's history.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"10 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147454713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Qilian-Haiyuan fault system is the main tectonic boundary of the northeastern Tibetan Plateau, controlling the regional tectonic deformation and seismic activity. Extensive Sentinel-1 SAR data (2014–2021) are used to map the regional tectonic deformation, strain distribution, and locking along primary and secondary faults. We firstly use SAR images on five ascending and six descending tracks to obtain the large-scale displacement rate fields by InSAR time series analysis. We calculate high-resolution east-west, vertical velocity fields, and horizontal strain rate fields by combining GNSS horizontal velocities. Additionally, we invert kinematic parameters of fault locking based on 2D elastic dislocation models, and explore the spatiotemporal evolution of creep rates on the Laohushan segment and its relationship with nearby earthquakes. We show that there are two spatially separated high-strain zones, one along the Tianzhu Gap and the 1920 Haiyuan earthquake rupture zone, and the other along the North Qilian fault. Creep rate of the eastern Laohushan segment has been decreasing over the past three decades, from ∼10 mm/yr to ≤2 mm/yr. We argue that the creep may be modulated by co- and post-seismic stress perturbations imparted by two ∼ M6 earthquakes in Jingtai in 1990 and 2000.
{"title":"Large-Scale Deformation, Strain Characteristics, and Locking Distribution of the Qilian-Haiyuan Fault System","authors":"Donglin Wu, Chunyan Qu, Dezheng Zhao, Han Chen, Yilin Rong, Xiaoyi Wang, Xinjian Shan","doi":"10.1029/2024jb030647","DOIUrl":"https://doi.org/10.1029/2024jb030647","url":null,"abstract":"The Qilian-Haiyuan fault system is the main tectonic boundary of the northeastern Tibetan Plateau, controlling the regional tectonic deformation and seismic activity. Extensive Sentinel-1 SAR data (2014–2021) are used to map the regional tectonic deformation, strain distribution, and locking along primary and secondary faults. We firstly use SAR images on five ascending and six descending tracks to obtain the large-scale displacement rate fields by InSAR time series analysis. We calculate high-resolution east-west, vertical velocity fields, and horizontal strain rate fields by combining GNSS horizontal velocities. Additionally, we invert kinematic parameters of fault locking based on 2D elastic dislocation models, and explore the spatiotemporal evolution of creep rates on the Laohushan segment and its relationship with nearby earthquakes. We show that there are two spatially separated high-strain zones, one along the Tianzhu Gap and the 1920 Haiyuan earthquake rupture zone, and the other along the North Qilian fault. Creep rate of the eastern Laohushan segment has been decreasing over the past three decades, from ∼10 mm/yr to ≤2 mm/yr. We argue that the creep may be modulated by co- and post-seismic stress perturbations imparted by two ∼ M6 earthquakes in Jingtai in 1990 and 2000.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"412 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147447892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Victor J. O. Marum, Filipe Terra-Nova, Gelvam A. Hartmann, Erwan Thébault, Plinio Jaqueto, Wilbor Poletti, Ricardo I. F. Trindade
The study of variations in geomagnetic field intensity over time and space is crucial to understand the evolution of the geodynamo and its interactions with the Earth's surface. In this work, we introduce the SAGEOMAG (South America GEOMAGnetic) database, a comprehensive and updated repository of geomagnetic field intensity records derived from archeological artifacts and volcanic materials over the past 5 millennia and adherent to the FAIR (Findable, Accessible, Interoperable and Reusable) principles. A key advantage of the SAGEOMAG database is the inclusion of statistical parameters at the specimen level for data quality control, as well as the data categorization according to the hierarchical level of record (site, fragment or specimen). Additionally, we propose new intensity references curves for South America (SARIC), modeled with a bootstrap algorithm that minimizes the influence of outliers and estimates the probability density function without needing explicit prior shape considerations. For records without intensity errors and age uncertainty details in the original studies, standard errors and uncertainties were assigned based on log-normal distributions. Our findings demonstrate that the modeling of master curves is highly sensitive to the quality filters applied to the data and the hierarchical level of the records. This study aims to improve the organization of geomagnetic data for South America and contribute to regional and global archeomagnetic field modeling, thereby enhancing our understanding of the geomagnetic field evolution and especially the South Atlantic Anomaly (SAA).
{"title":"Archeointensity Database and Geomagnetic Field Reference Curves for South America Over the Past 5 Millennia","authors":"Victor J. O. Marum, Filipe Terra-Nova, Gelvam A. Hartmann, Erwan Thébault, Plinio Jaqueto, Wilbor Poletti, Ricardo I. F. Trindade","doi":"10.1029/2025jb032478","DOIUrl":"https://doi.org/10.1029/2025jb032478","url":null,"abstract":"The study of variations in geomagnetic field intensity over time and space is crucial to understand the evolution of the geodynamo and its interactions with the Earth's surface. In this work, we introduce the SAGEOMAG (South America GEOMAGnetic) database, a comprehensive and updated repository of geomagnetic field intensity records derived from archeological artifacts and volcanic materials over the past 5 millennia and adherent to the FAIR (Findable, Accessible, Interoperable and Reusable) principles. A key advantage of the SAGEOMAG database is the inclusion of statistical parameters at the specimen level for data quality control, as well as the data categorization according to the hierarchical level of record (site, fragment or specimen). Additionally, we propose new intensity references curves for South America (SARIC), modeled with a bootstrap algorithm that minimizes the influence of outliers and estimates the probability density function without needing explicit prior shape considerations. For records without intensity errors and age uncertainty details in the original studies, standard errors and uncertainties were assigned based on log-normal distributions. Our findings demonstrate that the modeling of master curves is highly sensitive to the quality filters applied to the data and the hierarchical level of the records. This study aims to improve the organization of geomagnetic data for South America and contribute to regional and global archeomagnetic field modeling, thereby enhancing our understanding of the geomagnetic field evolution and especially the South Atlantic Anomaly (SAA).","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"17 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147447893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The 1975 Ms 7.3 Haicheng earthquake occurred in northwestern Liaodong Peninsula, which was successfully forecasted and marked a landmark achievement in seismology. However, the seismogenic mechanism of this earthquake remains poorly known. In this study, we obtain high-precision earthquake catalog and 3-D models of crustal P- and S-wave velocities (Vp, Vs) and their ratio (Vp/Vs) in the Haicheng seismic zone (HSZ) from an unprecedentedly dense seismic array that we recently deployed. Our results show the seismicity pattern in the HSZ is predominantly controlled by an interconnected conjugate fault system, comprising the WNW-striking Haichenghe fault and its NE-striking concealed secondary fault. Furthermore, a prominent fluid-rich zone characterized by low Vp, low Vs and high Vp/Vs ratio is clearly revealed in the middle crust at ∼15 km depth, directly beneath the hypocentral region of the 1975 Haicheng earthquake. A distinct seismic cluster is also observed adjacent to the main shock hypocenter, exhibiting spatial correlation with the underlying crustal fluid reservoir. This geometric correspondence indicates a fluid-driven triggering mechanism that contributes to the localized seismicity. We deem that the reactivation of preexisting seismogenic faults induced by crustal fluid migration could be a possible mechanism for the nucleation of such a large intraplate earthquake.
{"title":"Seismicity and Detailed Fault Zone Structure Beneath Haicheng Seismic Zone, NE China: Implications for the Fluid-Induced Fault Reactivation","authors":"Dong Yan, You Tian, Cai Liu, Xiaodong Song","doi":"10.1029/2025jb032942","DOIUrl":"https://doi.org/10.1029/2025jb032942","url":null,"abstract":"The 1975 Ms 7.3 Haicheng earthquake occurred in northwestern Liaodong Peninsula, which was successfully forecasted and marked a landmark achievement in seismology. However, the seismogenic mechanism of this earthquake remains poorly known. In this study, we obtain high-precision earthquake catalog and 3-D models of crustal P- and S-wave velocities (Vp, Vs) and their ratio (Vp/Vs) in the Haicheng seismic zone (HSZ) from an unprecedentedly dense seismic array that we recently deployed. Our results show the seismicity pattern in the HSZ is predominantly controlled by an interconnected conjugate fault system, comprising the WNW-striking Haichenghe fault and its NE-striking concealed secondary fault. Furthermore, a prominent fluid-rich zone characterized by low Vp, low Vs and high Vp/Vs ratio is clearly revealed in the middle crust at ∼15 km depth, directly beneath the hypocentral region of the 1975 Haicheng earthquake. A distinct seismic cluster is also observed adjacent to the main shock hypocenter, exhibiting spatial correlation with the underlying crustal fluid reservoir. This geometric correspondence indicates a fluid-driven triggering mechanism that contributes to the localized seismicity. We deem that the reactivation of preexisting seismogenic faults induced by crustal fluid migration could be a possible mechanism for the nucleation of such a large intraplate earthquake.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"8 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147440205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ben Latimer, William McCarthy, Tobias Mattsson, John Reavy
Anisotropy of Magnetic Susceptibility (AMS) and Anisotropy of Magnetic Remanence (AMR) are critical petrofabric tools for investigating the evolution of volcano-magmatic, tectonic, and surface process systems. These highly sensitive techniques can distinguish multiple magnetic fabrics within individual samples, crucial in assessing archives of emplacement and deformation in granitic intrusions where magmatic and tectonic processes occur concurrently or successively. However, mineral phases that dominate AMS and AMR signals are highly susceptible to hydrothermal alteration that may overprint pre-existing petrofabrics. Despite this, the mechanisms and extent to which hydrothermal alteration modifies magnetic fabrics remain poorly understood, raising concerns about the reliability of interpretations in studies involving hydrothermally altered rocks. This study assesses the significance of magnetic fabrics preserved in a hydrothermally altered fault zone that crosscuts a granitic pluton. Data are collected from unaltered granodiorite peripheral to the fault, the fault damage zone and the fault core to assess the impact of hydrothermal alteration on magnetic fabrics associated with magmatic and tectonic processes. Our integrated magnetic and hyperspectral approach to characterizing alteration type and intensity, combined with measurement of AMS and AMR fabrics, reveal a distinctive magnetic fabric associated with hydrothermal alteration that overprints earlier magmatic and tectonic fabrics. While composite magnetic fabrics are well documented in igneous systems, fabrics that directly record hydrothermal alteration imparting a systematic, measured fabric is incredibly rare and this paves the way for further work on the tracing of fluid flow in fault zones using rock magnetic fabrics as a paleoflow indicator.
{"title":"The Significance of Magnetic Fabrics Preserved in Hydrothermally Altered Rocks","authors":"Ben Latimer, William McCarthy, Tobias Mattsson, John Reavy","doi":"10.1029/2025jb033102","DOIUrl":"https://doi.org/10.1029/2025jb033102","url":null,"abstract":"Anisotropy of Magnetic Susceptibility (AMS) and Anisotropy of Magnetic Remanence (AMR) are critical petrofabric tools for investigating the evolution of volcano-magmatic, tectonic, and surface process systems. These highly sensitive techniques can distinguish multiple magnetic fabrics within individual samples, crucial in assessing archives of emplacement and deformation in granitic intrusions where magmatic and tectonic processes occur concurrently or successively. However, mineral phases that dominate AMS and AMR signals are highly susceptible to hydrothermal alteration that may overprint pre-existing petrofabrics. Despite this, the mechanisms and extent to which hydrothermal alteration modifies magnetic fabrics remain poorly understood, raising concerns about the reliability of interpretations in studies involving hydrothermally altered rocks. This study assesses the significance of magnetic fabrics preserved in a hydrothermally altered fault zone that crosscuts a granitic pluton. Data are collected from unaltered granodiorite peripheral to the fault, the fault damage zone and the fault core to assess the impact of hydrothermal alteration on magnetic fabrics associated with magmatic and tectonic processes. Our integrated magnetic and hyperspectral approach to characterizing alteration type and intensity, combined with measurement of AMS and AMR fabrics, reveal a distinctive magnetic fabric associated with hydrothermal alteration that overprints earlier magmatic and tectonic fabrics. While composite magnetic fabrics are well documented in igneous systems, fabrics that directly record hydrothermal alteration imparting a systematic, measured fabric is incredibly rare and this paves the way for further work on the tracing of fluid flow in fault zones using rock magnetic fabrics as a paleoflow indicator.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"5 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147383994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the history of Earth rotation variations and its connection to mantle dynamics is one of the most important problems is global geophysics. However, our knowledge of these variations—in particular those induced by climate on geological timescales—is limited due to both modeling deficiencies and the scarcity of paleoclimate data. In order to advance our understanding of this problem, here we first develop a new probabilistic deep learning methodology called Physics-Informed Diffusion Model (PIDM). We then use PIDM in conjunction with the recently available paleoclimate data—specifically, sea level variations since the Late Pliocene—to precisely reconstruct the history of climate-induced changes in the Earth's rotation rate (i.e., Length of Day variations: <span data-altimg="/cms/asset/e74e8899-d1be-4d45-893f-a3b47d40740b/jgrb70212-math-0001.png"></span><mjx-container ctxtmenu_counter="10" ctxtmenu_oldtabindex="1" jax="CHTML" role="application" sre-explorer- style="font-size: 103%; position: relative;" tabindex="0"><mjx-math aria-hidden="true" location="graphic/jgrb70212-math-0001.png"><mjx-semantics><mjx-mrow><mjx-mi data-semantic-annotation="clearspeak:simple" data-semantic-font="normal" data-semantic- data-semantic-role="greekletter" data-semantic-speech="normal upper Delta" data-semantic-type="identifier"><mjx-c></mjx-c></mjx-mi></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display="inline" unselectable="on"><math altimg="urn:x-wiley:21699313:media:jgrb70212:jgrb70212-math-0001" display="inline" location="graphic/jgrb70212-math-0001.png" xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi data-semantic-="" data-semantic-annotation="clearspeak:simple" data-semantic-font="normal" data-semantic-role="greekletter" data-semantic-speech="normal upper Delta" data-semantic-type="identifier" mathvariant="normal">Δ</mi></mrow>${Delta }$</annotation></semantics></math></mjx-assistive-mml></mjx-container>LOD). We reconcile <span data-altimg="/cms/asset/39c68a83-966a-4bc0-b38b-cf199fe860d6/jgrb70212-math-0002.png"></span><mjx-container ctxtmenu_counter="11" ctxtmenu_oldtabindex="1" jax="CHTML" role="application" sre-explorer- style="font-size: 103%; position: relative;" tabindex="0"><mjx-math aria-hidden="true" location="graphic/jgrb70212-math-0002.png"><mjx-semantics><mjx-mrow><mjx-mi data-semantic-annotation="clearspeak:simple" data-semantic-font="normal" data-semantic- data-semantic-role="greekletter" data-semantic-speech="normal upper Delta" data-semantic-type="identifier"><mjx-c></mjx-c></mjx-mi></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display="inline" unselectable="on"><math altimg="urn:x-wiley:21699313:media:jgrb70212:jgrb70212-math-0002" display="inline" location="graphic/jgrb70212-math-0002.png" xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi data-semantic-="" data-semantic-annotation="clearspeak:simple" data-semantic-font="normal" data-semantic-role="greekletter" data-semantic-spe
{"title":"Climate-Induced Length of Day Variations Since the Late Pliocene","authors":"Mostafa Kiani Shahvandi, Benedikt Soja","doi":"10.1029/2025jb032161","DOIUrl":"https://doi.org/10.1029/2025jb032161","url":null,"abstract":"Understanding the history of Earth rotation variations and its connection to mantle dynamics is one of the most important problems is global geophysics. However, our knowledge of these variations—in particular those induced by climate on geological timescales—is limited due to both modeling deficiencies and the scarcity of paleoclimate data. In order to advance our understanding of this problem, here we first develop a new probabilistic deep learning methodology called Physics-Informed Diffusion Model (PIDM). We then use PIDM in conjunction with the recently available paleoclimate data—specifically, sea level variations since the Late Pliocene—to precisely reconstruct the history of climate-induced changes in the Earth's rotation rate (i.e., Length of Day variations: <span data-altimg=\"/cms/asset/e74e8899-d1be-4d45-893f-a3b47d40740b/jgrb70212-math-0001.png\"></span><mjx-container ctxtmenu_counter=\"10\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/jgrb70212-math-0001.png\"><mjx-semantics><mjx-mrow><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic- data-semantic-role=\"greekletter\" data-semantic-speech=\"normal upper Delta\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:21699313:media:jgrb70212:jgrb70212-math-0001\" display=\"inline\" location=\"graphic/jgrb70212-math-0001.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow><mi data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic-role=\"greekletter\" data-semantic-speech=\"normal upper Delta\" data-semantic-type=\"identifier\" mathvariant=\"normal\">Δ</mi></mrow>${Delta }$</annotation></semantics></math></mjx-assistive-mml></mjx-container>LOD). We reconcile <span data-altimg=\"/cms/asset/39c68a83-966a-4bc0-b38b-cf199fe860d6/jgrb70212-math-0002.png\"></span><mjx-container ctxtmenu_counter=\"11\" ctxtmenu_oldtabindex=\"1\" jax=\"CHTML\" role=\"application\" sre-explorer- style=\"font-size: 103%; position: relative;\" tabindex=\"0\"><mjx-math aria-hidden=\"true\" location=\"graphic/jgrb70212-math-0002.png\"><mjx-semantics><mjx-mrow><mjx-mi data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic- data-semantic-role=\"greekletter\" data-semantic-speech=\"normal upper Delta\" data-semantic-type=\"identifier\"><mjx-c></mjx-c></mjx-mi></mjx-mrow></mjx-semantics></mjx-math><mjx-assistive-mml display=\"inline\" unselectable=\"on\"><math altimg=\"urn:x-wiley:21699313:media:jgrb70212:jgrb70212-math-0002\" display=\"inline\" location=\"graphic/jgrb70212-math-0002.png\" xmlns=\"http://www.w3.org/1998/Math/MathML\"><semantics><mrow><mi data-semantic-=\"\" data-semantic-annotation=\"clearspeak:simple\" data-semantic-font=\"normal\" data-semantic-role=\"greekletter\" data-semantic-spe","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"69 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147440207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To understand the effect of dislocations on the velocity and attenuation of seismic waves, the anelasticity of polycrystalline samples was measured in situ during dislocation creep. We used polycrystalline borneol as a rock analog. Because the effects of grain boundary mechanism on the anelastic properties of this material are well known, dislocation effect can be detected as a deviation from them. We developed a new experimental apparatus and conducted the forced oscillation tests continuously on the sample deforming under various creep stresses ranging from diffusion to dislocation creep regimes. The testing frequency was mostly fixed at 5 Hz, but was sometimes scanned from 16 to 0.5 Hz. When the creep stress was higher than 2 MPa, the dominant deformation mechanism changed from grain boundary diffusion creep to dislocation creep. However, modulus reduction was not observed, indicating that dislocations significantly affected creep, but did not affect anelasticity. The different effects of dislocations on creep and anelasticity were explained in terms of the viscous resistance to dislocation motion.
{"title":"Effect of Dislocations on Polycrystal Anelasticity Inferred From In Situ Forced Oscillation Test","authors":"Kosuke Yabe, Yasuko Takei, Riku Sugimoto","doi":"10.1029/2025jb032220","DOIUrl":"https://doi.org/10.1029/2025jb032220","url":null,"abstract":"To understand the effect of dislocations on the velocity and attenuation of seismic waves, the anelasticity of polycrystalline samples was measured in situ during dislocation creep. We used polycrystalline borneol as a rock analog. Because the effects of grain boundary mechanism on the anelastic properties of this material are well known, dislocation effect can be detected as a deviation from them. We developed a new experimental apparatus and conducted the forced oscillation tests continuously on the sample deforming under various creep stresses ranging from diffusion to dislocation creep regimes. The testing frequency was mostly fixed at 5 Hz, but was sometimes scanned from 16 to 0.5 Hz. When the creep stress was higher than 2 MPa, the dominant deformation mechanism changed from grain boundary diffusion creep to dislocation creep. However, modulus reduction was not observed, indicating that dislocations significantly affected creep, but did not affect anelasticity. The different effects of dislocations on creep and anelasticity were explained in terms of the viscous resistance to dislocation motion.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"75 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147380637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polyethylene (PE) is the most abundant component of plastic waste. Its chemical recycling primarily relies on pyrolysis, which produces pyrolysis oils that can be catalytically upgraded into light olefins. In practice, PE is often recycled alongside polyvinyl chloride (PVC) contaminants, which are difficult to completely separate given their use in multilayer materials. Upon heating, PVC readily releases acidic hydrogen chloride, which can negatively impact chemical recycling. However, most studies have focused on the chemical recycling of pure PE, with limited attention to the effects of PVC contamination. Here, by employing a pyrolyzer–gas chromatography–mass spectrometry/ flame ionization detector/thermal conductivity detector system, we reveal that PVC contamination significantly increases char formation at the expense of pyrolysis oils—the precursors for monomer recovery. Furthermore, rapid deactivation of the ZSM-5 catalyst is observed, attributed to acidity loss caused by framework aluminum leaching. These deleterious effects are effectively mitigated through an ionic liquid–based dehydrochlorination pretreatment of feedstock, the kinetic model of which is developed.
{"title":"Influence of polyvinyl chloride contaminant on chemical recycling of polyethylene via thermal and catalytic pyrolysis","authors":"Chaoran Zhang, Zhixiang Li, Yan Cheng, Wenjie Wang, Zhongyao Zhang, Xiaohu Ge, Wenyao Chen, Gang Qian, Yueqiang Cao, Xuezhi Duan, Xinggui Zhou, Jing Zhang","doi":"10.1002/aic.70332","DOIUrl":"https://doi.org/10.1002/aic.70332","url":null,"abstract":"Polyethylene (PE) is the most abundant component of plastic waste. Its chemical recycling primarily relies on pyrolysis, which produces pyrolysis oils that can be catalytically upgraded into light olefins. In practice, PE is often recycled alongside polyvinyl chloride (PVC) contaminants, which are difficult to completely separate given their use in multilayer materials. Upon heating, PVC readily releases acidic hydrogen chloride, which can negatively impact chemical recycling. However, most studies have focused on the chemical recycling of pure PE, with limited attention to the effects of PVC contamination. Here, by employing a pyrolyzer–gas chromatography–mass spectrometry/ flame ionization detector/thermal conductivity detector system, we reveal that PVC contamination significantly increases char formation at the expense of pyrolysis oils—the precursors for monomer recovery. Furthermore, rapid deactivation of the ZSM-5 catalyst is observed, attributed to acidity loss caused by framework aluminum leaching. These deleterious effects are effectively mitigated through an ionic liquid–based dehydrochlorination pretreatment of feedstock, the kinetic model of which is developed.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"1 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147368512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. S. L. Rowan, A. P. Butler, M. C. McDonnell, J. F. Águila, R. Flynn, G. A. Hamill, S. Donohue, M. D. Jackson
Affordable and effective early warning of saline intrusion into aquifers is a key challenge affecting coastal water supplies. This paper reports on self-potential (SP) monitoring close to a mobile saline-fresh water interface over a 3-month period. SP, groundwater level, temperature and fluid electrical conductivity (FEC) were monitored in 12 boreholes, distributed over a variety of depths and distances to the high-water mark (HWM). Power Spectral Density (PSD) analysis of SP data showed a clear semi-diurnal (principal-lunar, M2) tidal component, with an amplitude of around 1 mV. The M2 magnitude linearly decreased with depth and distance from the shore. Whilst PSD analysis showed M2 components in borehole water levels, none were detected in groundwater temperature and FEC. The results suggest that SP M2 components were generated remote from the boreholes by the movement of a saline interface, most likely associated with the upper saline plume. Superimposed on these tidal signals were periodic rises and falls in mean SP of around 5–10 mV. These responses appear linked to storm surge events, during which seawater advanced beyond the monitoring boreholes, although data interpretation is complex due to salinity changes at the reference electrode. The results provide further support for the use of SP as a precursor to saline intrusion. Critically, they provide the first quantitative spatial characterization of tidal SP responses, demonstrating that the M2 signal magnitude can be predicted from electrode depth and shoreline distance (R2 = 0.96) and suggest the possibility of using multi-point SP monitoring to remotely track saline plume movement.
{"title":"Observations of Tidal Induced Responses in Self-Potential Data in a UK Beach Sand Aquifer: Implications for Monitoring Seawater Intrusion","authors":"T. S. L. Rowan, A. P. Butler, M. C. McDonnell, J. F. Águila, R. Flynn, G. A. Hamill, S. Donohue, M. D. Jackson","doi":"10.1029/2025jb033414","DOIUrl":"https://doi.org/10.1029/2025jb033414","url":null,"abstract":"Affordable and effective early warning of saline intrusion into aquifers is a key challenge affecting coastal water supplies. This paper reports on self-potential (SP) monitoring close to a mobile saline-fresh water interface over a 3-month period. SP, groundwater level, temperature and fluid electrical conductivity (FEC) were monitored in 12 boreholes, distributed over a variety of depths and distances to the high-water mark (HWM). Power Spectral Density (PSD) analysis of SP data showed a clear semi-diurnal (principal-lunar, M<sub>2</sub>) tidal component, with an amplitude of around 1 mV. The M<sub>2</sub> magnitude linearly decreased with depth and distance from the shore. Whilst PSD analysis showed M<sub>2</sub> components in borehole water levels, none were detected in groundwater temperature and FEC. The results suggest that SP M<sub>2</sub> components were generated remote from the boreholes by the movement of a saline interface, most likely associated with the upper saline plume. Superimposed on these tidal signals were periodic rises and falls in mean SP of around 5–10 mV. These responses appear linked to storm surge events, during which seawater advanced beyond the monitoring boreholes, although data interpretation is complex due to salinity changes at the reference electrode. The results provide further support for the use of SP as a precursor to saline intrusion. Critically, they provide the first quantitative spatial characterization of tidal SP responses, demonstrating that the M<sub>2</sub> signal magnitude can be predicted from electrode depth and shoreline distance (<i>R</i><sup>2</sup> = 0.96) and suggest the possibility of using multi-point SP monitoring to remotely track saline plume movement.","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"15 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2026-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147371390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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