Journal of Geophysical Research: Solid Earth最新文献

{"title":"The Influence of Variable Host Rock Cohesion and Magma Viscosity on Intrusion-Fault Interaction: Insights From Laboratory Models","authors":"Sonja H. M. Greiner,&nbsp;Olivier Galland,&nbsp;Freysteinn Sigmundsson,&nbsp;Steffi Burchardt,&nbsp;Halldór Geirsson,&nbsp;Rikke Pedersen,&nbsp;Xia Wen","doi":"10.1029/2024JB029870","DOIUrl":"https://doi.org/10.1029/2024JB029870","url":null,"abstract":"<p>Magma transport through the Earth's shallow crust can be affected by pre-existing weaknesses like faults. Consequently, fault-channeled magma may reach the surface in unexpected locations. Hence, better understanding of magma-fault interaction is needed to improve hazard assesment. We investigate the effect of host rock cohesion and magma viscosity on intrusion-fault interaction using laboratory experiments. Vegetable oil and glucose syrup, serving as low- and high-viscosity analogue magmas, were injected into intact and faulted granular materials with variable cohesion (mixtures of silica flour and micro-glass beads), serving as a brittle plastic model crust. High-cohesion models produced sheet intrusions, that propagated along fault segments upon intersection. Low-cohesion models produced low-aspect ratio intrusions low width/thickness ratio. Without tectonic stresses, the cohesion strongly controls intrusion-fault interaction, while tested model magma viscosities exerted a weaker control. Our findings show that intrusion-fault interaction is a highly complex process and important to consider at active volcanoes.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB029870","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sound Velocities of Zoisite at High Pressures and Temperatures and Implications for the Water Content in Subducting Oceanic Crust","authors":"Rui Zhang,&nbsp;Duojun Wang,&nbsp;Nao Cai","doi":"10.1029/2024JB030238","DOIUrl":"https://doi.org/10.1029/2024JB030238","url":null,"abstract":"&lt;p&gt;The &lt;i&gt;P&lt;/i&gt;- and &lt;i&gt;S&lt;/i&gt;-wave velocities of zoisite were measured simultaneously using ultrasonic techniques under pressure and temperature of up to 11 GPa and 773 K, respectively. The results indicate that the velocity of zoisite increases with increasing pressure and decreases with increasing temperature. Using finite strain fitting, values of &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;K&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;S&lt;/mi&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;129&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;mtext&gt;GPa&lt;/mtext&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${K}_{S0}=129(3)hspace*{.5em}text{GPa}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;K&lt;/mi&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;S&lt;/mi&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;′&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;4.9&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${K}_{S0}^{mathit{prime }}=4.9$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;(3), &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;G&lt;/mi&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;73&lt;/mn&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;(&lt;/mo&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;mo&gt;)&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mspace&gt;&lt;/mspace&gt;\u0000 &lt;mtext&gt;GPa&lt;/mtext&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${G}_{0}=73hspace*{.5em}(2)hspace*{.5em}text{GPa}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;G&lt;/mi&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;′&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msubsup&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 &lt;mn&gt;2.0&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${G}_{0}^{mathit{prime }}=2.0$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;(2), &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msubsup&gt;\u0000 &lt;mi&gt;G&lt;/mi&gt;\u0000 &lt;mn&gt;0&lt;/mn&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;″&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871795","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}

{"title":"Investigating the Mechanisms of Earthquake-Induced Groundwater Radon Changes in a Hot Spring-Insight From Coupled Flow Rates, Water Temperature, and Radon Observation","authors":"Wei Liu,&nbsp;Zheming Shi,&nbsp;Yunfei Bai,&nbsp;Rui Yan,&nbsp;Yuchuan Ma","doi":"10.1029/2024JB030878","DOIUrl":"https://doi.org/10.1029/2024JB030878","url":null,"abstract":"<p>Radon (²²²Rn), a radioactive inert gas commonly found in the earth's crust, is sensitive to crustal strain. Radon monitoring is widely recognized as an effective method for earthquake precursor detection. However, the underlying physical mechanisms responsible for these anomalies have not been investigated quantitatively. Thus, in this study, changes in radon concentration were systematically analyzed by integrating flow rates and water temperature data from the Banglazhang #1 hot spring in Yunnan, China, following the 1996 Lijiang Mw 7.0 earthquake and the 2004 Sumatra Mw 9.1 earthquake, both of which induced significant hydrological responses. Our analysis demonstrated that meteorological factors were not the primary drivers of radon concentration changes. The change in the mixing ratio from different depths of water was identified as the primary mechanism driving radon concentration changes following the Lijiang earthquake. Furthermore, the release of radon from particle movement, along with the change in the mixing ratio after the earthquake, might explain the co-seismic response following the Sumatra earthquake. The water–rock interaction surface area increased from about 7 × 10⁴ m² to 1.85 × 10⁵ m² following the Sumatra earthquake. Our study showed that coupling of flow rates, water temperature, and radon could provide a robust explanation of the earthquake-induced hydrological response. Thus, monitoring multiple parameters is essential for accurately and promptly detecting earthquake-related signals.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871796","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}

{"title":"Extent and Mechanisms of the North China Craton Lithospheric Destruction Revealed by Multi-Geophysical Inversions","authors":"Anqi Zhang,&nbsp;Risheng Chu,&nbsp;Pengxiang Zhou,&nbsp;Chunquan Yu,&nbsp;Yingjie Yang","doi":"10.1029/2025JB031104","DOIUrl":"https://doi.org/10.1029/2025JB031104","url":null,"abstract":"<p>The North China Craton (NCC) has undergone significant destruction, yet the spatial extent and underlying mechanisms of the destruction remain subjects of debate. In this study, we conduct a joint inversion by integrating multiple geophysical data sets to establish an unprecedented large-scale compositional structure of the NCC lithospheric mantle. By incorporating lithospheric thickness constrained by thermal state, we provide a comprehensive assessment of the spatial extent and intensity of NCC destruction. Our results reveal significant variations in lithospheric thickness and mantle composition across the NCC and delineate a boundary marking the extent of its destruction. West of this boundary, including the core of the Ordos block, the lithosphere exhibits refractory characteristics and a thick lithospheric root, maintaining craton stability. In contrast, east of the boundary, including the Eastern NCC (ENCC), most of the Trans-North China Orogen (TNCO), and the northeastern part of the Western NCC (WNCC), the lithosphere shows signs of extensive modification. The ENCC features a refertilized lithospheric mantle and thin lithosphere, reflecting extensive reworking likely driven by large-scale lithospheric delamination during the Mesozoic. The TNCO and northeastern WNCC display localized mantle refertilization and high-degree partial melting in the asthenosphere, suggesting ongoing thermal erosions, likely driven by the influence of the Pacific slab's leading edge or its rollback. We propose that Cenozoic thermal erosion has extended the destruction of the NCC farther west than previously anticipated. This study identifies regions of significant lithospheric thinning and mantle compositional modification, improving our understanding of the NCC destruction and its evolving mechanisms.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143871794","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}

{"title":"Remagnetization of Serpentinite During Deformation: Evidence From a Fossil Oceanic Transform Fault Zone of the Troodos Ophiolite","authors":"Liang Qi,&nbsp;Simon Allerton,&nbsp;Adrian R. Muxworthy,&nbsp;Yong Zhang,&nbsp;Hristo Gergov","doi":"10.1029/2024JB030790","DOIUrl":"https://doi.org/10.1029/2024JB030790","url":null,"abstract":"<p>Serpentinization and associated chemical remagnetization of ultramafic rocks are common in tectonically active oceanic zones such as transform zones; however, it remains unclear how chemical remagnetization occurs during the deformation of serpentinite. This study aims to discuss this magnetization process with evidence from a serpentinite shear zone within the fossil transform fault of the Troodos ophiolite. We examine how serpentinite microstructures, serpentine polytypes, iron behaviors, rock magnetic properties and paleomagnetic directions evolve with increasing shearing deformation—a process that provides pathways for serpentinization fluid circulation. As serpentinite deformation increases from massive-fractured serpentinite adjacent to the shear zone to scaly and phyllonitic serpentinites within the shear zone, rock microstructure changes from unoriented mesh textures to oriented ribbon and fibrous structures. Meanwhile, the dominant serpentine mineral shifts from lizardite to chrysotile, indicating dynamic recrystallization during increasing deformation, likely resulting from elevated water/rock ratios driven by hydrothermal circulation. Rock magnetic results suggest that highly deformed scaly and phyllonitic serpentinites contain coarser magnetite grains and higher magnetite concentration compared to the less deformed massive-fractured serpentinites. These coarser magnetite grains are also attributed to higher water/rock ratios within the shear zone. More magnetite forms due to the iron released from the replacement of iron-rich lizardite by iron-poor chrysotile. The formation of magnetite records remagnetization, which helps reconstruct the deformation history of tectonically active zones. For example, paleomagnetic directions of the differentially deformed serpentinites in Troodos ophiolite indicate clockwise block rotations of up to 90°, providing evidence for dextral slip along a fossil transform fault.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030790","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Shallow Lingering and Deep Transient Seismicity Related to Hydraulic Fracturing in the Changning Shale Gas Field, Sichuan Basin, China","authors":"Jian Xu,&nbsp;Junlun Li,&nbsp;Wen Yang,&nbsp;Guoyi Chen,&nbsp;Yajing Liu,&nbsp;Alessandro Verdecchia,&nbsp;Rebecca M. Harrington,&nbsp;Renqi Lu,&nbsp;Yuyang Tan,&nbsp;Yapei Ye,&nbsp;Jizhou Tang","doi":"10.1029/2024JB030279","DOIUrl":"https://doi.org/10.1029/2024JB030279","url":null,"abstract":"<p>Characterizing seismic responses to hydraulic fracturing (HF) in shale-gas development is crucial for seismic-hazard assessment and mitigation-strategy design. Although intensive HF operations have led to severe induced seismic hazards in the Changning shale gas field (CSF) in China for over a decade, the typical spatiotemporal characteristics of induced seismicity during and after HF in this region remain unclear, due to a lack of detailed fluid-injection data. Using a 70-day-long dense deployment of 336 nodal-sensors in 2019, we develop an enhanced seismicity catalog and combine it with focal mechanism solutions, fluid-injection time series, seismic-reflection profiles, and geomechanical models to identify the distinct shallow and deep seismicity responses to HF. The first pattern consists of deep earthquake clusters that migrate along strike-slip faults in the limestone formation ∼1 km below the treatment depth. These clusters contain frequent <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>L</mi>\u0000 </msub>\u0000 <mo>&gt;</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation> ${M}_{mathrm{L}} &gt; 2$</annotation>\u0000 </semantics></math> earthquakes, including the largest <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>M</mi>\u0000 <mi>L</mi>\u0000 </msub>\u0000 <mn>3.3</mn>\u0000 </mrow>\u0000 <annotation> ${M}_{mathrm{L}}3.3$</annotation>\u0000 </semantics></math> event, and exhibit transient seismicity-rate changes in rapid response to HF. In contrast, the second pattern consists of shallow clusters in the target shale formation that persist for over a year following HF. The shallow clusters include smaller earthquakes and exhibit thrust-style faulting with no discernible spatial migration. Our geomechanical simulations suggest the deep fault reactivation is best explained by the combined effects of poroelastic-stress loading and pore-pressure increases. Stable seismicity rate and frequent casing deformation indicate post-HF, long-term aseismic deformation may drive the shallow seismicity. These distinct seismic responses during and after HF operations underscore the need for a spatiotemporally adaptive hazard mitigation strategy for the CSF.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865939","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}

{"title":"Laboratory Measurement of Sonic (1–20 kHz) P-Wave Velocity and Attenuation During Melting of Ice-Bearing Sand","authors":"Hanif S. Sutiyoso,&nbsp;Sourav K. Sahoo,&nbsp;Laurence J. North,&nbsp;Ismael Himar Falcon-Suarez,&nbsp;Timothy A. Minshull,&nbsp;Angus I. Best","doi":"10.1029/2024JB030465","DOIUrl":"https://doi.org/10.1029/2024JB030465","url":null,"abstract":"<p>We measured the acoustic properties of ice-bearing sand packs in the laboratory using an acoustic pulse tube within the frequency range of 1–20 kHz, similar to sonic well-logs. We analyzed how wave velocity and attenuation (the inverse of quality factor) change with ice saturation and measurement frequency during melting. We found strong frequency-dependent correlations for both acoustic parameters with ice saturation. For any frequency within the studied range, velocity decreases and attenuation increases as the ice melts. For lower ice saturations (<i>S</i>_<i>i</i> &lt; ∼0.5), attenuation was particularly sensitive to frequency linked to acoustic wave scattering from patchy ice saturation. We used rock physics models with three-phase approaches to assess our experimental results. The comparison highlights the influence of ice formation distribution (i.e., uniform vs. patchy), permeability, and gas content on both velocity and attenuation. Our results pave the way for monitoring ice saturation from sonic measurements, as ice saturation has contrasting effects on velocity and attenuation, and the effects vary with frequency. Overall, this research contributes to a better understanding of the acoustic response of ice-bearing sediments and provides valuable insights for various applications, including permafrost monitoring and natural gas hydrate dissociation studies.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030465","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of Hydrothermal Alteration and Microcracks on Hydraulic Properties and Poroelastic Deformation: A Case Study of the Blue Mountain Geothermal Field","authors":"Valerian Schuster,&nbsp;Erik Rybacki,&nbsp;Anja M. Schleicher,&nbsp;Roshan Koirala,&nbsp;Thomas H. W. Göbel","doi":"10.1029/2024JB030541","DOIUrl":"https://doi.org/10.1029/2024JB030541","url":null,"abstract":"<p>Geothermal energy plays a vital role in decarbonizing electricity and heat supply. Effective utilization of geothermal resources hinges on identifying or generating permeable reservoir zones and understanding how effective pressure variations affect fluid circulation and reservoir properties by poroelastic deformation. Hydrothermal alteration can modify the petrophysical properties of geothermal reservoir rocks, which may increase or decrease its productivity. Understanding these alteration effects is essential to predict and optimize long-term sustainable geothermal operations. Here, we investigate the impact of hydrothermal alteration on poroelastic and hydraulic properties of diverse lithologies in a series of deformation tests performed at several confining (0–80 MPa) and pore pressure (10–30 MPa) levels. Experimental results of hydrothermally altered dikes and phyllites obtained from the Blue Mountain geothermal field (Nevada, USA) are compared to thermally cracked La Peyratte granite (France) and correlated with petrophysical properties, mineral composition, and microstructures. Argillic alteration of dikes increases porosity and storage capacity but lowers thermal conductivity and increases pore compressibility. Conversely, silicate precipitation in phyllites increases stiffness and thermal conductivity but also reduces porosity and permeability. Experimentally determined effective pressure coefficients range from 0.1 to 0.9, differ for permeability and volumetric strain and decrease with increasing effective pressure. The presence of compliant microcracks and crack-like pores significantly increases the stress sensitivity of La Peyratte granite and silicified phyllites. This study demonstrates how thermal and chemical alteration impacts poromechanical and petrophysical characteristics of geothermal targets, which ultimately govern reservoir stability and subsidence, induced seismicity as well as fluid and heat extraction efficiency during geothermal operations.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030541","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Subducted Slab Slipping Underneath the Northern Edge of the Pacific Large Low-Shear-Velocity Province in D″","authors":"Keisuke Otsuru,&nbsp;Kenji Kawai,&nbsp;Robert J. Geller","doi":"10.1029/2024JB030654","DOIUrl":"https://doi.org/10.1029/2024JB030654","url":null,"abstract":"<p>We conduct waveform inversion for the 3-D seismic shear wave (S-wave) velocity structure in the lowermost mantle near the northern edge of the Pacific large low-shear-velocity province (LLSVP). We image a slab-like high-velocity anomaly slipping beneath the Pacific LLSVP in the lowermost 200 km of the mantle, extending toward an ultra-low velocity zone (ULVZ) beneath a point about 2,000 km southwest of Hawaii. Another strong low-velocity anomaly exists along the edge of the LLSVP just above the slab-like sheet, 50–200 km above the core-mantle boundary (CMB). These results suggest in general that (a) slabs can gather ULVZ materials scattered on the CMB and push them into LLSVPs, creating concentrated ULVZs near LLSVP edges, (b) slabs can uplift hot material from the CMB to create strong anomalies along the edges of LLSVPs, and (c) large seismic-wave velocity contrasts between strong low-velocity anomalies and slabs create sharp LLSVP boundaries.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030654","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetization of Ultramafic Rocks in the Troodos Ophiolite: Implications for Ridge Axis Serpentinization and Ophiolite Emplacement","authors":"Liang Qi,&nbsp;Adrian R. Muxworthy,&nbsp;Jenny S. Collier,&nbsp;Simon Allerton","doi":"10.1029/2024JB030452","DOIUrl":"https://doi.org/10.1029/2024JB030452","url":null,"abstract":"<p>Ultramafic rocks exposed in ophiolites are almost always serpentinized, but it is unclear whether the serpentinization occurs during lithospheric formation or subsequent ophiolite emplacement. The Troodos ophiolite offers an opportunity to discriminate between different serpentinization processes, incorporating rock magnetism, paleomagnetism and forward modeling of field magnetic data. Our results revealed distinct magnetic property zones: weakly magnetic mantle Artemis and Olympus zones, and a highly magnetic lower crust Cumulate zone. The Artemis and Olympus samples have magnetite concentrations &lt;1%, magnetic susceptibility &lt;0.01 SI and natural remanent magnetization (NRM) &lt;4 A/m, consistent with low-temperature serpentinization related to subduction or meteoric water. In contrast, the Cumulate zone rocks have magnetite content up to 8%, magnetic susceptibility up to 0.1 SI and NRM up to 12 A/m, interpreted as high-temperature serpentinite near a spreading ridge. This ridge-related serpentinization is supported by the paleomagnetic results. The Cumulate zone has a mean direction of <i>declination</i> = 280°, <i>inclination</i> = 69°, <i>α</i>₉₅ = 16°, comparable to the direction of the lower crust gabbro, which suggests serpentinization-associated chemical remagnetization during Cretaceous oceanic crust formation. Existing geological, gravity and seismic studies indicate a Pliocene subduction-related serpentinization event which led to the diapir uplift and surface relief of the Artemis and Olympus zones. Ongoing meteoric water-related serpentinization following the exposure of ultramafic rocks has caused surface remagnetization of the Artemis and Olympus zones in the current field.</p>","PeriodicalId":15864,"journal":{"name":"Journal of Geophysical Research: Solid Earth","volume":"130 4","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JB030452","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143861790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}