Journal of Geophysical Research: Solid Earth最新文献

Salt's inherent weakness and capacity for ductile deformation create significant mechanical contrasts that locally perturb the stress field in surrounding rocks, often leading to deviations from regional tectonic stresses. Variations in local stress are a critical factor for wellbore stability, seal integrity, and fluid flow in subsurface energy and storage applications. This study investigates paleo stress variations through fracture analysis along the deformed margin of the exhumed Salt Valley salt wall near Arches National Park (Paradox Basin, Utah), where regional tectonic compression drove salt wall amplification and folding and fracturing of the overlying strata. New field and unmanned aerial vehicle fracture data, when integrated with prior fracture-based studies in the region, suggest a two-phase deformation history: early, kinematically consistent shear fractures (salt wall amplification-related), predating later joints (salt dissolution and collapse-related). Our primary focus is understanding the patterns within the early shear fracture system. We applied a computationally efficient elastic dislocation (ED) modeling approach, constrained by a 3D structural framework model derived from restored cross sections, to simulate the stress response to salt wall amplification under tectonic compression. Both observed and modeled results demonstrate spatially variable local stress states: an extensional regime (vertical maximum stress) above the salt wall roof transitions to a strike-slip regime (horizontal maximum stress) near the underlying vertical salt wall margin. This consistency substantiates the ED modeling approach for interpreting complex stress states adjacent to salt, offering a valuable tool for refining subsurface structural and geotechnical interpretations without explicitly modeling salt rheology.

Eastern China has undergone significant intracontinental extension and intraplate magmatism since the Cenozoic, but related geodynamic mechanisms remain controversial. Here we use calculations of Residual Topography (RT) and Dynamic Topography (DT) as diagnostic indicators of active mantle flow in the region. The latest crustal structure is adopted to calculate new RT estimates, and 3D spherical mantle convection experiments based on a high-resolution seismic velocity model are constructed to estimate the DT across Eastern China. Comparative analyses reveal several insights: (a) RT and DT are correlated at medium wavelength, showing a low-west and high-east pattern. High positive values dominate Northeastern China, Cathaysia Block, and the South China Sea (SCS), whereas low negative values concentrate in the Ordos, Sichuan, and Songliao basins; (b) Positive DT in Northeastern China correlates with Quaternary intraplate volcanism, linked to mantle upwelling induced by the Pacific Plate subduction. Conversely, negative DT in Songliao Basin and Eastern North China Block (ENCB) reflects mantle downwelling associated with lithospheric delamination; (c) The stable Ordos and Sichuan basins display pronounced negative RT and DT, indicative of dense cratonic roots, while the elevated topography in the ENCB and Cathaysia Block is driven by mantle upwelling from the Pacific-Philippine plate subduction; (d) High positive RT and DT in the SCS correspond to widespread recent magmatism, primarily fueled by large-scale mantle upwelling beneath the SCS. The findings suggest that mantle convection caused by surrounding subduction systems plays a significant role in Cenozoic intraplate volcanism and lithospheric evolution in Eastern China.

The eastern margin of Eurasia records complex tectonic events from its interaction with the Paleo-Asian, Mongol-Okhotsk, and Paleo-Pacific Ocean plates during the late Paleozoic to early Mesozoic. However, the subduction histories remain controversial. We employed detrital zircon U-Pb geochronology and trace element analyses to investigate the provenance of strata of this age within the Jiamusi Massif of NE China. To mitigate age bias from variations in zircon fertility, we compiled zirconium concentrations from 338 granitoid samples across the massif, grouped into four categories: Neoproterozoic (996–722 Ma), early Paleozoic (538–446 Ma), late Paleozoic-early Mesozoic (338–209 Ma), and Cretaceous (112–92 Ma). Applying the zircon fertility factors (ZFFs) revealed no difference between the early Paleozoic and late Paleozoic-early Mesozoic suites, which we combined, resulting in values of 1.58, 1.45, and 1.0, respectively. After correcting detrital zircon age spectra using these ZFFs, a sediment provenance shift was evident from active magmatic arcs along the eastern margin of the Jiamusi Massif during the early Permian, to collisional orogenesis between the Jiamusi and Songliao massifs in the Late Triassic along the western margin. Integration with regional tectonic data defines a transition in geodynamics from subduction of the Mongol-Okhotsk Ocean in the early Permian to combined subduction and collision related to the Paleo-Pacific domain in the Late Triassic. This study improves the accuracy of interpreting provenance evolution through multi-dimensional provenance analysis using ZFF correction procedures and offers a reproducible methodology for refining tectonic reconstructions of accretionary orogens and other tectonically complex regions worldwide.

Silicate melts play a crucial role in planetary differentiation. The density contrast between silicate melts and the surrounding solid residue exerts a primary control on many magmatic processes. However, direct measurements of the density of silicate melts at high pressure (P) and temperature (T) conditions remain challenging, particularly for the highly viscous and reactive silica- and alkali-rich melts. Here we determined the high P-T densities of three sodium aluminosilicate melts with nepheline (NaAlSiO₄), jadeite (NaAlSi₂O₆), and albite (NaAlSi₃O₈) compositions, using the high-P X-ray microtomography technique up to 4.1 GPa and 2020 K. Our results suggest that the substitution of (NaAl)⁴⁺ for Si⁴⁺ along the NaAlSiO₄-NaAlSi₃O₈ join leads to higher melt density and lower melt compressibility. In addition, our new data, combined with a wide range of literature data, were employed to re-calibrate a modified hard-sphere equation of state (HS-EOS) for silicate melts, which provides a unified framework for calculating the density and other compressional properties of multi-component silicate melts in the CaO-MgO-Al₂O₃-SiO₂-FeO-Na₂O-K₂O (CMASFNK) system up to ∼25 GPa. The calibration also reveals that SiO₂, alkalis, and CaO are the major components contributing to the compositional dependence of melt elastic properties. The HS-EOS was then applied to alkali basaltic melts at cratonic mantle conditions and silica- and alkali-rich melts at early planetesimal melting conditions, with implications for the gravitational stability and extraction of melts in Earth's mantle and planetesimal settings.

Monterey Canyon, one of the most representative submarine canyons worldwide, remains debated for its evolutionary history due to limited observational coverage and imaging resolution in a complex marine setting. Here we present an advanced seismic velocity model with adaptive resolution, extending around 20 km seaward from the head of Monterey Canyon across the continental shelf to a depth of 1.5 km. This model is constructed using a novel multi-scale ambient noise imaging framework that integrates cross-scale distributed acoustic sensing observations from submarine fiber-optic cable with adaptive shear-wave velocity inversion based on Voronoi tessellation. Our results reveal low velocity zones at multiple spatial scales—from shallow anomalies near 0.1 km to deeper structures approaching 1.5 km—that define nested paleocanyon geometries, including deeply incised sediment pathways overprinted by younger fault-guided conduits. By incorporating existing geophysical observations and canyon evolution models, we suggest that these paleocanyons record a multi-phase evolutionary process: initially conditioned by deep-seated tectonic activity, subsequently reshaped by climate-modulated surface dynamics, and ultimately preserved by successive episodes of sediment transports and fault activities. This work offers new insights into landscape evolution at active continental margins and enables deeper understanding of Earth's multi-layered response to climatic and tectonic forcing. It also underscores the transformative potential of repurposing submarine telecommunication cables as dense, long-term seismic arrays—paving the way for a new era in marine geoscience.

In this study, we demonstrate that it is possible to fit the resilience at the high temperature limit using only the atomic mean square displacement determined from cryogenic temperature single crystal diffraction data. Our method introduces the Debye phonon model, under which the atomic mean square displacement displays quantum behavior at cryogenic temperatures and deviates from a linear temperature dependence. From the resilience of Si extrapolated from cryogenic temperature X-ray diffraction data, one can calculate the Si isotope fractionation using our recently developed force constants approach. We applied our method to epidote and coesite, which are common minerals in ultra-high pressure metamorphic rocks, and our predicted Si isotope fractionation lnα_Si30/28 are consistent with mass spectroscopy observations of Δ³⁰Si in Dabie eclogite and Alps whiteschist. Our results indicate that the geofluid involved in the fluid-rock interaction in Dabie and Alps orogens doesn't significantly alter the Si-isotope composition of ultrahigh pressure metamorphism. Our manuscript presents a novel experimental methodology to determine the high-temperature resilience and equilibrium isotope fractionation factors of silicon in minerals, which can be applied to the metastable upper mantle silicates that are non-quenchable at high temperatures and room pressure.

Mantle convection causes the most important contribution to the geoid and dynamic topography. With mantle density inferred from high-resolution tomography models and numerical methods solving the governing equations of viscous mantle flow, the modeled geoid can fit the observations well. However, there is still a large discrepancy between present dynamic topography predicted by mantle flow and residual topography deduced from observations: Especially, large negative topography is predicted in cratons, contrary to observations. In order to improve the fit of model dynamic topography compared to observations, in this study, we include chemical density anomalies in Earth's lithosphere to model geoid and dynamic topography. We also combine these anomalies with lateral viscosity variations and study the effect on predicted dynamic topography and geoid and investigate which density models would yield a good fit. In the sublithospheric mantle, under the assumption that the density anomalies are induced from temperature variations, we use temperature-dependent viscosity. Our results show that by adding chemical density anomalies in the continental lithosphere, we can improve the correlation between dynamic topography and residual topography by 37%–59% for the three tomography models compared with one of the residual tomography models considered (RT1) and 1%–11% compared with the other (RT2). Similarly, correlation can also be improved and amplitude ratio brought closer to 1 by downscaling lithospheric density anomalies. Our results could provide a good reference for further studies of the Earth's mantle.

The Mont Blanc granite, as other deformed granites, has splitting properties attributed to two perpendicular planes: one formed by aligned fractures and the other by aligned micas in foliation planes. It is shown that this microstructure results from ductile deformation with stress-driven dissolution of quartz and feldspar that passively concentrates insoluble micas, the dissolved minerals being reprecipitated in perpendicular fractures. Here we perform quantitative analyses of finite strain to show that this deformation involved horizontal shortening (17%–24%) and vertical stretching (21%–32%) that developed in a closed mass transfer system at centimeter to decimeter scale. A viscous creep model is proposed that relates strain rate, stress, and other parameters of deformation. While precise time evolution cannot be modeled due to the lack of the detailed openings and sealing of the fractures, a global steady-state deformation is proposed that leads to the building of creep law deformation mechanism maps. The measured characteristic fracture spacing (∼600 μm) is compatible with low diffusive mass transfer rate (1.5 10⁻²⁰ m³/s) and low differential stress values (2–3 MPa), which are also compatible with subcritical fracture propagation (2.6–3.7 MPa for characteristic lengths of 1–0.5 cm, respectively). This ductile deformation likely developed in the Mont Blanc massif from its uplift (∼22 Ma) up to main shear zones development (∼18–14 Ma), possibly influencing the shear zones geometry. Fracture-assisted pressure solution creep may be the main mechanism of ductile deformation of granitoids or gneisses with splitting properties, associating dissolution-foliation bands perpendicular to sealed fractures.

What happens when subduction stops is a key, but poorly understood, part of the tectonic cycle. Northern Borneo (Sabah) with a complex geological history of multiple episodes of subduction, magmatism, uplift, subsidence, and extension since the Mesozoic, is an ideal location for studying post-subduction processes. Major events in this region include subduction of the proto-South China Sea beneath Sabah, terminating ∼21 Ma; postulated subduction of the Celebes Sea plate, terminating ∼9 Ma; extension in central Sabah ∼9–10 Ma; rapid emplacement and exhumation of a granite intrusion ∼7 Ma; and the development of a fold-thrust belt offshore during the last 5 Myr. While these events have left imprints in the surface rock record, it has not been possible, until recently, to investigate deeper lithospheric processes. The installation of 46 broadband seismometers–the northern Borneo Orogeny Seismic Survey (nBOSS)–between 2018 and 2020 means we can now constrain the architecture of the crust and uppermost mantle beneath Sabah. We use two years of passive seismic data recorded by the nBOSS network, and 24 Malaysian Meteorological Service broadband seismometers to calculate P-wave receiver functions. We then jointly invert these with surface wave data to obtain shear velocity models of crustal structure. The thickest crust (60 km) occurs beneath the Crocker Range, while the thinnest crust (24 km) is found in central Sabah, potentially recording Miocene extension. The crust beneath Mt Kinabalu (4,095 m) is also comparatively thin. Distinct, low-velocity, dipping anomalies identified in models provide clear evidence for under thrusting of Dangerous Grounds continental crust following subduction and collision.