Solid Earth最新文献

{"title":"Driven magmatism and crustal thinning of coastal South China in response to subduction","authors":"Jinbao Su, Wenbin Zhu, Guangwei Li","doi":"10.5194/egusphere-2024-1264","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1264","url":null,"abstract":"<strong>Abstract.</strong> The late Mesozoic igneous rocks along the coastal South China Block (SCB) exhibit complex parental sources involving a depleted mantle, subducted sediment-derived melt, and melted crust. This period aligns with the magmatic flareup and lull in the SCB, debating with the compression or extension in coastal region. Our study employs numerical models to investigate the dynamics of the ascent of underplating magma along the Changle-Nan’ao Belt (CNB), simulating its intrusion and cooling processes while disregarding the formational background. The rheological structure of the lithospheric mantle significantly influences magma pathways, dictating the distribution of magmatism. This work reveals that the ascent of magma in the presence of faults is considerably faster than that in the absence of faults, and contemporaneous magmatic melts could produce different cooling and diagenetic processes. Additionally, the influence of pre-existing magma accelerates underplating magma emplacement. The ascending of magma forms a mush-like head, contributing to magmatic circulation beneath the crust and decreasing crustal thickness. Multiphase magmatism increases the geothermal gradient, reducing the lithospheric viscosity and promoting underplating magma ascent, leading to magmatic flare-ups and lulls. Our findings suggest that the Cretaceous magmatism at different times in the coastal SCB may be associated with the effects of lithospheric faults under similar subduction conditions. Boundary compression forces delay magma ascent, while rising magma induces a significant circulation, decreasing the crustal thickness of the coastal SCB. This study provides new insights into the complex interplay of magmatic processes during subduction, emphasizing the role of lithospheric structure in shaping the temporal and spatial evolution of coastal magmatism.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"304 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140939587","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":"The influence of viscous slab rheology on numerical models of subduction","authors":"Natalie Hummel, Susanne Buiter, Zoltán Erdős","doi":"10.5194/se-15-567-2024","DOIUrl":"https://doi.org/10.5194/se-15-567-2024","url":null,"abstract":"Abstract. Numerical models of subduction commonly use diffusion and dislocation creep laws from laboratory deformation experiments to determine the rheology of the lithosphere. The specific implementation of these laws varies from study to study, and the impacts of this variation on model behavior have not been thoroughly explored. We run simplified 2D numerical models of free subduction in SULEC, with viscoplastic slabs following (1) a diffusion creep law, (2) a dislocation creep law, and (3) both simultaneously, as well as several variations of model 3 with reduced resistance to bending. We compare the results of these models to a model with a constant-viscosity slab to determine the impact of the implementation of different lithospheric flow laws on subduction dynamics. In creep-governed models, higher subduction velocity causes a longer effective slab length, increasing slab pull and asthenospheric drag, which, in turn, affect subduction velocity. Numerical and analogue models implementing constant-viscosity slabs lack this feedback but still capture morphological patterns observed in more complex models. Dislocation creep is the primary deformation mechanism throughout the subducting lithosphere in our models. However, both diffusion creep and dislocation creep predict very high viscosities in the cold core of the slab. At the trench, the effective viscosity is lowered by plastic failure, rendering effective slab thickness the primary control on bending resistance and subduction velocity. However, at depth, plastic failure is not active, and the viscosity cap is reached in significant portions of the slab. The resulting high slab stiffness causes the subducting plate to curl under itself at the mantle transition zone, affecting patterns in subduction velocity, slab dip, and trench migration over time. Peierls creep and localized grain size reduction likely limit the stress and viscosity in the cores of real slabs. Numerical models implementing only power-law creep and neglecting Peierls creep are likely to overestimate the stiffness of subducting lithosphere, which may impact model results in a variety of respects.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"23 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887666","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":"Origin of the Bohai Sea, North China Craton and implication for bi-directional back-arc extension in East Asia continental margin","authors":"Alan Chen, Xuanhua Chen","doi":"10.5194/egusphere-2024-1263","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1263","url":null,"abstract":"<strong>Abstract.</strong> The Bohai Sea in eastern China is located in the back-arc extensional regime due to westward subduction of the Pacific Plate underneath the Eurasian Plate. It is one of the regions with frequent earthquakes. Previous recognition of the origin of the Bohai Sea was limited by the understanding of back-arc extensional mode perpendicular to the subduction zone in eastern Asian continental margin. In this paper, a new model for the genesis of the Bohai Sea is proposed, based on the construction of major fault system and investigation of several main boundaries enclosing the Bohai Sea. Through field investigation and analyses of tectonic landforms and boundary faults on the northwest coast of the Bohai Sea and eastern and western margins of the Liaodong Peninsula, and geological correlation of the Liaodong and Jiaodong Peninsulas and surrounding areas, we revealed a left-lateral strike-slip fault between the northwest coast of the Liaodong Bay and western margin of the Liaodong Peninsula, and proposed a right-lateral strike-slip fault between the eastern margin of the Liaodong Peninsula and northwestern margin of the Jiaodong Peninsula. This mode of movement may have been resulted from the NE stretching which is parallel to the subduction zone in northwestern Pacific margin. Therefore, we suggest that the formation of the Bohai Sea is resulted from the superimposition of the NE extension parallel to the subduction zone on the NW extension perpendicular to the subduction zone. We speculate that the two-direction extension perpendicular and parallel to the subduction zone should be the basic pattern of the back-arc extension with spherical-geometric effect.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"40 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140887717","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":"Uplift and denudation history of the Ellsworth Mountains: insights from low-temperature thermochronology","authors":"Joaquín Bastías-Silva, David Chew, Fernando Poblete, Paula Castillo, William Guenthner, Anne Grunow, Ian W. D. Dalziel, Airton N. C. Dias, Cristóbal Ramírez de Arellano, Rodrigo Fernandez","doi":"10.5194/se-15-555-2024","DOIUrl":"https://doi.org/10.5194/se-15-555-2024","url":null,"abstract":"Abstract. While thermochronological studies have constrained the landscape evolution of several of the crustal blocks of West and East Antarctica, the tectono-thermal evolution of the Ellsworth Mountains remains relatively poorly constrained. These mountains are among the crustal blocks that comprise West Antarctica and exhibit an exceptionally well-preserved Palaeozoic sedimentary sequence. Despite the seminal contribution of Fitzgerald and Stump (1991), who suggested an Early Cretaceous uplift event for the Ellsworth Mountains, further thermochronological studies are required to improve the current understanding of the landscape evolution of this mountain chain. We present new zircon (U–Th) / He (ZHe) ages, which provide insights into the landscape evolution of the Ellsworth Mountains. The ZHe ages collected from near the base and the top of the sequence suggest that these rocks underwent burial reheating after deposition. A cooling event is recorded during the Jurassic–Early Cretaceous, which we interpret as representing exhumation in response to rock uplift of the Ellsworth Mountains. Moreover, our results show that while ZHe ages at the base of the sequence are fully reset, towards the top ZHe ages are partially reset. Uplift and exhumation of the Ellsworth Mountains during the Jurassic–Early Cretaceous was contemporaneous with the rotation and translation of this crustal block with respect to East Antarctica and possibly the Antarctic Peninsula. Furthermore, this period is characterized by widespread extension associated with the disassembly and breakup of Gondwana, with the Ellsworth Mountains playing a key role in the opening of the far southern Atlantic. Based on these results, we suggest that uplift of the Ellsworth Mountains during the disassembly of Gondwana provides additional evidence for major rearrangement of the crustal blocks between the South American, African, Australian and Antarctic plates. Finally, uplift of the Ellsworth Mountains commenced during the Jurassic, which predates the Early Cretaceous uplift of the Transantarctic Mountains. We suggest that the rift-related exhumation of the Ellsworth Mountains occurred throughout two events: (i) a Jurassic uplift associated with the disassembly of southwestern Gondwana and (ii) an Early Cretaceous uplift related with the separation between Antarctica and Australia, which is also recorded in the Transantarctic Mountains.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"69 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140839588","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":"Transpressional tectonics during the Variscan-Alpine cycle transition: supporting a multi-rifting model, evidence from the European western Southern Alps","authors":"Emanuele Scaramuzzo, Franz A. Livio, Maria Giuditta Fellin, Colin Maden","doi":"10.5194/egusphere-2024-1135","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1135","url":null,"abstract":"<strong>Abstract.</strong> We delve into the transition between the Paleozoic Variscan cycle and the Meso-Cenozoic Alpine supercontinent cycle, both of which have played a pivotal role in shaping the central European-Mediterranean plate’s architecture. Our focus is on the European western Southern Alps (Varese Area, N Italy), where we documented the tectonic events occurred during this transition. Two main scenarios have been proposed so far for this transition: i) a single, long-lasting, Permo-Triassic rifting event, culminating in the opening of the Alpine Tethys, or ii) multiple, distinct rifting events, preceding the onset of the Alpine cycle. By means of a tectono-stratigraphic and thermochronological approach, we recognized a first early Permian rifting stage associated with magmatic activity, followed during the early-middle Permian by transpressive tectonics and regional-scale erosion that signal the end of the first cycle of crustal rifting. During the Middle Triassic, a second event initiated, which, we propose, marks the onset of the Alpine Tethys opening. This event could represent the stretching phase, which predates the well documented Upper Triassic crustal-thinning phase. Based on our findings, we propose that the Middle Triassic stretching phase represents the first stage of the Alpine Tethys rifting, thereby rejecting the hypothesis of a continuous Permo-Triassic long-lasting phase of extension.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"42 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140808781","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":"Popigai and Chicxulub craters: multiple impacts and their associated grabens","authors":"Jaroslav Klokocnik, Vaclav Cilek, Jan Kostelecky, Ales Bezdek","doi":"10.5194/egusphere-2024-866","DOIUrl":"https://doi.org/10.5194/egusphere-2024-866","url":null,"abstract":"<strong>Abstract.</strong> More advanced data (gravity field model EIGEN 6C4 with GOCE gradiometry data instead of EGM2008) and more sophisticated method (using a set of the gravity aspects instead of the gravity anomalies and the radial second derivative of the disturbing potential only) enable a deeper study of various geological features, here the impact craters Chicxulub and Popigai. We confirm our results from 2010, extend them, and offer more complicated models, namely by means of the gravity strike angles. Both craters are double or multiple craters. The probable impactor direction is from NE for Chicxulub and SE-NW for Popigai. The both crater formations seem to be associated with impact induced tectonics that triggered development of impact grabens.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"41 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140804240","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":"Seismic wave modeling of fluid-saturated fractured porous rock: including fluid pressure diffusion effects of discretely distributed large-scale fractures","authors":"Yingkai Qi, Xuehua Chen, Qingwei Zhao, Xin Luo, Chunqiang Feng","doi":"10.5194/se-15-535-2024","DOIUrl":"https://doi.org/10.5194/se-15-535-2024","url":null,"abstract":"Abstract. The scattered seismic waves of fractured porous rock are strongly affected by the wave-induced fluid pressure diffusion effects between the compliant fractures and the stiffer embedding background. To include these poroelastic effects in seismic modeling, we develop a numerical scheme for discretely distributed large-scale fractures embedded in fluid-saturated porous rock. Using Coates and Schoenberg's local-effective-medium theory and Barbosa's dynamic linear slip model characterized by complex-valued and frequency-dependent fracture compliances, we derive the effective viscoelastic compliances in each spatial discretized cell by superimposing the compliances of the background and the fractures. The effective governing equations for fractured porous rocks are viscoelastic anisotropic and numerically solved by the mixed-grid-stencil frequency-domain finite-difference method. The main advantage of our proposed modeling scheme over poroelastic modeling schemes is that the fractured domain can be modeled using a viscoelastic solid, while the rest of the domain can be modeled using an elastic solid. We have tested the modeling scheme in a single fracture model, a fractured model, and a modified Marmousi model. The good consistency between the scattered waves off a single horizontal fracture calculated using our proposed scheme and the poroelastic modeling validates that our modeling scheme can properly capture the fluid pressure diffusion (FPD) effects. In the case of a set of aligned fractures, the scattered waves from the top and bottom of the fractured reservoir are strongly influenced by the FPD effects, and the reflected waves from the underlying formation can retain the relevant attenuation and dispersion information. The proposed numerical modeling scheme can also be used to improve migration quality and the estimation of fracture mechanical characteristics in inversion.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"5 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140636961","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":"Localized shear versus distributed strain accumulation as shear-accommodation mechanisms in ductile shear zones: Constraining their dictating factors","authors":"Pramit Chatterjee, Arnab Roy, Nibir Mandal","doi":"10.5194/egusphere-2024-1077","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1077","url":null,"abstract":"<strong>Abstract.</strong> Understanding the underlying mechanisms of strain localization in Earth’s lithosphere is crucial to explain the mechanics of tectonic plate boundaries and various failure-assisted geophysical phenomena, such as earthquakes. Geological observations suggest that ductile shear zones are the most important lithospheric structures of intense shear localization, sharing a major part of tectonic deformations. Despite extensive studies in the past several decades, the factors governing how they accommodate the bulk shear, whether by distributed homogeneous strain (i.e., development of S tectonic foliation normal to the principal shortening strain axis) or by localized shearing (formation of shear-parallel C bands) remain largely unexplored. This article aims to address this gap in knowledge, providing observational evidences of varying S and C development in ductile shear zones from two geological terrains of Eastern India. The field observations are complemented with 2D-viscoplastic numerical simulations within a strain-softening rheological framework to constrain the factors controlling the two competing shear-accommodation mechanisms: homogeneously distributed strain accumulation versus shear band formation. The model based analysis recognizes the bulk shear rate (<em>γ_b</em>), the bulk viscosity (<em>η_v</em>) and the initial cohesion (<em>C_i</em>) of a shear zone as the most critical factors to determine the dominance of one mechanism over the other. For a given <em>C_i</em>, low <em>γ_b</em> and <em>η_v</em> facilitate the formation of S foliation (uniformly distributed strain), which transforms to C-dominated shear-accommodation mechanism with increasing <em>η_v</em>. However, increasing <em>γ_b</em>, facilitates shear accommodation in a combination of the two mechanisms leading to CS- structures. The article finally discusses the conditions in which ductile shear zones can enormously intensify localized shear rates to produce rapid slip events, such as frictional melting and seismic activities.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"7 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140636977","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":"The effect of stiffness contrasts at faults on stress orientation","authors":"Moritz O. Ziegler, Robin Seithel, Thomas Niederhuber, Oliver Heidbach, Thomas Kohl, Birgit Müller, Mojtaba Rajabi, Karsten Reiter, Luisa Röckel","doi":"10.5194/egusphere-2024-1109","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1109","url":null,"abstract":"<strong>Abstract.</strong> Even though the crustal stress state is primarily driven by gravitational volume forces and plate tectonics, interpretations of borehole breakout observations show occasionally abrupt rotations of horizontal stress orientation of up to 90° when faults are crossed. This indicates the influence of faults on the local stress state, which parameter control the degree of rotation. Herein, we investigate the phenomenon of principal stress rotation at a fault by means of a 2D generic numerical model. We parametrised the fault as a rock stiffness contrast and investigate systematically the full model parameter space in terms of the ratio of the applied principal stresses, the rock stiffness contrast, as well as the angle between fault strike and orientation of the principal stress axis. General findings are that the stress rotation is negatively correlated with the ratio of principal stresses. A small angle between the far field stress orientation and the fault facilitates stress rotation. A high contrast in rock stiffness further increases the stress rotation angle. Faults striking perpendicular to the maximum principal stress orientation experience no rotation at all. However, faults oriented parallel to the maximum principal stress orientation experience either no rotation or a 90° rotation, dependent on the ratio of principal stresses and the rock stiffness contrast. A comparison with observations from various boreholes worldwide shows that in general, the findings are well in agreement, even though the dip angle proves to have an influence on the stress rotation, in particular for shallow dipping faults.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"49 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140612579","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":"Statistical appraisal of geothermal heat flow observations in the Arctic","authors":"Judith Freienstein, Wolfgang Szwillus, Agnes Wansing, Jörg Ebbing","doi":"10.5194/se-15-513-2024","DOIUrl":"https://doi.org/10.5194/se-15-513-2024","url":null,"abstract":"Abstract. Geothermal heat flow is an important boundary condition for ice sheets, affecting, for example, basal melt rates, but for ice-covered regions, we only have sparse heat flow observations with partly high uncertainty of up to 30 m W m−2. In this study, we first investigate the agreement between such pointwise heat flow observations and solid Earth models, applying a 1D steady-state approach to perform a statistical analysis for the entire Arctic region. We find that most of the continental heat flow observations have a high reliability and agreement to solid Earth models, except a few data points, such as, for example, the NGRIP (North Greenland Ice Core Project) point in central Greenland. For further testing, we perform a conditional simulation with focus on Greenland in which the local characteristics of heat flow structures can be considered. Simple kriging shows that including or excluding the less reliable NGRIP point has a large influence on the surrounding heat flow. The geostatistical analysis with the conditional simulation supports the assumption that NGRIP might not only be problematic for representing a regional feature but likely is an outlier. Basal melt estimates show that such a local spot of high heat flow results in local high basal melt rates but leads to less variation than existing geophysical models.","PeriodicalId":21912,"journal":{"name":"Solid Earth","volume":"26 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140600168","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}