Physics of the Earth and Planetary Interiors最新文献

{"title":"Post-collisional lithospheric delamination in eastern Iran, revealed by non-linear teleseismic tomography and residual topography","authors":"Meysam Mahmoodabadi ,&nbsp;Farzam Yamini-Fard ,&nbsp;Mohammad Tatar ,&nbsp;Ahmad Rashidi","doi":"10.1016/j.pepi.2024.107180","DOIUrl":"10.1016/j.pepi.2024.107180","url":null,"abstract":"<div><p>The Eastern Iranian Mountain Ranges (EIR) emerged as a consequence of the Late Cretaceous collision between the Afghan and Lut blocks. However, the response of the uppermost mantle to this collision remains enigmatic. Additionally, although petrological evidence suggests that post-collisional delamination is possible, it has not been conclusively identified in prior regional seismic imagery. This observation leads us to further explore this possibility using a dense seismic network. To gain insight into the geodynamic implications for eastern Iran and address knowledge gaps, we extensively investigated the seismic structure of the uppermost mantle beneath the EIR using a dense seismic network of 34 temporary stations, complemented by data from nine additional local permanent stations. By meticulously analyzing 6589 relative arrival time residuals from teleseismic records with favorable signal-to-noise ratios, we applied a non-linear tomography method to map <em>P</em>-wave velocity perturbations in a relative sense. Our tomographic images unveiled distinct instances of rapid high-velocity anomalies beneath low-velocity regions in the shallow mantle, suggesting the potential occurrence of lithospheric dripping, followed by subsequent asthenospheric upwelling. This observation offers a plausible explanation for the observed post-collisional magmatism over the Lut Block. Furthermore, to maintain the approximately 1.5-km positive residual topography across the EIR, beyond the influence of crustal properties, additional support from the hot and buoyant asthenosphere becomes crucial, particularly in the absence of a substantial lithospheric mantle.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107180"},"PeriodicalIF":2.3,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140181982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering the crustal anisotropy and mantle flow beneath the indo-Burma ranges from the harmonic decomposition of the receiver functions","authors":"Hitank Kasaundhan,&nbsp;Dhiraj Kumar Singh,&nbsp;Mohit Agrawal","doi":"10.1016/j.pepi.2024.107183","DOIUrl":"10.1016/j.pepi.2024.107183","url":null,"abstract":"<div><p>The hyper-oblique indentation of the Indian plate beneath the Burmese sliver gives rise to the Indo-Burma Ranges (IBR) in the eastern part of the Indian subcontinent. This geological formation encompasses one of the enigmatic hotspots and includes the densely populated regions of India and Myanmar. Harmonic Decomposition (HD) of the receiver functions, derived from the Multi-Taper Correlation (MTC) technique, is used to model seismic anisotropy and morphological crustal deformation caused by subduction underneath IBR. We used teleseismic earthquake data from eleven broadband seismic stations installed within the IBR and its foredeep region. The findings indicate that the attitude of the fast symmetry axis or dipping direction of the interface is influenced by the trend of regional geological features and absolute plate motion, with the IBR exhibiting NN<em>E</em>-SSW and N-S directions and the Himalayan region showing NE-SW and E-W directions. Our results reveal that the coupling of the Indian plate with the Burmese and Eurasian plates induces lithospheric fabrics that align perpendicular to the coupling direction, resulting in anisotropy in the brittle upper crust. Directional analysis of the HD model for the interfaces at the middle or lower crust reveals the strike of the fast symmetry axis in the NNE-SSW direction, which suggests the alignment of minerals and partial melt in the direction of the major shear stress. The interface across the Moho reflects four-lobed periodicity, that is, 90^o ambiguity in the strike direction of the fast symmetry axis, varying from the <em>E</em>-W to the N-S directions. The ambiguity indicates the possibility of the 2D-induced entrained mantle flow along the subducting Indian plate and the 3D toroidal flow parallel to the trend of the IBR.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"350 ","pages":"Article 107183"},"PeriodicalIF":2.3,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140182147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lateral and radial viscosity structure beneath Fennoscandia inferred from seismic and magnetotelluric observations","authors":"Florence D.C. Ramirez ,&nbsp;Kate Selway ,&nbsp;Clinton P. Conrad ,&nbsp;Valerie Maupin ,&nbsp;Maxim Smirnov","doi":"10.1016/j.pepi.2024.107178","DOIUrl":"10.1016/j.pepi.2024.107178","url":null,"abstract":"<div><p>Fennoscandia is continuously uplifting in response to past deglaciation, termed glacial isostatic adjustment or GIA, and its mantle viscosity is well constrained from ice sheet and sea level data. Here, we compare those GIA-constrained viscosities for the Fennoscandian upper mantle with geophysically-constrained viscosities. We construct the upper mantle viscosity structure of Fennoscandia by inferring temperature and water content from seismic and magnetotelluric (MT) data. Using a 1-D MT model for Fennoscandian cratons together with a global seismic model, we infer an upper mantle viscosity (below 250 km) of ∼10^21±2 Pa·s, which encompasses the GIA-constrained viscosities of 10²⁰ − 10²¹ Pa·s. The GIA viscosities are better matched if the Fennoscandian upper mantle is a wet harzburgite or a dry pyrolite, where pyrolite is ∼10 times more viscous than harzburgite. Using the average temperatures and water contents for harzburgitic upper mantle, the GIA viscosities require 1–4 mm grain sizes indicating a diffusion creep regime. In northwestern Fennoscandia, where a high-resolution 2-D resistivity model is available, greater inferred mantle water content implies viscosities that are 10–100 times lower than those for the Fennoscandian Craton. Our work suggests that the combination of seismic and MT observations can improve upper mantle viscosity estimates, especially for regions with laterally-varying viscosity structures or where GIA constraints are not available. Although our method represents an important step forward, viscosity uncertainty can be further reduced by incorporating additional constraints on rock composition, grain size and mantle stress, as well as more accurate geophysical data, into the viscosity calculation.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107178"},"PeriodicalIF":2.3,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000360/pdfft?md5=409afc5998d5f5cfe7b9883a6bc4c5e7&pid=1-s2.0-S0031920124000360-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140181980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Effects of Fe-Ca-Mg substitutions on the equation-of-state of pyrope-rich garnet from ab initio modeling and experiments: Insights and implications for the upper mantle","authors":"Maribel Núñez-Valdez ,&nbsp;Niccolò Satta ,&nbsp;Sergio Speziale","doi":"10.1016/j.pepi.2024.107171","DOIUrl":"10.1016/j.pepi.2024.107171","url":null,"abstract":"<div><p>We report systematic first-principles results of structural properties and compression behavior based on density functional theory (DFT) and an exchange-correlation functional for solids, of Al-bearing garnets of general compositions in the pyrope-almandine-grossular solid solution system. The combination of DFT and a simple solid solution model is able to produce a compositional dependence of the compression curve consistent with trends observed in experimental studies. Using end-member properties extrapolated from our computations and perturbing an extant thermodynamic model we observe only marginal effects on the bulk sound velocity of pyrolite and MORB along relevant geothermal paths. However, this could hide important effects on the elemental partitioning between garnet and other major phases which should be further investigated both experimentally and computationally. We also present simulations of the effect of combined Fe and Ca substitutions for Mg on the elastic tensor of Al-bearing garnets, our simplified modeling shows only partial agreement with the trends observed in experiments. Therefore, further computational investigations, especially of the effect of Fe-Mg substitution on the tensor, are needed.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"350 ","pages":"Article 107171"},"PeriodicalIF":2.3,"publicationDate":"2024-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140181981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tectonic development in Singhbhum Craton, NE India decrypted from dyke swarms: A window to understand magma dynamics in Archean-Proterozoic supercontinents","authors":"Arun K. Ojha ,&nbsp;D.P. Monika Saini ,&nbsp;Amar Agarwal ,&nbsp;Ambrish K. Pandey","doi":"10.1016/j.pepi.2024.107169","DOIUrl":"https://doi.org/10.1016/j.pepi.2024.107169","url":null,"abstract":"<div><p>Singhbhum Craton (SC) hosted eight different dyke swarm events, which are collectively known as the Newer Dolerite Dykes. These have been correlated with different cratons and supercontinents based on age, geochemistry, and paleomagnetic data. However, our understanding of stress conditions during and after the dyke intrusions and the magma chamber dynamics is limited due to lack of information. In this study, we have investigated magma dynamics and crustal extension for different dyke swarm events in the SC to explore the magma chamber dynamics during the supercontinent breakup and at other cratons around the globe. Further, we have also quantified post-intrusion response to the far-field stress in different dyke swarms of the SC. For a comprehensive understanding of the magma dynamics and deformation history of the dyke swarms, we investigated dykes associated structures and estimated the magma pressure relative to the principal stresses. We used dyke wall attitude data to explore the paleostress conditions during the dyke intrusion, fault-slip data for post-emplacement deformation, and field structures with dyke thickness data to understand magma dynamics and crustal extension.</p><p>Paleostress analysis in four dyke swarms indicates relatively higher magma pressure in the Pipilia dyke swarm compared to Ghatgaon, Keonjhar, and Kaptipada dyke swarms. This is further supported by the fact that Pipilia dykes are thicker than the other three dyke swarms. Post-emplacement deformation is evident from the fault-slip observations, tectonic fractures, and veins cross-cutting dykes and host rock. Fault-slip observations suggest an extensional tectonic event followed by a compressive one. The extensional stress regime, active during the intrusion of Pipilia dyke swarm, overprints the Ghatgaon dyke swarm, while the far-field stress from the Singhbhum Shear Zone affects all the analyzed dykes and the host rock. These observations are in agreement with the thinned lithosphere of SC. We estimate that the Ghatgaon swarm caused the maximum average crustal extension/dilation of 9.65%, while the Keonjhar swarm led to the least average extension of 1.58%. We suggest that the Pipila dyke swarm event may have dilated a part of the Columbia supercontinent by ∼8.5% as the dilations for other regions in the supercontinents are not known.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"350 ","pages":"Article 107169"},"PeriodicalIF":2.3,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140137843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detailed seismic structure beneath the earthquake zone of Yogyakarta 2006 (Mw ∼6.4), Indonesia, from local earthquake tomography","authors":"Virga Librian ,&nbsp;Mohamad Ramdhan ,&nbsp;Andri Dian Nugraha ,&nbsp;Muhammad Maruf Mukti ,&nbsp;Syuhada Syuhada ,&nbsp;Birger-Gottfried Lühr ,&nbsp;Sri Widiyantoro ,&nbsp;Adityo Mursitantyo ,&nbsp;Ade Anggraini ,&nbsp;Zulfakriza Zulfakriza ,&nbsp;Faiz Muttaqy ,&nbsp;Yayan Mi'rojul Husni","doi":"10.1016/j.pepi.2024.107170","DOIUrl":"10.1016/j.pepi.2024.107170","url":null,"abstract":"<div><p>The earthquake, which occurred in Yogyakarta, Indonesia, on May 26, 2006, at 22:53:58 UTC with Mw ∼6.4, was one of the most destructive earthquakes in Indonesia. The earthquake caused thousands of fatalities, tens of thousands of injuries, and hundreds of thousands of house damages in the Yogyakarta area and its surroundings at a loss of billions of dollars. Previous studies from seismic tomography and satellite radar imaging hypothesized that the earthquake was caused by activating a so far unknown fault east of the Opak Fault. Although, in the beginning, the Opak fault was suspected to be the source of the Yogyakarta earthquake in 2006. This assumption was made because the damage was maximum in the Bantul area west of the Opak Fault. This study demonstrates that our seismic tomography achieved a higher resolution than the previous study and could resolve a failed complex fault system. We utilized more aftershocks (2170 events) and smaller grid sizes for seismic tomography inversion. Four focal mechanisms from aftershocks for Mw ≥ 4.5 were also conducted to support structure interpretation in the study area. Our results successfully delineate the Opak Fault and the second fault, namely the Ngalang Fault, parallel to the eastern part of the fault at a depth of 9 km. Two faults could be indicated by the velocity contrast of Vp, Vp/Vs ratio, and Vs from a horizontal section tomogram. Our focal mechanisms also support seismic tomography, revealing two fault planes in our study area. The results show that the two faults are connected by the Oyo Fault, which is ruptured in the opposite direction compared to the two faults.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"351 ","pages":"Article 107170"},"PeriodicalIF":2.3,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140275562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of planetary rotation on metal-silicate mixing and equilibration in a magma ocean","authors":"Quentin Kriaa ,&nbsp;Landeau Maylis ,&nbsp;Le Bars Michael","doi":"10.1016/j.pepi.2024.107168","DOIUrl":"10.1016/j.pepi.2024.107168","url":null,"abstract":"<div><p>At a late stage of its accretion, the Earth experienced high-energy planetary impacts. Following each collision, the metal core of the impactor sank into molten silicate magma oceans. The efficiency of chemical equilibration between these silicates and the metal core controlled the composition of the Earth interior and left a signature on geochemical and isotopic data. These data constrain the timing, pressure and temperature of Earth formation, but their interpretation strongly depends on the efficiency of metal-silicate mixing and equilibration. We investigate the role of planetary rotation on the dynamics of the sinking metal and on its chemical equilibration using laboratory experiments of particle clouds settling in a rotating fluid. Our clouds initially sink as spherical turbulent thermals, but after a critical depth, rotation becomes important and they transition to a vortical columnar flow aligned with the rotation axis. Applied to Earth formation, our results predict that rotation strongly affects the fall of metal in the magma ocean for impactors smaller than 459 km in radius on a proto-Earth that rotates twice faster than today. On a proto-Earth spinning 5 times faster than today, rotation is important for any impactor smaller than the Earth itself. In contrast with a thermal that grows in all directions, the vortical column grows vertically but keeps a constant horizontal extent. The slower dilution in vortical columns reduces chemical equilibration compared to previous estimates that neglect planetary rotation. We find that rotation significantly affects the degree of equilibration for highly siderophile elements with partition coefficients larger than <span><math><msup><mn>10</mn><mn>3</mn></msup></math></span>. In this case, for a planet spinning twice faster than today, the degree of equilibration decreases by up to a factor 2 compared to previous estimates that neglect the effect of rotation. Finally, the ultimate fate of iron drops is to be detrained from the vortical column as an iron rain, reconciling the traditional iron rain scenario with the model of turbulent thermal.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"352 ","pages":"Article 107168"},"PeriodicalIF":2.3,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140126037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elastic wave velocity measurements of sodium aluminosilicate glass and melt at high pressure and temperature","authors":"Naoki Takahashi ,&nbsp;Tatsuya Sakamaki ,&nbsp;Osamu Ikeda ,&nbsp;Sho Kakizawa ,&nbsp;Yuji Higo ,&nbsp;Akio Suzuki","doi":"10.1016/j.pepi.2024.107167","DOIUrl":"10.1016/j.pepi.2024.107167","url":null,"abstract":"<div><p>The combination of ultrasonic technique with synchrotron X-ray diffraction and radiography in a multi-anvil apparatus was utilized to measure the elastic wave velocities of sodium aluminosilicate glass and melt with the partially depolymerized composition of Na₃AlSi₃O₉ (NAS). The measurements were conducted at pressure and temperature of up to 7.3 GPa and at ambient temperature for glass and up to 4.3 GPa and 2120 K for melt, respectively. The compressional wave velocity (<em>V</em>_P) of the NAS glass remained mostly constant up to 4 GPa; subsequently, it increased with increasing pressure. Additionally, the NAS glass exhibited a minimum shear wave velocity (<em>V</em>_S) at 4–5 GPa. Alternatively, the <em>V</em>_P of the NAS melt was smaller than that of the NAS glass, showing a velocity minimum at ∼2 GPa. The negative pressure dependence of <em>V</em>_P of the NAS melt is completely different from the depolymerized diopside (Di) melt, which shows a monotonic increase in <em>V</em>_P with pressure. The contrasting behavior of the NAS and Di melts is caused by the difference in their structure, characterized by their degree of polymerization. Natural magma found in the interior of the Earth, such as basalt, has a partially depolymerized composition. This study indicates that the magma can exhibit elastic properties with negative pressure dependence, similar to the NAS melt.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"350 ","pages":"Article 107167"},"PeriodicalIF":2.3,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000256/pdfft?md5=5415ffd84d8ab5d465d2350f314ffe4c&pid=1-s2.0-S0031920124000256-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140129673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Spherical geometry convection in a fluid with an Arrhenius thermal viscosity dependence: The impact of core size and surface temperature on the scaling of stagnant-lid thickness and internal temperature","authors":"Pejvak Javaheri ,&nbsp;Julian P. Lowman ,&nbsp;Paul J. Tackley","doi":"10.1016/j.pepi.2024.107157","DOIUrl":"10.1016/j.pepi.2024.107157","url":null,"abstract":"&lt;div&gt;&lt;p&gt;The rock and rock-ice mixtures of the core-enveloping spherical shells comprising terrestrial body interiors have thermally determined viscosities well described by an Arrhenius dependence. Accordingly, the implied viscosity contrasts determined from the activation energies (E) characterizing such bodies can reach values exceeding &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;40&lt;/mn&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, for a temperature range that spans the conditions found from the lower mantle to the surface. In this study, we first explore the impact of implementing a cut-off to limit viscosity magnitude in cold regions. Using a spherical annulus geometry, we investigate the influence of core radius, surface temperature, and convective vigour on stagnant lid formation resulting from the extreme thermally induced viscosity contrasts. We demonstrate that the cut-off viscosity must be increased with decreasing curvature factor, &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; (&lt;span&gt;&lt;math&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mtext&gt;in&lt;/mtext&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, where &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mtext&gt;in&lt;/mtext&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;r&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; are the inner and outer radii of the annulus, respectively), if the solutions are to be not only computationally manageable but physically valid. We find that for statistically-steady systems, the mean temperature decreases with core size, and that a viscosity contrast of at least &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; is required for stagnant lid formation as &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; decreases below 0.5. Inverting the results from over 80 calculations featuring stagnant lids (from a total of approximately 180 calculations), we apply an energy balance model for heat flow across the thermal boundary layers and find that the non-dimensionalized temperature in the Approximately Isothermal Layer (AIL) in the convecting region under a stagnant lid is well predicted by &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mi&gt;AIL&lt;/mi&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msubsup&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mfrac&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mfrac&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msubsup&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msqrt&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msup&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msubsup&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/mrow&gt;&lt;/msqrt&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;/math&gt;&lt;/span&gt; where &lt;span&gt;&lt;math&gt;&lt;mi&gt;γ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; is a function of E and &lt;span&gt;&lt;math&gt;&lt;mi&gt;f&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;, and &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mtext&gt;out&lt;/mtext&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt; is the non-dimensionalized surface temperature. Moreover, the normalized (i.e., non-dimensional) thickness of the stagnant lid, &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;mo&gt;′&lt;/mo&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt;, can be obtained from a measurement of the non-dimensional surface heat flux once &lt;","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"349 ","pages":"Article 107157"},"PeriodicalIF":2.3,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000153/pdfft?md5=12d6c0f103726e2f43e8d3d47da8ce61&pid=1-s2.0-S0031920124000153-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 onset of anelastic behavior in fine-grained synthetic dunite","authors":"Tongzhang Qu ,&nbsp;Ian Jackson ,&nbsp;Ulrich H. Faul ,&nbsp;Emmanuel C. David","doi":"10.1016/j.pepi.2024.107160","DOIUrl":"10.1016/j.pepi.2024.107160","url":null,"abstract":"<div><p>Micromechanical models suggest that the onset of anelastic relaxation in polycrystalline olivine, critical to interpretation of the seismic wave attenuation and dispersion in the upper mantle, should be a mild dissipation peak caused by elastically accommodated grain-boundary sliding. Such behavior has been tentatively invoked to explain both a short-period shear modulus deficit and a dissipation plateau poorly resolved at 900–700 °C in previous forced-oscillation experiments on fine-grained dunite tested within mild-steel jackets. However, these observations may have been complicated by the austenite to ferrite plus cementite phase transition in the jacket material, compliance associated with interfacial Ni₇₀Fe₃₀ foils, and modeling of the mechanical properties of polycrystalline alumina as control specimen. To investigate the influence of these complications within the experimental setup and provide forced-oscillation data of better quality especially at moderate temperatures, we have conducted further forced-oscillation tests for which we removed the interfacial foils, employed single-crystal sapphire as reference sample, and used alternative jacket materials (stainless steel or copper) which experience no phase transition during the staged cooling. The newly acquired forced-oscillation data, although broadly consistent with the previous results, differ significantly especially in temperature sensitivity, and allow refinement of an appropriate Burgers creep-function model. A mild dissipation peak superimposed on monotonic dissipation background during the onset of anelastic relaxation in dry, melt-free and fine-grained dunite has now been consistently observed at temperatures of ∼950–1050 °C and seismic periods of 1–1000 s. Such a dissipation peak with relaxation strength 0.02 ± 0.01 is attributed to elastically accommodated grain-boundary sliding. The high activation energy (&gt; 600 kJ/mol) of viscoelastic behavior involving both dissipation and related dispersion suggests that grain-boundary diffusion may be limited by interfacial reaction within grain boundaries. The reduced relaxation strength makes it difficult to attribute the oceanic lithosphere-asthenosphere boundary to water-mediated elastically accommodated grain-boundary sliding.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"350 ","pages":"Article 107160"},"PeriodicalIF":2.3,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000189/pdfft?md5=c802be94068b4d599547a8d3330418ae&pid=1-s2.0-S0031920124000189-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140057192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}