Physics of the Earth and Planetary Interiors最新文献

{"title":"Wudalianchi volcanism and mantle dynamics in Northeast China: New insight from Pn and Sn tomography","authors":"Mofei Du ,&nbsp;Jianshe Lei ,&nbsp;Dapeng Zhao ,&nbsp;Yinshuang Ai ,&nbsp;Hongbin Lu ,&nbsp;Changqing Sun","doi":"10.1016/j.pepi.2024.107260","DOIUrl":"10.1016/j.pepi.2024.107260","url":null,"abstract":"<div><div>We determine new tomographic models of Pn anisotropic velocity and Sn isotropic velocity in and around the Wudalianchi volcanic area by inverting high-quality Pn and Sn arrival times manually picked from waveforms recorded at the newly deployed high-dense WAVESArray portable seismic stations. Our high-resolution Pn and Sn velocity models reveal strong lateral heterogeneities in the uppermost mantle under the study region. The average Pn and Sn velocities in the uppermost mantle are 8.2 and 4.5 km/s, respectively. Both Pn and Sn velocity models exhibit obvious low-velocity (low-V) anomalies under the Wudalianchi and Keluo volcanoes, whereas under the Songliao basin distinct high-velocity (high-V) zones are revealed. In particular, our Pn model reveals two separate low-V anomalies under the Nuominhe and Halaha volcanic groups, suggesting that they have different deep origins. A large-scale L-shaped low-V zone exists under the Keluo, Wudalianchi, Erkeshan, and Xunke volcanoes, characterized by Pn-wave fast propagation directions (FPDs) parallel with the low-V zone, suggesting that these volcanoes may have the same deep origin. Furthermore, southeast-opened U-shaped Pn FPDs exist around the Wudalianchi volcano, whereas NE-SW FPDs appear under the Great Xing'an range, which are generally consistent with SKS splitting measurements. This feature may reflect lithosphere-asthenosphere coupling beneath the Wudalianchi volcano associated with horizontal flows in the big mantle wedge and compressional tectonics under the Great Xing'an range. These results shed new lights on the Wudalianchi volcanism and mantle dynamics beneath Northeast China.</div></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"356 ","pages":"Article 107260"},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310256","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":"Randomization of the Earth's magnetic field driven by magnetic helicity","authors":"Alexander Bershadskii","doi":"10.1016/j.pepi.2024.107250","DOIUrl":"10.1016/j.pepi.2024.107250","url":null,"abstract":"<div><p>It is shown, using results of numerical simulations and geomagnetic observations, that the spatial and temporal randomization of the Earth's global and local magnetic fields is driven by magnetic helicity (an ideal magnetohydrodynamic invariant). In the frames of the distributed chaos notion, the magnetic helicity determines the degree of magnetic field randomization and the results of numerical simulations are in quantitative agreement with the geophysical observations despite the considerable differences in the scales and physical parameters.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"356 ","pages":"Article 107250"},"PeriodicalIF":2.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272015","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":"Space and time distribution of seismic source energy at Campi Flegrei, Italy through the last unrest phase (1.1.2000–31.12.2023)","authors":"Edoardo Del Pezzo ,&nbsp;Francesca Bianco","doi":"10.1016/j.pepi.2024.107258","DOIUrl":"10.1016/j.pepi.2024.107258","url":null,"abstract":"&lt;div&gt;&lt;p&gt;We describe the space-time pattern of seismicity occurring on Campi Flegrei Caldera (CFC), Italy, where ground deformations and seismicity represent the drivers of its current bradyseismic crisis, well known and extensively studied at an international level. In detail we consider the seismicity in the time interval starting on 1.1.2000 and ending on 31.12.2023. We revise the statistics of the earthquake occurrence, focusing at possible precursory time changes of the b-parameter of the Gutenberg and Richter (G&amp;R &lt;span&gt;&lt;math&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;) distribution and at the time distribution of the total seismic moment inside any swarm. To estimate the G&amp;R &lt;span&gt;&lt;math&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; we use a Monte Carlo method instead of the ordinary Least Squares or Maximum likelihood methods, to easily measure the uncertainty on the &lt;span&gt;&lt;math&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; taking into account uncertainties on the magnitude estimates. Results show that G&amp;R &lt;span&gt;&lt;math&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; calculated for cumulative and discrete distributions of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, the moment-magnitude, and &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, the so-called duration-magnitude, are the same inside the uncertainties; &lt;span&gt;&lt;math&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; are significantly different from the same parameters estimated for &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, being &lt;span&gt;&lt;math&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; close to the value of 1.0 and &lt;span&gt;&lt;math&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; for &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; close to 0.8. The “bounded” G&amp;R distribution fits the data yielding &lt;span&gt;&lt;math&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; close to those for the unbounded distribution. The mean annual rate of exceedance, calculated for the entire catalogue, results to be 0.033&lt;span&gt;&lt;math&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0.015&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt; (years&lt;sup&gt;−1&lt;/sup&gt;) corresponding to a return period of &lt;span&gt;&lt;math&gt;&lt;mn&gt;30&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;14&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt; years for &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;M&lt;/mi&gt;&lt;mi&gt;w&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;4.5&lt;/mn&gt;&lt;/math&gt;&lt;/span&gt;. The time dependence of G&amp;R b-parameter show a &lt;span&gt;&lt;math&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;value&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; time pattern characterized by variations slightly outside 1-&lt;span&gt;&lt;math&gt;&lt;mi&gt;σ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; uncertainty bar, tending to the value of 1 approaching present. As evidenced by several past studies, earthquakes in CFC occur in space-t","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"356 ","pages":"Article 107258"},"PeriodicalIF":2.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S003192012400116X/pdfft?md5=a859af686a6ea4310c7c90813110214b&pid=1-s2.0-S003192012400116X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272089","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":"Tidal triggering of seismic swarm associated with hydrothermal circulation at Blanco ridge transform fault zone, Northeast Pacific","authors":"Sambit Sahoo ,&nbsp;Batakrushna Senapati ,&nbsp;Dibyashakti Panda ,&nbsp;Shuanggen Jin ,&nbsp;Bhaskar Kundu","doi":"10.1016/j.pepi.2024.107259","DOIUrl":"10.1016/j.pepi.2024.107259","url":null,"abstract":"<div><p>Seismicity associated with hydrothermal systems (e.g., submarine volcanoes, mid-oceanic ridges, oceanic transform faults, etc.) share a complex relationship with the tidal forcing and induced fluid flow process under different tectonic settings. The hydrothermal circulation drives the deformation at the brittle-ductile transition zone within a permeable brittle crust. Although the tidal loading amplitudes are too small to generate a brittle deformation, the incremental pressure exerted by the tidal loading can modulate the flow of hydrothermal fluid circulation and trigger the critically stressed faults or fracture zones. We present a compelling case of tidal modulation in seismicity along the Blanco Ridge Transform Fault Zone (BRTFZ), in the northeast Pacific. The strong diurnal and fortnightly periodicity has been observed in the deeper seismic swarm (7–15 km), whereas the shallow seismic swarm (0–7 km) does not exhibit any such tidal periodicity. The dominance of diurnal and fortnightly periodicity in the deeper seismic swarm is explained by the high amplitude tidal cycles providing additional stress on the fluid circulation at the crust-mantle boundary. Moreover, our robust statistical correlation of seismicity with tidal stress and resonance destabilization model under rate-and-state friction formalism suggests that the fault segments are conditionally unstable and more sensitive to periodic tidal stress perturbation.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"356 ","pages":"Article 107259"},"PeriodicalIF":2.4,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142238660","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":"Lithospheric resistivity structure of the Xuefeng Orogenic Belt and its implications for intracontinental deformation in South China","authors":"Xin Yang ,&nbsp;Shan Xu ,&nbsp;Xiangyun Hu ,&nbsp;Zuzhi Hu ,&nbsp;Weiyang Liao ,&nbsp;Wenlong Zhou","doi":"10.1016/j.pepi.2024.107247","DOIUrl":"10.1016/j.pepi.2024.107247","url":null,"abstract":"<div><p>The Xuefeng Orogenic Belt (XFOB), located in the central part of the South China Block, is a typical Mesozoic intracontinental orogen in the central Jiangnan Orogenic Belt. By collecting magnetotelluric (MT) data across the XFOB, we obtained the resistivity structure of the lithosphere, which sheds light on the Mesozoic intracontinental orogenic processes in the XFOB. The resistivity structure reveals a low-resistivity body (&lt;10 Ω∙m), beneath the XFOB, dipping southeast wards from a depth of 10 km to the bottom of the crust. This conductor is interpreted as a relic of the lower detachment zone, which coincides with low-density areas obtained from joint inversion of seismic models. It is believed to result from mineral fluids migrating along the thrust fault and squeezing sulfides into folds. Four low-resistivity bodies were identified at three extensional locations along the Jiangshan-Shaoxing Fault and at the Cili-Baojing Fault. The low-resistivity body (&lt;10 Ω∙m) at the junction of the Shaoyang and the Hengyang Basin is located at the point where the Moho depth thins. The variation trend of the terrestrial heat flow values, with this low-resistivity body as the plate boundary, is consistent with the average variation of the terrestrial heat flow values within the block. We propose that the low-resistivity body under the Qidong-Yongzhou-Guilin fault conforms to the characteristics of the suture zone in the resistivity structure. Its existence indicates that the missing location of the Jiangshan-Shaoxing suture zone of the Yangtze and Cathaysia Block in the middle-southwest section of the South China Block is the Qidong-Yongzhou-Guilin fault. The Yangtze Block and the Hengyang Basin show high resistivity, the depth of which reaches 100 km and 40 km, respectively. Based on the resistivity model and geological data, the XFOB experienced Triassic compression, leading to basement decollement, thrusting, and nappe structures due to low-angle Paleo-Pacific Plate subduction. This compression also led to the uplift of the orogenic belt. Moreover, under the tension caused by the high-angle retreat of the Paleo-Pacific Plate, the Cretaceous extensional tectonics led to detachment along the thrust faults, forming half-graben and basin structures along the margins.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"355 ","pages":"Article 107247"},"PeriodicalIF":2.4,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142050258","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":"Subsurface structural trends in Central-Western India: Inferences from magnetotelluric data using the complex MT apparent resistivity tensor","authors":"Abdul Azeez K.K.","doi":"10.1016/j.pepi.2024.107248","DOIUrl":"10.1016/j.pepi.2024.107248","url":null,"abstract":"<div><p>The central-western part of the Indian subcontinent exhibits significant geological diversity and possesses a rich record of different tectonothermal events in the earth's evolutionary history, spanning from the Archean to the present. Precambrian geology in the region is mostly obscured by Cretaceous-Tertiary/Paleocene volcanic eruptions and Proterozoic to Quaternary/recent sedimentary cover. Magnetotelluric (MT) impedance and tipper responses from 146 stations, covering central-western India in a grid fashion with a spacing of ∼55 km, were analyzed to evaluate the subsurface structural trends, dimensionalities, and qualitative characteristics of the electric lithosphere in the region. An advanced Complex Apparent Resistivity Tensor (CART) approach, along with the popular Phase Tensor (PT) approach and induction arrows are utilized to achieve the above goals. The analysis revealed a high degree of 3D induction effects in the data at almost every station and period. The directionality information retrieved from the tensor properties showed that the structural trends in the deep crust and upper mantle of the major geologic domains correlate with the known surface tectonic trend of the respective geologic domain. This study provides vital evidence to support the suspected bifurcation of the Precambrian Aravalli-Delhi Mobile Belt (ADMB) tectonic trend and its extensions into neighboring Kutch, Saurashtra, and Central Indian Tectonic Zone (CITZ) domains. The analysis results indicate a lithospheric scale enhanced conductivity beneath the Malwa plateau, which marks the first major phase of the Reunion mantle plume eruption in India. A critical finding of this study is that the Resistivity Phase Tensor better defines the subsurface resistivity structure and provides much clearer structural information than the conventional Phase Tensor.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"355 ","pages":"Article 107248"},"PeriodicalIF":2.4,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142021351","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":"Microseismicity detection and spatial-temporal migration in the Xinfengjiang reservoir, Guangdong, China","authors":"Peng Zhang ,&nbsp;Xinlei Sun ,&nbsp;Jianye Zong ,&nbsp;Zhuo Xiao ,&nbsp;Yusong Shen","doi":"10.1016/j.pepi.2024.107245","DOIUrl":"10.1016/j.pepi.2024.107245","url":null,"abstract":"<div><p>There have been many earthquakes in the Xinfengjiang Reservoir (XFJR) in the past 60 years since the M6.1 earthquake that occurred in 1961. In the XFJR, seismicity has migrated from southeast to northwest; however, the mechanisms for this migration have not yet been fully investigated. In this study, we used six years of data from both permanent and temporary seismic networks in the XFJR to detect &gt;23,500 earthquake events using the EQTransformer. The minimum magnitude of completeness of the earthquake catalog decreased to −0.1, and the spatial distribution of the microearthquakes showed clear high-angle faults in the area, which included a new fault within the reservoir. The focal mechanism inversion results showed that earthquakes in the northwestern cluster changed from strike-slip to dip-slip faults with time whereas those in the southeastern cluster remained a mixture of strike-slip and dip-slip faults. Further analysis showed that spatiotemporal variation in the northwestern reservoir was due to earthquake migration along different faults. Overall, we concluded that earthquake in the whole XFJR area were affected by water infiltration along fault zone; Coulomb stress transfer may also contribute to the migration of earthquakes from southeast to northwest direction.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"355 ","pages":"Article 107245"},"PeriodicalIF":2.4,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142050259","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":"The link between gas extraction and shallow seismicity around the Dalan gas field of Zagros Mountains, Iran","authors":"Mir Ali Hassanzadeh ,&nbsp;Mohammadreza Jamalreyhani ,&nbsp;Shiva Arvin ,&nbsp;Shaghayegh VahidRavesh","doi":"10.1016/j.pepi.2024.107246","DOIUrl":"10.1016/j.pepi.2024.107246","url":null,"abstract":"<div><p>We analyze seismicity from 2013 to 2023 near Bushkan village in the Fars arc of the Zagros folded belt, colocated with the Dalan natural gas field. A previous study suggested unusual seismic behavior in the 2014–15 cluster, linking larger events to shallow depths (∼5 km) on steep reverse faults within the Dalan anticline. Nevertheless, ongoing debates persist regarding the potential correlation of seismicity with activities in the Dalan field. Our study investigates seismic activities using relocation, moment tensor inversion, stress inversion, and remote sensing techniques. We relocated 35 events above magnitude 3 and reconstructed source parameters for 12 events (M 4+) with uncertainties. Focal mechanisms were inverted, and morphology remote sensing was employed to ascertain the active stress state. Besides the 2014–15 cluster, we found a separate strike-slip cluster in 2018 at shallower depths (3–4 km), unusual for Zagros earthquakes. We suggest that pore pressure variations influence seismic sequences in the Dalan gas field area. However, distinguishing between human-induced and natural earthquakes in regions like Zagros with naturally elevated seismicity is challenging.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"355 ","pages":"Article 107246"},"PeriodicalIF":2.4,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141993282","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":"Reevaluating the fate of subducted magnesite in the Earth's lower mantle","authors":"Lélia Libon ,&nbsp;Georg Spiekermann ,&nbsp;Ingrid Blanchard ,&nbsp;Johannes M. Kaa ,&nbsp;Serena Dominijanni ,&nbsp;Melanie J. Sieber ,&nbsp;Mirko Förster ,&nbsp;Christian Albers ,&nbsp;Wolfgang Morgenroth ,&nbsp;Catherine McCammon ,&nbsp;Anja Schreiber ,&nbsp;Vladimir Roddatis ,&nbsp;Konstantin Glazyrin ,&nbsp;Rachel J. Husband ,&nbsp;Louis Hennet ,&nbsp;Karen Appel ,&nbsp;Max Wilke","doi":"10.1016/j.pepi.2024.107238","DOIUrl":"10.1016/j.pepi.2024.107238","url":null,"abstract":"<div><p>The role that subducted carbonates play in sourcing and storing carbon in the deep Earth's interior is uncertain, primarily due to poor constraints on the stability of carbonate minerals when interacting with mantle phases. Magnesite (<span><math><msub><mtext>MgCO</mtext><mn>3</mn></msub></math></span>) is the most prominent carbonate phase to be present at all mantle pressure-temperature conditions. In this study, we combined multi-anvil apparatus and laser-heated diamond anvil cell experiments to investigate the stability of magnesite in contact with iron-bearing bridgmanite. We examined the presence of melt, decarbonation, and diamond formation at shallow to mid-lower mantle conditions (25 to 68 GPa; 1350 to 2000 K). Our main observation indicates that magnesite is not stable at shallow lower mantle conditions. At 25 GPa and under oxidizing conditions, melting of magnesite is observed in multi-anvil experiments at temperatures corresponding to all geotherms except the coldest ones. Whereas, at higher pressures and under reducing conditions, in our laser-heated diamond-anvil cell experiments, diamond nucleation is observed as a sub-solidus process even at temperatures relevant to the coldest slab geotherms. Our results indicate that magnesite was reduced and formed diamonds when in contact with the ambient peridotite mantle at depths corresponding to the shallowest lower mantle (33 GPa). Thus, we establish that solid magnesite decomposes at depths of ∼700 km as it contacts the ambient mantle. Consequently, the recycling of carbonates will hinder their transport deeper into the lower mantle.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"355 ","pages":"Article 107238"},"PeriodicalIF":2.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142006623","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":"Impact of localization and inflation on geomagnetic data assimilation","authors":"K. Gwirtz ,&nbsp;W. Kuang ,&nbsp;C. Yi ,&nbsp;A. Tangborn","doi":"10.1016/j.pepi.2024.107237","DOIUrl":"10.1016/j.pepi.2024.107237","url":null,"abstract":"<div><p>In geomagnetic data assimilation (DA), information on the Earth's core magnetic field is combined with numerical dynamo models to estimate the dynamic state of the deep interior and produce forecasts of future magnetic field variations. We present a series of numerical experiments exploring the use of localization and inflation schemes in an Ensemble Kalman Filter (EnKF) based geomagnetic DA system. Localization and inflation schemes are (often necessary) modifications to ensemble-based DA systems, which can improve performance, particularly when computational expense limits ensemble size (the number of simultaneous model runs). We find that the studied localization and inflation schemes enable small ensembles to not only match, but exceed the performance of a larger ensemble. Detailed analysis of the results show that, without localization and inflation, even the larger ensembles make adjustments during assimilation which are either too strong or too weak, and lead to poorer estimates of the dynamo state and forecast uncertainties. The use of localization and inflation allows one to better control the impact of assimilation on elements of the dynamo state, thus mitigating some of these issues.</p></div>","PeriodicalId":54614,"journal":{"name":"Physics of the Earth and Planetary Interiors","volume":"355 ","pages":"Article 107237"},"PeriodicalIF":2.4,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0031920124000955/pdfft?md5=43bcc5d6c37c70349093fd2bc6006627&pid=1-s2.0-S0031920124000955-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141932556","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}