Earth and Planetary Science Letters最新文献

{"title":"Magmatic N2 degassing dominates nitrogen loss during sediment subduction and granitoid genesis","authors":"Yunzhe Chen ,&nbsp;Peng Wu ,&nbsp;Tiago Angelo ,&nbsp;Christopher Spencer ,&nbsp;Long Li","doi":"10.1016/j.epsl.2024.119094","DOIUrl":"10.1016/j.epsl.2024.119094","url":null,"abstract":"<div><div>Subducting sediments contain much more abundant nitrogen (N) than the other slab components. The fate of sedimentary N along subduction directly determines the quantity of surficial N that can be released back to the atmosphere/crust or further delivered to the deep mantle, which has a strong impact on the long-term evolution of the N budgets and isotopic signatures of Earth's major reservoirs. Previous studies on the fate of subducted sedimentary N have been intensively focused on assessing the extent of metamorphic N devolatilization from metasedimentary rocks varying from ultrahigh-pressure eclogites facies (subducted to as deep as 90 km) in cold subduction zones to medium-pressure amphibolite facies in extremely hot subduction zones. However, the fate of sedimentary N after these metamorphic stages, particularly during sediment melting and subsequent magmatic crystallization, has not been examined so far. Here, we present the N data of the Cretaceous peraluminous granitoids in the Oman-United Arab Emirates area, which were formed by melting of subducted pelagic sediments followed by intrusion and crystallization in the lithospheric mantle before the entire lithospheric section was obducted to form the Oman-United Arab Emirates ophiolites. The 27 studied samples show surprisingly low N contents (4.0 - 13.7 ppm; mean: 6.9 ± 2.3 ppm; 1σ) and a narrow δ¹⁵N range (mostly in the range of –1.4‰ to +2.2‰; mean: +0.4 ± 1.5‰; 1σ). Data modeling indicates that the N in these granitoids contains little mantle contribution and was predominantly inherited from their source rocks. Compared with potential source rocks, these granitoids display orders of magnitude lower N contents but comparable δ¹⁵N values, indicating that the significant N loss during the genesis of these granitoids was associated with little N isotope fractionation. This suggests that magmatic N₂ degassing (with minor N isotope fractionation) rather than metamorphic N devolatilization (with much larger N isotope fractionation) is the dominant mechanism driving the N loss from subducted sediments.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119094"},"PeriodicalIF":4.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct in situ evidence of tidal roles in the formation of contourite depositional systems","authors":"Shaoru Yin ,&nbsp;F. Javier Hernández-Molina ,&nbsp;Miguel Bruno Mejías ,&nbsp;Juan J. Gomiz-Pascual ,&nbsp;Michele Rebesco ,&nbsp;Tom Manley ,&nbsp;Patricia L. Manley ,&nbsp;Jiabiao Li","doi":"10.1016/j.epsl.2024.119100","DOIUrl":"10.1016/j.epsl.2024.119100","url":null,"abstract":"<div><div>Tidal currents are ubiquitous in the oceans, but the role of these currents in contributing to form contourite depositional systems is poorly understood. Here we evaluated the significance of these currents in the formation and shaping of the contourite depositional systems. We examined in situ current data, spanning three months to one year, from four contourite sites at the exit of the Strait of Gibraltar, the northern North Atlantic Ocean, the Pacific margin of the Antarctic Peninsula, and the Lake Champlain. These current data indicate that tidal currents contribute to varying degrees to the formation of contourite erosional and depositional features, depending on the relative strengths of local tidal currents and background water mass circulation. Tidal currents enhance sediment resuspension in moats and channels, and encourage deposition on drifts, thereby promoting the development of contourite depositional systems. Baroclinic (internal) tidal currents are likely the dominant agent. Our findings indicate that tidal influences, especially those of internal tides, need to be considered in studies of the generation and evolution of contourite depositional systems.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119100"},"PeriodicalIF":4.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142594107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unsteady slip pulses under spatially-varying prestress","authors":"Anna Pomyalov,&nbsp;Eran Bouchbinder","doi":"10.1016/j.epsl.2024.119111","DOIUrl":"10.1016/j.epsl.2024.119111","url":null,"abstract":"&lt;div&gt;&lt;div&gt;It has been recently established that self-healing slip pulses under uniform background/ambient stress (prestress) &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; are intrinsically unstable frictional rupture modes, i.e., they either slowly expand or decay with time &lt;em&gt;t&lt;/em&gt;. Furthermore, their spatiotemporal dynamics have been shown to follow a reduced-dimensionality description corresponding to a special one-dimensional curve &lt;span&gt;&lt;math&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;, parameterized by &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;, in a plane defined by the pulse propagation velocity &lt;span&gt;&lt;math&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; and size &lt;span&gt;&lt;math&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;. Yet, uniform prestress is rather the exception than the rule in natural faults. Here, we study the effects of a spatially-varying prestress &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; (in the fault direction &lt;em&gt;x&lt;/em&gt;) on 2D slip pulses, initially generated under a uniform &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; along a rate-and-state friction fault. We consider both periodic and constant-gradient prestress distributions &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; around the reference uniform &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt;. For a periodic &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;, pulses either sustain and form quasi-limit cycles in the &lt;span&gt;&lt;math&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; plane or decay predominantly monotonically along the &lt;span&gt;&lt;math&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; curve depending on the instability index of the initial pulse and the properties of the periodic &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;. For a constant-gradient &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;, expanding and decaying pulses closely follow the &lt;span&gt;&lt;math&gt;&lt;mi&gt;L&lt;/mi&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;c&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; curve, with small systematic shifts determined by the sign and magnitude of the gradient. We also find that a spatially-varying &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; can revert the expanding/decaying nature of the initial reference pulse. Finally, we show that a constant-gradient &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;b&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;x&lt;/mi&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;, of sufficient magnitude and specific sign, can lead to the n","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119111"},"PeriodicalIF":4.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stable silicon isotope fractionation reflects the routing of water through a mesoscale hillslope","authors":"Andrew Guertin ,&nbsp;Charlie Cunningham ,&nbsp;Julien Bouchez ,&nbsp;Marine Gelin ,&nbsp;Jon Chorover ,&nbsp;Hannes Bauser ,&nbsp;Minseok Kim ,&nbsp;Peter Troch ,&nbsp;Louis A. Derry ,&nbsp;Jennifer L. Druhan","doi":"10.1016/j.epsl.2024.119098","DOIUrl":"10.1016/j.epsl.2024.119098","url":null,"abstract":"<div><div>Concentration - isotope Ratio - Discharge (C-R-Q) relationships offer a promising means of disentangling the underlying hydrologic, geochemical, and ecological factors that produce variations in stream solute chemistry across a variety of critical zone systems. However, natural environments are both temporally and spatially complex, and prevailing interpretations of these C-R-Q patterns remain difficult to validate. Here we employ three replicate artificially constructed hillslopes at the Landscape Evolution Observatory (LEO) in Tucson, Arizona as simplified analogs to natural catchments. LEO allows us to record silicon stable isotope (δ³⁰Si) signatures of fluid discharge under a controlled irrigation schedule in a system devoid of vegetation. This unique meso‑scale experiment enables, for the first time, evaluation of metalloid stable isotope signatures at the scale of natural hillslopes constrained to known fluid transit time distributions (TTDs) and limited to fractionation in association with secondary mineral formation. We report δ³⁰Si in discharge samples collected over three randomized storm events of varying intensity. The data reflect consistent enrichment in the fluid phase between +1.00 and +2.07 ‰ across the three hillslopes, despite highly variable irrigation scenarios, reflecting substantial loss of SiO₂ from solution due to secondary mineral precipitation. We compare results from an isotope-enabled Reactive Transport Model (RTM) and the discharge measurements from LEO to constrain the contributions of both characteristic watershed TTDs and fractionation pathways in emergent δ³⁰Si signatures. Our study confirms and expands upon recent work in natural systems attributing intra-site variability in silicon stable isotope signatures to the routing of fluid through catchments.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119098"},"PeriodicalIF":4.8,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Exploring frictional properties of upper plate fault reactivation in subduction zones: The Atacama Fault System in northern Chile","authors":"Yerko González ,&nbsp;Gabriel González ,&nbsp;Elena Spagnuolo ,&nbsp;Giacomo Pozzi ,&nbsp;Erik Jensen ,&nbsp;Stefano Aretusini ,&nbsp;Anja M. Schleicher","doi":"10.1016/j.epsl.2024.119106","DOIUrl":"10.1016/j.epsl.2024.119106","url":null,"abstract":"<div><div>The Maule 2010 and Tohoku-Oki 2011 earthquakes demonstrated how dormant upper plate faults can be reactivated as normal faults by plate margin relaxation following megathrust slip. However, the reactivation mechanisms of these types of faults are yet unexplored. To provide a better understanding of these mechanisms, we collected fault core samples from fault segments of the Atacama Fault System in northern Chile. The sampled fault segments have clear morphological evidence of Quaternary reactivation as normal fault. We performed laboratory experiments to measure the fault strength, stability and dynamic weakening. We consider low-velocity tests for exploring the frictional strength and velocity dependence of friction via a double-direct shear apparatus and ii) high-velocity tests for investigating the frictional properties at seismic velocities via a rotary shear apparatus. The experiments revealed that fault cores have low frictional strength, velocity-strengthening behaviour and strong dynamic weakening. Additionally, a novel experimental procedure that simulates stress relaxation by stepwise reducing of the normal stress on the sample assembly showed: 1. Accelerating creep towards dynamic weakening in chlorite-rich gouges and 2. oscillatory sliding in fault gouges enriched in illite. By extrapolating our experimental observations to natural conditions, we conclude that stable sliding is favoured during the interseismic phase of the subduction earthquake cycle, whereas unstable sliding is favoured during the coseismic and postseismic phases. The latter occurs via normal stress reduction during the shift from interseismic compression to co- and postseismic tension at the plate margin.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119106"},"PeriodicalIF":4.8,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraints on the continental weathering intensity through the Permian using lithium isotopes of well-preserved brachiopod shells","authors":"Wen-qian Wang ,&nbsp;Feifei Zhang ,&nbsp;Chun-Yao Liu ,&nbsp;Philip A.E. Pogge von Strandmann ,&nbsp;Guolin Xiong ,&nbsp;Quanfeng Zheng ,&nbsp;Claudio Garbelli ,&nbsp;Yichun Zhang ,&nbsp;Dongxun Yuan ,&nbsp;Shu-zhong Shen","doi":"10.1016/j.epsl.2024.119101","DOIUrl":"10.1016/j.epsl.2024.119101","url":null,"abstract":"<div><div>Lithium isotopic compositions (δ⁷Li) in marine carbonates provide a powerful means to track continental weathering intensity through geological history and promote our understanding of how and why Earth remained habitable. However, δ⁷Li values in ancient carbonates can be affected by factors such as primary carbonate mineralogy (e.g., aragonite, high-Mg calcite, low-Mg calcite) and post-depositional diagenesis, which may alter their primary signals. Modern articulate brachiopod shells have shown a constant δ⁷Li offset compared to contemporary seawater, suggesting that fossil brachiopod shells could serve as robust archives for this geochemical proxy due to their diagenetically resistant low-Mg calcite composition. Despite this potential, few studies have explored this topic. In this study, we analyze and compare the geochemical compositions of fossil brachiopod shells and their enclosing carbonate rocks from Permian strata in South China to investigate whether brachiopod shells can reliably preserve the δ⁷Li values of ancient seawater and, if they do, to obtain new constraints on changes in the continental weathering regimes through the Permian. We used several diagenetic screening methods, including scanning electron microscopy, cathodoluminescence microscopy, and elemental concentrations to detect potential diagenetic alteration. Our results indicate that 32 out of 49 shells preserve primary δ⁷Li values. Notably, we observed that δ⁷Li offsets between brachiopod shells and their enclosing carbonate rocks vary across the studied sections, likely due to diagenetic alteration of the bulk carbonates. Using the δ⁷Li values from well-preserved brachiopod shells, we reconstructed δ⁷Li variations of Permian seawater. We identified three distinct intervals: (1) extremely low δ⁷Li_sw values (as low as 6.7 ± 2.9‰, <em>n</em> = 12, 1sd) during the Asselian and Sakmarian stages, (2) high δ⁷Li_sw values (32.6 ± 4.5‰, <em>n</em> = 3, 1sd) similar to modern seawater during the Kungurian stage, and (3) relatively low δ⁷Li_sw values (13.6 ± 3.9‰, <em>n</em> = 14, 1sd) from the Capitanian to the Changhsingian stages. These significant changes in δ⁷Li values of Permian seawater indicate dramatic changes in continental weathering regimes during the Permian, possibly linked to major climate changes, such as the termination of the Late Paleozoic Ice Age and warming associated with the emplacement of the large igneous provinces.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119101"},"PeriodicalIF":4.8,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142587390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 slow slip event cycle along the Izmit segment of the North Anatolian Fault","authors":"Estelle Neyrinck ,&nbsp;Baptiste Rousset ,&nbsp;Cécile Doubre ,&nbsp;Luis Rivera ,&nbsp;Cécile Lasserre ,&nbsp;Marie-Pierre Doin ,&nbsp;Philippe Durand ,&nbsp;Roger Bilham ,&nbsp;Ziyadin Çakir ,&nbsp;FLATSIM Working Group","doi":"10.1016/j.epsl.2024.119104","DOIUrl":"10.1016/j.epsl.2024.119104","url":null,"abstract":"<div><div>The occurrence of aseismic creep along seismogenic faults significantly impacts seismic hazard assessment by releasing accumulated stress and reducing the slip deficit. Since the 1999 <span><math><msub><mrow><mi>M</mi></mrow><mrow><mi>w</mi></mrow></msub><mn>7.6</mn></math></span> Izmit earthquake on the North Anatolian Fault in Türkiye, while aseismic creep has been observed as a postseismic response to the Izmit rupture, additional slow slip events were detected in 2015 and 2016, accommodating several millimeters of relative displacement over periods of approximately one month. By automating Interferometry Synthetic Aperture Radar time series processing from 2016 to 2021 (FLATSIM project) and applying specific post-processing, we extract the tectonic signal to estimate the slip dynamics of the Izmit segment, including the detection and characterization of slow slip events. Modeling the slip distribution at depth on a 2D fault interface within a layered elastic half-space, we estimate a locking depth of <span><math><mn>11</mn><mspace></mspace><mi>k</mi><mi>m</mi></math></span> and steady creep between 2 and <span><math><mn>5</mn><mspace></mspace><mi>k</mi><mi>m</mi></math></span>. Above the steady creep zone, we identify two new shallow slow slip events in March 2018 and November 2019, with moment magnitudes of 4.3 and 4.4, respectively. Based on creepmeter measurements, we estimate a lateral propagation velocity of <span><math><mn>6.4</mn><mspace></mspace><mi>k</mi><mi>m</mi><mo>/</mo><mi>d</mi><mi>a</mi><mi>y</mi></math></span> for the 2019 event. The location of these shallow slow slip events above the sedimentary-bedrock interface suggests a critical role of variations in frictional properties in the occurrence of transient slip events.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119104"},"PeriodicalIF":4.8,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Variations in antimony isotope and toxic metals across the Guadalupian-Lopingian (Permian) boundary at Penglaitan, China: Implications for the Emeishan volcanism and marine extinction","authors":"Shuyang Li ,&nbsp;Yuangeng Huang ,&nbsp;Zhong-Qiang Chen ,&nbsp;Linjie Chen ,&nbsp;Paul B. Wignall ,&nbsp;Junhang Dong ,&nbsp;Xing Liu ,&nbsp;Hongtao Zheng ,&nbsp;Guan Wang ,&nbsp;Zhensheng Wei ,&nbsp;Zhenli Zhu","doi":"10.1016/j.epsl.2024.119096","DOIUrl":"10.1016/j.epsl.2024.119096","url":null,"abstract":"<div><div>The Guadalupian-Lopingian (G-L) extinction event during the Permian stands a major diversity decline. The Emeishan Large Igneous Province (ELIP) has long been posited as the principal trigger, but direct geochemical evidence establishing a connection between these events has remained elusive. Here, we present antimony (Sb) concentration and isotope (δ¹²³Sb) analyses conducted across the G-L boundary at Penglaitan, South China. Our investigation reveals a large spike in Sb concentration concurrent with a significant decline in δ¹²³Sb values spanning the G-L boundary. The δ¹²³Sb values range from −0.49‰ to +0.48‰ with the lightest values occurring at the main extinction horizon of marine benthos. Other toxic metals (As, Hg, Pb, etc.) are enriched in the same horizons and are likely of volcanic origin. Our estimates based on mass balance calculations indicate that the ELIP increased oceanic toxic metal loading by an order of magnitude. Their toxic effects may have contributed to stressed regional marine environment and biodiversity loss in South China during the G-L transition.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119096"},"PeriodicalIF":4.8,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 chlorine evolution of arc magmas and the crustal water filter","authors":"Jackson Stone Borchardt ,&nbsp;Cin-Ty A. Lee","doi":"10.1016/j.epsl.2024.119048","DOIUrl":"10.1016/j.epsl.2024.119048","url":null,"abstract":"<div><div>Degassing of water from magmatic systems is key to transporting metals from magmas to form ore deposits, but elements like chlorine, through the formation of anion complexes, can be important in solubilizing and mobilizing these metals into water-rich fluids. Reconstructing the Cl systematics of evolving magmas is thus an important step towards understanding the origins of ore deposits, but the magmatic record is not well preserved because Cl can be lost during degassing. Here, we reconstruct the pre-degassing history of Cl in subduction zone (arc) magmas through amphiboles, which incorporate Cl directly into their crystal structures, preserving pre-eruptive magmatic signatures. Amphibole-reconstructed Cl contents indicate that magmatic differentiation can lead to a 4-fold increase in concentration due to Cl's incompatible behavior. The amphibole-reconstructed Cl contents of arc magmas are also significantly higher than values reported from melt inclusions, suggesting that many melt inclusions may have been trapped after magmas had already lost some Cl. We show that such Cl loss is likely associated with preferential partitioning of Cl into hydrous fluids degassed from the magma during crustal storage or ascent. The extent of Cl depletion can thus be used to estimate how much water was lost during early degassing. If Cl is important to certain ore deposits, magmatic water content may play an indirect role. Magmas too rich in water will lose water and hence Cl at greater depths, rendering such magmas less able to transport metals to the upper crust. By contrast, drier magmas may not produce enough Cl-rich fluids to mobilize metals. Thus, magmas with intermediate water contents may produce enough Cl-rich fluids at the right depths for certain types of ore deposits.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119048"},"PeriodicalIF":4.8,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Complex basalt evolution in the Chang'e-6 landing area","authors":"Sheng Gou ,&nbsp;Zongyu Yue ,&nbsp;Yangting Lin ,&nbsp;Kaichang Di ,&nbsp;Patrick C. Pinet ,&nbsp;Roberto Bugiolacchi ,&nbsp;Yuyang He ,&nbsp;Wei Yang ,&nbsp;Honglei Lin ,&nbsp;Hengci Tian ,&nbsp;Sen Hu","doi":"10.1016/j.epsl.2024.119091","DOIUrl":"10.1016/j.epsl.2024.119091","url":null,"abstract":"<div><div>China's Chang'e-6 (CE6) sample return mission targeted the southern part of the Apollo basin inside the South Pole-Aitken (SPA) basin on the lunar farside. The spectrally peculiar mare basalts in the CE6 landing area had undergone complex evolution: (1) At least three mare floodings with low- to intermediate-titanium (Ti) contents and a total volume of &gt; 798 km³ occurred during the Imbrian and Eratosthenian periods; (2) The scales of basalt eruption decreased with time, and nine wrinkle ridges (WRs) formed during different stages of floodings; (3) Exotic non-mare materials at the CE6 sampling site might be chiefly from noritic Chaffee S crater (∼16.6 cm-thick) and anorthositic Vavilov crater (∼1.7 cm-thick). (4) Impact gardening would mix local low/intermediate-Ti basalts and exotic non-mare materials. After analyzing the local basalt-dominant samples collected by the CE6 probe with sophisticated instruments in the terrestrial laboratories, a series of lunar scientific problems would be addressed definitely, for example, the ages and compositions of the mare basalts, the evolution of the low- and intermediate-Ti basalts, and the effects of solar wind on the lunar regolith. In addition, if the returned samples contain exotic impact melts and ejecta of both the Apollo and SPA basins, analyses on these non-mare materials would help to constrain the timing of the Apollo and SPA impact events, the extent and composition of the proposed (differentiated) SPA melt pool, and even the compositions of the lunar lower crust/upper mantle. Addressing these fundamental problems would be a significant contribution to the lunar science community.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"648 ","pages":"Article 119091"},"PeriodicalIF":4.8,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}