Earth and Planetary Science Letters最新文献

{"title":"Seasonal upper ocean temperatures from coccolith clumped isotopes and a proxy-model comparison for the late Early Eocene Climatic Optimum","authors":"Alexander J. Clark ,&nbsp;Xiaoqing Liu ,&nbsp;Madalina Jaggi ,&nbsp;Stefano M. Bernasconi ,&nbsp;Victoria E. Taylor ,&nbsp;A. Nele Meckler ,&nbsp;Heather M. Stoll","doi":"10.1016/j.epsl.2026.119863","DOIUrl":"10.1016/j.epsl.2026.119863","url":null,"abstract":"<div><div>The Early Eocene Climatic Optimum (EECO) is a time interval of great interest to the paleoclimate community due to the overall hot temperatures and polar amplification reconstructed by multiple temperature proxies. However, these conditions have been hard to reproduce in climate models and temperature estimates from different proxy carriers for the same regions can differ by 10 °C. Coccolith clumped isotopes—with a robust calibration recently established from laboratory cultures and sediment traps—represent an as-yet untested temperature proxy for this interval. Coccoliths are produced by coccolithophores with well-constrained depth and ecological preferences and therefore provide a clear depth and seasonal target for a proxy-model comparison for the late EECO (∼51.0–50.3 Ma).</div><div>We measured coccolith clumped isotopes in 15 globally distributed sites and find a 10 °C upper ocean meridional temperature gradient, similar to previous studies using different proxy systems and carriers such as Mg/Ca and δ¹⁸O in foraminifera. We compare our coccolith clumped isotope-derived temperatures to the DeepMIP model compilation, using the known modern ecological constraints of coccolithophores, and divide the model simulations into groups sorted by the difference in global mean surface temperature relative to preindustrial levels (ΔGMST). The best fitting model simulations have ΔGMST between 9.0–13.0 °C. Proxy-model temperature differences up to ±6 °C reveal a hemispheric asymmetry, with warmer proxy/colder model temperatures in the Southern Ocean and cooler proxy/warmer model temperatures in the northern mid-latitudes, highlighting the need for improved model constraints to more accurately simulate ocean circulation and heat transport phenomena.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"679 ","pages":"Article 119863"},"PeriodicalIF":4.8,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036669","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":"Accumulation of remineralised carbon and nutrients in the mid-depth Atlantic during Heinrich Stadial 1 and the Younger Dryas","authors":"Joseph A. Stewart ,&nbsp;Laura F. Robinson ,&nbsp;James W.B. Rae ,&nbsp;Naomi Pratt ,&nbsp;Tianyu Chen ,&nbsp;Maria Luiza de Carvalho Ferreira ,&nbsp;Andrea Burke ,&nbsp;Tao Li ,&nbsp;Tina van de Flierdt","doi":"10.1016/j.epsl.2026.119866","DOIUrl":"10.1016/j.epsl.2026.119866","url":null,"abstract":"<div><div>Atmospheric CO₂ and the temperature of the interior Atlantic Ocean both increased in 2-steps during the last deglaciation, particularly during Heinrich Stadial 1 (HS1; ∼16 ka) and the Younger Dryas (YD; ∼12 ka). However, what drove these punctuated rises remains a long-standing question. The role of deep-ocean carbon storage, release, and redistribution continues to be debated. To establish the role of ocean circulation in deglacial carbon and nutrient cycling, we present new multi-proxy data in sub-fossil corals from mid-depths in the Equatorial Atlantic, including boron isotopes (δ¹¹B; seawater pH), Ba/Ca (seawater [Ba] and refractory nutrients), and neodymium isotopes (ε_Nd; provenance of seawater signal). Corals are dated to a precise radiometric age scale and combined with previously published radiocarbon and temperature proxy measurements on the same samples. Our data reveal abrupt intervals (∼500 years) of notably low pH, Ba-rich, and radiocarbon-depleted (old) waters at 15.4 and 12.0 ka during HS1 and the YD at depths of ∼1700 m. However, very low ε_Nd (unradiogenic) values suggest that these corals were bathed in northern-sourced Atlantic waters throughout the deglaciation. These results imply that these (old) carbon- and nutrient-rich intermediate waters were not sourced from the carbon- and nutrient-rich Southern Ocean via Antarctic Intermediate Water (AAIW). Instead, carbon and nutrient accumulation at mid-depths in the tropical Atlantic was likely the result of remineralisation of organic matter at times of Atlantic Meridional Overturning Circulation (AMOC) slowdown. The Atlantic Ocean interior was therefore accumulating heat and carbon during these times when deepwater flushing was minimal, thus acting to partially dampen atmospheric CO₂ rise and warming caused by ventilation of the Southern and Pacific Oceans.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"679 ","pages":"Article 119866"},"PeriodicalIF":4.8,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146090729","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":"Induced seismicity in the southern Sichuan basin regulated by heterogeneous folding","authors":"Bingfeng Zhang ,&nbsp;Xuewei Bao ,&nbsp;Mengfan Jiang ,&nbsp;Kecheng Zhou","doi":"10.1016/j.epsl.2026.119860","DOIUrl":"10.1016/j.epsl.2026.119860","url":null,"abstract":"<div><div>The potential for strong induced earthquakes in industrial production fields is largely controlled by the spatial arrangement of pre-existing faults shaped by regional tectonics. The 2021 Ms 6.0 Luxian earthquake in the southern Sichuan basin is an unusual case in which the seismogenic fault geometry deviates from the prevailing regional stress field and geological framework. To date, the seismogenic environment and the tectonic processes responsible for this destructive event remain poorly understood. In this study, we present a sedimentary shear-wave velocity model and eleven moment tensor solutions across the Luxian shale gas field, derived using data collected by our newly deployed seismic network. Our results reveal previously unrecognized, nearly reversed lateral variations in the amplitudes of synclinal low-velocity anomalies between terrestrial and marine strata, in addition to a first-order velocity contrast that correlates with the regional anticline–syncline architecture. The central Yujiasi syncline exhibits weaker low-velocity anomalies in the shallow terrestrial strata than areas to the north and south, reflecting lower strain intensity likely influenced by shallower décollement layers. Detected seismicity and anomalous reverse-faulting events with fold-parallel P-axes (including the Ms 6.0 earthquake) cluster mainly within two strain transition zones of the Yujiasi syncline, where stress is expected to concentrate and form fold-normal fault planes. These observations provide direct evidence that heterogeneous folding regulates the spatial distribution of induced seismicity in the southern Sichuan basin. They also help identify areas susceptible to induced seismic hazards and provide guidance for planning hydraulic fracturing operations in the region.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"679 ","pages":"Article 119860"},"PeriodicalIF":4.8,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036670","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":"Continued continental weathering during snowball earth mitigated greenhouse gas buildup and prolonged global glaciation","authors":"Shintaro Kadoya ,&nbsp;Mohit Melwani Daswani","doi":"10.1016/j.epsl.2026.119837","DOIUrl":"10.1016/j.epsl.2026.119837","url":null,"abstract":"<div><div>Global glaciations, also known as snowball events, represent some of Earth’s most significant climate changes. The Neoproterozoic Sturtian glaciation lasted 4–15 times longer than the subsequent Marinoan glaciation, but the causes of this dramatic difference remain unclear. The standard theory attributes the termination of such events to a pause in silicate weathering due to the absence of liquid water on continents. However, recent evidence of syn-glacial dolomite precipitation suggests the possibility of continental weathering during global glaciation. We numerically investigate water-rock reactions under limited water and fresh rock supplies to identify the key factors controlling subglacial weathering and to evaluate their impact on the carbon cycle during global glaciation. The compositions of the discharge fluid and mineral assemblage reach their steady state over a timescale determined by the rate of fresh rock supply. These steady-state compositions are identical when the ratio of the meltwater production rate (<span><math><msub><mi>F</mi><mtext>w</mtext></msub></math></span>) to the fresh rock supply rate (<span><math><msub><mi>F</mi><mtext>r</mtext></msub></math></span>) is constant (<span><math><mrow><msub><mi>F</mi><mtext>w</mtext></msub><mo>/</mo><msub><mi>F</mi><mtext>r</mtext></msub><mo>=</mo><mi>k</mi></mrow></math></span>). Furthermore, the maximum estimated CO₂ consumption could match Earth’s volcanic CO₂ emission, assuming present-day Antarctic conditions for meltwater production and fresh rock supply. This finding contradicts the standard assumption that silicate weathering ceases during global glaciation and suggests a mechanism for the prolonged duration of the Sturtian glaciation. These results demonstrate that subglacial weathering represents a previously unrecognized feedback mechanism that could account for the dramatically different durations of Neoproterozoic snowball Earth events.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"679 ","pages":"Article 119837"},"PeriodicalIF":4.8,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036665","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":"Experimental determination of equilibrium fractionation of triple oxygen isotopes between dissolved sulfite species and water","authors":"Yu Wei ,&nbsp;Hao Yan ,&nbsp;Yan Fang","doi":"10.1016/j.epsl.2026.119862","DOIUrl":"10.1016/j.epsl.2026.119862","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Sulfite, a key intermediate sulfoxyanion in both the reductive and oxidative sulfur cycles, rapidly exchanges oxygen isotopes with ambient water under circumneutral to acidic conditions. Equilibrium oxygen isotope fractionation factors (&lt;sup&gt;18&lt;/sup&gt;&lt;em&gt;α&lt;/em&gt; and &lt;sup&gt;17&lt;/sup&gt;&lt;em&gt;α&lt;/em&gt;) between sulfite and water are therefore critical for interpreting the triple oxygen isotope composition of sulfate and for constraining sulfur cycling. However, equilibrium &lt;sup&gt;18&lt;/sup&gt;&lt;em&gt;α&lt;/em&gt; values remain poorly constrained, with significant discrepancies among experimental and theoretical estimates, largely due to experimental challenges in determining sulfite oxygen isotope compositions and uncertainties in theoretical calibrations. Moreover, equilibrium &lt;sup&gt;17&lt;/sup&gt;&lt;em&gt;α&lt;/em&gt; values have previously been derived only through theoretical calculation. In this study, we applied a pH-shifting technique to eliminate kinetic isotope effects during sulfite precipitation. We also employed a recently developed high-temperature reduction–discharge–CO&lt;sub&gt;2&lt;/sub&gt;/O&lt;sub&gt;2&lt;/sub&gt; isotope exchange technique to minimize the influence of sulfite hygroscopicity and precisely measured the triple oxygen isotope composition of sulfite equilibrated with water across a pH range of 4.60 to 8.89 and temperature range of 12 to 55 °C. Our results show a consistent, monotonic dependence of oxygen isotope fractionation between bulk sulfite (encompassing all S(IV)-oxyanions, including SO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2–&lt;/sup&gt; and the bisulfite isomers (HS)O&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;–&lt;/sup&gt; and SO&lt;sub&gt;2&lt;/sub&gt;(OH)&lt;sup&gt;–&lt;/sup&gt;) and water on both pH and temperature. We attribute the former to pH-controlled speciation of dissolved sulfite. From our data, we derived equilibrium fractionation factors for oxygen isotopes between bisulfite and water, and between sulfite (SO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2–&lt;/sup&gt;) and water:&lt;/div&gt;&lt;div&gt;1000ln&lt;sup&gt;18&lt;/sup&gt;&lt;em&gt;α&lt;/em&gt;&lt;sub&gt;bisulfite–H2O&lt;/sub&gt; = (7.06 ± 1.06) × 10&lt;sup&gt;3&lt;/sup&gt;/T – 8.80 ± 3.49&lt;/div&gt;&lt;div&gt;1000ln&lt;sup&gt;18&lt;/sup&gt;&lt;em&gt;α&lt;/em&gt;&lt;sub&gt;sulfite–H2O&lt;/sub&gt; = (6.59 ± 1.32) × 10&lt;sup&gt;3&lt;/sup&gt;/T – 12.56 ± 4.34&lt;/div&gt;&lt;div&gt;The associated mass-dependent fractionation exponents (&lt;em&gt;θ&lt;/em&gt; = ln&lt;sup&gt;17&lt;/sup&gt;&lt;em&gt;α&lt;/em&gt;/ln&lt;sup&gt;18&lt;/sup&gt;&lt;em&gt;α&lt;/em&gt;) are temperature-independent within our studied range, with values of 0.5202 ± 0.0003 for bisulfite and 0.5155 ± 0.0008 for sulfite. These imply that the Δ′&lt;sup&gt;17&lt;/sup&gt;O values of bisulfite and sulfite are offset by -0.152‰ and −0.143‰, respectively, from that of ambient water (assuming a reference slope of 0.5305) at 25 °C. Our findings offer new insights into the isotope fractionations associated with microbial sulfate reduction and pyrite oxidation. The observed pH-dependent variations in sulfate δ&lt;sup&gt;18&lt;/sup&gt;O signatures during abiotic aerobic pyrite weathering may reflect oxidation of distinct sulfite species under variable pH conditions. Furthermore, the isotope fractionation observed between residual sulfate and water during microbial sulfat","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"679 ","pages":"Article 119862"},"PeriodicalIF":4.8,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036697","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":"Comment on: Evolution of iron formation to ore during Ediacaran to early Paleozoic tectonic stability, by Fuentes et al. (2025)","authors":"B. Rasmussen ,&nbsp;J-W. Zi ,&nbsp;J.R. Muhling ,&nbsp;I.R. Fletcher","doi":"10.1016/j.epsl.2026.119864","DOIUrl":"10.1016/j.epsl.2026.119864","url":null,"abstract":"","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"679 ","pages":"Article 119864"},"PeriodicalIF":4.8,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036667","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":"Zircon deformation features reveal sequence of transient high stress, tension and shearing during seismic faulting: A case study from the Ivrea-Verbano Zone, Italy","authors":"Sandra Piazolo ,&nbsp;Antonio Langone","doi":"10.1016/j.epsl.2026.119858","DOIUrl":"10.1016/j.epsl.2026.119858","url":null,"abstract":"<div><div>The mechanisms associated with the propagation of fault ruptures remain debated in terms of sequence of events, processes and magnitude of stresses involved. Microstructures of zircon grains located within and in the immediate vicinity of pseudotachylyte veins reveal a sequence of events transient in time and space and allow recognition of different processes during rupture. The dynamic rupture causes, at its propagating tip, a damage zone of several centimetres thickness. In this damage zone, zircon grains exhibit crystal-plastic deformation signatures ranging from crystal lattice bending continuous throughout whole grains, to distinct planar deformation bands and {112} twin lamellae. Presence of planar deformation bands and {112} twin lamellae suggest locally high stresses, based on similar features reported from meteorite impacts. Absence of well-developed subgrains indicate dominance of low temperature plasticity at the rupture tip. Subsequently, those grains with highest dislocation densities undergo in-situ grain fragmentation. The observed correlation of grains with very high dislocation densities and in-situ grain fragmentation suggests that the effective tensile strength of these grains is sufficiently decreased by the high stored elastic energy to cause their fragmentation when subject to tensile stresses in the wake of the propagating rupture tip. Subsequent displacement along connected damage zone fracture surfaces results in pseudotachylytes formation.</div><div>Our data shows that dynamic rupture initiation and propagation results in stresses heterogeneously distributed in space, magnitude and sign causing both ductile and brittle deformation. Our study highlights the value of the accessory mineral zircon in deciphering the nature of rupture zone dynamics.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"679 ","pages":"Article 119858"},"PeriodicalIF":4.8,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146036666","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":"Reply to the comment on “The influence of cementation on fault stability”","authors":"G. Volpe ,&nbsp;R. Affinito ,&nbsp;L. Calzolari ,&nbsp;G. Pozzi ,&nbsp;C. Marone ,&nbsp;C. Collettini","doi":"10.1016/j.epsl.2026.119867","DOIUrl":"10.1016/j.epsl.2026.119867","url":null,"abstract":"","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"679 ","pages":"Article 119867"},"PeriodicalIF":4.8,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146001678","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":"Geochemical controls on the formation of lithium brines in closed-basins of the Lithium Triangle","authors":"Gordon D.Z. Williams ,&nbsp;Julien Barre ,&nbsp;Pascale Louvat ,&nbsp;Sylvain Bérail ,&nbsp;Romain Millot ,&nbsp;Avner Vengosh","doi":"10.1016/j.epsl.2026.119849","DOIUrl":"10.1016/j.epsl.2026.119849","url":null,"abstract":"<div><div>Sustainable lithium mining is critical to the renewable energy transition. Closed-basin brines are a major source of lithium yet the processes governing lithium enrichment remain poorly understood. In the Lithium Triangle (LT) of South America, hypersaline brines display anomalously high lithium concentrations including at the Salar de Uyuni (SDU) in Bolivia. Using new geochemical and isotopic data from the SDU, Bolivia, we update the accepted conceptual model of evaporative concentration and sequential mineral precipitation based on the formation of calcite, gypsum, and halite. Here we identify ulexite (Na-Ca-borate) precipitation as a previously overlooked but key process in the evaporative evolution of inflow waters that fundamentally alters brine chemistry prior to halite saturation. Additionally, we reveal that surficial brines are largely disconnected from the major lithium inflow, and instead their chemistries are controlled by cyclic halite dissolution-precipitation, leading to the conservative enrichment of solutes like lithium, boron, and magnesium. We suggest that deep brines exploited for lithium extraction are fossil and reflect different stages of evaporation, while modern processes make little contribution to the solute and lithium balance. This new conceptual model revises the classic geochemical pathway and has broad implications for lithium brines and resource sustainability across the LT.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"679 ","pages":"Article 119849"},"PeriodicalIF":4.8,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146001768","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":"Inheritance of depleted mantle 186Os signatures in Tibetan ophiolitic chromitites","authors":"Yong Xu ,&nbsp;Qing Xiong ,&nbsp;Bin Qin ,&nbsp;Ruohan Gao ,&nbsp;Xiaohan Gong ,&nbsp;Degao Zhai ,&nbsp;D. Graham Pearson ,&nbsp;Jingao Liu","doi":"10.1016/j.epsl.2026.119855","DOIUrl":"10.1016/j.epsl.2026.119855","url":null,"abstract":"<div><div>The strongly compatible ¹⁹⁰Pt-¹⁸⁷Re-^{186, 187}Os systematics are relatively resistant to post-magmatic alteration and potentially preserve snapshots of deep mantle processes, making them valuable for tracing the origins of ultramafic-mafic rocks. To compare high-Cr and low-Cr podiform chromitites within ophiolite suites and uncover their formation mechanisms and related mantle evolution, we conducted the first combined high-precision ¹⁸⁶Os-¹⁸⁷Os and platinum group elemental (PGE: Os, Ir, Ru, Pt, and Pd) investigation of the Luobusa (mean Cr#=78) and Zedang (mean Cr#= 61) ophiolitic chromitites from south Tibet, China. The contrasting ¹⁸⁷Os/¹⁸⁸Os ratios between the Luobusa high-Cr (0.1271 ± 0.0002) and Zedang low-Cr (0.1292 ± 0.0004) chromitites correlate with their different degrees of fractionation between palladium-group (PPGE) and iridium-group (IPGE) PGE. This relationship follows a global trend and largely reflects the distinct natures of their parental magmas (boninitic vs. MORB-like). Importantly, both chromitites exhibit relatively homogeneous unradiogenic ¹⁸⁶Os/¹⁸⁸Os ratios (Luobusa: 0.1198359±0.0000026; Zedang: 0.1198355±0.0000005), which are independent of indices of magmatic differentiation such as Cr# and PGE fractionation. These values are comparable, within analytical uncertainties, to the averages of global abyssal peridotites and Phanerozoic Os-rich alloys, and are slightly lower than the primitive mantle and H ordinary chondrites. The ¹⁸⁶Os similarity between the Luobusa chromitites and abyssal peridotites is consistent with their known ¹⁸⁷Os similarity that features an unradiogenic ¹⁸⁷Os/¹⁸⁸Os peak at ∼0.126. The combined unradiogenic ¹⁸⁶Os-¹⁸⁷Os systematics also show no resolvable genetic linkage to plume-related magmatism or recycled crustal materials. Instead, their parental magmas appear to originate from a depleted mantle source.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"678 ","pages":"Article 119855"},"PeriodicalIF":4.8,"publicationDate":"2026-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035311","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}