Earth and Planetary Science Letters最新文献

{"title":"Snapshots of magmatic evolution revealed by zircon depth profiling","authors":"Erik J. Schoonover ,&nbsp;Michael R. Ackerson ,&nbsp;Joshua M. Garber ,&nbsp;Andrew J. Smye ,&nbsp;Andrew R. Kylander-Clark ,&nbsp;Jesse R. Reimink","doi":"10.1016/j.epsl.2024.118987","DOIUrl":"10.1016/j.epsl.2024.118987","url":null,"abstract":"<div><div>Upper-crustal granitoids are a late-stage product of crustal differentiation. This last stage in the evolution has been proposed to be the key interval that governs volcanic eruptions, ore formation, and fluid migration. Though numerous techniques have been employed to understand the evolution of late-stage felsic magmas, there remains little agreement regarding their crystallization histories. Here we use laser ablation depth profiling of zircon trace elements to probe the thermochemical evolution of well-characterized granitoid rocks from the Tuolumne Intrusive Suite (CA, USA). In combination with titanite trace-element data, we can determine the <em>T-X</em> trajectory of the magmatic system during zircon growth at the latest stage of crystallization. Our data also allows for a robust empirical calibration of the widely used Ti-in-zircon thermometer arising from the onset of titanite crystallization captured in zircon rims. These data show that Tuolumne zircon growth occurred at an <em>a</em>TiO₂ of 0.4–0.5, which is lower than many previous estimates. We further model zircon growth up- and down-temperature from titanite saturation, and document extended thermochemical growth records preserved in zircons from these upper-crustal melts. The calculated temperatures are consistent with zircon growth from 775 to 625 °C, indicating that zircon growth occurred over a wide temperature range down to, or potentially below, the water-saturated granite solidus. These findings provide empirically-calibrated values for use in other Ti-in-zircon and Zr-in-titanite temperature calculations, particularly to understand late-stage, low-temperature melts in granitoid systems.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 118987"},"PeriodicalIF":4.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326698","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":"Metamorphic CO2 fluxes offset the net geological carbon sink in the Himalayan-Tibetan orogen","authors":"Samyak Pradhan,&nbsp;Indra Sekhar Sen","doi":"10.1016/j.epsl.2024.119018","DOIUrl":"10.1016/j.epsl.2024.119018","url":null,"abstract":"<div><div>The carbon budget of the Himalayan-Tibetan orogen often neglects the poorly constrained CO₂ fluxes from the mantle and metamorphism that emerge directly from hot springs or diffusely through the soil, which can potentially warm the climate. What exists are either metamorphic phase relations, thermodynamic model-based CO₂ flux estimates, or field-based estimates in a single catchment extrapolated to the entire orogen having diverse geological and tectonics characteristics, heat flow, and hydrological regimes. Here, we apply a steady-state isotope mass balance model to observations of carbon isotope ratios to quantify the fluxes of CO₂ degassed using a global compilation of hot springs located on the fault systems of the Himalayan Tibetan orogen. We estimate that the hot springs could degas up to ∼84 % of the dissolved CO₂, releasing up to 1.5 ± 1.0 × 10¹¹ mol CO₂ yr^-1. When combined with diffused soil CO₂ emissions, the Himalayan Tibetan orogen has the potential to emit 3.0 ± 1.3 × 10¹¹ mol CO₂ yr^-1, which is similar in magnitude to CO₂ emission from continental rifts as well as the CO₂ drawdown due to silicate weathering in the orogen. We find that CO₂ released from the catchments of Himalayan-Tibetan orogen is primarily controlled by metamorphic processes <span><math><mrow><mo>(</mo><msubsup><mn>79</mn><mrow><mo>−</mo><mn>25</mn></mrow><mrow><mo>+</mo><mn>21</mn></mrow></msubsup><mrow><mspace></mspace><mo>%</mo></mrow><mo>)</mo></mrow></math></span>, with secondary controls from mantle degassing <span><math><mrow><mo>(</mo><msubsup><mn>7</mn><mrow><mo>−</mo><mn>7</mn></mrow><mrow><mo>+</mo><mn>17</mn></mrow></msubsup><mrow><mspace></mspace><mo>%</mo></mrow><mo>)</mo></mrow></math></span>, and carbonate dissolution (<span><math><mrow><msubsup><mn>14</mn><mrow><mo>−</mo><mn>14</mn></mrow><mrow><mo>+</mo><mn>26</mn></mrow></msubsup><mspace></mspace></mrow></math></span>%) and is insensitive to contributions from younger biospheric sources. Reevaluation of the geological carbon budget in Narayani Basin, Nepal, shows that metamorphic CO₂ in the collisional orogen is comparable to other carbon sources and sinks. We conclude that metamorphic CO₂ could offset the CO₂ drawdown by silicate weathering and OC_biosphere burial in the Himalayan-Tibet orogen, resulting in global warming over million-year time scales.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119018"},"PeriodicalIF":4.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326699","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 fate of ultramafic-rich mélanges in cold to hot subduction zones: Implications for diapirism (or not) and chemical geodynamics","authors":"Anna M. Rebaza ,&nbsp;Ananya Mallik ,&nbsp;Emily H.G. Cooperdock ,&nbsp;Bridgett I. Holman","doi":"10.1016/j.epsl.2024.119020","DOIUrl":"10.1016/j.epsl.2024.119020","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Buoyant ultramafic-rich (serpentine- or chlorite-rich) mélange diapirs in sediment-starved subduction zones can transport slab material to arc sources. While the buoyancy of chlorite-rich mélanges was previously investigated, serpentine-rich mélanges were never explored. Thus, the overall contribution of ultramafic-rich mélanges to buoyancy, the conditions for diapir formation, and their fate in subduction zones are not well constrained. Here, we investigate the partial melting behavior and the associated density transformations of a serpentine-rich matrix (5–10 wt.% H&lt;sub&gt;2&lt;/sub&gt;O) with minor sediments (9:1 ratio) at fore-arc (∼65 km) to sub-arc (∼95 km) depths (2–3 GPa and 800–1250 °C) and compare to that of chlorite-rich mélanges from the literature. Our results show that the solidus of serpentine-rich matrices is between 1050 and 1100 °C and requires either diapiric rise of the mélange into the hotter mantle wedge or interactions with a hotter asthenosphere through slab tears to partially melt and produce basaltic melts, whether in hot or cold slab channels. Chlorite-rich mélanges may account for the sources of some arc lavas, but partial melting of serpentine-rich mélanges produce melts depleted in CaO, TiO&lt;sub&gt;2&lt;/sub&gt;, alkalis, and are highly enriched in MgO compared to basaltic arc lavas. Both serpentine-rich and chlorite-rich matrices dehydrate to form denser peridotite and lose buoyancy at ∼800 °C and ≥1000 °C, respectively. Even if diapirism initiates in such mélanges near the slab-mantle interface, they would likely lose buoyancy upon ascent into the hotter mantle wedge resulting in stalled or failed diapirs. Diapir growth (τa) is controlled by the interplay of density, thickness and viscosity of the mélange, as well as the timescale of slab subduction (τs) and thermal structure of the subduction zone. We observe that the onset of diapirs in cold subduction zones requires mélanges that may sometimes be thicker than that observed by field and geophysical studies, while hot subduction zones overall require thinner mélanges. Thus, ultramafic-rich mélange diapirs may occur but only under specific conditions and when the diapiric ascent timescale is faster than the thermal equilibration barrier of ∼800–1000 °C (especially at the core of the mélange). Dehydration or partial melting of ultramafic-rich mélanges can affect the large ion lithophile element (LILE), volatiles, and high-field strength element (HFSE) budgets in the mantle wedge. Partial melting (caused by a diapiric rise or slab tear) does not fractionate LILEs from HFSEs at &lt;em&gt;T&lt;/em&gt; ≥ 1100 °C and if the mélange has a lower LILE/HFSE to begin with, that signature is transferred to arc sources. Dehydration releases aqueous fluids rich in fluid-mobile elements (LILE and volatiles) relative to HFSE. Thus, the characteristic high LILE/HFSE signature of aqueous fluids is transferred to arc magma sources. Given high LILE/HFSE ratio is a ubiquitous arc magma signature, but slab","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119020"},"PeriodicalIF":4.8,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322750","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":"Receiver function image of the mantle transition zone beneath western China: Fragmented subduction and counterflow upwelling","authors":"Zheng Tang ,&nbsp;Jordi Julià ,&nbsp;Walter D. Mooney ,&nbsp;Yanqiang Wu","doi":"10.1016/j.epsl.2024.119019","DOIUrl":"10.1016/j.epsl.2024.119019","url":null,"abstract":"<div><div>A uniform image of the mantle transition zone (MTZ) beneath western China and neighboring regions is produced through Variable Bin Radius Stacking of receiver functions. We utilized a large data set of 218,050 receiver functions from 1,991 broadband seismic stations. Our results, after 3-D velocity corrections, show significant lateral variations in topography of the 410- and 660-km discontinuity and thickness of the MTZ. The observed lateral variations of the MTZ correlate with seismic-velocity anomalies identified in independent tomographic studies, which are interpreted as cold and hot thermal anomalies from lithospheric downwellings and mantle upwellings, respectively. In the southern Tibetan Plateau, the MTZ topography reveals four segmented zones of up to ∼20 km thicker-than-average MTZ from west to east interfingered with regions of thin-to-normal MTZ. These segmented MTZ thickenings likely originate from a series of cold lithospheric fingers associated with the fragmented subduction of the Indian lithosphere, while the thin-to-normal MTZ may result from an absence of the subducting Indian slab. These observations provide novel evidence for the proposed fragmentation of the Indian subduction. Moreover, we observe regions of thickened MTZ under the Tien Shan orogen and the Qaidam block, which likely result from the foundering of cold delaminated/broken-off lithospheric blocks triggered by the underthrusting of the Junggar and Tarim blocks. Regions of thinned MTZ beneath the Tien Shan region are additionally observed, which could be attributed to counterflow upwellings.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119019"},"PeriodicalIF":4.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315997","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":"Characterization and geodynamic interpretation of Nazca Plate bathymetric anomalies","authors":"Gabriel Orozco ,&nbsp;Luis E. Lara ,&nbsp;Andrés Tassara","doi":"10.1016/j.epsl.2024.119009","DOIUrl":"10.1016/j.epsl.2024.119009","url":null,"abstract":"<div><div>The interaction between upwelling plumes and the oceanic lithosphere can provide important clues about the internal structure and dynamics of the Earth. Plume-derived processes disturb the lithosphere at different depths, amplitudes, and wavelengths. While the spatially wider process is dynamic uplift, commonly described as on the order of 1000 km wide and 1 km high bathymetric swell, volcanism is the most focused plume manifestation. These two end-members are commonly described and measured in terms of volumetric rates, such as buoyancy flux and volcanic production rate, respectively. However, intermediate processes such as magmatic trapping at lithospheric depths, although reported, has remained less studied. While the topographic separation between volcanic and regional (non-volcanic) features has numerous developments, the recognition of signatures of processes occurring at intermediate depths is a problem that has been less studied.</div><div>To better understand the relationship between plate structure and the distribution of plume effects, we investigated the spatial distribution of topographic plume signatures on the relatively fast and thin oceanic Nazca plate. Using morphological criteria, we adjusted the width of two filtered surfaces, which together allow us to divide the bathymetric anomalies into three components that could be reflecting morphological features supported below, inside, and above the plate.</div><div>The resulting decomposition suggests the existence of two superimposed components of swells on the Nazca plate, contrasting in distribution, morphology, and nature: local swells exhibit a clear spatial correlation with volcanic chains. The regional swell component in turn collectively encompasses all hotspots in the Nazca plate and show widths up to 2000 km. We hypothesize distinct driving processes for both swell components, with local swells connected to the intra-lithospheric domain and regional swells probably associated with sub-lithospheric processes.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119009"},"PeriodicalIF":4.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315995","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":"Evidence for a missing late veneer from 182W and 142Nd systematics in the Archean São Francisco Craton","authors":"F.P. Leitzke ,&nbsp;J.J. Pakulla ,&nbsp;J. Tusch ,&nbsp;A. Ravindran ,&nbsp;R. Gordilho-Barbosa ,&nbsp;S.A. Zincone ,&nbsp;M. Hellers ,&nbsp;A.A. Martins ,&nbsp;R.R. Spreafico ,&nbsp;R. Yang ,&nbsp;F. Wombacher ,&nbsp;J.S.F. Barbosa ,&nbsp;C. Münker","doi":"10.1016/j.epsl.2024.119022","DOIUrl":"10.1016/j.epsl.2024.119022","url":null,"abstract":"<div><div>The oldest crustal remnants on Earth are represented by greenstone belts and tonalite-trondhjemite-granodiorite (TTG) associations that form most of Archean blocks worldwide. Although several studies reported combined long-lived radiogenic isotope and trace element data of Archean rocks, the chemical evolution of the early Earth is still a matter of debate, often due to younger metamorphic disturbance that overprints primary patterns. To provide further insights, combined data for short-lived (¹⁴⁶Sm–¹⁴²Nd and ¹⁸²Hf–¹⁸²W) and long-lived (¹⁴⁷Sm–¹⁴³Nd and ¹⁷⁶Lu–¹⁷⁶Hf) isotope systems were acquired from a set of Eo- to Paleoarchean amphibolites, TTG gneisses, granites and a gabbroic rock in the northern segment of the São Francisco Craton (SFC) in Brazil, a largely unexplored area regarding short-lived radiogenic isotope datasets. Our samples cover an age range from ca. 3.65 to 3.30 Ga comprising both mafic and felsic rocks. Excesses of µ¹⁸²W in the samples indicate the presence of a long-lasting Hadean component in the source of Archean rocks from the SFC, which was preserved for at least ca. 1.0 Ga. Conversely, all samples depict µ¹⁴²Nd similar to modern upper mantle values. The most plausible interpretation of the µ¹⁸²W and µ¹⁴²Nd data is a (partially) missing Hadean late veneer component similar to that previously found, for example, at the Pilbara Craton, in NW Australia.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119022"},"PeriodicalIF":4.8,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315996","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":"Paleomagnetic constraints on the primary iron minerals of the late Paleoproterozoic Xuanlong-type ironstone in the North China Craton","authors":"Yuhang Cai ,&nbsp;Shuan-Hong Zhang ,&nbsp;Junling Pei ,&nbsp;Yabo Tong ,&nbsp;Zaizheng Zhou ,&nbsp;Lifu Hou","doi":"10.1016/j.epsl.2024.119013","DOIUrl":"10.1016/j.epsl.2024.119013","url":null,"abstract":"<div><div>The Xuanlong-type ironstone is a late Paleoproterozoic (∼1.64 Ga) hematite-dominated granular iron formation (GIF) in the North China Craton (NCC). However, recent geochemical studies indicated this GIF was precipitated in a weakly oxygenated environment. The conflicts between the mineral composition of the Xuanlong-type ironstone and its geochemical interpretations can be attributed to the potential occurrence of secondary hematite. Here we used paleomagnetic, rock magnetic measurements and petrographic analysis to determine the mineralization age of the hematite. Our objectives were to determine the primary iron mineralogy and to further explore the paleoenvironmental information preserved in the Xuanlong-type ironstone. Rock magnetic measurements and petrographic analysis identified Al-substituted hematite and siderite as the magnetic minerals. The high-temperature characteristic remanent magnetizations, which passed a C-classification reversal test and a fold test, yielded a paleomagnetic pole position at 51°N, 197°E. This pole position is in close proximity to the coeval paleomagnetic pole reconstructed from the ∼1.64 Ga Cuizhuang Formation in the southern NCC. Therefore, the high-temperature component of the natural remanent magnetization is interpreted as primary remanent magnetization acquired through crystal growth of Al-substituted hematite during early diagenesis. The degree of Al-substitution in hematite seems to be influenced by the alternating dense and porous laminae within the hematitic ooids of Xuanlong-type ironstones. It is hypothesized that these laminae are a result of periodic sea level fluctuations, considering that the ironstones were likely formed in a shallow water setting.</div></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"647 ","pages":"Article 119013"},"PeriodicalIF":4.8,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312629","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":"Astronomical forcing of terrestrial organic carbon burial in East Asia during the Eocene","authors":"Juan Liu ,&nbsp;Juye Shi ,&nbsp;Yongchao Lu ,&nbsp;Xiaojie Fan ,&nbsp;Ze Zhang ,&nbsp;Rui Zhang ,&nbsp;Zhixiang Wang ,&nbsp;Ke Xu ,&nbsp;Anguo Xiao ,&nbsp;David B. Kemp ,&nbsp;Chunju Huang","doi":"10.1016/j.epsl.2024.119014","DOIUrl":"10.1016/j.epsl.2024.119014","url":null,"abstract":"<div><p>Carbon sources and sinks are primary components of the climate system, but their response to external forcing remain unconstrained, especially for past greenhouse climates. Lakes are important carbon sinks that play a key role in the global carbon cycle. In this study, we investigate organic carbon burial processes and the possible role played by astronomical forcing in low to middle latitude lakes in China during the Eocene. Sediment noise modeling of lake level fluctuations in the three basins suggests that TOC maxima coincided with lake level maxima. We suggest that elevated lake levels likely led to stagnation of bottom waters, thereby promoting the development and preservation of organic matter. Total organic carbon (TOC) data spanning the Eocene from three borehole cores of separate basins show a common cyclicity of ∼1.2 Myr. According to the three TOC time series studied, maxima in TOC are linked to maxima in long-term 1.2 Myr obliquity modulation cycles, with long-term 2.4 Myr eccentricity cycles either at a maxima or minima. Our analysis elucidates a likely control on the burial of organic carbon by long-term astronomical climate cycles. The superposition of different orbital cycles may have driven the process of differential enrichment of organic matter by inducing perturbations in the carbon cycle through nonlinear climate effects. Overall, our chemostratigraphy results illustrate the sensitivity of the terrestrial carbon cycle to orbital forcing on geological timescales.</p></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"646 ","pages":"Article 119014"},"PeriodicalIF":4.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272576","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":"Potassium isotope evidence for subducted upper and lower oceanic crust in ocean island basalt sources","authors":"Haiyang Liu ,&nbsp;Ying-Yu Xue ,&nbsp;Jörg Geldmacher ,&nbsp;Kaj Hoernle ,&nbsp;Uwe Wiechert ,&nbsp;Shichao An ,&nbsp;Hai-Ou Gu ,&nbsp;He Sun ,&nbsp;Fanfan Tian ,&nbsp;Xiaoqiang Li ,&nbsp;Kun Wang ,&nbsp;Hongli Zhu ,&nbsp;Wei-Dong Sun","doi":"10.1016/j.epsl.2024.119015","DOIUrl":"10.1016/j.epsl.2024.119015","url":null,"abstract":"<div><p>The Madeira mantle plume is proposed to contain a complete package of recycled oceanic lithosphere. It has not been possible, however, to establish if both lower oceanic crust and peridotitic lithospheric mantle are present within the Madeira magma source. This study reports potassium (K) and oxygen isotope data of lavas from the Madeira Archipelago, which show that δ⁴¹K (-0.50 ± 0.06‰ to -0.31 ± 0.01‰) correlates with Sr-Nd-Pb-Hf isotopic compositions, confirming the incorporation of recycled crustal material. The increase in δ⁴¹K from Madeira's early shield stage lavas (-0.50 ± 0.06‰ to -0.40 ± 0.05‰) to the subsequent post-erosional stage lavas (-0.34 ± 0.04‰ to -0.31 ± 0.01‰) is consistent with the mantle source becoming progressively depleted in recycled upper oceanic crust (converted to eclogite or pyroxenite) through melt extraction with decreasing age. The post-erosional lavas, however, require a source with higher δ⁴¹K values than in depleted peridotitic lithospheric mantle. Modeling demonstrates that during dehydration of high-temperature altered lower oceanic crust, the initial heavy K isotopic signature is preserved, consistent with the high δ⁴¹K values of the post-erosional lavas being derived from hydrothermally-altered lower oceanic crust in the Madeira plume source. Consequently, K isotopes provide direct evidence that ocean island magma sources can contain both upper and lower recycled oceanic crust. This study provides important constraints on the cause of the temporal changes in geochemical composition of ocean island basalts, the origin of mantle heterogeneity and the recycling of K through subduction zones and the deep mantle.</p></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"646 ","pages":"Article 119015"},"PeriodicalIF":4.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272573","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":"Early generation of a refractory inclusions-enriched H-chondritic parent body: A safe harbor for Ca, Al-rich inclusions","authors":"Samuel Ebert ,&nbsp;Kazuhide Nagashima ,&nbsp;Alexander N. Krot ,&nbsp;Shigeru Wakita ,&nbsp;Jean-Alix Barrat ,&nbsp;Addi Bischoff","doi":"10.1016/j.epsl.2024.119010","DOIUrl":"10.1016/j.epsl.2024.119010","url":null,"abstract":"<div><p>Calcium-aluminum-rich inclusions (CAIs) commonly observed in chondritic meteorites are the oldest dated solids formed in the Solar System. Short-lived isotope chronologies (²⁶Al-²⁶Mg, ¹⁸²Hf-¹⁸²W) suggest a ∼2 Ma gap between the formation of CAIs and the accretion of the final chondrite parent bodies. One thin section, 3.27 cm² in size, of an ordinary chondrite NWA 3358 (H3.1) studied contains 52 refractory inclusions (CAIs and amoeboid olivine aggregates (AOAs)) comprising 0.14 % of its area, which is the highest abundance of refractory inclusions among non-carbonaceous chondrites containing on average ∼0.009 area % of CAIs and AOAs. In combination with a low chondrule/matrix ratio of ∼1.5, this makes NWA 3358 a unique ordinary chondrite. The aqueously-formed fayalites (Fa_&gt;99) in NWA 3358 have the inferred initial ⁵³Mn/⁵⁵Mn ratio of (5.56 ± 0.44) × 10⁻⁶ which is the highest measured value for secondary minerals in chondrites and corresponds to the formation time of ∼1.0–1.5 Ma after CAIs. Based on the ⁵³Mn-⁵³Cr chronology of fayalite formation and the thermal modeling, we infer that the first-generation of an H chondrite parent body, ∼6–12 km in diameter, accreted within 1.0 Ma after formation of CAIs, filling the gap of ∼2 Ma between CAIs and the earliest chondrite parent bodies. This early accretion provides a possible mechanism of CAIs/AOAs storage in the inner solar nebula and could explain the high amount of refractory inclusions in NWA 3358. A later destruction of these first-generation bodies may also explain the presence of CAIs and chondrules of different ages within later formed chondrite parent bodies.</p></div>","PeriodicalId":11481,"journal":{"name":"Earth and Planetary Science Letters","volume":"646 ","pages":"Article 119010"},"PeriodicalIF":4.8,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0012821X24004424/pdfft?md5=8b09b36f84f5eb27d51cdd486c15c50e&pid=1-s2.0-S0012821X24004424-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142272575","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}