Geochemistry Geophysics Geosystems最新文献

{"title":"Offshore Record of Explosive Volcanic Eruptions in the Southern Part of the Panamá Basin During the Past 10 Myr: 2. Inferences About the Construction of the Northern Andean Arc and Regional Geodynamics","authors":"Mathilde Bablon,&nbsp;Pablo Samaniego,&nbsp;Jean-Luc Le Pennec,&nbsp;François Nauret,&nbsp;François Michaud,&nbsp;Marianne Saillard,&nbsp;Silvana Hidalgo,&nbsp;Jean-Luc Devidal,&nbsp;François Orange,&nbsp;Céline Liorzou,&nbsp;Gueorgui Ratzov","doi":"10.1029/2025GC012278","DOIUrl":"10.1029/2025GC012278","url":null,"abstract":"<p>Volcanic material preserved in marine and lacustrine sediments is a key high-resolution archive for studying the past eruptive history of volcanic regions. In this work, we use the geochemical and isotopic compositions of marine volcanic glass shards, the thicknesses, and age models of tephra layers preserved in the deep sediments of the eastern equatorial Pacific, to study their volcanic source, the long-term evolution of volcanism, and its relationship with the regional geodynamics. We highlight that explosive eruptions associated with the Galápagos hotspot occurred in the Late Miocene and Early Pleistocene, which may reflect plume-ridge interplays. We also show that the oldest products of the Northern Andean arc were deposited at ∼4.8 Ma, shortly before the extinction of volcanic activity in northern Peru-southern Ecuador, due to the gradual flattening of the slab. The eruptive activity, apparently restricted to the Eastern Cordillera of Ecuador during the Pliocene, intensified and expanded from 2 Ma, with products of more varied compositions reflecting the construction of stratovolcanoes. This increase in volcanic activity, coeval with episodes of uplift of the Coastal Cordillera and with the development of the regional fault system that accommodates crustal deformations, may reflect the presence under the Ecuadorian Andes of the young Nazca oceanic crust, which carries the Carnegie Ridge. Finally, our results suggest that tephra of the Northern Andean arc recorded in sediments of the Panamá Basin were essentially emplaced by Plinian eruptions of a VEI-5-6 (Volcanic Explosivity Index), except one VEI-7 caldera-forming eruption, which occurred at 216 ± 5 ka.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012278","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Influence of ɛ-to-Py FeOOH Phase Transition on the Lower Mantle Heterogeneities","authors":"Sparsh Sharma,&nbsp;Gaurav Shukla","doi":"10.1029/2025GC012502","DOIUrl":"10.1029/2025GC012502","url":null,"abstract":"<p>Hydrous minerals transported by cold subducting slabs to the lowermost mantle are believed to significantly influence mantle properties and the heterogeneities in the core-mantle boundary (CMB) region. FeOOH is one of the essential iron-bearing hydrous minerals whose high-pressure phases, <i>ε</i>-FeOOH and Pyrite-type FeOOH (Py-FeOOH), can remain stable at the pressure-temperature conditions pertaining to the deep lower mantle. Using the first-principles density functional theory (DFT) based methods, we compute the thermoelastic properties of <i>ε</i>-FeOOH and Py-FeOOH and investigate the role of these two minerals in the deep Earth. Our calculations suggest that the phase transition of <i>ε</i>-FeOOH to Py-FeOOH will result in an increase of <i>V</i>_<i>P</i> and <i>V</i>_<i>S</i> by roughly 9% and 10%, respectively, which can contribute to the positive velocity anomalies in the high-velocity zones (HVZs) found in the lower mantle regions below the eastern and western pacific. Our anisotropy studies for ε-FeOOH depict a decreasing trend of anisotropy with temperature, which might indicate the presence of <i>ε</i>-FeOOH in the upper regions of the LLSVPs. Due to its high density and thermoelastic properties, Py-FeOOH might contribute to ULVZs, ORPs and other features at the core-mantle boundary.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012502","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Ar-Ar Dating of the Nephelinite-to-Basanite Transition at Etinde and Mount Cameroon (Cameroon Volcanic Line, West Africa) Provides Insights Into the Origin of Intraplate Magmatism","authors":"Sophie L. Baldwin,&nbsp;J. Godfrey Fitton,&nbsp;Linda A. Kirstein,&nbsp;Dan N. Barfod,&nbsp;M. Stephen Njome","doi":"10.1029/2025GC012391","DOIUrl":"10.1029/2025GC012391","url":null,"abstract":"<p>Intraplate magmatism is widespread in continental and oceanic domains. Some occurrences, such as Hawai'i, fit the predictions of the mantle-plume hypothesis well. However, many occurrences require alternative explanations. The Cameroon volcanic line (CVL) in West Africa is one of the most voluminous and long-lived non-plume intraplate magmatic provinces, providing an ideal location for testing alternative intraplate magma-generation hypotheses. Two CVL volcanoes, Etinde and Mount Cameroon, located on the African continental margin are composed mostly of nephelinite and basanite, respectively. We present 12 new Ar-Ar dates and show that the Etinde mafic nephelinites (0.572 ± 0.032 and 0.5152 ± 0.0073 Ma) predate the Mount Cameroon basanites (0.442 ± 0.014 Ma to present). Basanite samples from Etinde had much younger ages (0.113 ± 0.019 and 0.073 ± 0.011 Ma) and likely originated in the Mount Cameroon magmatic system. Indistinguishable radiogenic isotope ratios and similar primitive-mantle-normalized incompatible-element patterns indicate that the magmas feeding the two volcanoes share the same mantle source. The temporal progression from nephelinite (Etinde) to basanite (Mount Cameroon and minor, late eruptions on Etinde) is marked by a reduction in La/Yb and an increase in SiO₂ content in the most mafic magmas. These features are consistent with the progressive melting of a common carbonate-enriched mantle source in which the proportion of carbonate in the melt declined with increasing melt fraction. We propose that the carbonate-enriched mantle flowed outwards from beneath Africa and decompressed as it encountered a thinner lithosphere at the continent-ocean boundary, leading to magmatism at Etinde and Mount Cameroon.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012391","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Offshore Record of Explosive Volcanic Eruptions in the Southern Part of the Panamá Basin During the Past 10 Myr: 1. Tephrostratigraphy, Cross-Correlations and Geochemical Characterization","authors":"Mathilde Bablon,&nbsp;Marianne Saillard,&nbsp;François Michaud,&nbsp;François Nauret,&nbsp;Pablo Samaniego,&nbsp;Jean-Luc Le Pennec,&nbsp;Silvana Hidalgo,&nbsp;Gueorgui Ratzov,&nbsp;Jean-Luc Devidal,&nbsp;François Orange,&nbsp;Céline Liorzou","doi":"10.1029/2025GC012276","DOIUrl":"10.1029/2025GC012276","url":null,"abstract":"<p>Northern Andean volcanism is characterized by an intense Quaternary activity, whose onshore deposits have partly covered Mio-Pliocene products associated with the early development of the arc, making it difficult to obtain an exhaustive catalog of past eruptions. To improve our knowledge of the largest eruptions that occurred in the Northern Andean arc, we analyzed several cores from drilling sites off Ecuador to seek tephra records. We characterize for the first time the mineralogical and geochemical characteristics of tephra beds recorded in the southern part of the Panamá Basin in the sediments of DSDP and ODP drilling Sites 504, 677, 678, 1238, 1239 and 1240. We show that products of at least 27 major eruptions from the Northern Andes have reached the Pacific Ocean since the Early Pliocene, and we have correlated 11 of them between several drilling sites. Products of the oldest volcanism had mainly rhyolitic compositions belonging to a High-K calc-alkaline magmatic series, whereas magmas display more heterogeneous SiO₂ and K₂O contents from the beginning of the Pleistocene. Correlations established in this work allow us to provide new temporal constraints to age models of sedimentary sequences of Sites 677, 1238 and 1240 constructed based on biostratigraphy. In addition, we show that sediments of ODP Site 1240, the closest to the Galápagos islands, recorded several Pleistocene rhyolitic eruptions associated with the hotspot's activity, possibly revealing past oceanic ridge-hotspot interactions.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012276","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Mid-Ocean Ridge (MOR) Ash Dispersal on Axial Seamount, Juan de Fuca Ridge","authors":"Ryan A. Portner,&nbsp;Guangyu Xu,&nbsp;Arran P. Murch,&nbsp;David A. Clague,&nbsp;Brian M. Dreyer,&nbsp;Jennifer B. Paduan","doi":"10.1029/2025GC012229","DOIUrl":"10.1029/2025GC012229","url":null,"abstract":"<p>Rare eruption of primitive normal mid-ocean ridge basalt (N-MORB) magma (∼9.5 wt% MgO) on the summit of Axial Seamount generated abundant ash that was dispersed for several km. The unique geochemical signature of this ash deposit is distinct from otherwise typical MORB with more evolved compositions. As such, it is a key marker bed that can be used to track the dispersal of ash from an inferred source. The deposit rapidly fines over 1–4 km and becomes more chemically heterogeneous with distance. Toroidal bottom current circulation around Axial's summit caldera primarily constrained it to the southwest part of the summit with limited dispersal to the southeast and northern flanks. Computer simulations that best match the observed dispersal pattern suggest that ash was lofted to ∼250 masf by a moderate heat transfer rate (∼10⁹ W) from a small hydrothermal megaplume and co-genetic lava flow. Models invoking lower heat transfer rates from just a cooling lava flow could only loft the finest material to &lt;225 m above the seafloor, and could not recreate the observed dispersal pattern, even under a strong bottom current regime. Radiocarbon ages and lithostratigraphy imply that the marker bed formed ∼600 years BP, after caldera formation, which occurred sometime between 1400 and 1000 years BP. Chemostratigraphic trends show that eruptions tapped more primitive magmas (8.0–9.7 wt% MgO) for several hundreds of years after caldera formation. This observation is interpreted to reflect catastrophic changes in crustal permeability that reduced the volume and magma storage times in crustal reservoirs, which in turn allowed magmas to rapidly ascend to the surface.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012229","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"A Coral Biomineralization Model for Dual Clumped Isotopes","authors":"James M. Watkins,&nbsp;Qicui Jia,&nbsp;Shuo Zhang,&nbsp;Laurent S. Devriendt,&nbsp;Sang Chen","doi":"10.1029/2025GC012263","DOIUrl":"10.1029/2025GC012263","url":null,"abstract":"&lt;p&gt;Corals exhibit larger and more variable deviations from equilibrium in stable isotope composition (&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;δ&lt;/mi&gt;\u0000 &lt;mn&gt;13&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${delta }^{13}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;C, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msup&gt;\u0000 &lt;mi&gt;δ&lt;/mi&gt;\u0000 &lt;mn&gt;18&lt;/mn&gt;\u0000 &lt;/msup&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${delta }^{18}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;O, &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mn&gt;47&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${{Delta }}_{47}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; and &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mn&gt;48&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${{Delta }}_{48}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;) than most marine biocalcifiers. The disequilibrium isotope effects complicate paleoclimate applications but offer a window into biocalcification processes. Here, we merge a &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mn&gt;47&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${{Delta }}_{47}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;-&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;Δ&lt;/mi&gt;\u0000 &lt;mn&gt;48&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${{Delta }}_{48}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; isotope model in the &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mtext&gt;CaCO&lt;/mtext&gt;\u0000 &lt;mn&gt;3&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${text{CaCO}}_{3}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;-DIC-&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;H&lt;/mi&gt;\u0000 &lt;mn&gt;2&lt;/mn&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${mathrm{H}}_{2}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;O system (Watkins &amp; Devriendt, 2022, https://doi.org/10.1029/2021gc010200) with a coral biomineraliz","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012263","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145101491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Multi-Stage Crustal Thickening, Surface Uplift, and Collision in the Western Himalaya-Karakoram-Tibet Orogen Revealed by Chemical Mohometry","authors":"Ian W. Hillenbrand,&nbsp;Victor E. Guevara","doi":"10.1029/2025GC012287","DOIUrl":"10.1029/2025GC012287","url":null,"abstract":"<p>The Himalaya-Karakoram-Tibet (HKT) orogen provides an unrivaled opportunity to study the dynamic linkages between deep and surface processes during collisional orogenesis. However, these efforts are hindered by conflicting interpretations on the number and timing of collisional events, and the timing of crustal thickening and associated surface uplift. Here, we resolve this with quantitative paleo-crustal thickness estimates in the northwestern HKT orogen. We show that: (a) the paleo-Asian margin had thick crust (50–60 km) at least 65 Ma prior to terminal collision, consistent with a continental arc setting, (b) crustal thickening to 60 km or more occurred at ca. 60–50 Ma in the Kohistan-Ladakh arc and by 40–25 Ma in the paleo-Asian margin, indicating a multi-stage Himalayan collision, and (c) modern crustal thicknesses in the northwestern HKT have been sustained since ca. 40–25 Ma suggesting an orogenic steady-state in which crustal thickening, crustal flow, and surface uplift have been balanced by erosion.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012287","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145022083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Intermediate Water Sources and Sediment Provenance in the High-Latitude South Pacific Ocean (Campbell Plateau) During the Paleogene","authors":"Erika Tanaka,&nbsp;Kazutaka Yasukawa,&nbsp;Ann G. Dunlea,&nbsp;Ingrid Hendy,&nbsp;Takashi Miyazaki,&nbsp;Bogdan Stefanov Vaglarov","doi":"10.1029/2025GC012314","DOIUrl":"10.1029/2025GC012314","url":null,"abstract":"<p>During the Paleogene, Earth experienced a significant transition from a hot to a cold climate, or from a “Hothouse” to a “Coolhouse.” In the warm early Paleogene, the oceanic environment lacked a large polar ice sheet and had a reduced equator-to-pole sea-surface temperature gradient. Large-scale tectonic events occurred in the high-latitude South Pacific during this period, such as the northward movement of Zealandia away from the Antarctic continent, the deepening of the Tasman Sea accompanied by seafloor spreading, and the opening of the Tasman Gateway. However, variations in oceanic circulation and depositional environments in the high-latitude South Pacific associated with global climate change or tectonic settings during the Paleogene have not been fully characterized. Here, we report the chemical compositions and Sr-Nd isotopic ratios of carbonate fractions and bulk sediments from International Ocean Discovery Program Site U1553. The rare earth element patterns and Sr isotopes of the samples suggest that, since 62 Ma, Site U1553 was located in the open ocean rather than on continental shelves or margins. Leachate Nd isotopic data indicate that intermediate water from the South Indian Ocean flowed north of Australia and onto the Campbell Plateau throughout the Eocene, probably via the proto-Eastern Australian Current (Eastern Australian Current) since 52 Ma. This circulation pattern was likely linked to the opening and deepening of the Tasman Sea. Seawater around the Campbell Plateau had the low <i>ε</i>_Nd values during the Eocene, which may have contributed to the development of an <i>ε</i>_Nd gradient between the South and North Pacific Oceans.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012314","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Transfer of Strontium and Carbon From Subducting Sediment Into the Leading Edge of the Mantle Wedge","authors":"Amol Dayanand Sawant,&nbsp;Peter B. Kelemen,&nbsp;Matthew Jerram,&nbsp;Martin Q. Fleisher,&nbsp;Louise Bolge,&nbsp;Juan Carlos de Obeso,&nbsp;Diego Fernandez","doi":"10.1029/2025GC012267","DOIUrl":"10.1029/2025GC012267","url":null,"abstract":"<p>Carbon mobilization at subduction zones can be constrained by focusing on Sr as a proxy, as Sr readily substitutes for Ca—a major cation in the crystal structures of carbonates. Unmelted high/ultrahigh pressure (HP/UHP) pelitic metasediments exhumed from less than 100 km depth along the slab-mantle interface show loss of Sr and retention of most other incompatible trace elements, when compared with their potential protoliths, for example, average shales/average upper continental crust/average subducting sediments. Sr and CaO/SiO₂ in subducting sediments and unmelted HP/UHP metasediments are correlated, suggesting that Ca-carbonate is one of the major hosts for Sr in subducting sediments, and that Sr and carbonates are lost during subsolidus devolatilization of subducting HP/UHP metasediments beneath forearcs. In turn, the elevated Sr in arc magmas suggests that carbonated Sr-rich wedge peridotites may be dragged down into the source of arc magmas via wedge convection, where they contribute to C and Sr during partial melting. Decoupling of Sr from most of the other trace elements in subduction zone metasediments suggests that previous mass balance attempts using Sr, Nd, and Pb concentrations and isotope ratios to constrain the relative contributions of mantle peridotites, subducting sediments and subducting oceanic crust to arc melts need to be reexamined. Metasediments could have contributed more to arc magmas than previously estimated.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025GC012267","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Resolving Crustal and Subcrustal Dynamic Sources in Continental Arc Magmas: The Cenozoic Andean Arc of Central Chile","authors":"M. Muñoz-Gómez,&nbsp;C. M. Fanning,&nbsp;F. Tapia,&nbsp;I. Payacán,&nbsp;F. Fuentes,&nbsp;M. Farías,&nbsp;R. Charrier,&nbsp;M. Polvé,&nbsp;S. Quiñones,&nbsp;K. Deckart,&nbsp;A. Fock","doi":"10.1029/2024GC012154","DOIUrl":"10.1029/2024GC012154","url":null,"abstract":"<p>The Andean margin of Central Chile (∼32°40′–34°30′S) records abundant Cenozoic arc magmatic activity with variable compositional characteristics. This is examined through the analysis of an extensive database of new and published whole-rock geochemistry and Sr-Nd isotopic compositions, in addition to zircon Hf and O isotopic compositions. The whole-rock data record an increasing assimilation of continental crust material that developed through the compressional regime set in the margin in the Early Miocene that led to the construction of the modern Andes. The same is recorded by the Hf and O isotopic compositions, but these also allow identification of components involved in the magma genesis: (a) the sub arc mantle derived primary magmas, (b) a late Paleozoic—Early Triassic crystalline component, as that currently outcropping immediately to the east of the study area, (c) a deep enriched component, which likely corresponds to the Cuyania terrane, a Grenville age basement recognized further east in this Andean region, and (d) a deep juvenile low-δ¹⁸O component, interpreted here as basement with oceanic crust affinities. This latter component reveals a possible composite nature for the Chilenia terrane, the postulated Grenville age basement in the region. The Cenozoic Andean arc magmas correspond to the differentiated products of an extensive intra-crustal re-working, taking place along tens of kilometers below their emplacement level, and whose main imprint is on the magmatic isotopic composition. Our results document the role of the continental crust, particularly regarding its evolving architecture and constitution, over the composition of arc magmas.</p>","PeriodicalId":50422,"journal":{"name":"Geochemistry Geophysics Geosystems","volume":"26 9","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024GC012154","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145005566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}