1
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Wang B, Moynier F, Hu Y. Rubidium isotopic compositions of angrites controlled by extensive evaporation and partial recondensation. Proc Natl Acad Sci U S A 2024; 121:e2311402121. [PMID: 38147555 PMCID: PMC10769822 DOI: 10.1073/pnas.2311402121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 11/29/2023] [Indexed: 12/28/2023] Open
Abstract
The planetesimals in the solar system exhibit varying degrees of moderately volatile elements (MVEs) depletion compared to the protosolar composition. Revealing the relevant mechanisms is crucial for exploring early solar system evolution. Most volatile-depleted materials in the solar system exhibit enrichments in the heavier isotopes of MVEs, which have traditionally been attributed to the loss of volatiles through partial evaporation. Angrites are so far an exception as they are enriched in the lighter isotopes of K. This has been interpreted as reflecting condensation processes. Here, we present Rb isotopic data of angrites and find that they have lighter Rb isotopic compositions than Vesta, Mars, and the Moon. The δ87Rb value of the angrite parent body (APB) is estimated to range between -1.19‰ and -0.67‰. The extremely light Rb isotopic composition of the APB is likely a result of the kinetic recondensation of Rb after near-complete evaporation during the magma ocean stage. This finding provides further support for the partial recondensation model to explain the light Rb and K isotopic compositions of the APB. In addition, the APB, alongside other terrestrial planetary bodies (e.g., Earth, Mars, Moon, and Vesta), exhibit a strong correlation between their Rb and K isotopic compositions. This coupling of Rb and K isotopes is indicative of a volatility-driven isotopic fractionation rather than nucleosynthetic anomalies. The extremely light Rb-K isotopic signatures of the APB suggest that beyond evaporation, condensation plays an equally significant role in shaping the planetary-scale distributions of volatile elements.
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Affiliation(s)
- Baoliang Wang
- Institut de Physique du Globe de Paris, Université Paris Cité, CNRS, Paris75005, France
| | - Frederic Moynier
- Institut de Physique du Globe de Paris, Université Paris Cité, CNRS, Paris75005, France
| | - Yan Hu
- Institut de Physique du Globe de Paris, Université Paris Cité, CNRS, Paris75005, France
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2
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German CR, Reeves EP, Türke A, Diehl A, Albers E, Bach W, Purser A, Ramalho SP, Suman S, Mertens C, Walter M, Ramirez-Llodra E, Schlindwein V, Bünz S, Boetius A. Volcanically hosted venting with indications of ultramafic influence at Aurora hydrothermal field on Gakkel Ridge. Nat Commun 2022; 13:6517. [PMID: 36316329 PMCID: PMC9622739 DOI: 10.1038/s41467-022-34014-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022] Open
Abstract
The Aurora hydrothermal system, Arctic Ocean, hosts active submarine venting within an extensive field of relict mineral deposits. Here we show the site is associated with a neovolcanic mound located within the Gakkel Ridge rift-valley floor, but deep-tow camera and sidescan surveys reveal the site to be ≥100 m across-unusually large for a volcanically hosted vent on a slow-spreading ridge and more comparable to tectonically hosted systems that require large time-integrated heat-fluxes to form. The hydrothermal plume emanating from Aurora exhibits much higher dissolved CH4/Mn values than typical basalt-hosted hydrothermal systems and, instead, closely resembles those of high-temperature ultramafic-influenced vents at slow-spreading ridges. We hypothesize that deep-penetrating fluid circulation may have sustained the prolonged venting evident at the Aurora hydrothermal field with a hydrothermal convection cell that can access ultramafic lithologies underlying anomalously thin ocean crust at this ultraslow spreading ridge setting. Our findings have implications for ultra-slow ridge cooling, global marine mineral distributions, and the diversity of geologic settings that can host abiotic organic synthesis - pertinent to the search for life beyond Earth.
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Affiliation(s)
- Christopher R. German
- grid.56466.370000 0004 0504 7510Woods Hole Oceanographic Institution, Woods Hole, USA
| | - Eoghan P. Reeves
- grid.7914.b0000 0004 1936 7443Department of Earth Science & Centre for Deep Sea Research, University of Bergen, Bergen, Norway
| | - Andreas Türke
- grid.7914.b0000 0004 1936 7443Department of Earth Science & Centre for Deep Sea Research, University of Bergen, Bergen, Norway ,grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Alexander Diehl
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Elmar Albers
- grid.7704.40000 0001 2297 4381Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Wolfgang Bach
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Autun Purser
- grid.10894.340000 0001 1033 7684Alfred Wegener Institute Helmholtz Centre for Polar & Marine Research, Bremerhaven, Germany
| | - Sofia P. Ramalho
- grid.7311.40000000123236065Centre for Environmental & Marine Studies (CESAM), Department of Biology, University of Aveiro, Aveiro, Portugal
| | - Stefano Suman
- grid.56466.370000 0004 0504 7510Woods Hole Oceanographic Institution, Woods Hole, USA
| | - Christian Mertens
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381Institute of Environmental Physics, University of Bremen, Bremen, Germany
| | - Maren Walter
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.7704.40000 0001 2297 4381Institute of Environmental Physics, University of Bremen, Bremen, Germany
| | - Eva Ramirez-Llodra
- grid.6407.50000 0004 0447 9960Norwegian Institute for Water Research (NIVA), Oslo, Norway ,REV Ocean, Lysaker, Norway
| | - Vera Schlindwein
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.10894.340000 0001 1033 7684Alfred Wegener Institute Helmholtz Centre for Polar & Marine Research, Bremerhaven, Germany
| | - Stefan Bünz
- grid.10919.300000000122595234Centre for Arctic Gas Hydrate, Environment and Climate (CAGE), University of Tromso–The Arctic University of Norway, Tromsø, Norway
| | - Antje Boetius
- grid.7704.40000 0001 2297 4381MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany ,grid.10894.340000 0001 1033 7684Alfred Wegener Institute Helmholtz Centre for Polar & Marine Research, Bremerhaven, Germany ,grid.419529.20000 0004 0491 3210Max Planck Institute for Marine Microbiology, Bremen, Germany
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3
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Zhao SY, Yang AY, Langmuir CH, Zhao TP. Oxidized primary arc magmas: Constraints from Cu/Zr systematics in global arc volcanics. SCIENCE ADVANCES 2022; 8:eabk0718. [PMID: 35319995 PMCID: PMC8942352 DOI: 10.1126/sciadv.abk0718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
Arc volcanics are more oxidized than mid-ocean ridge basalts (MORB), but it is debated whether this is a mantle feature or a result of magmatic evolution. Copper, a sulfur-loving element, has been used to trace the behavior of redox-sensitive sulfur during mantle melting and infer similar redox states of sub-arc and sub-ridge mantle. Previous studies, however, neglected elevated sulfur contents in the sub-arc mantle, leading to underestimation of oxygen fugacities, and did not recognize systematic Cu variations in arc volcanics. Here, we show that the Cu/Zr ratio is a sensitive indicator that responds to sulfur content, oxygen fugacity, and extent of melting of the mantle. Because of higher mantle S contents, Cu systematics of arc magmas require one log unit higher oxygen fugacities of sub-arc than sub-ridge mantle. Low Cu contents of thick-crusted arc volcanics result from low extents of melting of sulfur-rich mantle, obviating the need for deep crustal sulfide fractionation, with substantial implications for the origin of porphyry-Cu deposits.
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Affiliation(s)
- Si-Yu Zhao
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Alexandra Yang Yang
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
- CAS Center for Excellence in Deep Earth Science, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China
| | | | - Tai-Ping Zhao
- CAS Center for Excellence in Deep Earth Science, Guangzhou, China
- Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
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4
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Bao X, Lithgow-Bertelloni CR, Jackson MG, Romanowicz B. On the relative temperatures of Earth's volcanic hotspots and mid-ocean ridges. Science 2022; 375:57-61. [PMID: 34990241 DOI: 10.1126/science.abj8944] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Volcanic hotspots are thought to be fed by hot, active upwellings from the deep mantle, with excess temperatures (Tex) ~100° to 300°C higher than those of mid-ocean ridges. However, Tex estimates are limited in geographical coverage and often inconsistent for individual hotspots. We infer the temperature of oceanic hotspots and ridges simultaneously by converting seismic velocity to temperature. We show that while ~45% of plume-fed hotspots are hot (Tex ≥ 155°C), ~15% are cold (Tex ≤ 36°C) and ~40% are not hot enough to actively upwell (50°C ≤ Tex ≤ 136°C). Hot hotspots have an extremely high helium-3/helium-4 ratio and buoyancy flux, but cold hotspots do not. The latter may originate at upper mantle depths. Alternatively, the deep plumes that feed them may be entrained and cooled by small-scale convection.
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Affiliation(s)
- Xiyuan Bao
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095, USA
| | | | - Matthew G Jackson
- Department of Earth Science, University of California, Santa Barbara, CA 93106, USA
| | - Barbara Romanowicz
- Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA
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5
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Thermochemical anomalies in the upper mantle control Gakkel Ridge accretion. Nat Commun 2021; 12:6962. [PMID: 34845208 PMCID: PMC8630051 DOI: 10.1038/s41467-021-27058-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 10/15/2021] [Indexed: 11/30/2022] Open
Abstract
Despite progress in understanding seafloor accretion at ultraslow spreading ridges, the ultimate driving force is still unknown. Here we use 40Ar/39Ar isotopic dating of mid-ocean ridge basalts recovered at variable distances from the axis of the Gakkel Ridge to provide new constraints on the spatial and temporal distribution of volcanic eruptions at various sections of an ultraslow spreading ridge. Our age data show that magmatic-dominated sections of the Gakkel Ridge spread at a steady rate of ~11.1 ± 0.9 mm/yr whereas amagmatic sections have a more widely distributed melt supply yielding ambiguous spreading rate information. These variations in spreading rate and crustal accretion correlate with locations of hotter thermochemical anomalies in the asthenosphere beneath the ridge. We conclude therefore that seafloor generation in ultra-slow spreading centres broadly reflects the distribution of thermochemical anomalies in the upper mantle.
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6
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Ball PW, White NJ, Maclennan J, Stephenson SN. Global influence of mantle temperature and plate thickness on intraplate volcanism. Nat Commun 2021; 12:2045. [PMID: 33824348 PMCID: PMC8024351 DOI: 10.1038/s41467-021-22323-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 03/04/2021] [Indexed: 11/24/2022] Open
Abstract
The thermochemical structure of lithospheric and asthenospheric mantle exert primary controls on surface topography and volcanic activity. Volcanic rock compositions and mantle seismic velocities provide indirect observations of this structure. Here, we compile and analyze a global database of the distribution and composition of Neogene-Quaternary intraplate volcanic rocks. By integrating this database with seismic tomographic models, we show that intraplate volcanism is concentrated in regions characterized by slow upper mantle shear-wave velocities and by thin lithosphere (i.e. <100 km). We observe a negative correlation between shear-wave velocities at depths of 125–175 km and melt fractions inferred from volcanic rock compositions. Furthermore, mantle temperature and lithospheric thickness estimates obtained by geochemical modeling broadly agree with values determined from tomographic models that have been converted into temperature. Intraplate volcanism often occurs in regions where uplifted (but undeformed) marine sedimentary rocks are exposed. Regional elevation of these rocks can be generated by a combination of hotter asthenosphere and lithospheric thinning. Therefore, the distribution and composition of intraplate volcanic rocks through geologic time will help to probe past mantle conditions and surface processes. Here, the authors compile a global geochemical database of Neogene-Quaternary intraplate volcanism. By comparing the distribution and composition of these rocks with tomographic models they show that intraplate volcanism can be used to constrain upper-mantle structure at the time of eruption.
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Affiliation(s)
- P W Ball
- Bullard Laboratories, Department of Earth Sciences, University of Cambridge, Madingley Rise, Cambridge, UK. .,Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia.
| | - N J White
- Bullard Laboratories, Department of Earth Sciences, University of Cambridge, Madingley Rise, Cambridge, UK.
| | - J Maclennan
- Bullard Laboratories, Department of Earth Sciences, University of Cambridge, Madingley Rise, Cambridge, UK
| | - S N Stephenson
- Bullard Laboratories, Department of Earth Sciences, University of Cambridge, Madingley Rise, Cambridge, UK.,Department of Earth Sciences, University of Oxford, Oxford, UK
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7
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Geochemical Constraints on Mantle Melting and Magma Genesis at Pohnpei Island, Micronesia. MINERALS 2020. [DOI: 10.3390/min10090816] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The lithospheric mantle is of paramount importance in controlling the chemical composition of ocean island basalts (OIBs), influencing partial melting and magma evolution processes. To improve the understanding of these processes, the pressure–temperature conditions of mantle melting were investigated, and liquid lines of descent were modelled for OIBs on Pohnpei Island. The studied basaltic samples are alkalic, and can be classified as SiO2-undersaturated or SiO2-saturated series rocks, with the former having higher TiO2 and FeOT contents but with no distinct trace-element composition, suggesting melting of a compositionally homogenous mantle source at varying depths. Both series underwent sequential crystallization of olivine, clinopyroxene, Fe–Ti oxides, and minor plagioclase and alkali feldspar. Early magnetite crystallization resulted from initially high FeOT contents and oxygen fugacity, and late feldspar crystallization was due to initially low Al2O3 contents and alkali enrichment of the evolved magma. The Pohnpei lavas formed at estimated mantle-melting temperatures of 1486–1626 °C (average 1557 ± 43 °C, 1σ), and pressures of 2.9–5.1 GPa (average 3.8 ± 0.7 GPa), with the SiO2-undersaturated series forming at higher melting temperatures and pressures. Trace-element compositions further suggest that garnet rather than spinel was a residual phase in the mantle source during the melting process. Compared with the Hawaiian and Louisville seamount chains, Pohnpei Island underwent much lower degrees of mantle melting at greater depth, possibly due to a thicker lithosphere.
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8
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High H 2O Content in Pyroxenes of Residual Mantle Peridotites at a Mid Atlantic Ridge Segment. Sci Rep 2020; 10:579. [PMID: 31953494 PMCID: PMC6969183 DOI: 10.1038/s41598-019-57344-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 12/29/2019] [Indexed: 11/08/2022] Open
Abstract
Global correlations of mid-ocean-ridges basalt chemistry, axial depth and crustal thickness have been ascribed to mantle temperature variations affecting degree of melting. However, mantle H2O content and elemental composition may also play a role. How H2O is distributed in the oceanic upper mantle remains poorly constrained. We tackled this problem by determining the H2O content of orthopyroxenes (opx) and clinopyroxenes (cpx) of peridotites from a continuous lithospheric section created during 26 Ma at a 11°N Mid-Atlantic Ridge segment, and exposed along the Vema Transform. The H2O content of opx ranges from 119 ppm to 383 ppm; that of cpx from 407 ppm to 1072 ppm. We found anomalous H2O-enriched peridotites with their H2O content not correlating inversely with their degree of melting, although H2O is assumed to be incompatible during melting. Inverse correlation of H2O with Ce, another highly incompatible component, suggests post-melting H2O enrichment. We attribute a major role to post-melting temperature-dependent diffusion of hydrogen occurring above the melting region, where water-rich melt flows faster than residual peridotites through dunitic conduits cross-cutting the uprising mantle. Accordingly, estimates of the H2O content of the MORB mantle source based on H2O in abyssal peridotites can be affected by strong uncertainties.
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9
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Arnould M, Ganne J, Coltice N, Feng X. Northward drift of the Azores plume in the Earth's mantle. Nat Commun 2019; 10:3235. [PMID: 31324813 PMCID: PMC6642178 DOI: 10.1038/s41467-019-11127-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 06/21/2019] [Indexed: 11/19/2022] Open
Abstract
Mantle plume fixity has long been a cornerstone assumption to reconstruct past tectonic plate motions. However, precise geochronological and paleomagnetic data along Pacific continuous hotspot tracks have revealed substantial drift of the Hawaiian plume. The question remains for evidence of drift for other mantle plumes. Here, we use plume-derived basalts from the Mid-Atlantic ridge to confirm that the upper-mantle thermal anomaly associated with the Azores plume is asymmetric, spreading over ~2,000 km southwards and ~600 km northwards. Using for the first time a 3D-spherical mantle convection where plumes, ridges and plates interact in a fully dynamic way, we suggest that the extent, shape and asymmetry of this anomaly is a consequence of the Azores plume moving northwards by 1-2 cm/yr during the past 85 Ma, independently from other Atlantic plumes. Our findings suggest redefining the Azores hotspot track and open the way for identifying how plumes drift within the mantle.
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Affiliation(s)
- Maëlis Arnould
- Laboratoire de Géologie, École Normale Supérieure, CNRS UMR 8538, PSL Research University, 75005, Paris, France.
- Laboratoire de Géologie de Lyon, Terre, Planètes, Environnement, École Normale Supérieure de Lyon, Université de Lyon, Université Claude Bernard, CNRS UMR 5276, 2 rue Raphaël Dubois, 69622, Villeurbanne, France.
- EarthByte Group, School of Geosciences, Madsen Building F09, University of Sydney, Sydney, 2006, NSW, Australia.
| | - Jérôme Ganne
- IRD, CNRS, GET, Université Toulouse III, 14 Avenue Edouard Belin, 31400, Toulouse, France
| | - Nicolas Coltice
- Laboratoire de Géologie, École Normale Supérieure, CNRS UMR 8538, PSL Research University, 75005, Paris, France
| | - Xiaojun Feng
- School of Safety Engineering, China University of Mining and Technology, Jiangsu, 221116, China
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10
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Constraining Mantle Heterogeneity beneath the South China Sea: A New Perspective on Magma Water Content. MINERALS 2019. [DOI: 10.3390/min9070410] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The nature of upper mantle is important to understand the evolution of the South China Sea (SCS); thus, we need better constrains on its mantle heterogeneity. Magma water concentration is a good indicator, but few data have been reported. However, the rarity of glass and melt inclusions and the special genesis for phenocrysts in SCS basalts present challenges to analyzing magmatic water content. Therefore, it is possible to estimate the water variations through the characteristics of partial melting and magma crystallization. We evaluated variations in Fe depletion, degree of melt fractions, and mantle source composition along the fossil spreading ridge (FSR) using SCS basalt data from published papers. We found that lava from the FSR 116.2° E, FSR 117.7° E, and non-FSR regions can be considered normal lava with normal water content; in contrast, lava from the FSR 117° E-carbonatite and 114.9–115.0° E basalts have higher water content and show evidence of strong Fe depletion during the fractional crystallization after elimination of the effects of plagioclase oversaturation. The enriched water in the 117° E-carbonatite basalts is contained in carbonated silicate melts, and that in the 114.9–115.0° E basalts results from mantle contamination with the lower continental crust. The lava from the 117° E-normal basalt has much lower water content because of the lesser influence of the Hainan plume. Therefore, there must be a mantle source compositional transition area between the southwestern and eastern sub-basins of the SCS, which have different mantle evolution histories. The mantle in the west is more affected by contamination with continental materials, while that in the east is more affected by the Hainan mantle plume.
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11
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Haughton GA, Hayman NW, Searle RC, Le Bas T, Murton BJ. Volcanic-Tectonic Structure of the Mount Dent Oceanic Core Complex in the Ultraslow Mid-Cayman Spreading Center Determined From Detailed Seafloor Investigation. GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS : G(3) 2019; 20:1298-1318. [PMID: 35860338 PMCID: PMC9285398 DOI: 10.1029/2018gc008032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/22/2019] [Accepted: 01/23/2019] [Indexed: 06/15/2023]
Abstract
The flanks of the ultraslow-spreading Mid-Cayman Spreading Center (MCSC) are characterized by domal massifs or oceanic core complexes (OCCs). The most prominent of these, Mount Dent, comprises lower-crustal and upper-mantle lithologies and hosts the Von Damm vent field ~12 km west of the axial deep. Here, presented autonomous underwater vehicle-derived swath sonar (multibeam) mapping and deep-towed side-scan sonar imagery lead to our interpretation that: (i) slip along the OCC-bounding detachment fault is ceasing, (ii) the termination zone, where detachment fault meets the hanging wall, is disintegrating, (iii) the domed surface of the OCC is cut by steep north-south extensional faulting, and (iv) the breakaway zone is cut by outward facing faults. The Von Damm vent field and dispersed pockmarks on the OCC's south flank further suggest that hydrothermal fluid flow is pervasive within the faulted OCC. On the axial floor of the MCSC, bright acoustic backscatter and multibeam bathymetry reveal: (v) a volcanic detachment hanging wall, (vi) a major fault rifting the southern flank of Mount Dent, and (vii) a young axial volcanic ridge intersecting its northern flank. These observations are described by a conceptual model wherein detachment faulting and OCC exhumation are ceasing during an increase in magmatic intrusion, brittle deformation, and hydrothermal circulation within the OCC. Together, this high-resolution view of the MCSC provides an instructive example of how OCCs, formed within an overall melt-starved ultraslow spreading center, can undergo magmatism, hydrothermal activity, and faulting in much the same way as expected in magmatically more robust slow-spreading centers elsewhere.
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Affiliation(s)
- G. A. Haughton
- School of Ocean and Earth SciencesUniversity of SouthamptonSouthamptonUK
| | - N. W. Hayman
- Institute for Geophysics, Jackson School for GeosciencesUniversity of TexasAustinTXUSA
| | - R. C. Searle
- Department of Earth SciencesDurham UniversityDurhamUK
| | - T. Le Bas
- National Oceanography CenterSouthamptonUK
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12
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Shervais JW, Reagan M, Haugen E, Almeev RR, Pearce JA, Prytulak J, Ryan JG, Whattam SA, Godard M, Chapman T, Li H, Kurz W, Nelson WR, Heaton D, Kirchenbaur M, Shimizu K, Sakuyama T, Li Y, Vetter SK. Magmatic Response to Subduction Initiation: Part 1. Fore-arc Basalts of the Izu-Bonin Arc From IODP Expedition 352. GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS : G(3) 2019; 20:314-338. [PMID: 30853858 PMCID: PMC6392113 DOI: 10.1029/2018gc007731] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 11/19/2018] [Accepted: 11/22/2018] [Indexed: 06/09/2023]
Abstract
The Izu-Bonin-Mariana (IBM) fore arc preserves igneous rock assemblages that formed during subduction initiation circa 52 Ma. International Ocean Discovery Program (IODP) Expedition 352 cored four sites in the fore arc near the Ogasawara Plateau in order to document the magmatic response to subduction initiation and the physical, petrologic, and chemical stratigraphy of a nascent subduction zone. Two of these sites (U1440 and U1441) are underlain by fore-arc basalt (FAB). FABs have mid-ocean ridge basalt (MORB)-like compositions, however, FAB are consistently lower in the high-field strength elements (TiO2, P2O5, Zr) and Ni compared to MORB, with Na2O at the low end of the MORB field and FeO* at the high end. Almost all FABs are light rare earth element depleted, with low total REE, and have low ratios of highly incompatible to less incompatible elements (Ti/V, Zr/Y, Ce/Yb, and Zr/Sm) relative to MORB. Chemostratigraphic trends in Hole U1440B are consistent with the uppermost lavas forming off axis, whereas the lower lavas formed beneath a spreading center axis. Axial magma of U1440B becomes more fractionated upsection; overlying off-axis magmas return to more primitive compositions. Melt models require a two-stage process, with early garnet field melts extracted prior to later spinel field melts, with up to 23% melting to form the most depleted compositions. Mantle equilibration temperatures are higher than normal MORB (1,400 °C-1,480 °C) at relatively low pressures (1-2 GPa), which may reflect an influence of the Manus plume during subduction initiation. Our data support previous models of FAB origin by decompression melting but imply a source more depleted than normal MORB source mantle.
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Affiliation(s)
| | - Mark Reagan
- Department of Earth and Environmental ScienceUniversity of IowaIowa CityIAUSA
| | - Emily Haugen
- Department of GeologyUtah State UniversityLoganUTUSA
- Now at Department of GeologyCalifornia State UniversitySacramentoCAUSA
| | - Renat R. Almeev
- Institut für MineralogieLeibniz Universität HannoverHannoverGermany
| | | | - Julie Prytulak
- Department of Earth SciencesUniversity of DurhamDurhamUK
| | | | - Scott A. Whattam
- Department of GeosciencesKing Fahd University of Petroleum and MineralsDhahranSaudi Arabia
| | - Marguerite Godard
- Géosciences Montpellier, CNRSUniversité de MontpellierMontpellierFrance
| | - Timothy Chapman
- School of GeosciencesUniversity of SydneySydneyNew South WalesAustralia
| | - Hongyan Li
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhouChina
| | - Walter Kurz
- Institute of Earth Sciences, NAWI Graz GeocenterUniversity of GrazGrazAustria
| | - Wendy R. Nelson
- Department of Physics, Astronomy, and GeosciencesTowson UniversityTowsonMDUSA
| | | | - Maria Kirchenbaur
- Institut für MineralogieLeibniz Universität HannoverHannoverGermany
- Institut für MineralogieUniversität zu KölnKölnGermany
| | - Kenji Shimizu
- Japan Agency for Marine‐Earth Science and TechnologyKochi Institute for Core Sample ResearchKochiJapan
| | | | - Yibing Li
- Chinese Academy of Geological ScienceInstitute of GeologyBeijingChina
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Korenaga J. Crustal evolution and mantle dynamics through Earth history. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2017.0408. [PMID: 30275159 PMCID: PMC6189559 DOI: 10.1098/rsta.2017.0408] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/31/2018] [Indexed: 05/13/2023]
Abstract
Resolving the modes of mantle convection through Earth history, i.e. when plate tectonics started and what kind of mantle dynamics reigned before, is essential to the understanding of the evolution of the whole Earth system, because plate tectonics influences almost all aspects of modern geological processes. This is a challenging problem because plate tectonics continuously rejuvenates Earth's surface on a time scale of about 100 Myr, destroying evidence for its past operation. It thus becomes essential to exploit indirect evidence preserved in the buoyant continental crust, part of which has survived over billions of years. This contribution starts with an in-depth review of existing models for continental growth. Growth models proposed so far can be categorized into three types: crust-based, mantle-based and other less direct inferences, and the first two types are particularly important as their difference reflects the extent of crustal recycling, which can be related to subduction. Then, a theoretical basis for a change in the mode of mantle convection in the Precambrian is reviewed, along with a critical appraisal of some popular notions for early Earth dynamics. By combining available geological and geochemical observations with geodynamical considerations, a tentative hypothesis is presented for the evolution of mantle dynamics and its relation to surface environment; the early onset of plate tectonics and gradual mantle hydration are responsible not only for the formation of continental crust but also for its preservation as well as its emergence above sea level. Our current understanding of various material properties and elementary processes is still too premature to build a testable, quantitative model for this hypothesis, but such modelling efforts could potentially transform the nature of the data-starved early Earth research by quantifying the extent of preservation bias.This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.
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Affiliation(s)
- Jun Korenaga
- Department of Geology and Geophysics, Yale University, New Haven, CT 06520, USA
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Parai R, Mukhopadhyay S. Xenon isotopic constraints on the history of volatile recycling into the mantle. Nature 2018; 560:223-227. [PMID: 30089920 DOI: 10.1038/s41586-018-0388-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 06/05/2018] [Indexed: 11/09/2022]
Abstract
The long-term exchange of volatile species (such as water, carbon, nitrogen and the noble gases) between deep Earth and surface reservoirs controls the habitability of the Earth's surface. The present-day volatile budget of the mantle reflects the integrated history of outgassing and retention of primordial volatiles delivered to the planet during accretion, volatile species generated by radiogenic ingrowth and volatiles transported into the mantle from surface reservoirs over time. Variations in the distribution of volatiles between deep Earth and surface reservoirs affect the viscosity, cooling rate and convective stress state of the solid Earth. Accordingly, constraints on the flux of surface volatiles transported into the deep Earth improve our understanding of mantle convection and plate tectonics. However, the history of surface volatile regassing into the mantle is not known. Here we use mantle xenon isotope systematics to constrain the age of initiation of volatile regassing into the deep Earth. Given evidence of prolonged evolution of the xenon isotopic composition of the atmosphere1,2, we find that substantial recycling of atmospheric xenon into the deep Earth could not have occurred before 2.5 billion years ago. Xenon concentrations in downwellings remained low relative to ambient convecting mantle concentrations throughout the Archaean era, and the mantle shifted from a net degassing to a net regassing regime after 2.5 billion years ago. Because xenon is carried into the Earth's interior in hydrous mineral phases3-5, our results indicate that downwellings were drier in the Archaean era relative to the present. Progressive drying of the Archean mantle would allow slower convection and decreased heat transport out of the mantle, suggesting non-monotonic thermal evolution of the Earth's interior.
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Affiliation(s)
- Rita Parai
- Department of Earth and Planetary Sciences, Washington University in St. Louis, Saint Louis, MO, USA.
| | - Sujoy Mukhopadhyay
- Department of Earth and Planetary Sciences, University of California, Davis, Davis, CA, USA
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15
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Nielsen SG, Horner TJ, Pryer HV, Blusztajn J, Shu Y, Kurz MD, Le Roux V. Barium isotope evidence for pervasive sediment recycling in the upper mantle. SCIENCE ADVANCES 2018; 4:eaas8675. [PMID: 30009259 PMCID: PMC6040842 DOI: 10.1126/sciadv.aas8675] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 05/31/2018] [Indexed: 06/08/2023]
Abstract
The upper mantle, as sampled by mid-ocean ridge basalts (MORBs), exhibits significant chemical variability unrelated to mechanisms of melt extraction at ridges. We show that barium isotope variations in global MORBs vary systematically with radiogenic isotopes and trace element ratios, which reflects mixing between depleted and enriched MORB melts. In addition, modern sediments and enriched MORBs share similar Ba isotope signatures. Using modeling, we show that addition of ~0.1% by weight of sediment components into the depleted mantle in subduction zones must impart a sedimentary Ba signature to the overlying mantle and induce low-degree melting that produces the enriched MORB reservoir. Subsequently, these enriched domains convect toward mid-ocean ridges and produce radiogenic isotope variation typical of enriched MORBs. This mechanism can explain the chemical and isotopic features of enriched MORBs and provide strong evidence for pervasive sediment recycling in the upper mantle.
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Affiliation(s)
- Sune G. Nielsen
- NIRVANA (Non-traditional Isotope Research for Advanced Novel Applications) Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Tristan J. Horner
- NIRVANA (Non-traditional Isotope Research for Advanced Novel Applications) Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Helena V. Pryer
- NIRVANA (Non-traditional Isotope Research for Advanced Novel Applications) Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Jerzy Blusztajn
- NIRVANA (Non-traditional Isotope Research for Advanced Novel Applications) Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Yunchao Shu
- NIRVANA (Non-traditional Isotope Research for Advanced Novel Applications) Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
- Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Mark D. Kurz
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
| | - Véronique Le Roux
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
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16
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Heterogeneity in mantle carbon content from CO 2-undersaturated basalts. Nat Commun 2017; 8:14062. [PMID: 28082738 PMCID: PMC5241784 DOI: 10.1038/ncomms14062] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 11/25/2016] [Indexed: 11/08/2022] Open
Abstract
The amount of carbon present in Earth's mantle affects the dynamics of melting, volcanic eruption style and the evolution of Earth's atmosphere via planetary outgassing. Mantle carbon concentrations are difficult to quantify because most magmas are strongly degassed upon eruption. Here we report undegassed carbon concentrations from a new set of olivine-hosted melt inclusions from the Mid-Atlantic Ridge. We use the correlations of CO2 with trace elements to define an average carbon abundance for the upper mantle. Our results indicate that the upper mantle carbon content is highly heterogeneous, varying by almost two orders of magnitude globally, with the potential to produce large geographic variations in melt fraction below the volatile-free solidus. Such heterogeneity will manifest as variations in the depths at which melt becomes interconnected and detectable, the CO2 fluxes at mid-ocean ridges, the depth of the lithosphere-asthenosphere boundary, and mantle conductivity.
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17
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Record of massive upwellings from the Pacific large low shear velocity province. Nat Commun 2016; 7:13309. [PMID: 27824054 PMCID: PMC5105175 DOI: 10.1038/ncomms13309] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 09/20/2016] [Indexed: 11/09/2022] Open
Abstract
Large igneous provinces, as the surface expression of deep mantle processes, play a key role in the evolution of the planet. Here we analyse the geochemical record and timing of the Pacific Ocean Large Igneous Provinces and preserved accreted terranes to reconstruct the history of pulses of mantle plume upwellings and their relation with a deep-rooted source like the Pacific large low-shear velocity Province during the Mid-Jurassic to Upper Cretaceous. Petrological modelling and geochemical data suggest the need of interaction between these deep-rooted upwellings and mid-ocean ridges in pulses separated by ∼10-20 Ma, to generate the massive volumes of melt preserved today as oceanic plateaus. These pulses impacted the marine biota resulting in episodes of anoxia and mass extinctions shortly after their eruption.
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18
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Dalton CA, Langmuir CH, Gale A. Geophysical and Geochemical Evidence for Deep Temperature Variations Beneath Mid-Ocean Ridges. Science 2014; 344:80-3. [PMID: 24700855 DOI: 10.1126/science.1249466] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Colleen A. Dalton
- Department of Earth and Environment, Boston University, 685 Commonwealth Avenue, Boston, MA 02215, USA
| | - Charles H. Langmuir
- Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA
| | - Allison Gale
- Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA
- Department of Plant and Earth Science, University of Wisconsin, River Falls, 410 South 3rd Street, River Falls, WI 54022, USA
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19
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Cottrell E, Kelley KA. Redox Heterogeneity in Mid-Ocean Ridge Basalts as a Function of Mantle Source. Science 2013; 340:1314-7. [DOI: 10.1126/science.1233299] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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20
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Cannat M, Cann J, Maclennan J. Some Hard Rock Constraints on the Supply of Heat to Mid-Ocean Ridges. MID-OCEAN RIDGES 2013. [DOI: 10.1029/148gm05] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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21
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White WM, Duncan RA. Geochemistry and Geochronology of the Society Islands: New Evidence for Deep Mantle Recycling. EARTH PROCESSES: READING THE ISOTOPIC CODE 2013. [DOI: 10.1029/gm095p0183] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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22
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The Influence of Mantle Plumes in Generation of Indian Oceanic Crust. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm070p0057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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23
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Langmuir CH, Klein EM, Plank T. Petrological Systematics of Mid-Ocean Ridge Basalts: Constraints on Melt Generation Beneath Ocean Ridges. MANTLE FLOW AND MELT GENERATION AT MID-OCEAN RIDGES 2013. [DOI: 10.1029/gm071p0183] [Citation(s) in RCA: 341] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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24
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Forsyth DW. Geophysical Constraints on Mantle Flow and Melt Generation Beneath Mid-Ocean Ridges. MANTLE FLOW AND MELT GENERATION AT MID-OCEAN RIDGES 2013. [DOI: 10.1029/gm071p0001] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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25
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Mantle Flow and Melt Migration Beneath Oceanic Ridges: Models Derived from Observations in Ophiolites. ACTA ACUST UNITED AC 2013. [DOI: 10.1029/gm071p0123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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26
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Kushiro I. Partial Melting of a Fertile Mantle Peridotite at High Pressures: An Experimental Study Using Aggregates of Diamond. EARTH PROCESSES: READING THE ISOTOPIC CODE 2013. [DOI: 10.1029/gm095p0109] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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27
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Saunders AD, Fitton JG, Kerr AC, Norry MJ, Kent RW. The North Atlantic Igneous Province. LARGE IGNEOUS PROVINCES: CONTINENTAL, OCEANIC, AND PLANETARY FLOOD VOLCANISM 2013. [DOI: 10.1029/gm100p0045] [Citation(s) in RCA: 153] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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28
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Lassiter JC, DePaolo DJ. Plume/Lithosphere Interaction in the Generation of Continental and Oceanic Flood Basalts: Chemical and Isotopic Constraints. LARGE IGNEOUS PROVINCES: CONTINENTAL, OCEANIC, AND PLANETARY FLOOD VOLCANISM 2013. [DOI: 10.1029/gm100p0335] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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29
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Hart SR, Ravizza GE. Os Partitioning Between Phases in Lherzolite and Basalt. EARTH PROCESSES: READING THE ISOTOPIC CODE 2013. [DOI: 10.1029/gm095p0123] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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30
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Perfit MR, Chadwick WW. Magmatism at Mid-Ocean Ridges: Constraints from Volcanological and Geochemical Investigations. FAULTING AND MAGMATISM AT MID-OCEAN RIDGES 2013. [DOI: 10.1029/gm106p0059] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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31
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Zhou H, Dick HJB. Thin crust as evidence for depleted mantle supporting the Marion Rise. Nature 2013; 494:195-200. [DOI: 10.1038/nature11842] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 12/11/2012] [Indexed: 11/09/2022]
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Abstract
The magmatic layers of the oceanic crust are created at constructive plate margins by partial melting of the mantle as it wells up. The chemistry of ocean floor basalts, the most accessible product of this magmatism, is studied for the insights it yields into the compositional heterogeneity of the mantle and its thermal structure. However, before eruption, parental magma compositions are modified at crustal pressures by a process that has usually been assumed to be fractional crystallization. Here we show that the global distributions of trace elements in ocean floor basalts describe a systematic pattern that cannot be explained by simple fractional crystallization alone, but is due to cycling of magma through the global ensemble of magma chambers. Variability in both major and incompatible trace-element contents about the average global pattern is due to fluctuations in the magma fluxes into and out of the chambers, and their depth, as well as to differences in the composition of the parental magmas.
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Affiliation(s)
- Hugh St C O'Neill
- Research School of Earth Sciences, Australian National University, Canberra, Australian Capital Territory 0200, Australia.
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34
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Mitchell NC. Aspects of marine geoscience: a review and thoughts on potential for observing active processes and progress through collaboration between the ocean sciences. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2012; 370:5567-5612. [PMID: 23129713 DOI: 10.1098/rsta.2012.0395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Much progress has been made in the UK in characterizing the internal structures of major physiographic features in the oceans and in developing understanding of the geological processes that have created or shaped them. UK researchers have authored articles of high impact in all areas described here. In contrast to terrestrial geoscience, however, there have been few instrumented observations made of active processes by UK scientists. This is an area that could be developed over the next decades in the UK. Research on active processes has the potential ability to engage the wider public: Some active processes present significant geo-hazards to populations and offshore infrastructure that require monitoring and there could be commercial applications of technological developments needed for science. Some of the suggestions could involve studies in shallow coastal waters where ship costs are much reduced, addressing tighter funding constraints over the near term. The possibilities of measuring aspects of volcanic eruptions, flowing lava, turbidity currents and mass movements (landslides) are discussed. A further area of potential development is in greater collaboration between the ocean sciences. For example, it is well known in terrestrial geomorphology that biological agents are important in modulating erosion and the transport of sediments, ultimately affecting the shape of the Earth's surface in various ways. The analogous effect of biology on large-scale geomorphology in the oceans is also known but remains poorly quantified. Physical oceanographic models are becoming increasingly accurate and could be used to study further the patterns of erosion, particle transport and deposition in the oceans. Marine geological and geophysical data could in turn be useful for further verification of such models. Adapting them to conditions of past oceans could address the shorter-period movements, such as due to internal waves and tides, which have been barely addressed in palaeoceanography.
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Affiliation(s)
- Neil C Mitchell
- School of Earth, Atmospheric and Environmental Sciences, University of Manchester, UK.
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35
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Sinton JM, Smaglik SM, Mahoney JJ, Macdonald KC. Magmatic processes at superfast spreading mid-ocean ridges: Glass compositional variations along the East Pacific Rise 13°-23°S. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/90jb02454] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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36
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Scott DR, Stevenson DJ. A self-consistent model of melting, magma migration and buoyancy-driven circulation beneath mid-ocean ridges. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/jb094ib03p02973] [Citation(s) in RCA: 220] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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37
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Furukawa Y. Magmatic processes under arcs and formation of the volcanic front. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb00350] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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38
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Schilling JG, Hanan BB, McCully B, Kingsley RH, Fontignie D. Influence of the Sierra Leone mantle plume on the equatorial Mid-Atlantic Ridge: A Nd-Sr-Pb isotopic study. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb00337] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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39
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Tanimoto T, Stevenson DJ. Seismic constraints on a model of partial melts under ridge axes. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb03402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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40
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41
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Rogers NW, Hawkesworth CJ, Ormerod DS. Late Cenozoic basaltic magmatism in the Western Great Basin, California and Nevada. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb02738] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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42
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43
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Duncan RA, Fisk MR, White WM, Nielsen RL. Tahiti: Geochemical evolution of a French Polynesian Volcano. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb00991] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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44
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Wang X, Cochran JR. Gravity anomalies, isostasy, and mantle flow at the East Pacific Rise crest. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb01551] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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45
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Kinzler RJ, Grove TL. Corrections and further discussion of the primary magmas of mid-ocean ridge basalts, 1 and 2. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/93jb02164] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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46
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Abbott D, Burgess L, Longhi J, Smith WHF. An empirical thermal history of the Earth's upper mantle. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb00112] [Citation(s) in RCA: 210] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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47
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Kelemen PB, Holbrook WS. Origin of thick, high-velocity igneous crust along the U.S. East Coast Margin. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/95jb00924] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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48
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Bown JW, White RS. Effect of finite extension rate on melt generation at rifted continental margins. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb01478] [Citation(s) in RCA: 155] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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49
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Shen Y, Forsyth DW. Geochemical constraints on initial and final depths of melting beneath mid-ocean ridges. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb02768] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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50
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Niu Y, Batiza R. Magmatic processes at a slow spreading ridge segment: 26°S Mid-Atlantic Ridge. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/94jb01663] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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