Article
Geosciences, Multidisciplinary
Yasuhiro Kuwayama, Kei Hirose, Laura Cobden, Mayu Kusakabe, Shigehiko Tateno, Yasuo Ohishi
Summary: Through high-pressure and high-temperature X-ray diffraction measurements, we discovered that a phase transition occurs in pyrolite even at high temperatures and pressures, indicating the presence of post-perovskite above the core-mantle boundary. This has significant implications for seismology, geodynamics, and heat transfer.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
James Panton, J. Huw Davies, Tim Elliott, Morten Andersen, Don Porcelli, Matthew G. Price
Summary: Measurements of Pb isotope ratios in mid-ocean ridge basalts and ocean island basalts show broad linear correlations and scatter. Previous modeling suggests a change in U and Pb behaviors between 2.25 and 2.5 billion years ago, leading to net recycling of high U/Pb material in Earth's later history. However, simulations fail to reproduce the observed scatter in Pb isotope ratios. New 3D mantle convection simulations including melting, U recycling, and Pb extraction are able to fit the observed gradient and scatter of Pb isotope ratios without requiring long-term accumulation of subducted oceanic crust at the core-mantle boundary.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2022)
Article
Geosciences, Multidisciplinary
Yang Li, Zhigang Zhang, Juan Li, Zhidong Shi, Liang Zhao
Summary: Thermal conductivity of the mantle varies with pressure and composition, and it plays a crucial role in the thermochemical evolution of the Earth's mantle. Increasing depth-dependent thermal conductivity leads to a larger core-mantle boundary heat flow and more stable thermochemical piles, while decreasing composition-dependent thermal conductivity slightly destabilizes the primordial thermochemical piles. The long-term stability of the piles decreases if the primordial mantle material is compositionally more viscous and this destabilizing effect is enhanced by decreasing composition-dependent thermal conductivity. Overall, the combined effects of depth- and composition-dependent thermal conductivity and compositional viscosity ratio significantly influence the thermochemical evolution of the mantle.
SCIENCE CHINA-EARTH SCIENCES
(2023)
Article
Geochemistry & Geophysics
Guanjie Xiang, Zhensheng Wang, Timothy M. Kusky
Summary: The Earth's mantle is more than 2800 km deep, compositionally heterogenous, and potentially stratified. Recently, plume-like anomalies at around 1000 km depth have been observed to exhibit different types of anomalous behavior. 2D modeling indicates that the penetration, necking, and lateral extension of mantle plumes at this depth are influenced by factors such as source volume, excess temperature, viscosity, and composition-related density stratification.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geosciences, Multidisciplinary
J. S. Maia, M. A. Wieczorek, A. -C. Plesa
Summary: In this study, the viscosity structure of the Venusian mantle was investigated by modeling the dynamic gravity and topography signatures and using a Bayesian inference approach. The results revealed the existence of a thin low-viscosity zone in the uppermost mantle, about 235 km thick, with a viscosity reduction of 5-15 times compared to the underlying mantle. This reduced viscosity may be a result of partial melting, similar to the asthenosphere in Earth, indicating that Venus is predominantly governed by ongoing magmatic processes.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Erin Heilman, Thorsten W. Becker
Summary: Mantle plumes can play a significant role in the evolution of Earth and plate tectonics, potentially causing the termination of subduction zones and contributing to the complexity of mantle structures. This effect may be particularly relevant for the early Earth and remain relevant in modern times.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
Yang Li, Frederic Deschamps, Zhidong Shi, Joshua M. Guerrero, Wen-Pin Hsieh, Liang Zhao, Paul J. Tackley
Summary: The composition-dependent thermal conductivity of primordial dense material has a secondary role in the long-term evolution of Earth's mantle, but if the material is enriched in heat-producing elements, it slightly affects the height and coverage of these reservoirs.
EARTH PLANETS AND SPACE
(2022)
Article
Geochemistry & Geophysics
Claudia Stein, Ulrich Hansen
Summary: The Earth's core-mantle boundary (CMB) has complex seismic anomalies such as large low shear-wave velocity provinces (LLSVPs) and ultra-low velocity zones (ULVZs). To simulate the dynamics of these structures, ad hoc assumptions are made in models of mantle convection. Density and mass, which are critical for the dynamics, are hardly constrained. One possible origin for the dense layer above the CMB is core-mantle interaction. The study analyzes the penetration of dense material into the mantle using a chemical gradient and suggests that convection-assisted diffusion plays a crucial role in the formation of chemically distinct piles and can explain the coexistence of LLSVPs and ULVZs.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Mechanics
Yadan Mao
Summary: This study provides a detailed analysis of continent motion and thermal-mechanic feedback by using a simplified model. The results reveal that plate motion characteristics and frequencies change with plate size, and these changes have significant implications for continent motion and geological evolution.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Geochemistry & Geophysics
T. D. Jones, N. Sime, P. E. van Keken
Summary: The evolution of mantle composition is a destructive process where some portion of the mantle retains primitive chemical signatures and is buried within a slab graveyard at the core-mantle boundary. High-resolution finite element models show that sinking oceanic crust forms thermochemical piles which initially contain high concentrations of primitive material. This process does not require large-scale domains of anomalously high density and viscosity on early Earth.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2021)
Article
Geochemistry & Geophysics
F. Horton, J. Curtice, K. A. Farley, M. D. Kurz, P. D. Asimow, J. Treffkorn, X. M. Boyes
Summary: The Paleocene basaltic lavas exposed on Baffin Island have the highest He-3/He-4 ratios among terrestrial igneous rocks, potentially containing pristine primordial mantle material. Research findings suggest a common high-He-3/He-4 mantle component shared by Baffin Island and Iceland lavas. The variability in high-He-3/He-4 mantle reservoirs may reflect ancient mantle heterogeneity or helium addition in the upper or lower mantle.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geosciences, Multidisciplinary
Debajyoti Basu Sarkar, William B. Moore
Summary: This study investigates the lithospheric deformation associated with heat-pipe volcanic activity using numerical simulations. The results show that increased surface temperature prolongs the duration of heat-pipe volcanic activity, and plate tectonics are highly influenced by the temperature sensitivity of mantle viscosity.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geosciences, Multidisciplinary
J-A Hernandez, C. E. Mohn, M. G. Guren, M. A. Baron, R. G. Tronnes
Summary: Melting curves of Ca-perovskite were determined using ab initio density functional theory, showing that it has high thermal stability and a high melting temperature in the lower mantle pressure range. The study also revealed that the liquidus field of Ca-perovskite expands relative to other minerals with increasing pressure.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Henri Samuel, Maxim D. Ballmer, Sebastiano Padovan, Nicola Tosi, Attilio Rivoldini, Ana-Catalina Plesa
Summary: The Martian mantle likely has a compositionally distinct layer at the bottom enriched in iron and heat-producing elements which affects the thermal and chemical evolution of Mars significantly. This enriched basal layer delays deep cooling and influences many present-day characteristics of the planet. Due to its enrichment in iron and HPE, large volumes of stable melt near the core-mantle boundary may be mistaken for core material.
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
(2021)
Article
Mechanics
Alexander Chamolly, Neil M. Ribe
Summary: This study investigates the influence of spherical geometry on the dynamics of gravity-driven subduction of the oceanic lithosphere on Earth using a simple model and scaling analysis. The results show that sphericity has a significant impact on sinking speed and stress, with larger plates experiencing less reduction in sinking speed but greater increase in stress compared to smaller plates.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Astronomy & Astrophysics
Ravit Helled, Stephanie Werner, Caroline Dorn, Tristan Guillot, Masahiro Ikoma, Yuichi Ito, Mihkel Kama, Tim Lichtenberg, Yamila Miguel, Oliver Shorttle, Paul J. Tackley, Diana Valencia, Allona Vazan
Summary: The Ariel ESA mission aims to measure the atmospheric composition of exoplanets to better understand their bulk compositions. This will advance exoplanet characterisation and provide new insights into the nature of planets in our galaxy.
EXPERIMENTAL ASTRONOMY
(2022)
Article
Geochemistry & Geophysics
S. M. Langemeyer, J. P. Lowman, P. J. Tackley
Summary: More than two decades of research have made progress in generating plate-like surface behavior in models of mantle convection. The properties required for dynamic plates from mantle convection have been widely recognized and used in both 2-D and 3-D geometries. Studying the properties needed to obtain deep mantle features with LLSVP-like characteristics has become a topic of interest. The study focuses on discovering the properties that can produce a detached pair of 3-D features different from the ambient mantle.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geosciences, Multidisciplinary
Yang Li, Frederic Deschamps, Zhidong Shi, Joshua M. Guerrero, Wen-Pin Hsieh, Liang Zhao, Paul J. Tackley
Summary: The composition-dependent thermal conductivity of primordial dense material has a secondary role in the long-term evolution of Earth's mantle, but if the material is enriched in heat-producing elements, it slightly affects the height and coverage of these reservoirs.
EARTH PLANETS AND SPACE
(2022)
Article
Multidisciplinary Sciences
Chuan-Zhou Liu, Henry J. B. Dick, Ross N. Mitchell, Wu Wei, Zhen-Yu Zhang, Albrecht W. Hofmann, Jian-Feng Yang, Yang Li
Summary: This study reveals the preservation of ancient mantle lithosphere information in abyssal peridotites and unexpected connection between young oceanic and ancient continental lithosphere, indicating a significant compositional recycling process.
Article
Geochemistry & Geophysics
Maria Koroni, Anselme Borgeaud, Andreas Fichtner, Frederic Deschamps
Summary: The core-mantle boundary (CMB) is a significant internal boundary in the Earth that strongly influences its dynamics. However, there is currently a lack of agreement between models of CMB topographic variations. This study analyzes seismic waves interacting with the CMB to understand the difficulties in inferring CMB topography and provides sensitivity kernels to explain the behavior of measured traveltimes.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Jianfeng Yang, Liang Zhao, Yang Li
Summary: Fluids associated with subducting slabs play a crucial role in regulating water discharge, arc magmatism, and intermediate-depth earthquakes. This study presents high-resolution numerical models that show the impact of plastic weakening and friction coefficient on fault patterns, while plate age and elasticity have minimal influence. Brittle bending faults facilitate seawater infiltrating into subducting slabs, explaining sporadic lower plane earthquakes.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geosciences, Multidisciplinary
Min Huang, Yang Li, Liang Zhao
Summary: Seismic tomography observations reveal the existence of two large low shear velocity provinces beneath Africa and the Pacific, which are suggested to be thermochemical piles of primordial material in the lower mantle. The evolution of these provinces is of great importance to our understanding of mantle dynamics.
SCIENCE CHINA-EARTH SCIENCES
(2022)
Article
Geochemistry & Geophysics
Jun Su, Christine Houser, John W. Hernlund, Frederic Deschamps
Summary: Seismic tomography models provide information on the distribution and magnitude of P- and S-wave velocity variations in the Earth's mantle. The presence of large low shear velocity provinces (LLSVPs) beneath the Pacific and Africa has important implications for their origin. However, the absence of these features in P-wave velocity models may be due to lower resolution compared to S-wave velocity models. By applying tomographic filters and analyzing thermochemical mantle convection models, it is revealed that distinct phase and/or composition can be differentiated from cases where only temperature varies. A new proxy called 'large uncorrelated modulus provinces' (LUMPs) is developed to explore uncorrelated P- and S-wave velocity anomalies.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Astronomy & Astrophysics
Laetitia Lebec, Stephane Labrosse, Adrien Morison, Paul J. Tackley
Summary: The presence of a high-pressure ice layer between the silicate core and the liquid ocean in large icy moons and ocean worlds has been considered as a hindrance to habitability. However, recent studies have challenged this view and demonstrated the possibility of nutrient transfer under specific conditions. Our study takes into account the dynamical implications of the phase equilibrium at the ice-ocean interface, which allows exchanges between the high-pressure ice layer and the liquid ocean. We propose a scaling relationship between the bottom temperature, top vertical velocity, and Rayleigh number, considering different values of a dimensionless parameter phi.
Article
Astronomy & Astrophysics
Harry A. Ballantyne, Martin Jutzi, Gregor J. Golabek, Lokesh Mishra, Kar Wai Cheng, Antoine B. Rozel, Paul J. Tackley
Summary: A giant impact is suggested as the explanation for the Martian Dichotomy, with recent studies favoring a hybrid origin caused by impact-induced crust-production. This study uses a large suite of impact simulations and a sophisticated geophysical scheme to investigate the feasibility of a giant impact on either hemisphere of Mars. The results suggest that a cannonical Borealis-forming impact is not possible, but instead favor an impact and subsequent localised magma ocean in the southern hemisphere that results in a thicker crust than the north.
Review
Geosciences, Multidisciplinary
Liang Zhao, Zhengtang Guo, Huaiyu Yuan, Xinxin Wang, Hao Shen, Jianfeng Yang, Baolu Sun, Ning Tan, Hui Zhang, Yonggang Liu, Yang Li, Jiamin Wang, Weiqiang Ji, Rixiang Zhu
Summary: Plate tectonics play a vital role in regulating atmospheric CO2 concentration over geological timescales. Current research on tectonic CO2 dynamics requires the development of models that include four modules: simulating carbon processes, calculating CO2 fluxes, reconstructing carbon cycling within tectonic scenarios, and comparing with atmospheric CO2 history data. The primary technical challenge lies in simulating the complex carbon dynamics across different scales in time and space.
SCIENCE CHINA-EARTH SCIENCES
(2023)
Article
Geochemistry & Geophysics
G. Choblet, F. Deschamps, H. Amit, M. Lasbleis
Summary: The heat flux pattern at Earth's core-mantle boundary has a significant impact on core dynamics, but the traditional linear approximation method has biases. We analyze the influence of thermochemical mantle on seismic velocities and derive a formalism to infer the CMB heat flux from seismic shear velocity anomalies. Applying this formalism provides better fits than the commonly used linear fits.
PHYSICS OF THE EARTH AND PLANETARY INTERIORS
(2023)
Article
Geochemistry & Geophysics
Joshua Martin Guerrero, Frederic Deschamps, Yang Li, Wen-Pin Hsieh, Paul James Tackley
Summary: The effect of heterogeneous thermal conductivity on the stability of primordial material reservoirs in the mantle is examined using 2D spherical annulus geometry simulations. The depth-dependent profiles of mantle conductivity in numerical models often mask the effects of temperature and composition dependencies. By considering these dependencies and the reduction in thermochemical pile conductivity, it is found that a depth-dependent ratio of at least 9 is needed for stable primordial reservoirs. When the lowermost mantle's mean conductivity is greater than twice the surface conductivity, reservoirs can remain stable for very long periods of time.
Article
Geochemistry & Geophysics
Lingyu Zhang, Kristoffer Szilas
Summary: This study presents new petrological and geochemical data for the Narssaq Ultramafic Body (NUB) in the Itsaq Gneiss Complex of SW Greenland. The results indicate that the ultramafic rocks of NUB are not mantle residues, but instead represent crustal cumulates derived from high-Mg magmas.
EARTH AND PLANETARY SCIENCE LETTERS
(2024)
Article
Geochemistry & Geophysics
Rong Xu, Sarah Lambart, Oliver Nebel, Ming Li, Zhongjie Bai, Junbo Zhang, Ganglan Zhang, Jianfeng Gao, Hong Zhong, Yongsheng Liu
Summary: This study investigated the iron isotope compositions of Cenozoic basalts in Southeast China, finding significant variations related to different types of basalts and their respective sources.
EARTH AND PLANETARY SCIENCE LETTERS
(2024)
Article
Geochemistry & Geophysics
C. J. Ebinger, Miriam C. Reiss, Ian Bastow, Mary M. Karanja
Summary: The East African rift system is formed above mantle upwellings and the formation of rifts is related to lithospheric thinning and magmatic activity. The amount of splitting varies spatially and the fast axes are predominantly parallel to the orientation of the rifts. Thick lithospheric modules have less splitting and different orientations, which may indicate mantle plume flow. Splitting rotates and increases in strength as it enters the rift zones, suggesting that the anisotropy is mainly present at shallow depths.
EARTH AND PLANETARY SCIENCE LETTERS
(2024)
Correction
Geochemistry & Geophysics
Ekaterina Rojas-Kolomiets, Owen Jensen, Michael Bizimis, Gene Yogodzinski, Lukas Ackerman
EARTH AND PLANETARY SCIENCE LETTERS
(2024)
Article
Geochemistry & Geophysics
Robert W. Nicklas, Igor S. Puchtel, Ethan F. Baxter
Summary: Oxygen fugacity is a fundamental parameter for understanding redox processes in igneous systems. This study compares the Fe-XANES oxybarometry method with the V-in-olivine method for evaluating fO(2) in MORB lavas. The results show that the V-in-olivine method is not applicable to samples with low MgO content, and that the majority of Archean komatiite sources have lower fO(2) than modern MORB.
EARTH AND PLANETARY SCIENCE LETTERS
(2024)
Article
Geochemistry & Geophysics
Chunfei Chen, Stephen F. Foley, Sebastian Tappe, Huange Ren, Lanping Feng, Yongsheng Liu
Summary: The volatile components CO2 and H2O play a major role in mantle melting and heterogeneity. In this study, Ca isotopes were used to trace the lithological heterogeneity in alkaline magmatic rocks. The results revealed the presence of K-richterite and carbonate components as the source of alkaline magmas with low delta 44/40Ca values. These findings highlight the importance of Ca isotopes as a robust tracer of lithological variation caused by volatiles in the Earth's upper mantle.
EARTH AND PLANETARY SCIENCE LETTERS
(2024)
Article
Geochemistry & Geophysics
Timothee Jautzy, Gilles Rixhon, Regis Braucher, Romain Delunel, Pierre G. Valla, Laurent Schmitt, Aster Team
Summary: Although the current approach to estimate catchment-wide denudation rates using only 10Be concentrations has made significant progress in geomorphology, this study argues for the inclusion of 26Al measurements and testing of steady-state assumptions in slow eroding, formerly glaciated landscapes. The study conducted measurements of both 10Be and 26Al in stream sediments from the Vosges Massif in France and found that elevation, slope, channel steepness, and precipitation were the primary factors controlling denudation rates. The study also revealed a significant relationship between the extent of past glaciation and the cosmogenic (un-)steadiness in the stream sediments.
EARTH AND PLANETARY SCIENCE LETTERS
(2024)
Article
Geochemistry & Geophysics
Erik van der Wiel, Douwe J. J. van Hinsbergen, Cedric Thieulot, Wim Spakman
Summary: Numerical models of Earth's mantle dynamics can predict the vigour and mixing of mantle flow, and the average slab sinking rates are an unexplored parameter that can provide intrinsic information on these characteristics. Through numerical experiments, it has been found that slab sinking rates are strongly correlated with mantle convection and mixing, and may explain geochemical observations from hotspot volcanoes.
EARTH AND PLANETARY SCIENCE LETTERS
(2024)