Article
Geochemistry & Geophysics
Yiran Wang, Jianghong Deng, Renqiang Liao, Long Chen, Dongyong Li, He Liu, Weidong Sun
Summary: The serpentinized mantle wedge undergoes magnesium isotopic fractionation during late-stage serpentinization, resulting in slightly heavier magnesium isotopic compositions. This is likely due to the removal of isotopically light magnesium by infiltrating slab fluids. Mantle wedge peridotites have magnesium isotopic compositions that are similar to subcontinental lithospheric mantle peridotites and lighter than oceanic mantle peridotites, suggesting mantle heterogeneity.
Article
Geosciences, Multidisciplinary
Samuel Angiboust, Jesus Munoz-Montecinos, Aitor Cambeses, Tom Raimondo, Damien Deldicque, Antonio Garcia-Casco
Summary: Recent seismological studies have found transient seismicity clusters in the mantle wedge above subduction zones, but their physical significance remains poorly understood. This study documents brittle-viscous features in jadeitites from Russia, Myanmar, and Guatemala, providing insights into deformation mechanisms in deep subduction environments. The observed deformation patterns in these jadeitites suggest external fluid influx within fracture zones, contributing to seismic instabilities in the mantle wedge.
EARTH-SCIENCE REVIEWS
(2021)
Article
Geosciences, Multidisciplinary
L. M. Kenyon, I Wada
Summary: In this study, a 3-D mantle wedge flow field is used for a generic oblique subduction system. The elastic tensors of mineral aggregates in the mantle wedge are calculated for different olivine crystal preferred orientations (CPO) and applied in the forward calculation of shear-wave splitting (SWS) through the mantle wedge. The results show that the hexagonal approximation of the full tensor does not significantly affect the SWS parameters for most CPO types except for C-type CPO. Furthermore, regardless of the 3-D mantle flow field resulting from oblique subduction, the fast direction is margin-normal for A-, C-, and E-type CPOs and margin-parallel for B-type CPO.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Y. Boneh, M. Pec, G. Hirth
Summary: The mineral talc is stable over a wide range of pressure and temperature, and can form in mafic and ultramafic rocks and faults along plate boundaries. It is known to be one of the weakest minerals and may play a role in fault deformation and seismic activity. However, little is known about its mechanical properties under high temperatures and confining pressures. In this study, deformation experiments were conducted on talc cylinders under conditions simulating deep faults and subduction zones. The results show that talc's strength is highly dependent on temperature, with thermal weakening leading to increased strain localization. The observed friction coefficients for talc are consistent with those inferred for subducted slabs and the San Andreas fault. The presence of talc may explain the low strength of faults and subduction interfaces where slow slip events occur.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
Lindsey M. Kenyon, Ikuko Wada
Summary: The study investigates the evolution of olivine crystal preferred orientation and its effect on shear wave splitting in the mantle wedge of oblique subduction zones. Model simulations show that seismic fast axis does not always align with flow direction in these zones. The research demonstrates significant variations in SWS parameters with subduction obliquity and initial polarization, requiring a range of shear waves to interpret accurately.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Jonathan C. Aitchison, Dominique Cluzel, Trevor R. Ireland, Renjie Zhou, Dongyang Lian, Daniel Patias, Zhen Yan, Jingsui Yang
Summary: This study demonstrates the association of zircons and rutiles recovered from ophiolitic rocks in New Caledonia with subducting sediments, indicating the transfer of solid-phase materials between plates. The presence of these minerals in forearc harzburgite suggests their incorporation into the mantle wedge host likely occurred at around 50-60 km depth within the subduction channel. The conveyance of high field strength elements within solid-state accessory mineral phases into suprasubduction mantle wedges represents a significant phenomenon at convergent margins globally.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Geochemistry & Geophysics
L. Notini, M. Scambelluri, A. Tommasi, A. Zanetti, F. Ferri, A. Rodriguez-Vargas, E. Rampone
Summary: This study provides important petrologic information on the mantle wedge above an active subduction zone in Southern Colombia. The researchers analyzed a unique suite of rock samples and found evidence of hydration, metasomatism, and partial melting in the mantle wedge. They also observed variations in lithotypes, textures, and mineral abundance, indicating different interactions with melts and fluids. This study sheds light on the complex petrological processes occurring in the mantle wedge and contributes to our understanding of subduction zone dynamics.
Article
Geosciences, Multidisciplinary
Adam F. Holt
Summary: Subduction zones generate pressure fields that cause dynamic topography on Earth's surface. However, global mantle flow models often oversimplify subduction zones and associated pressure fields. This study reveals the existence of positive pressure and resultant uplift beneath subducting plates, which can be better predicted by incorporating subduction zones into mantle flow models.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Ikuko Wada
Summary: The study shows that the solid-state mantle flow in subduction zones is influenced by local subduction parameters and the azimuthal directions of mantle inflow and outflow. Along concave and convex arc margins, the mantle flow direction is affected by the strike and obliquity of the subducting slab, resulting in variations in the temperature of the mantle wedge region.
JOURNAL OF GEODYNAMICS
(2021)
Article
Geochemistry & Geophysics
Jianghong Deng, Yongsheng He, Robert E. Zartman, Xiaoyong Yang, Weidong Sun
Summary: Mantle wedge serpentinites play a crucial role in the oxidation process of arc magmas, and a mechanism involving iron isotope fractionation and iron oxidation has been proposed to explain this phenomenon.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Geochemistry & Geophysics
Tongbin Shao, Yongsheng Zhou, Maoshuang Song, Xi Ma, Lei Zhang, Wenming Yao, Jiaxiang Dang, Jianfeng Li
Summary: The deformation behavior of antigorite is controlled by a semibrittle regime, which may be affected by the deformation geometry and phase stability. Dehydration does not directly trigger earthquakes, but fine-grained antigorite in cold subduction zones may induce seismic activity by producing water and talc in the process of shear friction.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Review
Geochemistry & Geophysics
Victor P. Nechaev, Frederick L. Sutherland, Eugenia Nechaeva
Summary: This study reviews the data on the Phanerozoic plume activity and the geochemistry of their igneous rocks, aiming to explore the changes in intensity and geochemistry of mantle plumes related to the Earth's evolution and galactic seasonality. The data indicate that peaks of various igneous activities, including both plume-related and subduction/collision-related magmatism, were associated with galactic summers, while significant drops in igneous activity were observed during galactic winters. The materials subducted into the transitional and lower mantle had a large influence on plume magmas during galactic summers, but were less significant in the galactic spring and autumn seasons.
Article
Geochemistry & Geophysics
Cheng-Chien Peng, Ban-Yuan Kuo, Eh Tan
Summary: The response of the underlying mantle to the subduction of an oceanic plate remains controversial, with numerical models suggesting the presence of 3D flow with different components induced by slab entrainment and rollback. Seismology studies have documented different types of flow in most subduction zones, evoking debates concerning the flow mechanisms. The observed anisotropy pattern in the Cocos subduction zone suggests a transition from entrained poloidal flow to rollback-induced toroidal flow with strong coupling along the lithosphere-asthenosphere boundary.
EARTH AND PLANETARY SCIENCE LETTERS
(2021)
Article
Geochemistry & Geophysics
Qasid Ahmad, Martin Wille, Jabrane Labidi, Stephan Konig, Colin Devey, Klaus Mezger
Summary: Subduction redistributes elements between Earth's geochemical reservoirs, altering the chemical composition of various parts of Earth and influencing the evolution of life. The study of lavas from Pitcairn Island reveals the recycling of pelagic sediments with distinct chemical and isotopic characteristics, which has an impact on the source of ocean island basalts.
EARTH AND PLANETARY SCIENCE LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Diandian Peng, Lijun Liu
Summary: Numerical modeling of subduction plays a crucial role in understanding Earth's internal dynamics and its surface tectonic responses. This study evaluates the impact of model domain and boundary conditions on regional simulations by comparing them with global simulations. The results show that regional models cannot accurately replicate seismic tomography in East Asia and South America due to the limitation of reproducing large-scale mantle flow, while they perform well in North America and Fiji-Tonga due to the influence of fast-retreating overriding plates.
EARTH-SCIENCE REVIEWS
(2023)
Article
Geochemistry & Geophysics
Jonathan Wolf, Maureen D. Long, Kuangdai Leng, Tarje Nissen-Meyer
Summary: Observations of seismic anisotropy at the base of the mantle provide insights into geodynamic scenarios and patterns of flow at the base of the mantle. However, limitations in current studies include the use of ray theoretical framework in forward modelling and lack of consideration of finite-frequency wave propagation effects.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Maureen D. Long, Lara S. Wagner, Scott D. King, Rob L. Evans, Sarah E. Mazza, Joseph S. Byrnes, Elizabeth A. Johnson, Eric Kirby, Maximiliano J. Bezada, Esteban Gazel, Scott R. Miller, John C. Aragon, Shangxin Liu
Summary: The article discusses the lithospheric evolution of the eastern margin of North America and the unusual properties of the Central Appalachian Mountains, providing evidence for lithospheric loss beneath the region and proposing possible mechanisms. Through various geophysical and geological methods, the study concludes that the lithosphere in this area is thin and has undergone past episodes of lithospheric loss involving mantle upwelling and partial melting.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Yantao Luo, Maureen D. Long, Paul Karabinos, Yvette D. Kuiper, Stephane Rondenay, John C. Aragon, Lucas Sawade, Peter Makus
Summary: Southern New England displays diverse geological features resulting from past tectonic events. Seismological studies in Connecticut have revealed deep Moho variations, potential remnants of past subduction events, and a negative velocity gradient at the base of the lithosphere. These features suggest complex tectonic processes shaping the region's geology.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2021)
Article
Geochemistry & Geophysics
Jonathan Wolf, Maureen D. Long, Kuangdai Leng, Tarje Nissen-Meyer
Summary: This study systematically assesses the accuracy and limitations of several methods for resolving seismic anisotropy in the deep mantle. The research reveals inaccuracies and suggests modifications to improve the reliability of the measurement techniques. Recommendations are also provided to ensure accurate comparisons and measurements of lowermost mantle anisotropy.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geology
Gillian B. Goldhagen, Heather A. Ford, Maureen D. Long
Summary: Using data from the SEISConn seismic experiment, this study characterizes the upper-mantle structure beneath southern New England. The researchers identify a well-defined lithosphere-asthenosphere boundary, a thin lithosphere, and a possible extension of the Northern Appalachian Anomaly. They also suggest the preservation of inherited structure in the present-day lithosphere.
Article
Geosciences, Multidisciplinary
Yantao Luo, Maureen D. Long, Stephane Rondenay, Paul Karabinos, Yvette D. Kuiper
Summary: This study reveals the significant offset and dipping discontinuities of the Moho beneath the New England Appalachians, indicating tectonic movements in the Paleozoic or younger. By using scattered wavefield migration, new insights are obtained, including the discovery of a doubled Moho and mafic underplating.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Geochemistry & Geophysics
Jonathan Wolf, Maureen D. Long
Summary: Flow in the mantle's bottom boundary layer is crucial for shaping structures and processes in the deep mantle. This study investigates the influence of remnant slabs on lowermost mantle flow and reveals their significant role in driving the behavior of the lowermost mantle.
EARTH AND PLANETARY SCIENCE LETTERS
(2022)
Article
Geochemistry & Geophysics
Angelo Pisconti, Neala Creasy, James Wookey, Maureen D. Long, Christine Thomas
Summary: Recent advances in seismic anisotropy studies have provided significant insights into the structure and deformation of the D '' region beneath the South Atlantic. By analyzing seismic phases, researchers have detected a discontinuity within the D '' region and evidence of anisotropy. The study proposes a regional variation in mineralogy and deformation, suggesting the presence of distinct domains within and outside the large low seismic velocity province.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geochemistry & Geophysics
Ved Mittal, Maureen D. Long, Rob L. Evans, Joseph S. Byrnes, Maximiliano Bezada
Summary: The Central Appalachian Anomaly (CAA) is a region beneath eastern North America with abnormal seismic velocity, seismic attenuation, and electrical conductivity structure. Through the Mid-Atlantic Geophysical Integrative Collaboration (MAGIC) experiment, new observations from teleseismic earthquakes at MAGIC stations provide insights into the structure and properties of the upper mantle in the CAA region. These observations, combined with previous estimates of attenuation and conductivity, suggest that 1%-2% partial melt is necessary to explain the anomalies in velocity, attenuation, and electrical conductivity beneath the MAGIC array.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2023)
Article
Geochemistry & Geophysics
Jonathan Wolf, Daniel A. Frost, Maureen D. Long, Edward Garnero, Adeolu O. Aderoju, Neala Creasy, Ebru Bozdag
Summary: Shear-wave splitting measurements are commonly used to resolve seismic anisotropy in both the upper and lowermost mantle. However, practical constraints such as limited suitable phases and poor signal-to-noise ratios or large measurement uncertainties limit the application of these techniques. This study investigates how a beamforming methodology can improve shear-wave splitting measurement confidence intervals and shows the potential of beamforming to improve the detection of lowermost mantle anisotropy.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
Article
Geochemistry & Geophysics
Jonathan Wolf, Maureen D. D. Long
Summary: The study reveals that ultralow velocity zones (ULVZs) and seismic anisotropy are commonly detected in the lowermost mantle at the edges of large low velocity provinces (LLVPs). By jointly investigating ULVZ structure and lowermost mantle anisotropy near the Pacific LLVP, the study provides insights into the geodynamic scenarios for flow in the deep mantle. The findings contribute to our understanding of mantle flow processes at the edges of LLVP structures.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2023)
Article
Geosciences, Multidisciplinary
Shangxin Liu, Scott D. King, Maureen D. Long, Margaret H. Benoit, John C. Aragon
Summary: Using high-resolution seismic data along the MAGIC profile, we found a shallowing trend of both the 410-km and 660-km discontinuities beneath the central Appalachian region. This could be explained by hydro-thermal upwelling and hot upwelling return flow associated with the descending lower mantle Farallon slab. The rising hydrous hot upwelling may trigger dehydration melting atop the 410-km discontinuity, leading to the low velocity upper mantle anomaly observed in the region.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
Jonathan Wolf, Maureen D. Long, Mingming Li, Edward Garnero
Summary: This study utilizes a global digital database to examine the seismic anisotropy distribution in the D '' layer of Earth's mantle and assess whether it is more likely to be located at the edges of the two large-low velocity provinces. The findings indicate that this hypothesis lacks statistical justification when considering previous observations of lowermost mantle anisotropy. The study also highlights the uneven global ray coverage of the lowermost mantle, with the edges and interiors of LLVPs being less well-sampled.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2023)
Article
Geosciences, Multidisciplinary
Jonathan Wolf, Maureen D. Long
Summary: We investigate the applicability of the PS-SKS splitting technique using global wavefield simulations and apply this technique to measure upper mantle anisotropy beneath the Pacific Ocean basin. Our results suggest that the upper mantle anisotropy in this region is mainly influenced by shearing due to the Pacific plate. Furthermore, we observe a rotation of fast polarization directions north of Fiji, possibly indicating far-field mantle flow effects associated with the subduction of the Australian plate beneath the Pacific.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
Haiying Gao, Maureen D. Long
Summary: The Cascadia subduction zone represents a thermally hot endmember of global subduction systems with complex and three-dimensional heterogeneities. However, consensus on many important aspects of its magmatic, tectonic, and geodynamic setting remains elusive.