Article
Geosciences, Multidisciplinary
Claudia Sanchez, Mie Ichihara, Osamu Kuwano
Summary: To study brittle and ductile fracturing of magma, bubble expansion and fracturing were investigated in a Maxwell-type viscoelastic fluid and a Bingham-type yield-strength fluid. Both fluids were found to be elastic, but showed different viscous behavior. In the Maxwell fluid, bubbles expanded viscously at low flux, fractured in a brittle manner at high flux, and behaved transitionally at intermediate flux. No fracturing was observed in the Bingham fluid. This suggests that the G ' > G '' condition alone is not sufficient to infer brittle fracturing.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
H. E. Cho, Shun-ichiro Karato
Summary: This study investigates the finite deformation of a weak inclusion embedded in a strong matrix in order to understand the possible causes for shear localization and geochemical heterogeneity in the Earth's lower mantle. The results show that finite strain leads to a significant strain weakening under simple shear deformation. The findings have important implications for understanding the lower mantle rheology and the preservation of geochemical heterogeneity and seismic anisotropy distribution.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geology
Hugh Tuffen, Jamie Farquharson, Fabian B. Wadsworth, Cameron Webb, Jacqueline Owen, Jonathan M. Castro, Kim Berlo, C. Ian Schipper, Katia Wehbe
Summary: This study documents the characteristics of breadcrust bombs from the 2008-2009 eruption of Chaiten volcano in Chile. The researchers found that the formation of breadcrust is induced by H2O diffusion and the associated viscosity increase, rather than by cooling as previously believed. The study also highlights the importance of dehydration quench in the continued vesiculation process of shallow conduit magma with very low H2O content.
Article
Geochemistry & Geophysics
F. Xu, D. Yamazaki, S. A. Hunt, N. Tsujino, Y. Higo, Y. Tange, K. Ohara, D. P. Dobson
Summary: This study experimentally verifies the rheology control of bridgmanite under low strain magnitude. The results demonstrate that bridgmanite dominates the bulk viscosity of post-spinel without strain localization and provides direct evidence for geodynamical models considering mantle compositional and rheological evolution in the lower mantle.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Julie Newman, Vasileios Chatzaras, Basil Tikoff, Jan R. Wijbrans, William M. Lamb, Martyn R. Drury
Summary: The study explores a natural deformed shear zone in the Turon de Tecouere massif of the French Pyrenees, finding that differential stresses and strain rates vary spatially and temporally, hypothesizing that strain localization occurs due to reactions decreasing grain size and promoting grain size sensitive deformation mechanisms.
Article
Geochemistry & Geophysics
Yixi Li, Shengsi Sun, Yunpeng Dong, Dengfeng He, Chao Cheng, Ziqiang Yang, Bin Zhang
Summary: The rheological behavior of metamorphosed migmatites in the North Qinling Terrane reveals the high temperature melt-present deformation and shear localization. The presence of peritectic amphibole and incongruent water-present melting reactions suggest the involvement of biotite-or amphibole-breakdown. The study is significant for understanding the evolution of mid-dle-lower crust during orogenesis.
Article
Geosciences, Multidisciplinary
Atsuko Namiki, Matthew R. Patrick, Michael Manga, Bruce F. Houghton
Summary: The fragmentation process in Hawaiian fountains is primarily driven by inertia, producing large fluidal pyroclasts, but with the release of volcanic gas in the fountain, smaller and more vesicular pyroclasts are also generated. The adiabatic expansion of volcanic gas induced by rapid cooling may lead to brittle fragmentation, a widespread process in explosive eruptions of varying importance.
Article
Geochemistry & Geophysics
Agnis Triahadini, Koki Aizawa, Tasuku M. Hashimoto, Keita Chiba, Kazunari Uchida, Yuto Yamamoto, Kanta Miyano, Dan Muramatsu, Satoru Aniya, Ayumu Okubo, Yuta Kawamura
Summary: Unzen volcano in Japan has been closely monitored since 1989 and studies have shown the transport of magma obliquely beneath the Tachibana Bay. Through magnetotelluric surveys, a 3-D resistivity model reveals a high-resistivity zone beneath Shimabara Peninsula and a low-resistivity zone to the west and east. This high-resistivity zone is believed to be a highly crystallized mush zone with low permeability.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2023)
Article
Geosciences, Multidisciplinary
Lulu Wu, Chuanbo Shen, Douglas A. Paton, Yanping Hou, Estelle J. Mortimer, Lianfu Mei, Rongyao Sun, Xiaowei Zeng, Guanzhong Shi
Summary: This study investigates the spatial strain variations during multiphase rifting in the Hailar Basin using high-quality seismic reflection data and borehole data. The results show that crustal rheology played a dominant role in rift development during the final rift phase, while the influence of geodynamic processes significantly decreased.
Article
Engineering, Marine
Yuxiang Zhang, Zuxing Chen, Zhigang Zeng
Summary: Submarine volcanic eruptions pose a threat to marine environments and resources. Magma mixing is an important factor in triggering volcanic eruptions. This study estimated the timescale of magma mixing and found that andesitic magma had a short residence time (0.1-0.3 years), while rhyolitic magma had a longer residence time (80-120 years). Efficient magma mixing allowed andesites to erupt, explaining their rarity in basalt-rhyolite dominant settings. However, rapid magma mixing and eruption negatively impact the development and preservation of seafloor hydrothermal resources. Thus, the stability of sub-seafloor magma systems should be evaluated in the assessment of seafloor sulfide resources and mining prospects.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2023)
Article
Geochemistry & Geophysics
T. K. Cawood, J. P. Platt
Summary: The study reconstructed the geometry and rheology of the Simplon Shear Zone, finding that the width increases with depth and during exhumation, weak mica layers formed, increasing strain localization.
Article
Geology
A. Cambeses, A. Garcia-Casco, J. F. Molina, P. Montero, S. Basak, I. Morales, F. Bea
Summary: The study of calc-alkaline lamprophyres and minettes from Zeneta, SE Spain Neogene Volcanic Province reveals a hybrid nature involving mantle-derived alkaline lamproitic and continental crust-derived granitic parental magmas. Interaction and mixing of these compositionally contrasted magmas resulted in the formation of hybrid calc-alkaline lamprophyre minette. The identification of mixing and fractionation processes in calc-alkaline minettes genesis opens a new scenario to be considered in understanding the petrogenesis of these rocks.
INTERNATIONAL GEOLOGY REVIEW
(2021)
Article
Geosciences, Multidisciplinary
Monica Piochi, Margherita Polacci, Fabio Arzilli, Guido Ventura
Summary: The study examines the textural complexity of alkaline tube pumices from a volcanic eruption in Italy, revealing the presence of large vesicle tubes, elongated vesicles, and sub-spherical vesicles associated with mineral phenocrysts. The analysis of Capillary number values suggests variations in magma strain-rate and rheology before fragmentation, with high values indicating bubble-breakup induced by tip-streaming. This research highlights the importance of micrometric heterogeneities for understanding magma dynamics and fragmentation processes.
JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH
(2021)
Article
Geochemistry & Geophysics
Liuyang Xu, Sheng Jin, Yaotian Yin, Wenbo Wei, Gaofeng Ye, Hao Dong, Letian Zhang, Jian'en Jing, Chengliang Xie
Summary: A stepwise procedure was proposed to obtain a multiscale 3-D resistivity model beneath the Caosiyao porphyry Mo deposit by joint inversion of data collected from audio-frequency magnetotelluric and broad-band magnetotelluric sites. The model reveals high-resolution structures, providing insights into the multiscale metallogenic system of the deposit.
GEOPHYSICAL JOURNAL INTERNATIONAL
(2022)
Article
Geochemistry & Geophysics
Nilanjan Chatterjee, Naresh C. Ghose
Summary: The Late Aptian Rajmahal Traps were formed by volcanic activity related to the Kerguelen Plume at the eastern margin of the Indian Shield. The magmas crystallized at upper crustal depths and were in equilibrium with the mantle at deeper depths. It is likely that the mantle-derived magmas accumulated below the upwarped Moho and were transported to the upper crust before eruption.
Article
Geosciences, Multidisciplinary
Mary C. Benage, Heather M. N. Wright, Michelle L. Coombs
Summary: This study investigates the impact of heterogeneous andesitic eruptions on microlite crystallization and vesiculation, revealing structural and compositional differences between the LSA and HSA end members, indicating eruption from multiple isolated shallow magma reservoirs. HSA pyroclasts have lower crystallinities, while LSA pyroclasts exhibit higher crystallinities influenced by composition.
BULLETIN OF VOLCANOLOGY
(2021)
Article
Geology
Thomas Giachetti, Kathleen R. Trafton, Joshua Wiejaczka, James E. Gardner, James M. Watkins, Thomas Shea, Heather M. N. Wright
Summary: New textural observations of pumice aggregates during volcanic eruptions suggest that some primary products of magma fragmentation can survive by sintering together, providing insights into the potential energy of fragmentation.
Article
Geology
Lucas R. Tesser, Carlos E. Ganade, Roberto F. Weinberg, Miguel A. S. Basei, Renato Moraes, Laisa A. Batista
Summary: This study reports the first identification of sapphirine-bearing ultrahigh-temperature metamorphic rocks in the Borborema Province in NE Brazil, providing insights into their formation mechanisms and timing. The results suggest a correlation between high geothermal gradients, continental rifting events, and the opening of oceanic basins, as well as their association with the formation of the Columbia supercontinent.
JOURNAL OF METAMORPHIC GEOLOGY
(2022)
Article
Geochemistry & Geophysics
Ben S. Knight, Fabio A. Capitanio, Roberto F. Weinberg
Summary: The relationship between shear stress at the base of the crust and the yield stress affects the evolution of viscoplastic orogenic wedges, with increasing crustal thickness leading to an increase in velocity required to transition from viscous-to-viscoplastic and then to plastic-dominated wedges.
Article
Geochemistry & Geophysics
Lingzhu Kong, Yingde Jiang, Karel Schulmann, Jian Zhang, Roberto F. Weinberg, Min Sun, Sheng Wang, Tan Shu, Jun Ning
Summary: The structural and metamorphic effects of a Devonian extension-shortening cycle in the NW Chinese Altai were investigated. The study revealed the presence of a sub-horizontal metamorphic fabric (S1) and identified the age and timing of the extension and shortening phases. The findings suggest that the cycles of extension and contraction in the Altai range could result from alternating retreating and advancing subduction.
Article
Geochemistry & Geophysics
Uchitha N. Arachchige, Alexander R. Cruden, Roberto Weinberg, Anja Slim, Jonas Kopping
Summary: This study investigates the formation of saucer-shaped sills in the upper crust and finds that their formation is influenced by the ratio of elastic moduli between the host material layers, the ratio of sill radius to overburden depth, and the visco-plastic instability of the host material. The experiments successfully simulate the complexity of natural saucer-shaped sills and their marginal segmentation.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2022)
Article
Geochemistry & Geophysics
Roberto F. Weinberg, Jean-Francois Moyen, Jian-Kang Yi, Di-Cheng Zhu, Oliver Nebel, Shaorong Chen, Qing Wang
Summary: Thermo-chemical modeling and chemical data indicate that the formation of arc melts involves re-melting of older intrusions triggered by mantle-derived melts, followed by magma mixing. This paper studies a case where the compositional and thermal record of zircons preserved in a diorite dyke swarm provides insights into these processes. The findings suggest that magma mixing and re-crystallization can explain the complex chemistry of arc magmatic rocks.
JOURNAL OF PETROLOGY
(2023)
Article
Multidisciplinary Sciences
Di-Cheng Zhu, Qing Wang, Roberto F. Weinberg, Peter A. Cawood, Sun-Lin Chung, Yong-Fei Zheng, Zhidan Zhao, Zeng-Qian Hou, Xuan-Xue Mo
Summary: The generation of continental crust in collision zones involves the interplay between oceanic subduction and continental collision. The Gangdese continental crust in southern Tibet went through two stages of continental arc magmatism: fractional crystallization and remelting. The remelting process leads to the chemical maturation of juvenile continental crust, strengthening crustal stratification.
NATURE COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
Zibra Ivan, Anthony I. S. Kemp, Smithies R. Hugh, Rubatto Daniela, Korhonen Fawna, Hammerli Johannes, Tim E. Johnson, Gessner Klaus, Roberto F. Weinberg, Jeff D. Vervoort, Martin Laure, Sandra S. Romano
Summary: Converging lines of evidence suggest that Earth transitioned from a stagnant-lid to a plate tectonics regime during the late Archean, but the details and timing of this transition are debated. Geological records indicate that subduction, a key component of plate tectonics, has been active since the Mesoarchean, but the tectonic processes within ancient convergent margins are poorly understood.
NATURE COMMUNICATIONS
(2022)
Article
Geochemistry & Geophysics
Harro Schmeling, Gabriele Marquart, Roberto Weinberg, Pirunthavan Kumaravel
Summary: This study explores two characteristic modes of magmatic processes in the continental crust, namely, batholith emplacement mode and convective recycling mode. The formation of magmas is influenced by factors such as heat input, melt mobility, and density of evolved rocks. The Altiplano-Puna low-velocity zone (LVZ) may represent the batholith emplacement mode, while the Tibetan LVZ may represent the convective recycling mode.
GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
(2023)
Article
Geosciences, Multidisciplinary
Pei-yuan Hu, Qing-guo Zhai, Peter A. Cawood, Roberto F. Weinberg, Guo-chun Zhao, Yue Tang, Yi-ming Liu
Summary: Paleogeographic reconstruction of Precambrian terranes reworked by Phanerozoic orogens, such as the Tibetan Plateau, reveals complex lithotectonic relations due to intracrustal reworking. Global and regional detrital zircon rare earth element (REE) databases show trends in LREE/HREE and Eu/Eu* that record the crustal evolution of the source and provide a new approach for paleogeographic reconstructions. By analyzing sedimentary and igneous rocks in the Lhasa terrane and detrital zircon samples from the northern margin of Gondwana, it is demonstrated that the Lhasa terrane had an African affinity in the Rodinia-Gondwana supercontinent cycles (ca. 1.4-0.4 Ga).
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Wei Xu, Roberto F. F. Weinberg, Shi-Hong Tian, Zeng-Qian Hou, Zhu-Sen Yang, Lu Chen, Feng Lai
Summary: We studied geochemical data of Late Eocene volcanic rocks (including K-rich adakite-like rocks) from the southern Qiangtang terrane in central Tibet. The volcanic rocks show a continuous compositional range from high-K alkaline basalt to high-K calc-alkaline rhyolite, and have a narrow range of depleted Sr-Nd isotopic compositions compared to the pre-Eocene SQT crust. We propose that the KARs in the SQT formed through fractional crystallization of hydrous, alkaline melts derived from the lithospheric mantle, with amphibole and plagioclase dominating the fractionation process. Partial melting of the lithospheric mantle beneath the SQT may have been triggered by thermal perturbations caused by north-directed subduction of the Indian continental lithosphere beneath southern Tibet.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geochemistry & Geophysics
Pablo Farias, Roberto F. Weinberg, Alfonso Sola, Melanie Finch
Summary: U-Pb dating of zircon, monazite, and titanite combined with trace element composition is used to characterize the thermal evolution of the migmatitic Agua del Sapo complex. The complex experienced two consecutive early Paleozoic orogenies, associated with subduction and melting at upper-amphibolite facies. The accessory phases of detrital zircon, monazite, and titanite record different growth and dissolution-precipitation events during these orogenies. The prolonged high heat flow until 380 Ma blurs the boundary between the Famatinian and the subsequent Achalian/Chanic orogenies.
Article
Geosciences, Multidisciplinary
H. M. N. Wright, R. Cioni, K. V. Cashman, P. Mothes, M. Rosi
Summary: During the eruption sequence of Guagua Pichincha volcano in Ecuador from 1999-2001, rock samples provided information about magma storage, ascent, decompression, degassing, repressurization, and regassing prior to eruption. The melt inclusions revealed high water and carbon dioxide contents, while mineral crystals exhibited variations in their compositions. The seismic activity and surface tilt changes indicated a sudden evacuation of magma in the shallow conduit. These findings are significant for understanding volcanic eruptions.
BULLETIN OF VOLCANOLOGY
(2023)
Article
Environmental Sciences
Carlos E. Ganade, Pierre Lanari, Daniela Rubatto, Joerg Hermann, Roberto F. Weinberg, Miguel A. S. Basei, Lucas R. Tesser, Renaud Caby, Yao Agbossoumonde, Caroline M. Ribeiro
Summary: Research findings suggest that a magmatic flare-up event in the Kabye Massif, Togo, led to crustal thickening. This was caused by increased magma productivity and crustal thickening resulting from dehydration of serpentinized mantle during the subduction of the hyper-extended margin of an approaching continent.
COMMUNICATIONS EARTH & ENVIRONMENT
(2021)