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  • 1
    Publication Date: 2022-01-31
    Description: The Guaymas Basin spreading center, at 2000 m depth in the Gulf of California, is overlain by a thick sedimentary cover. Across the basin, localized temperature anomalies, with active methane venting and seep fauna exist in response to magma emplacement into sediments. These sites evolve over thousands of years as magma freezes into doleritic sills and the system cools. Although several cool sites resembling cold seeps have been characterized, the hydrothermally active stage of an off-axis site was lacking good examples. Here, we present a multidisciplinary characterization of Ringvent, an ~1 km wide circular mound where hydrothermal activity persists ~28 km northwest of the spreading center. Ringvent provides a new type of intermediate-stage hydrothermal system where off-axis hydrothermal activity has attenuated since its formation, but remains evident in thermal anomalies, hydrothermal biota coexisting with seep fauna, and porewater biogeochemical signatures indicative of hydrothermal circulation. Due to their broad potential distribution, small size and limited life span, such sites are hard to find and characterize, but they provide critical missing links to understand the complex evolution of hydrothermal systems.
    Type: Article , PeerReviewed
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  • 2
    Publication Date: 2019-07-24
    Description: Author Posting. © The Oceanography Society, 2019. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 32, no. 1, supplement (2019): 46-47.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    Publication Date: 2022-10-26
    Description: Author Posting. © American Geophysical Union, 2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Solid Earth 123(11), (2018): 9376-9406. doi: 10.1029/2018JB015985.
    Description: Improved constraints on the mechanical behavior of magma chambers is essential for understanding volcanic processes; however, the role of crystal mush on the mechanical evolution of magma chambers has not yet been systematically studied. Existing magma chamber models typically consider magma chambers to be isolated melt bodies surrounded by elastic crust. In this study, we develop a physical model to account for the presence and properties of crystal mush in magma chambers and investigate its impact on the mechanical processes during and after injection of new magma. Our model assumes the magma chamber to be a spherical body consisting of a liquid core of fluid magma within a shell of crystal mush that behaves primarily as a poroelastic material. We investigate the characteristics of time‐dependent evolution in the magma chamber, both during and after the injection, and find that quantities such as overpressure and tensile stress continue to evolve after the injection has stopped, a feature that is absent in elastic (mushless) models. The time scales relevant to the postinjection evolution vary from hours to thousands of years, depending on the micromechanical properties of the mush, the viscosity of magma, and chamber size. We compare our poroelastic results to the behavior of a magma chamber with an effectively viscoelastic shell and find that only the poroelastic model displays a time scale dependence on the size of the chamber for any fixed mush volume fraction. This study demonstrates that crystal mush can significantly influence the mechanical behaviors of crustal magmatic reservoirs.
    Description: We thank James Rice, Tushar Mittal, Chris Huber and Helge Gonnerman for useful discussions in the early stages of this work. S. Adam Soule was supported by National Science Foundation Grant OCE‐1333492. Meghan Jones was supported by the U.S. Department of Defense through the National Defense Science and Engineering Graduate Fellowship (NDSEG) Program. The numerical codes used for computing the results in the work can be found at https://github.com/YangVol/MushyChamber.
    Description: 2019-03-30
    Keywords: Magma chamber ; Crystal mush ; Poroelasticity
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 4
    Publication Date: 2022-06-06
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Teske, A., McKay, L. J., Ravelo, A. C., Aiello, I., Mortera, C., Núñez-Useche, F., Canet, C., Chanton, J. P., Brunner, B., Hensen, C., Ramírez, G. A., Sibert, R. J., Turner, T., White, D., Chambers, C. R., Buckley, A., Joye, S. B., Soule, S. A., & Lizarralde, D. Characteristics and evolution of sill-driven off-axis hydrothermalism in Guaymas Basin - the Ringvent site. Scientific Reports, 9(1), (2019): 13847, doi:10.1038/s41598-019-50200-5.
    Description: The Guaymas Basin spreading center, at 2000 m depth in the Gulf of California, is overlain by a thick sedimentary cover. Across the basin, localized temperature anomalies, with active methane venting and seep fauna exist in response to magma emplacement into sediments. These sites evolve over thousands of years as magma freezes into doleritic sills and the system cools. Although several cool sites resembling cold seeps have been characterized, the hydrothermally active stage of an off-axis site was lacking good examples. Here, we present a multidisciplinary characterization of Ringvent, an ~1 km wide circular mound where hydrothermal activity persists ~28 km northwest of the spreading center. Ringvent provides a new type of intermediate-stage hydrothermal system where off-axis hydrothermal activity has attenuated since its formation, but remains evident in thermal anomalies, hydrothermal biota coexisting with seep fauna, and porewater biogeochemical signatures indicative of hydrothermal circulation. Due to their broad potential distribution, small size and limited life span, such sites are hard to find and characterize, but they provide critical missing links to understand the complex evolution of hydrothermal systems.
    Description: This work was funded by NSF OCE grant 1449604 “Rapid Proposal: Guaymas Basin site survey cruise for IODP proposal 833” to Andreas Teske; NSF C-DEBI grant “Characterizing subseafloor life and environments in Guaymas Basin” to Andreas Teske, Ivano Aiello and Ana Christina Ravelo; and collaborative NSF Biological Oceanography grants 1357238 and 1357360 “Collaborative Research: Microbial carbon cycling and its interaction with sulfur and nitrogen transformations in Guaymas Basin hydrothermal sediments” to Andreas Teske and Samantha B. Joye, respectively. We thank the Alvin and Sentry teams for a stellar performance during Guaymas Basin cruise AT37-06, and the science crew of RV El Puma for their dedication, skill, and “can-do” collaborative spirit during the 2014 Guaymas coring campaign. Sequencing of bacterial and archaeal communities was supported by the Deep Carbon Observatory, and performed at the Marine Biological Laboratory in Woods Hole, MA.
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 5
    Publication Date: 2022-05-26
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Mitchell, S. J., Houghton, B. F., Carey, R. J., Manga, M., Fauria, K. E., Jones, M. R., Soule, S. A., Conway, C. E., Wei, Z., & Giachetti, T. Submarine giant pumice: A window into the shallow conduit dynamics of a recent silicic eruption. Bulletin of Volcanology, 81(7), (2019): 42, doi:10.1007/s00445-019-1298-5.
    Description: Meter-scale vesicular blocks, termed “giant pumice,” are characteristic primary products of many subaqueous silicic eruptions. The size of giant pumices allows us to describe meter-scale variations in textures and geochemistry with implications for shearing processes, ascent dynamics, and thermal histories within submarine conduits prior to eruption. The submarine eruption of Havre volcano, Kermadec Arc, in 2012, produced at least 0.1 km3 of rhyolitic giant pumice from a single 900-m-deep vent, with blocks up to 10 m in size transported to at least 6 km from source. We sampled and analyzed 29 giant pumices from the 2012 Havre eruption. Geochemical analyses of whole rock and matrix glass show no evidence for geochemical heterogeneities in parental magma; any textural variations can be attributed to crystallization of phenocrysts and microlites, and degassing. Extensive growth of microlites occurred near conduit walls where magma was then mingled with ascending microlite-poor, low viscosity rhyolite. Meter- to micron-scale textural analyses of giant pumices identify diversity throughout an individual block and between the exteriors of individual blocks. We identify evidence for post-disruption vesicle growth during pumice ascent in the water column above the submarine vent. A 2D cumulative strain model with a flared, shallow conduit may explain observed vesicularity contrasts (elongate tube vesicles vs spherical vesicles). Low vesicle number densities in these pumices from this high-intensity silicic eruption demonstrate the effect of hydrostatic pressure above a deep submarine vent in suppressing rapid late-stage bubble nucleation and inhibiting explosive fragmentation in the shallow conduit.
    Description: This study was funded primarily through an NSF Ocean grant: OCE-1357443 (SJM, BFH and RJC). MM is supported by NSF EAR 1447559. The μXRT analysis was performed at the Lawrence Berkeley National Lab Advanced Light Source beamline 8.3.2 and the large CT scan by SAS at the University of Texas Austin micro-CT facility. Capillary flow porometry and He-pycnometry were assisted by TG and MRJ at the University of Oregon. Microprobe analysis was conducted at the University of Hawai’i at Mānoa. CEC was supported by post-doctoral research fellowship from the Japan Society for the Promotion of Science (JSPS16788). We would like to thank Kenichiro Tani, Takashi Sano, and Eric Hellebrand for their assistance with geochemical data acquisition, JoAnn Sinton and Wagner Petrographic for thin section preparation, Zachary Langdalen for binary processing of BSE images, Warren M. McKenzie for measuring clast densities, and Dula Parkinson for guidance with the μXRT imaging. We further acknowledge the full scientific team, crew and Jason ROV team (Woods Hole Oceanographic Institute) aboard the R/V Roger Revelle (Scripps Institute of Oceanography) during the MESH expedition in 2015, without whom, this study would not have been possible. Finally, we thank Andrew Harris, Katharine Cashman, Lucia Gurioli and an anonymous reviewer for their insightful and helpful reviews of the manuscript.
    Keywords: Giant pumice ; Submarine volcanism ; Banding ; Tube pumice ; Bubble deformation ; Conduit dynamics
    Repository Name: Woods Hole Open Access Server
    Type: Article
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