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S. Adam
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ArticleThe mechanical response of a magma chamber with poroviscoelastic crystal mush(American Geophysical Union, 2021-01-28) Liao, Yang ; Soule, S. Adam ; Jones, Meghan R. ; Le Mével, HélèneImproved understanding of the impact of crystal mush rheology on the response of magma chambers to magmatic events is critical for better understanding crustal igneous systems with abundant crystals. In this study, we extend an earlier model by Liao et al. (2018); https://doi.org/10.1029/2018jb015985 which considers the mechanical response of a magma chamber with poroelastic crystal mush, by including poroviscoelastic rheology of crystal mush. We find that the coexistence of the two mechanisms of poroelastic diffusion and viscoelastic relaxation causes the magma chamber to react to a magma injection event with more complex time-dependent behaviors. Specifically, we find that the system’s short-term evolution is dominated by the poroelastic diffusion process, while its long-term evolution is dominated by the viscoelastic relaxation process. We identify two post-injection timescales that represent these two stages and examine their relation to the material properties of the system. We find that better constraints on the poroelastic diffusion time are more important for the potential interpretation of surface deformation using the model.
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ArticleMicrobial communities under distinct thermal and geochemical regimes in axial and off-axis sediments of Guaymas Basin(Frontiers Media, 2021-02-12) Teske, Andreas P. ; Wegener, Gunter ; Chanton, Jeffrey P. ; White, Dylan ; MacGregor, Barbara J. ; Hoer, Daniel ; de Beer, Dirk ; Zhuang, Guangchao ; Saxton, Matthew A. ; Joye, Samantha B. ; Lizarralde, Daniel ; Soule, S. Adam ; Ruff, S. EmilCold seeps and hydrothermal vents are seafloor habitats fueled by subsurface energy sources. Both habitat types coexist in Guaymas Basin in the Gulf of California, providing an opportunity to compare microbial communities with distinct physiologies adapted to different thermal regimes. Hydrothermally active sites in the southern Guaymas Basin axial valley, and cold seep sites at Octopus Mound, a carbonate mound with abundant methanotrophic cold seep fauna at the Central Seep location on the northern off-axis flanking regions, show consistent geochemical and microbial differences between hot, temperate, cold seep, and background sites. The changing microbial actors include autotrophic and heterotrophic bacterial and archaeal lineages that catalyze sulfur, nitrogen, and methane cycling, organic matter degradation, and hydrocarbon oxidation. Thermal, biogeochemical, and microbiological characteristics of the sampling locations indicate that sediment thermal regime and seep-derived or hydrothermal energy sources structure the microbial communities at the sediment surface.
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ArticleSubmarine giant pumice: A window into the shallow conduit dynamics of a recent silicic eruption.(Springer, 2019-06-29) Mitchell, Samuel J. ; Houghton, Bruce ; Carey, Rebecca ; Manga, Michael ; Fauria, Kristen ; Jones, Meghan R. ; Soule, S. Adam ; Conway, Chris E. ; Wei, Zihan ; Giachetti, ThomasMeter-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.
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ArticleThe Deep Ocean Observing Strategy: addressing global challenges in the deep sea through collaboration(Marine Technology Society, 2022-06-08) Smith, Leslie M. ; Cimoli, Laura ; LaScala-Gruenewald, Diana ; Pachiadaki, Maria G. ; Phillips, Brennan T. ; Pillar, Helen R. ; Stopa, Justin ; Baumann-Pickering, Simone ; Beaulieu, Stace E. ; Bell, Katherine L. C. ; Harden-Davies, Harriet ; Gjerde, Kristina M. ; Heimbach, Patrick ; Howe, Bruce M. ; Janssen, Felix ; Levin, Lisa A. ; Ruhl, Henry A. ; Soule, S. Adam ; Stocks, Karen ; Vardaro, Michael F. ; Wright, Dawn J.The Deep Ocean Observing Strategy (DOOS) is an international, community-driven initiative that facilitates collaboration across disciplines and fields, elevates a diverse cohort of early career researchers into future leaders, and connects scientific advancements to societal needs. DOOS represents a global network of deep-ocean observing, mapping, and modeling experts, focusing community efforts in the support of strong science, policy, and planning for sustainable oceans. Its initiatives work to propose deep-sea Essential Ocean Variables; assess technology development; develop shared best practices, standards, and cross-calibration procedures; and transfer knowledge to policy makers and deep-ocean stakeholders. Several of these efforts align with the vision of the UN Ocean Decade to generate the science we need to create the deep ocean we want. DOOS works toward (1) a healthy and resilient deep ocean by informing science-based conservation actions, including optimizing data delivery, creating habitat and ecological maps of critical areas, and developing regional demonstration projects; (2) a predicted deep ocean by strengthening collaborations within the modeling community, determining needs for interdisciplinary modeling and observing system assessment in the deep ocean; (3) an accessible deep ocean by enhancing open access to innovative low-cost sensors and open-source plans, making deep-ocean data Findable, Accessible, Interoperable, and Reusable, and focusing on capacity development in developing countries; and finally (4) an inspiring and engaging deep ocean by translating science to stakeholders/end users and informing policy and management decisions, including in international waters.
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ArticleCharacteristics and evolution of sill-driven off-axis hydrothermalism in Guaymas Basin - the Ringvent site(Nature Research, 2019-09-25) Teske, Andreas ; McKay, Luke J. ; Ravelo, Ana Christina ; Aiello, Ivano ; Mortera, Carlos ; Núñez-Useche, Fernando ; Canet, Carles ; Chanton, Jeffrey P. ; Brunner, Benjamin ; Hensen, Christian ; Ramírez, Gustavo A. ; Sibert, Ryan J. ; Turner, Tiffany ; Chambers, Christopher R. ; Buckley, Andrew ; Joye, Samantha B. ; Soule, S. Adam ; Lizarralde, DanielThe 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.
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ArticleOn the mechanical effects of poroelastic crystal mush in classical magma chamber models(American Geophysical Union, 2018-09-30) Liao, Yang ; Soule, S. Adam ; Jones, MeghanImproved 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.
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ArticleNew opportunities and untapped scientific potential in the abyssal ocean(Frontiers Media, 2022-02-03) Marlow, Jeffrey ; Anderson, Rika E. ; Reysenbach, Anna-Louise ; Seewald, Jeffrey S. ; Shank, Timothy M. ; Teske, Andreas P. ; Wanless, V. Dorsey ; Soule, S. AdamThe abyssal ocean covers more than half of the Earth’s surface, yet remains understudied and underappreciated. In this Perspectives article, we mark the occasion of the Deep Submergence Vehicle Alvin’s increased depth range (from 4500 to 6500 m) to highlight the scientific potential of the abyssal seafloor. From a geologic perspective, ultra-slow spreading mid-ocean ridges, Petit Spot volcanism, transform faults, and subduction zones put the full life cycle of oceanic crust on display in the abyss, revealing constructive and destructive forces over wide ranges in time and space. Geochemically, the abyssal pressure regime influences the solubility of constituents such as silica and carbonate, and extremely high-temperature fluid-rock reactions in the shallow subsurface lead to distinctive and potentially unique geochemical profiles. Microbial residents range from low-abundance, low-energy communities on the abyssal plains to fast growing thermophiles at hydrothermal vents. Given its spatial extent and position as an intermediate zone between coastal and deep hadal settings, the abyss represents a lynchpin in global-scale processes such as nutrient and energy flux, population structure, and biogeographic diversity. Taken together, the abyssal ocean contributes critical ecosystem services while facing acute and diffuse anthropogenic threats from deep-sea mining, pollution, and climate change.
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ArticleChitin utilization by marine picocyanobacteria and the evolution of a planktonic lifestyle(National Academy of Sciences, 2023-05-16) Capovilla, Giovanna ; Braakman, Rogier ; Fournier, Gregory P. ; Hackl, Thomas ; Schwartzman, Julia ; Lu, Xinda ; Yelton, Alexis ; Longnecker, Krista ; Soule, Melissa C. Kido ; Thomas, Elaina ; Swarr, Gretchen ; Mongera, Alessandro ; Payette, Jack G. ; Castro, Kurt G. ; Waldbauer, Jacob R. ; Kujawinski, Elizabeth B. ; Cordero, Otto X. ; Chisholm, Sallie W.Marine picocyanobacteria Prochlorococcus and Synechococcus, the most abundant photosynthetic cells in the oceans, are generally thought to have a primarily single-celled and free-living lifestyle. However, while studying the ability of picocyanobacteria to supplement photosynthetic carbon fixation with the use of exogenous organic carbon, we found the widespread occurrence of genes for breaking down chitin, an abundant source of organic carbon that exists primarily as particles. We show that cells that encode a chitin degradation pathway display chitin degradation activity, attach to chitin particles, and show enhanced growth under low light conditions when exposed to chitosan, a partially deacetylated soluble form of chitin. Marine chitin is largely derived from arthropods, which underwent major diversifications 520 to 535 Mya, close to when marine picocyanobacteria are inferred to have appeared in the ocean. Phylogenetic analyses confirm that the chitin utilization trait was acquired at the root of marine picocyanobacteria. Together this leads us to postulate that attachment to chitin particles allowed benthic cyanobacteria to emulate their mat-based lifestyle in the water column, initiating their expansion into the open ocean, seeding the rise of modern marine ecosystems. Subsequently, transitioning to a constitutive planktonic life without chitin associations led to cellular and genomic streamlining along a major early branch within Prochlorococcus. Our work highlights how the emergence of associations between organisms from different trophic levels, and their coevolution, creates opportunities for colonizing new environments. In this view, the rise of ecological complexity and the expansion of the biosphere are deeply intertwined processes.
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ArticleBroadening inclusivity at sea(Frontiers Media, 2024-06-13) Wang, Lu ; Adams, Caitlin ; Fundis, Allison ; Hsiao, Janet ; Machado, Casey ; Malik, Mashkoor ; Quadara, Rachel ; Rodriguez, Coralie ; Soule, S. Adam ; Suhre, Kelley ; Wu, Liang ; Elmore, Aurora C.Ocean sciences in the U.S. remains a field with one of the lowest rates of diversity, having disproportionately low representation from marginalized groups, including Black, Asian, LatinX, Indigenous, and other people of color; LGBTQIA+ individuals; disabled persons; women; those with neurological differences; and those from low-income groups. With equity and inclusion in mind, recent efforts have been made to increase the number of ocean science professionals from marginalized groups through multiple entry points, including internships. However, there still exists a large gap between the diversity found in the general population and the diversity within ocean sciences. Perhaps one reason why this field continues to have lower diversity owes to the unique component of many oceanographic careers, which continues to present an especially high barrier for marginalized groups: participating in sea-going research expeditions. Herein, we have synthesized possible ways to prioritize the physical and emotional safety of marginalized ocean science professionals participating in a research expedition, including guidance on preparation, implementation, and providing support post-cruise. These suggestions are intended to be useful for the broader oceanographic research community to consider the safety and well-being of individuals from marginalized groups at sea, since the field of ocean sciences - like all fields - would greatly benefit from increased representation and diversity.