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Abstract Holsnøy, Norway, offers a world-class natural laboratory for studying the impact of fluid on subducting lower crust. Holsnøy is composed of dry, metastable lower crustal granulite that was infiltrated by fluids along shear zones and seismic fractures during subduction. The infiltration facilitated the localized growth of eclogite facies mineral assemblages along the fluid flow pathways. The duration of the eclogite facies metamorphism, however, remains uncertain. Previous garnet diffusion chronometry studies have estimated timescales ranging from hundreds of years to millions of years based on diffusional relaxation between metastable granulite facies garnet cores and eclogite facies garnet rims and fractures. The shorter timescales are inferred from extremely sharp Ca gradients across chemical contacts present in some garnets whereas the longer timescales are from wider Mg and Fe profiles present in all garnets. The different timescale estimates have led to divergent models for the region’s tectonometamorphic evolution. Here we show that the sharp Ca contacts can be explained by diffusion-induced compositional stress. As Ca is significantly larger than Mg and Fe, its movement strains the crystal lattice and generates stress that limits the relaxation of sharp chemical contacts. When compositional stress is accounted for, the sharp contacts yield timescales that are consistent with the wider Mg and Fe diffusion profiles. We determine that eclogite facies conditions (670–700 °C, 1.5–2.2 GPa) lasted a maximum of c. 300 kyr. The relatively short duration of eclogite facies conditions requires that multiple transient heating events were superimposed on a longer (>106 yr) overall timescale of metamorphism. Granulite facies garnet cores are surrounded by multiple generations of eclogite facies rims formed by interface-coupled dissolution–reprecipitation (ICDR) reactions. The garnet rims indicate two rapid, regional-scale fluid pulses and additional smaller, more localized pulses. The fluid pulses may be linked to episodes of seismic moment release as well as transient heating via exothermic hydration reactions and/or shear deformation. Our model results predict up to 400 MPa of differential stress at the garnet core–rim contacts, consistent with observed eclogite facies microfractures that extend into relic granulite facies garnet cores. The microfractures indicate that ICDR was aided by compositional stress: diffusion ahead of the reaction front generated stress and fracturing that created porosity for further ICDR. Thus, compositional stress can markedly impact both diffusion systematics and intracrystalline deformation. Together, these results show that despite their brevity, transient thermal, fluid flux, and/or baric episodes may exert the primary controls on the mineralogical and rheological development of subducted lithologies, in contrast to the long, slow burial and exhumation typically envisioned for regional metamorphism. 

ABSTRACT Using the youngest detrital-zircon date(s) of a sedimentary deposit to constrain its maximum depositional age (MDA) is a widespread and growing application of geochronology. Most MDA studies analyze zircon grains at random, but this strategy can be costly and inefficient in cases where the youngest age group is only a small fraction of the population. We propose that handpicking sharply faceted zircon grains will increase the likelihood of encountering first-cycle zircon that have not undergone significant sedimentary transport, thus producing MDA estimates that are closer to the depositional age. We evaluate this procedure by conducting intra-sample comparisons of randomly selected versus handpicked zircon separates from 30 samples analyzed via laser-ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS). Our results show that handpicking zircon produces an overall shift towards younger ages in comparison to their randomly analyzed counterparts by an average of ∼ 406 Myr. In randomly analyzed separates, only 1.6% of grains were within 5 Myr of an independent estimate of the MDA, while handpicked separates contained 14.2%, an approximately nine-fold increase. However, handpicking can also lead to selection of older grains if they have been minimally transported, as with one handpicked Mesozoic sample that yielded 81% of ∼ 1.1 Ga zircon interpreted to be derived from a local granitic source. Handpicking is most effective in samples where young, sharply faceted grains are diluted by older, rounded grains, as with one sample that exhibited an ∼ 18-fold increase in the proportion of near-depositional-age zircons relative to its counterpart where grain selection was random. Because handpicking zircon imparts a severe bias on the resulting U–Pb age distribution, we recommend that two separate aliquots be used for quantitative provenance characterization through random analysis and MDA analysis through handpicking. 

Groundwater, a crucial natural resource on a global scale, plays a significant role in Texas, impacting various essential ecosystem services either directly or indirectly. Despite efforts of state- and community-level regulations and conservation efforts, there is an ongoing trend of declining groundwater levels in the state of Texas. In this study, we utilized the systems thinking and system dynamics modeling approach to better understand this problem and investigate possible leverage points to achieve more sustainable groundwater resource levels. After conceptualizing a causal loop diagram (CLD) of the underlying feedback structure of the issue (informed by the existing literature), a small system dynamics (SD) model was developed to connect the feedback factors identified in the CLD to the stocks (groundwater level) and flows (recharge rate and groundwater pumping) that steer the behaviors of groundwater systems across time. After completing model assessment, experimental simulations were conducted to evaluate the current state relative to simulated treatments for improved irrigation efficiency, restricted pumping rates, cooperative conservation protocols among users, and combination strategy (of all treatments above) in the long-term. Results showed that groundwater stress (and the associated repercussions on related ecosystem service) could be alleviated with a combination strategy, albeit without complete groundwater level recovery. 

Colloids can be used either as model systems for directed assembly or as the necessary building blocks for making functional materials. Previous work primarily focused on assembling colloids under a single external field, where controlling particle−particle interactions is limited. This work presents results under a combination of electric and magnetic fields. When these two fields are orthogonally applied, we can independently tune the magnitude and direction of the dipolar attraction and repulsion between the particles. As a result, we obtain well-aligned, highly dense, but individually separated linear chains at intermediate particle concentrations. Both the inter- and intrachain spacings can be tuned by adjusting the particle concentration and relative strengths of both fields. At high particle concentrations and by tuning the electric field frequency, the individual microspheres can assemble into colloidal oligomers such as trimers, tetramers, heptamers, and nonamers in response to the electric field due to the synergy between dipolar and electrohydrodynamic interactions. These oligomers, in turn, serve as building blocks for making hierarchical structures with finer architectures upon superimposing a one-dimensional (1D) magnetic field. In addition to experiments, Monte Carlo (MC) simulations have been performed on colloids confined near the electrode, interacting through a Stockmayer-like potential. They faithfully reproduce key observations in the experiments. Our work demonstrates the potential of using orthogonal electric and magnetic fields to assemble diversified types of highly aligned structures for applications in high-strength composites, optical materials, or structured battery electrodes. 

Global herbicide-resistant weed populations continue rising due to selection pressures exerted by herbicides. Despite this, herbicides continue to be farmers’ preferred weed-control method due to cost and efficiency relative to physical or biological methods. However, weeds developing resistance to herbicides not only challenges crop production but also threatens ecosystem services by disrupting biodiversity, reducing soil health, and impacting water quality. Our objective was to develop a simulation model that captures the feedback between weed population dynamics, agricultural management, profitability, and farmer decision-making processes that interact in unique ways to reinforce herbicide resistance in weeds. After calibration to observed data and evaluation by subject matter experts, we tested alternative agronomic, mechanical, or intensive management strategies to evaluate their impact on weed population dynamics. Results indicated that standalone practices enhanced farm profitability in the short term but lead to substantial adverse ecological outcomes in the long term, indicated by elevated herbicide resistance (e.g., harm to non-target species, disrupting natural ecosystem functions). The most management-intensive test yielded the greatest weed control and farm profit, albeit with elevated residual resistant seed bank levels. We discuss these findings in both developed and developing-nation contexts. Future work requires greater connectivity of farm management and genetic-resistance models that currently remain disconnected mechanistically. 

Leisure boating is becoming more popular in developed societies, stressing seagrass systems. Spatial management and marine zoning, along with education, enforcement, and appropriate signage can reduce this stress. Yet, achieving conservation goals with marine zoning depends on social and organizational factors. Coproduction models that work collaboratively with stakeholders in marine zone or protected area (MPA) planning can improve conservation outcomes. The Florida Keys National Marine Sanctuary (FKNMS; U.S.) encompasses one of the largest seagrass meadows in the world, with the mission to balance marine use with conservation of natural resources. Over the last twelve years, FKNMS has experienced exponential increases in leisure boating, which is having important consequences to the functioning of its managed coastal ecosystems. Following a decade-long planning process, in 2022 FKNMS released a revised draft management plan that uses marine zoning to increase the resilience of FKNMS natural resources by reducing local stresses on the system. In the decade leading to the release of this management plan, for-hire coastal fishers worked with scientists to coproduce comprehensive marine zoning recommendations to reduce leisure boating stresses to seagrass habitats that support important fisheries. Coproduced zoning recommendations would protect 100% and 60% more seagrass and living bottom compared to the FKNMS plan. These recommendations would create an MPA network protecting two seagrass meadows that are centers of activity for important fishery species that form spawning aggregations within a seasonal no fishing MPA. This example highlights how long-term investment in coproduction can result in more comprehensive management plans supported by stakeholders. 

Quantum many-body scars are notable as nonthermal, low-entanglement states that exist at high energies. In this study, we used attractively interacting dysprosium gases to create scar states that are stable enough to be driven into a strongly nonlinear regime while retaining their character. We measured how the kinetic and total energies evolve after quenching the confining potential. Although the bare interactions are attractive, the atoms behave as if they repel each other: Their kinetic energy paradoxically decreases as the gas is compressed. The missing “phantom” energy is quantified by benchmarking our experimental results against generalized hydrodynamics calculations. We present evidence that the missing kinetic energy is carried by undetected, very high momentum atoms. 

Water productivity (or efficiency) data inform water policy, zoning, and planning, along with water allocation decisions under water scarcity pressure. This paper demonstrates that different water productivity metrics lead to different conclusions about who is using water more effectively. In addition to supporting the population's drinking and sanitation needs, water generates many other public and private social, environmental, and economic values. For the group of municipalities comprising the Phoenix metropolitan area, we compare several water productivity metrics by calculating the water value intensity (WVI) of potable water delivered by the municipality to its residential and non-residential customers. Core cities with more industrial water uses are less productive by the conventional efficiency measure of water used per capita, but core cities generate more tax revenues, business revenues, and payroll per unit of water delivered, achieving a higher water productivity by these measures. We argue that policymakers should consider a more diverse set of socio-economic water productivity measures to ensure that a broader set of values are represented in water allocation policies.