In order to reconcile petrological and geophysical observations in the temporal domain, the uncertainties of diffusion timescales need to be rigorously assessed. Here we present a new diffusion chronometry method: Diffusion chronometry using Finite Elements and Nested Sampling (DFENS). This method combines a finite element numerical model with a nested sampling Bayesian inversion meaning the uncertainties of the parameters that contribute to diffusion timescale estimates can be rigorously assessed, and that observations from multiple elements can be used to better constrain a single timescale. By accounting for the covariance in uncertainty structure in the diffusion parameters, estimates on timescale uncertainties can be reduced by a factor of 2 over assuming that these parameters are independent of each other. We applied the DFENS method to the products of the Skuggafjöll eruption from the Bárðarbunga volcanic system in Iceland, which contains zoned macrocrysts of olivine and plagioclase that record a shared magmatic history. Olivine and plagioclase provide consistent pre-eruptive mixing and mush disaggregation timescales of less than 1 year. The DFENS method goes some way to improving our ability to rigorously address the uncertainties of diffusion timescales, but efforts still need to be made to understand other systematic sources of uncertainty such as crystal morphology, appropriate choice of diffusion coefficients, growth, and the petrological context of diffusion timescales.

Fluvio-lacustrine features on the martian surface attest to a climate that was radically different in the past. Since climate models have difficulty sustaining a liquid hydrosphere at the surface, multiple cycles of runoff episodes may have characterized the ancient Mars climate. A fundamental question thus remains: what was the duration of these runoff-producing episodes? Here we use morphometric measurements from newly identified coupled lake systems (containing both an open- and a closed-basin lake). We combined hydrological balances with precipitation outputs from climate models, and found that breaching runoff episodes likely lasted 10^2–10^5 yr; other episodes may have been shorter but could not be longer. Runoff episode durations are model-dependent and spatially variable, and no climate model scenario can satisfy a unique duration for all coupled systems. In the near future, these quantitative constraints on early Mars lake persistence may be tested through in situ observations from Perseverance rover.

The combination of Sr and O isotopes allow for the determination of crustal homogenization and hybridization during magma accumulation. We present oxygen isotope values of mineral separates, whole rock and in situ Sr isotope ratios of plagioclase from <1 Ma andesitic to dacitic composition lava flows from four volcanoes in the Central Andes with geographic relationship to the Altiplano Puna Magma Body (APMB): Uturuncu (1.1 Ma to 250 ka), Ollagüe (1.2 Ma to 130 ka), Aucanquilcha (1.04 Ma to 240 ka) and Lascar (49 ka to 0 ka). Sr isotope ratios were determined in situ using both laser ablation and standard cation exchange methods of plagioclase phenocryst and on whole rock powders. Oxygen isotope analyses were determined by laser fluorination of mineral separates. Mineral separate O isotope data has been re-calculated to account for mineral-melt 18O/16O-fractionation at various SiO2 contents to better constrain magma source variations and magma isotope heterogeneity with time and space. Variation in δ18OWR values for each lava suite is relatively limited (Lascar - δ18OWR =7.4-9.0‰; Aucanquilcha- δ18OWR =8.2-9.2‰; Ollagüe- δ18OWR =7.9-9.4‰) with the exception of Uturuncu which displays a large O isotopic value range (δ18OWR =8.7-11.4‰). Whole-rock 87Sr/86Sr ratios show a correlation of the lowest ratios along the arc front and generally increase towards the center of the APMB. Lascar (87Sr/86Sr= 0.7057-0.7067) and Aucanquilcha (87Sr/86Sr= 0.7058-0.7068) rocks exhibit the most homogeneous Sr isotope ratios and δ18OPL values, while Uturuncu exhibits the largest range of ratios (87Sr/86Sr= 0.7101-0.7165). Furthermore, in situ 87Sr/86Sr ratios of Uturuncu plagioclase phenocrysts exhibit more variation within a single crystal (87Sr/86Sr= 0.7098-0.7165) than the observed at all four volcanoes. Uturuncu magmas contain the highest variability, both in plagioclase mineral separates and whole rock values, and therefore must contain high 18O crustal material. This hypothesis is further supported by the textures and isotopic variation within plagioclase phenocrysts suggesting repeated crustal contamination followed by mixing occurring in the shallow crustal reservoir. Conversely, the arc front source is more homogeneous and hybridized, and arc-front magmas assimilate similar composition crustal material.

Southern Africa is facing unprecedented strains on its agriculture, including a rapidly increasing population and demand for cereals. The global issues of climate change, water scarcity, and soil erosion are also affecting southern Africa, which expects a drier climate in the future. A promising tool in the fight for food security is Conservation Agriculture (CA), a technique based on minimum soil disturbance, mulching using crop residues, and crop rotation and/or intercrops. CA is promoted by organisations including the United Nations due to its potential to increase crop yields in arid/semi-arid climates; increase drought resilience; and increase infiltration of rainwater, reducing flooding and erosion. Despite its benefits and promotion, little is understood of the hydrodynamics of soils under CA cultivation. In order to investigate these hydrological processes, we installed Electrical Resistivity Tomography (ERT) monitoring systems (PRIME, developed by BGS) at three agricultural research sites in southern Africa (Zambia, Malawi, & Zimbabwe) under CA and conventional tillage systems. The sites are also instrumented with soil temperature, moisture, and matric potential sensors, as well as monitored groundwater boreholes, enabling comparison between monitoring techniques and the tracking of water from the ground surface to depth. ERT deployments for the respective sites include surface 2D, shallow cross-borehole 3D, and surface 3D electrode arrays. Each PRIME system is configured for twice daily data collection, and uses data telemetry for remote data retrieval. ERT monitoring allows us to monitor the hydrodynamics from the root zone, through the soil profile and vadose zone, to the aquifer. Initial results show variability between the sites, and heterogeneous nature of the vadose zone within the sites. This heterogeneity has been shown to influence preferential fluid flow pathways in the vadose zone. Monitoring over rainfall events has shown a strong, rapid response of pronounced, shallow wetting fronts, with limited changes at depth. We are beginning the process of comparing the hydrodynamics between CA and conventional plots, and the procedure of optimising data processing to enable better imaging of soil moisture changes at depth in the presence of rapid near surface changes.

This presentation demonstrates a CT scanning and image analysis workflow to characterize wellbore cement degradation under corrosive geologic CO2 storage (GCS) conditions. The workflow includes 1) acquisition of raw CT images of the cement sample (before and after exposure to CO2); 2) application of rigid registration to align raw CT images; 3) acquisition of grayscale intensity difference images; 4) application of noise filtering technique to obtain images with good quality; 5) acquisition of 3D pore structure change of the cement sample after CO2 exposure from grayscale intensity difference images, showing degradation of wellbore cement. To demonstrate an application of the workflow, an experiment of reaction between CO2 and wellbore cement under corrosive GCS conditions was conducted and the wellbore cement samples used in the experiment went through aforementioned CT scanning and image analysis procedures. CT image analysis results demonstrate a region with increased porosity in the exterior of the cement sample (Zone 1) and a region with decreased porosity next to Zone 1 due to CaCO3 precipitation (Zone 2). Next to Zone 2, a region with increased porosity due to Ca(OH)2 and C-S-H dissolution (Zone 3) was observed. In summary, this study proves feasibility to use 3D CT scanning and CT image analysis techniques to investigate CO2-induced degradation of wellbore cement.

Machine learning (ML) techniques have become increasingly important in seismology and earthquake science. Lab-based studies have used acoustic emission data to predict time-to-failure and stress state, and in a few cases the same approach has been used for field data. However, the underlying physical mechanisms that allow lab earthquake prediction and seismic forecasting remain poorly resolved. Here, we address this knowledge gap by coupling active-source seismic data, which probe asperity-scale processes, with ML methods. We show that elastic waves passing through the lab fault zone contain information that can predict the full spectrum of labquakes from slow slip instabilities to highly aperiodic events. The ML methods utilize systematic changes in p-wave amplitude and velocity to accurately predict the timing and shear stress during labquakes. The ML predictions improve in accuracy closer to fault failure, demonstrating that the predictive power of the ultrasonic signals improves as the fault approaches failure. Our results demonstrate that the relationship between the ultrasonic parameters and fault slip rate, and in turn, the systematically evolving real area of contact and asperity stiffness allow the gradient boosting algorithm to ‘learn’ about the state of the fault and its proximity to failure. Broadly, our results demonstrate the utility of physics-informed machine learning in forecasting the imminence of fault slip at the laboratory scale, which may have important implications for earthquake mechanics in nature.

Studies on the Fe, Cu, and Zn isotopic compositions of volcanic rocks and sulfides provide an important tool for understanding magmatic, hydrothermal, and alteration processes. In this study, the δ56Fe and δ57Fe values of the MORBs are higher than those of the seafloor hydrothermal fluids, while the reverse is true for the δ66Zn and δ68Zn values, suggesting that basalt-fluid interactions preferentially incorporate isotopically light Fe and heavy Zn into the fluid, resulting in the relative enrichment of the heavier Fe and lighter Zn isotopes in altered basaltic rocks. Most of the δ56Fe values (–1.96 to +0.11‰) of the sulfide minerals are within the range of the vent fluids, but they are significantly lower than those of MORBs and back-arc basin basalts (BABBs), suggesting that the Fe in the sulfides was mainly derived from the fluids. However, the majority of the δ56Fe and δ57Fe values of chalcopyrite are larger than those of sphalerite and pyrite. This suggests that high-temperature sulfide minerals are enriched in 56Fe and 57Fe, whereas medium- and low-temperature sulfides are depleted in 56Fe and 57Fe. Moreover, the δ65Cu (–0.88 to –0.16‰) and δ66Zn (–0.39 to –0.03‰) values of the sulfide minerals are significantly lower than those of the MORBs, BABBs, and fluids, suggesting that 63Cu and 64Zn were preferentially removed from the fluids and incorporated into the chalcopyrite and sphalerite, respectively. Consequently, vent fluid injection and deposition can cause the heavier Cu and Zn isotopic compositions of hydrothermal plumes, seawater, and sediments.

All LIDAR instruments are not the same, and advancement of LIDAR technology requires an ongoing interest and demand from the community to foster further development of the required components. The purpose of this paper is to make the community aware of the need for further technical development, and the potential payoff of investing experimental time, money and thought into the next generation of LIDARs. Technologies for development: We advocate for future development of LIDAR technologies to measure the polarization state of the reflected light at selected multiple wavelengths, chosen according to the species of interest (e.g., H2O and CO2 in the Martian setting). Key scientific questions: In the coming decade, dollars spent on these LIDAR technologies will go towards addressing key climate questions on Mars and other rocky bodies, particularly those with seasonally changing (i.e. insolation driven) plumes of multiple icy volatiles such as Mars, Enceladus, Triton, or Pluto, and insolation-driven dust lifting, such as cometary bodies and the Moon. We will show from examining past Martian and terrestrial lidars that orbital and landed LIDARs can be effective for producing new insights into insolation-driven processes in current planetary climate on several bodies, beyond that available to our current fleet of largely passive instruments on planetary missions.

Transition metal cofactors are crucial for many biological processes. Despite being primarily considered to be toxic, the transition metal cadmium (Cd) was discovered to be a substitute for zinc (Zn) in photosynthetic carbon fixation pathways in marine diatoms. However, it is not known how conditions in the geosphere impacted Cd availability and its incorporation as an alternative metal cofactor for phytoplankton. We employed mineral chemistry network analysis to investigate which geochemical factors may have influenced the availability of Cd and Zn during the putative time period that alternative Cd-based pathway evolved. Our results show that Zn minerals are more chemically diverse than are Cd minerals, but Zn- and Cd-containing minerals have similar mean electronegativities when specifically considering sulfur (S)-containing species. Cadmium and zinc sulfides are the most common Cd- and Zn-containing mineral species over the past 500 million years. In particular, the Cd and Zn sulfides, respectively greenockite and sphalerite, are highly abundant during this time period. Furthermore, S-containing Cd- and Zn minerals are commonly co-located in geologic time, allowing them to be weathered and transported to the ocean in tandem, rather than occurring from separate sources. We suggest that the simultaneous weathering of Cd and Zn sulfides allowed for Cd to be a bioavailable direct substitute for Zn in protein complexes during periods of Zn depletion. The biogeochemical cycles of Zn and Cd exemplify the importance of the coevolution of the geosphere and biosphere in shaping primary production in the modern ocean.

Tephra layers are often used to reconstruct past eruptions. However, accurate interpretation of tephra layers depends on their degree of preservation. We asked: how much volcanological information do terrestrial tephra layers typically retain? We addressed this question with a study of the tephra layer produced by the May 1980 eruption of Mount St Helens, comparing historical records of deposit thickness and grain size distribution with measurements made four decades after the eruption. Using published isopach maps as a guide, we looked for the tephra layer in locations 15 – 600 km from Mount St Helens, selecting sample locations we judged to have high preservation potential. We found that preservation of the 1980 tephra deposit was often extremely good: observed thickness, mass loading and grain size distributions were similar to equivalent measurements made in 1980. However, we also observed high variability in preservation on small spatial scales, and our results indicate that landscape-scale volcanological reconstruction is sensitive to sample number and location, even when many sites display excellent preservation. Tephra preservation is clearly a complex and contingent process influenced by climate, biology, topography, parent material (i.e., grain size, morphology and geochemistry) and time. The relative importance of these factors will vary from place to place. We propose that the only way to tease apart these factors – and to fully understand the information content of tephra layers - is through direct observation of tephra deposits (whether natural or experimental) over extended time periods.

Cohesive properties of clay promote the formation of clay flocs and gels and relatively small suspended clay concentrations can enhance or suppress turbulence in a flow. Flows are naturally non-uniform, varying in space and time, yet the dynamics of non-uniform open-channel clay suspension flows are poorly understood. To research the influence of suspended cohesive clay on changing flow dynamics under non-uniform flow conditions, new experiments were conducted using decelerating and accelerating clay suspension open-channel flows in a recirculating flume. The flows transition between clay flow types, with different degrees of turbulence enhancement and attenuation as the flow adapts to the change in velocity. The experimental results show that decelerating clay suspension flows have a longer adaptation time than accelerating clay suspension flows. The formation of bonds between cohesive sediment particles is a time-dependent process and establishing clay bonds, as in the decelerating flows, requires more time than breaking them, as in the accelerating flows. This hysteresis is more pronounced for higher concentration decelerating flows that pass through a larger variety of flow phases of turbulence enhancement and attenuation. These different adaptation time scales and associated clay flow type transitions are likely to affect erosional and depositional processes in a variety of fluvial and submarine settings.

Channel avulsions on river deltas are the primary means to distribute sediment and build land at the coastline. Many studies have detailed how avulsions generate delta lobes, whereby multiple lobes amalgamate to form a fan-shaped deposit. Physical experiments demonstrated that a condition of sediment transport equilibrium can develop on the topset, characterized by neither deposition nor erosion of sediment, and material is dispersed to the foreset. This alluvial grade condition assumes steady subsidence and uniform basin depth. In nature, however, alluvial grade is disrupted by variable subsidence, and progradation of lobes into basins with variable depth: conditions that are prevalent for tectonically active margins. We explore sediment dispersal and deposition patterns across scales using measurements of delta and basin morphology compiled from field surveys and remote sensing, collected over 150 years, from the Selenga Delta (Baikal Rift Zone), Russia. Tectonic subsidence events, associated with earthquakes on normal faults crossing the delta, displace portions of the topset several meters below mean lake level. This allogenic process increases regional river gradient and triggers lobe-switching avulsions. The timescale for these episodes is shorter than the predicted autogenic lobe avulsion timescale. During quiescent periods between subsidence events, channel-scale avulsions occur relatively frequently because of in-channel sediment aggradation, dispersing sediment to regional lows of the delta. The hierarchical avulsion processes, arise for the Selenga Delta, preserves discrete stratal packages that contain predominately deep channels. Exploring the interplay between discrete subsidence and sediment accumulation patterns will improve interpretations of stratigraphy from active margins and basin models.

Serpentinization of ultramafic rocks is fundamental to modern plate tectonics and for volatile (re-)cycling into the mantle and magmatic arcs. Serpentinites are also highly reactive with CO2 such that they are prime targets for carbon sequestration. Serpentinization and carbonation of ultramafic rocks results in changes in their physical properties such that they should be detectable using geophysical surveys; this could provide constraint on the reactivity of rocks without extensive sample characterization. We constrain the physio-chemical relationships in altered ophiolitic ultramafic rocks using petrographic observations, major-element chemistry, quantitative X-ray diffraction, and physical properties on a suite of >400 samples from the Canadian Cordillera. Serpentinization results in a systematic decrease in density that reflects the increase in serpentine abundance and carbonation results in an increase in density, mostly reflecting the formation of magnesite; based on these data we present two formulations for determining extent of serpentinization: one based on major-element chemistry and the other on density. Magnetic susceptibility is variable during serpentinization; most harzburgitic samples show a 100-fold increase in magnetic susceptibility, whereas most dunitic samples and a minor proportion of harzburgitic samples show very little change in magnetic susceptibility. We use quantitative mineralogy and physical properties of the samples to constrain a model for using density and magnetic susceptibility to approximate the mineralogy of ultramafics rock. Although further work is required to understand the role of remanence in applying these models to geophysical data, this presents an advancement and opportunity to prospect for the most reactive ultramafic rocks for carbon sequestration.

This paper provides an overview of research on core from Oman Drilling Project Hole BT1B and the surrounding area, plus new data and calculations, constraining processes in the Tethyan subduction zone beneath the Samail ophiolite. The area is underlain by gently dipping, broadly folded layers of allochthonous Hawasina pelagic sediments, the metamorphic sole of the Samail ophiolite, and Banded Unit peridotites at the base of the Samail mantle section. Despite reactivation of some faults during uplift of the Jebel Akdar and Saih Hatat domes, the area preserves the tectonic “stratigraphy” of the Cretaceous subduction zone. Gently dipping listvenite bands, parallel to peridotite banding and to contacts between the peridotite and the metamorphic sole, replace peridotite at and near the basal thrust. Listvenites formed at less than 200°C and (poorly constrained) depths of 25 to 40 km by reaction with CO2-rich, aqueous fluids migrating from greater depths, derived from devolatilization of subducting sediments analogous to clastic sediments in the Hawasina Formation, at 400-500°. Such processes could form important reservoirs for subducted CO2. Listvenite formation was accompanied by ductile deformation of serpentinites and listvenites – perhaps facilitated by fluid-rock reaction – in a process that could lead to aseismic subduction in some regions. Addition of H2O and CO2 to the mantle wedge, forming serpentinites and listvenites, caused large increases in the solid mass and volume of the rocks. This may have been accommodated by fractures formed as a result of volume changes, perhaps mainly at a serpentinization front.

Integrating detrital zircon U/Pb and whole-rock Nd data throughout the Himalayan arc provides the means to distinguish between the Tethyan (TH), Greater (GH), and Lesser Himalayan (LH) tectonostratigraphic zones within the thrust belt. In the Kaghan valley of northern Pakistan, debate exists over the existence and location of the Main Central thrust (MCT) and the tectonostratigraphic affinity of the rocks in the Hazara-Kashmir syntaxis. Three new detrital zircon U/Pb age spectra and two new εNd(0) values from the footwall rocks of the Batal fault yield 1.0-2.0 Ga age populations and an average εNd(0) value of -13.6. Four new detrital zircon U/Pb age spectra and two new εNd(0) values from the hanging wall rocks have primarily <1.2 Ga age populations and an average εNd(0) value of -16.7. Most detrital zircon analyses exhibit Pb-loss from younger (<600 Ma) intrusive or metamorphic events. The absence of zircon <1.0 Ga in the footwall samples indicates that they are LH rocks, while εNd(0) values indicate that they are not Paleoproterozoic LH rocks, but are comparable to other Meso- and Neoproterozoic LH rocks along the Himalayan arc. Neoproterozoic and younger detrital zircon age populations from the hanging wall samples and the presence of ~47 Ma intrusive leucogranite indicate that these are either TH or GH rocks, with εNd(0) values also consistent with TH or GH values. Combining these data show that the hanging wall rocks are either TH or GH rocks, and that the footwall rocks are Mesoproterozoic LH rocks. In most places, the MCT is defined as GH rocks thrust over LH rocks. However, in NW India, the GH/LH contact is buried in the subsurface, and the MCT at the surface is a TH/LH contact. Therefore, these data define the Batal fault in the Kaghan valley as equivalent to the MCT, with TH/GH rocks thrust over LH rocks, and link it with the Indus River valley to the west in Pakistan and NW India to the east.

Lava domes form by the effusive eruption of viscous lava and are inherently unstable and prone to collapse. Dome collapses can generate pyroclastic flows and trigger explosive eruptions and thus represent a significant natural hazard. Many processes may contribute to the instability and collapse of lava domes, including advance of the dome margins, overtopping of confining topography, internal gas overpressure, and gravitational instability of the dome structure. Collapses that result from these processes can generally be grouped into two types: active and passive. Active collapses are driven by processes associated with active lava effusion, (e.g. dome growth or gas pressurization), while passive collapses are not directly associated with eruptive activity and can be triggered by overtopping of topographic obstacles or weakening of the dome structure. We use data collected by uncrewed aerial systems (UAS, commonly called ‘drones’) and a slope stability model to both identify and assess the stability of potential collapse sites for both passive and active processes. We collected visual and thermal infrared images by UAS and used structure-from-motion photogrammetry to generate thermal maps and digital elevation models (DEMs) of two example lava domes at Sinabung Volcano (Sumatra, Indonesia) and Merapi Volcano (Java, Indonesia). We evaluate the stability of erupted lava using the Scoops3D numerical model to assess the risk of passive and active collapses, including an assessment of the effect of lava material properties and internal pore pressure on the dome stability. We compare the collapse risk from Scoops3D with UAS-derived temperature maps and DEM differencing to evaluate the stability, size, and location of observed or potential collapses. We test whether Scoops3D can hindcast the sites and magnitudes of passive collapses at Sinabung that occurred in 2014 and 2015 and assess the stability of the remaining lava dome (growth has ended in spring 2018). For both volcanoes. Through application of these techniques, we are able to evaluate the collapse risk due to multiple processes that may act contemporaneously to generate dome instability. This study demonstrates how identification and classification of individual collapse mechanisms can be used to assess hazards at dome-forming volcanoes.

We describe a three-dimensional discrete fracture hybrid model (DFHM) that returns forecasts of both induced seismicity and of power generation in an Enhanced Geothermal System (EGS). Our model considers pore-pressure increase as the mechanism driving induced seismicity, similarly to other hybrid models, but it employs discrete fracture modelling for flow and heat that allows accurate and realistic transient solutions of pore pressure and temperature in fractured reservoirs. Earthquakes and flow are thus considered as closely coupled processes. In the DFHM model, the creation phase of an EGS is described as a Markovian process with a transitional probability that encapsulates the irreducible uncertainty with regards to induced seismicity. We conditioned this transitional probability on field observations from the 2006 EGS project in Basel, achieving a good match with observations of seismicity evolution. Specifically, our model effectively reproduces and explains the observed long-term exponential decay of seismicity after the well was shut in, suggesting that pore pressure diffusion in a critically stressed fractured reservoir is sufficient to explain long-lasting post-injection seismic activity as observed in Basel. We then investigate alternative injection scenarios, using Monte Carlo simulations to capture the uncertainties in fault locations and stressing conditions. We show that the number of induced events depends not only on the total injected volume but also on the injection strategy. We demonstrate that multi-stage injection schemes are superior to single-stage ones, since the former are associated with less seismic risk and can generate at least the same revenue in the long term.

To better understand the mechanisms of crustal exhumation related to tectonic extension, we report on the progressive doming and detachment faulting of the Cretaceous Liaonan metamorphic core complex (MCC). The detachment fault zone of Liaonan MCC is comprised of two branches, i.e., the Jinzhou detachment fault zone (JDFZ) and the poorly-researched Dongjiagou shear zone (DSZ). Thus, integrated structural, microstructural, quartz c-axis fabrics, and fluid inclusion analysis, and U-Pb on zircon dating were performed on mylonites along the DSZ. In contrast with the JDFZ that possesses characteristics of detachment fault zone, the DSZ encompasses Archean gneisses and Neoproterozoic meta-sedimentary rocks, between which exists an obvious metamorphic contrast forming a tectonic discontinuity contact (TDC). However, rocks from both sides of the TDC possess structures and fabrics for identical geometries and kinematics that are consistent with those along the JDFZ. Thermometric analysis of fluid inclusions from syn-tectonic quartz veins (630 °C, 470 °C, 350 °C) and quartz c-axis fabric from mylonites along the DSZ show that the shearing penetrates throughout the Archean to Neoproterozoic rocks. Dating of zircons from syn-kinematic granitic dikes from DSZ yields an age ca. 134 Ma, which is similar to the ages of early shearing along the JDFZ (ca. 133~134 Ma). The results imply that the shearing initiated in both JDFZ and DSZ at an early stage, then progressive shearing continued, and finally developed the detachment faulting along the JDFZ. Based on the timing and processes of the regional extension, a geodynamic model of MCC’s is proposed.

Awu is one of the remote and little known active volcanoes of Indonesia. It is the northernmost active volcano of Sangihe arc with 18 eruptions in less than 4 centuries, causing a cumulative death toll of 11048. Two of these eruptions were classified as VEI 4. Since 2004, a lava dome occupies the center of Awu crater, channeling the fumarolic gas output along the crater wall. A combined DOAS and MultiGAS measurements highlight a relatively small SO degassing (13 t/d) into the atmosphere. In contrast the measurements spotlight an elevated and non-negligible CO emission into the atmosphere of 2600 t/d, representing 1% of the global CO emission budget from volcanoes. The cause for this high CO degassing may reside in the peculiar geodynamic context of the region, where the slowing down of arc-to-arc collision has enhanced heating of the slab, leading to greater production of fluid rich in carbon.

The utilization of first-order information about seafloor morphology, derived from multibeam sonar data, has become common in the investigation of deep-sea benthic habitats. When combined with complementary datasets, these data can be used to study deep-sea coral ecosystems and predict environments that are favorable for fish spawning, larval nurseries, and juvenile fish habitats. The identification and protection of these environments is critical where biodiversity is vulnerable or unique in order to rehabilitate or maintain ecological communities and encourage higher fecundity. In August of 2019, the expedition Deep Connections: Exploring Atlantic Canyons and Seamounts was conducted to explore understudied deep-sea environments aboard the NOAA Ship Okeanos Explorer off the coast of the United States and Canada (EX1905L1 and EX1905L2). This expedition included multibeam mapping and seafloor exploration with a Remotely Operated Vehicle (ROV). Observations from ROV dives include several fish species including multiple sightings of Atlantic halibut (Hippoglossus hippoglossus), which is considered endangered on the International Union for Conservation of Nature Red List of Threatened Species. Identifying and classifying the habitats where Atlantic halibut is observed would facilitate future endeavors of protection or rehabilitation. Spawning events are known to coincide with areas of increased seafloor slope associated with high energy systems such as canyons. Utilizing multibeam data included in the Global Multi-Resolution Topography (GMRT) Synthesis, we characterize canyons at the edges of George’s and Brown’s Banks based on morphology, roughness, and seafloor slope and aspect. We combine these data with observations of Atlantic halibut from ROV video to seek correlations that can be used to identify potential habitats. This information can be used to guide further exploration and characterization of the seafloor to better understand the spatial extent of Atlantic halibut habitat in the region.

The story the Antarctic Core Collection’s (ACC) transition from Florida State University (FSU) to Oregon State University (OSU) is one of the largest-scale data rescue efforts in recent history. The ACC is the world’s largest collection of seafloor sediment samples from the Southern Ocean. The collection was officially established in 1963 as the US Antarctic Program took shape. For the next fifty years, the collection grew to represent the scientific discoveries of over one-hundred and twenty research cruises and expeditions around Antarctica. FSU hosted the irreplaceable collection at its Antarctic Research Facility, an iconic lab in the center of campus. In 2016, the university chose not to renew its contract for supporting the facility. Recognizing the value and potential of the collection, the National Science Foundation began a search for another university to host these important samples and enable future research. In 2017, OSU’s Marine and Geology Repository (OSU-MGR) initiated a plan to relocate this historic collection of over eighteen kilometers of core samples from Tallahassee, FL to Corvallis, OR. The project began by planning and constructing a state-of-the-art facility with temperature-controlled space to house the next fifty years of coring expeditions to the Southern Oceans and beyond. In the summer of 2018, the ACC was carefully packaged, digitally inventoried, and shipped to OSU. In this process, the OSU-MGR staff have worked to improve metadata records to build an effective modern inventory of the ACC using new digital collection management techniques, including QR coded labels and scanners. These metadata are managed on tablets with the OSU-MGR App and indexed in an Elasticsearch cluster to streamline the repository’s workflows and to display summary statistics. Current and future curation projects will comply with FAIR data principles, with the goal of making all OSU-MGR collections and associated datasets more easily discoverable online.

The University of Houston’s USIP (Undergraduate Student Instrument Project) Remote Sensing team is designing and building an airborne LiDAR with the intention of using it to 3D map landslides and for possible mineral exploration. The maps will be used to conduct landslide analyses and failure predictions while the magnetometer feedback will be used to determine the presence of possible metallic minerals in the area. The LiDAR will employ the use of two lasers with different output wavelengths; 1550nm will be used for typical terrain mapping and 532nm will be used for snow depth reading to extrapolate the underlying terrain characteristics. Trade studies are currently underway for the lasers, sensors, IMU’s and magnetometers. It is planned for the LiDAR to collect data near Fairbanks, Alaska, with further research into potential study sites being conducted. The scan pattern is still being decided on with the most likely option being a circular scan for the 532nm laser and a zig zag pattern for the 1550nm laser both set at a maximum scan angle of 20 degrees. The Remote Sensing team has been facing unforeseen obstacles due to the nature of the COVID-19 pandemic. Upon initial lockdown, weekly scheduled in person meetings and lab work were prohibited. After the first week, though, new mediums of communication were established. The USIP group decided to conduct online meetings through Microsoft Teams and use Slack for text-based communication outside of meetings. Unfortunately, lockdown and COVID chaos brought psychological issues to group members that can be difficult to overcome. This included high stress levels caused by the chaotic events as well as isolation-induced depression. After some deliberation amongst all USIP groups, it was decided to occasionally hold non work-related meetings through Microsoft Teams. This reduced some of the isolation depression by relaxing, talking, and eating pizza. After lockdown restrictions were lifted, the university had begun preventing the previous number of students from being in the lab at once. On top of that, individuals were understandably hesitant to go to the lab, often opting out. Despite this, small groups of USIP students have been going to the labs to clean, disinfect, and get the lab ready for work. New lab procedures have also been created to adhere to social distancing norms.

Gravity currents frequently occur when excess suspended sediments are flushed along a river and discharged into greater natural water environments such as lakes, reservoirs, and estuaries. Gravity and turbidity currents have been broadly investigated, but the effect of aquatic vegetation on their propagation in natural waters still presents several open questions. We conducted a series of laboratory experiments to investigate how flexible vegetation affects the propagation and flow structure of gravity currents on a constant slope. We used both rigid cylinders and flexible synthetic plants to mimic natural submerged vegetation canopies. By varying density configurations of the vegetation array and comparing the outcomes of rigid cylinders and flexible plants, the data showed distinct patterns based on array density and plant morphology. A two-layer current was created when the array density is large enough to redirect the flow, as opposed to sparser conditions where the denser fluid passes swiftly through the array. Flexible vegetation further suppresses the propagation speed of gravity currents compared to arrays of rigid cylinder with the same density, highlighting the importance of the multi-scale processes driven by complex plant morphologies that are not represented by rigid cylinder arrays.

Turbulence generated by aquatic vegetation in rivers, lakes, and estuaries, can significantly alter the flow structure throughout the whole water column, affecting gas transfer mechanisms at the air-water interface, driving changes in indicators of water quality. We conducted a series of laboratory experiments with rigid cylinder arrays to mimic vegetation using a staggered configuration in a recirculating Odell-Kovasznay type race-track flume. 2D planar Particle Image Velocimetry (PIV) was used to characterize the mean flow field and turbulent flow statistics, to characterize the effect of emergent and submerged vegetation in terms of turbulent kinetic energy, Reynolds stresses, and turbulent shear production. The surface gas transfer rate was determined by measuring the dissolved oxygen (DO) concentration during the re-aeration process in water based on the methodology proposed by the American Society of Civil Engineers (ASCE). Our data provide new insight on how stem- and canopy- scale turbulence affect the surface gas transfer rate at different submergence ratios and array densities. The relation between mean flow velocity and turbulent shear production in these scenarios is used to develop a modified surface renewal (SR) model using turbulent shear production as an indicator of gas transfer efficiency, which allows us to more accurately predict surface gas transfer rates in vegetated flows.