Earth and Space Research

Impact ionisation mass spectrometers, such as the Cosmic Dust Analyser (CDA) onboard Cassini and the SUrface Dust Analyzer (SUDA) onboard Europa Clipper, are key instruments to investigate the composition of icy ocean moons1. They are capable of detecting organics in ice grains ejected from cryovolcanic processes (e.g. Enceladus’ plume) and micrometeoritic bombardment of the icy surface. Laboratory analogue experiments that replicate ice grain impact ionisation mass spectra are crucial in order to reliably identify chemical features of organics in spacecraft data. The laser-induced liquid beam ion desorption (LILBID) technique allows the accurate simulation of impact ionisation mass spectra at a range of impact velocities, by desorbing ionic and neutral molecules and fragments from a μm-sized liquid beam containing water and dissolved analytes2. This work investigates amygdalin (C20H27NO11) and its mass spectral fingerprint with LILBID, aiming to assist in the analysis of organic molecules with impact ionisation mass spectrometry. Upon measurement, amygdalin undergoes protonation-induced chemical transformations (PICTs), enabled by the high laser energy input and proton-rich environment created upon disintegration of the water matrix. The observed reactivity is a distinct phenomenon that can be set apart from other well-characterised processes that analytes can be subject to upon measurement with LILBID and impact ionisation mass spectrometry (e.g. fragmentation). PICTs observed in amygdalin feature its initial nitrile group as well as other functional groups obtained after the first transformation (e.g. carboxylic acid), resulting in multiple reactions products identified by their characteristic molecular ions. Complementary measurements with nuclear magnetic resonance spectroscopy confirmed that reactivity does not occur in solution prior to desorption, and must therefore occur under LILBID measurement. In principle, functional groups similar to nitrile (e.g., amide or ketone) in other compounds could also be subject to PICTs. PICTs may also occur with spaceborne impact ionisation, potentially complicating the identification of organics contained in ice grains. This work builds towards a better understanding of PICTs and their effect(s) on the detection of organic compounds using impact ionisation mass spectrometry, and has key implications for the interpretation of Cassini’s CDA data and for investigations of the composition of icy ocean moons with upcoming space missions (e.g. Europa Clipper or ESA’s large-class mission to Enceladus).[1] S. Kempf et al., Space Sci. Rev. 221, 10 (2025)[2] F. Klenner et al., Rapid Comm. Mass Spectrometry 33 (22), 1751–1760 (2019)

Abstract The Alpine fault is a major transpressive plate boundary in southwestern New Zealand known on paleoseismological grounds to produce great (Mw∼8) earthquakes on <300 yr timescales. The fault is now late in its typical and well-determined interseismic period, having last ruptured in a great earthquake in 1717 C.E. Between October 2021 and November 2023, the Southern Alps Long Skinny Array (SALSA) consisting of 43 broadband and 4 short-period seismometers, was installed with ∼10 km interstation spacing along a 450 km stretch of the Alpine fault, between Maruia and Milford Sound/Piopiotahi. SALSA’s geometry was designed to enable the synthesis of virtual earthquakes representing slip at arbitrary points on the Alpine fault as part of research into the range of far-field ground motions that might result from geologically plausible rupture scenarios. Virtual earthquakes provide a means of evaluating ground motions from a much larger number of kinematic rupture scenarios than is computationally tractable using full-waveform simulations. In addition to providing closely spaced noise measurements, SALSA has yielded novel recordings of microseismicity and tremor along most of the onshore extent of the Alpine fault and will enable ongoing research into the present-day state of the fault and future rupture behavior. Here, we describe the rationale for deploying SALSA and present initial results and analysis that illustrate the dataset and indicate avenues for future research.

Fault-related folds and their associated secondary faults play a critical yet often underrecognized role in accommodating strain and generating earthquakes in active fold-and-thrust belts. In the Seattle fault zone (SFZ), Washington, USA, we present new paleoseismic, geomorphic, and geophysical evidence for late Pleistocene and Holocene earthquakes on shallow, south-dipping secondary faults—the Lytle Beach and Vasa Park faults—that lie within the hanging wall of the greater SFZ and are on trend with the primary, blind Blakely Harbor fault. Our data show that these structures have ruptured independently, producing localized uplift and deformation at the surface, with the most recent event (RH2) likely occurring in the early nineteenth century. While a temporal overlap between the late Pleistocene RH1 and VP1 earthquakes raises the possibility of a ≥35 km rupture along the Blakely Harbor fault, structural and temporal evidence instead supports independent rupture on individual faults related to folding. We interpret these faults as bending-moment reverse faults that formed within a synclinal hinge zone of the main fault, reflecting mechanical and kinematic influences of the broader fault system. Combined with prior studies, our findings indicate that faulting related to folding dominates the mode of strain release within the SFZ since the late Pleistocene with more frequent earthquake recurrence (∼350 yr) over the past ∼2500 yr.

ABSTRACT This study tested the Baja–British Columbia (Baja-BC) hypothesis using paleobiological and geochemical data in three separate ways. First, the pattern and values of paleotemperatures obtained from mollusks sampled from the Nanaimo Group, British Columbia (part of the Insular superterrane), were compared to those from basins in western North America (Sacramento and San Joaquin Valleys, California, and Rosario Basin, Baja California, Mexico) during the Coniacian–Maastrichtian time interval. Sequentially younger fossils in the Nanaimo Group show cooling that is consistent with a northernly moving microcontinent into higher latitudes with cooler climate and seawater temperature. The fossils in the basins in western North America do not show this pattern. Second, there is a reduction in the number of ammonite species shared by the Nanaimo Group and western North American sedimentary basins during the Santonian–Maastrichtian time interval. These data are consistent with increasing distance between the two regions over Late Cretaceous time. Third, nautiloid cephalopod assemblages from the Nanaimo Group and North America basins differ sufficiently to allow estimates of the possible deep, open-water distance between the Insular superterrane and North America during the Coniacian–Maastrichtian interval. These results are all consistent with the “far-traveled” Insular microcontinent hypothesis. However, the data also suggest that the Insular superterrane could have been farther offshore than previous models invoking the Baja–British Columbia hypothesis.

NASA's ICESat-2 mission was launched in 2018 carrying a photon-counting laser altimeter, with a primary objective of measuring height changes across Earth's surface.ICESat-2 has provided measurements of ice surface height between 88N and S with high vertical accuracy and alongtrack spatial resolution, repeated four times each year.Its accuracy and coverage has enabled near-complete recovery of height changes across the ice sheets, capturing subtle changes in the interior, rapid changes along the

<strong class="journal-contentHeaderColor">Abstract.</strong> The basal unit near the base of the Antarctic Ice Sheet (AIS) plays a critical role in AIS dynamics and the preservation of old ice, yet its structure and origin remain poorly understood. Using a new airborne ice-penetrating radar dataset collected by the NSF Center for Oldest Ice Exploration (NSF COLDEX), we investigate the radar characteristics of the basal unit at the southern flank of Dome A, East Antarctica. We combine manual mapping with Delay-Doppler analysis to characterize the spatial distribution of incoherent scattering and to distinguish between two types of radar-apparent basal unit top boundaries: a sharp transition from specular to scattering reflections (type I) and a gradual disappearance of specular reflections due to radar signal attenuation (type II). We find that incoherent scattering is widespread upstream and decreases downstream, correlating with both subglacial topographic roughness and a shift from type I to type II boundaries. These patterns are interpreted as resulting from spatial variability in englacial temperature, with warmer ice downstream enhancing signal attenuation and obscuring radar features. Although incoherent scattering is not visible in the downstream region, its absence may reflect radar detection limits rather than true absence of scattering reflectors in the basal unit. Moreover, the observed correlation between scattering and subglacial roughness suggests deeper geological controls in which subglacial lithology influences both basal temperature and subglacial geomorphology.

Abstract The carbon isotopic composition of pedogenic carbonate (δ 13 C c ) is a widely used proxy for paleoatmospheric CO 2 levels. However, the estimated CO 2 is often highly uncertain due to the lack of constraints on other variables that influence this system. To improve paleosol‐based CO 2 reconstructions, here we propose the Joint Proxy Inversion (JPI) of a paleosol‐based proxy system model, which integrates various proxies (e.g., pedogenic carbonate δ 13 C and δ 18 O) that share sensitivities to common environmental parameters (e.g., CO 2 , precipitation) via a forward proxy model in a Bayesian hierarchical framework. JPI generates self‐consistent posterior distributions of environmental parameters conditioned on multi‐proxy data sets while accounting for proxy and model uncertainties. The JPI was applied to data from Quaternary loess deposits from the Chinese Loess Plateau to test its performance. Sensitivity tests and posterior CO 2 estimates suggest insensitivity of proxy values to CO 2 when the analysis integrates δ 13 C, δ 18 O c , and clumped isotope values of pedogenic carbonates only. Improved results were achieved after incorporating a precipitation‐sensitive proxy, a model component representing environmental variation as a function of time, and a parameterized relationship between global temperature and CO 2 . The improved model performance is indicated by agreement between posteriors of environmental parameters (i.e., CO 2 , temperature, precipitation) and other independent records. Compared to the traditional proxy interpretation approach, the paleosol‐JPI offers a more holistic and rigorous way to interpret multi‐proxy records with shared environmental sensitivities, provides additional information on climate and environmental systems, and is capable of reconstructing paleo‐CO 2 levels with higher precision and fidelity.

Abstract During subduction, the downgoing oceanic crust is exposed to high temperatures in the mantle wedge, causing volatile‐bearing minerals to break down and release hydrous fluids into the forearc. These fluids percolate upwards, reacting with the mantle wedge to form hydrated ultramafic lithologies, including serpentinite. To accurately track the fate and impact of water on the forearc, we develop time‐dependent models that self‐consistently capture both serpentinite ingrowth and the associated rheological weakening of the plate interface. Unlike many subduction models that investigate forearc serpentinization and prescribe plate velocities, geometries, or steady‐state conditions, our approach allows plates to evolve dynamically without predefined velocities or geometries. During subduction infancy, serpentinite accumulates rapidly. As subduction matures, serpentinite ingrowth decreases, and more serpentinite is also dragged downward by the slab. To elucidate the links between subduction dynamics and serpentinization, we consider variations in serpentinite strength and hydration state of the incoming plate. Subducting fully water‐saturated sediments yield ∼3× greater forearc serpentinite than within the moderately hydrated reference case. The water‐saturated case produces a weaker interface and, in turn, subduction zone convergence rates ∼40% higher than in an endmember case with anhydrous sediment. A lower serpentinite strength also produces higher convergence rates despite more downdragging of serpentinite from the forearc. We find that hydrous sediments not only lubricate the interface directly by weakening it, as previously suggested, but also by dehydrating and releasing water that produces weak serpentinite in the mantle wedge, with such feedback only able to be captured within fully coupled dynamic models.

A new era of Lunar exploration: Canada is heading to the Moon With Canadian astronaut Jeremy Hansen leading the way, Canada is heading to the Moon with humans and robots, as explained by Dr. Gordon Osinski from Western University. Canada has a long history in space – a history that many people may not be aware of. With the launch of the Alouette-1 satellite in 1962, Canada became the third country in space, following the former USSR and the U.S. Since then, Canada has played an important role in space, with satellites such as the Radarsat program to monitor Earth, a pioneering astronaut program, and contributions to various robotic planetary and astronomy missions.

Abstract Uranium‐series dates from coral boulders constrain the timing of a medieval tsunami from the Puerto Rico Trench. Previously reported evidence for this tsunami includes hundreds of coral boulders that came to rest hundreds of meters inland on Anegada, British Virgin Islands. New U‐series dates on these coral boulders provide limiting dates for the tsunami. The narrowest limits were by dating interior bands of a coral that retains the hemispherical form of a living coral colony, and which include adjustments for the number of annual density band couplets between the dated samples and the boulder exteriors. By those limits, the tsunami dates between 1381 and 1391 CE, and likely occurred during summer or fall. The tsunami is important as the only reported sign that the eastern Puerto Rico Trench has produced a great earthquake. The dating may aid in defining the earthquake source and in communicating tsunami hazards.