Geological Sciences

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Co-expression of multi-genes for polynary perovskite electrocatalysts for reversible solid oxide cells
(Springer Nature, 2025-03-25) Zhang, Xiaoxin; He, Hongyuan; Chen, Yu; Yang, Guangming; Xiao, Xiao; Lv, Haiping; Xiang, Yongkang; Wang, Shuxiong; Jiang, Chang; Li, Jianhui; Chen, Zhou; Liu, Subiao; Yan, Ning; Yong, Xue; Alodhayb, Abdullah N.; Pan, Yuanming; Chen, Ning; Lin, Jinru; Tu, Xin; Shao, Zongping; Sun, Yifei
High-entropy LnBaCo2O5+δ perovskites are explored as rSOC air electrodes, though high configuration entropy (Sconfig) alone poorly correlates with performance due to multifactorial interactions. We systematically engineer LnBaCo2O5+δ perovskites (Ln = lanthanides) with tunable Sconfig and 20 consistent parameters, employing Bayesian-optimized symbolic regression to decode activity descriptors. The model identifies synergistic contributions from Sconfig, ionic radius, and electronegativity, enabling screening of 177,100 compositions. Three validated oxides exhibit superior activity/durability, particularly (Pr0.05La0.4Nd0.2Sm0.1Y0.25)BaCo2O5+δ, showing enhanced oxygen vacancy concentration and disordered transport pathways. First-principles studies reveal optimized charge transfer kinetics via cobalt-oxygen bond modulation. Further, the interplay between first ionization energy, atomic mass, and ionic Lewis acidity dictates stability. This data-driven approach establishes a quantitative framework bridging entropy engineering and catalytic functionality in complex oxides.
Discovery of Ge2+ in quartz: Evidence from EPR/XAS experiments and DFT calculations, and implications for Ge/Si systematics
(Elsevier, 2025-03-15) Mashkovtsev, Rudolf I.; Botis, Sanda M.; Lin, Jinru; Deevsalar, Reza; Cheung, Leo Ka Long; Wiens, Eli; Tunc, Ayetullah; Chen, Ning; Chernikov, Roman; Pan, Yuanming
The Ge/Si systematics as a biogeochemical tracer with diverse applications from paleo-climatic reconstructions to discrimination of magma sources and elucidation of Earth’s early evolution hinges on the coherent behavior of these elements in the tetravalent state. However, determination of Ge speciation in quartz and other silicate minerals is technically challenging because this element almost invariably occurs at several parts per million or lower concentrations. This contribution reports a detailed study of Ge speciation in quartz by combining single-crystal electron paramagnetic resonance spectroscopy, synchrotron X-ray absorption spectroscopy, and ab initio theoretical calculations. Our single-crystal and powder electron paramagnetic resonance spectra of artificially irradiated quartz reveal a suite of previously reported Ge electron centers (GECs) such as [GeHLi2]0 and [GeHH2]0 centers as well as a new GeHLi center. These multiply-compensated GECs in artificially irradiated quartz suggest that their precursors before irradiation involve the diamagnetic Ge2+ state. Ge K-edge X-ray absorption spectroscopic data of selected quartz samples further support the presence of Ge2+. Theoretical calculations reproduce the experimental 1H and 7Li hyperfine constants of the [GeHLi2]0 center and suggest the new GeHLi center to be a new variant of the multiply-compensated GECs with the second monovalent cation in a distant c-axis channel, again supporting the Ge2+ state. The presence of Ge2+ in sedimentary-diagenetic quartz, in particular, challenges existing thermodynamic data that Ge4+ is the only stable oxidation state in aqueous solutions under near-surface conditions. Incorporation of Ge2+ in quartz and other silicates can significantly affect Ge/Si fractionations, with important implications for their applications as a biogeochemical tracer from surficial environments to magmatic-hydrothermal systems, Earth’s core-mantle differentiation, and other planetary processes.
Quantified growth and possible heterochronic development of two corynexochid trilobites from the middle Cambrian (Miaolingian Series, Wuliuan Stage) Mount Cap Formation, eastern Mackenzie Mountains, northwestern Canada
(Cambridge University Press, 2024-10-21) Handkamer, Neal M.; Pratt, Brian R.
The ontogeny of two species of corynexochid trilobites from the middle Cambrian Mount Cap Formation of the eastern Mackenzie Mountains, northern Canada, is documented. Sahtuia carcajouensis (Dolichometopidae) and Mackenzieaspis parallelispinosa (Zacanthoididae) are both endemic to this formation and only known from one locality. They, along with several other corynexochid taxa, occur in a succession of mudstone with scattered carbonate interbeds, deposited in a weakly storm-agitated setting near the flank of a semi-enclosed basin. The ontogeny of both species is characterized by mainly normal cranidial development, but a unique distribution of segments in their thoraxes and pygidia. The number of trunk segments was typical for their respective families, whereas the final number of segments released into the thorax was reduced. This occurred in both species through timing modifications to segment release, indicating heterochrony. Sahtuia carcajouensis and Mackenzieaspis parallelispinosa are likely derived from two separate clades, and heterochrony probably arose separately but synchronously. The endemicity of both species probably reflects unique paleoecological conditions in this part of the basin. Preliminary results indicate that the fossil-bearing mudstone was deposited under well-oxygenated conditions that underwent high nutrient flux and possibly experienced varying salinity. These factors may have affected the organisms’ physiology, or perhaps provoked an adaptation to achieve early maturation.
Morphologically complex plant macrofossils from the Late Silurian of Arctic Canada
(Botanical Society of America, 2002-06) Kotyk, Michele E.; Basinger, James F.; Gensel, Patricia G.; de Freitas, Tim A.
In addition to vegetative remains, fertile remains from ten plants, representing seven distinct taxa whose size and complexity are much greater than most contemporaneous fossils, are reported from late Ludlow (Ludfordian) sediments of Bathurst Island in Nunavut, Canada. Evidence for the age of these beds is gathered from stratigraphic relationships and index fossils including conodonts, graptolites, and brachiopods. Zosterophylls dominate the collection, some of which constitute the earliest record of fertile structures arranged in dense clusters and longitudinal rows along axes. Representatives include a plant that resembles Bathurstia, one species of Zosterophyllum, and two specimens that bear affinity to this genus. Distichophytum is also represented, as is a new zosterophyll named Macivera gracilis. The prevalence of sporangial clustering and reduced sporangial stalks in this flora leads to a discussion of the origins and significance of these morphological features. Following a review of some of the other Silurian floras, particularly the Baragwanathia-bearing Lower Plant Assemblage of Victoria, Australia, which also shows morphological advancement over the rhyniophytoid-dominated floras common to Laurussia, it is concluded that the Bathurst Island flora presents the best evidence to date of substantial morphological diversity, complexity, and stature of vascular land plants in this period.
Endorhizal Fungi in Ranunculus from Western and Arctic Canada: Predominance of Fine Endophytes at High Latitudes
(Bentham Open Archives, 2010-01) Walker, X. J.; Basinger, J. F.; Kaminskyj, S. J. W.
Ranunculus roots were sampled across a latitudinal transect encompassing 52 °N and 82 °N, for years spanning 1963-2007. Samples from 2004 and later were preserved in formalin; earlier samples were taken from herbarium accessions. Roots were examined for colonization by arbuscular mycorrhizae, fine endophyte, and septate endophyte fungi using lactofuchsin-stained material imaged with epifluorescence microscopy. Endorhizal quantitation was assessed for each endorhizal morphotype. Roots from High Arctic (79 °N-82 °N) and mid-latitude (52 °N-54 °N) sites both contained all three endorhizal morphotypes; however, overall fungal colonization was almost three-fold higher in midlatitude samples. Most Ranunculus root colonization (29 % of the root length) in High Arctic samples was from fine endophyte fungi, whereas fine endophyte colonization was ∼ 20 % of root length in mid-latitude roots. In contrast, arbuscular mycorrhizal colonization was 2 % of root length in High Arctic samples and 57 % in mid-latitude samples. Septate endophyte colonization was 11 % and 36 % of root length for High Arctic and mid-latitude samples, respectively. These values are consistent with our previous results for other taxa, and suggest that fine endophytes are important contributors to soil microbial diversity as related to plant survival and competitiveness in the high latitudes.
Latisemenia longshania, gen. et sp. nov., a new Late Devonian seed plant from China
(The Royal Society Publishing, 2015-10) Wang, De-Ming; Basinger, James F.; Huang, Pu; Liu, Le; Xue, Jin-Zhuang; Meng, Mei-Cen; Zhang, Ying-Ying; Deng, Zhen-Zhen
The earliest known ovules in the Late Devonian (Famennian) are borne terminally on fertile branches and are typically enclosed in a cupule. Among these ovules are some that have terete integumentary lobes with little or no fusion. Here, we report a new taxon, Latisemenia longshania, from the Famennian of South China, which bears cupulate ovules that are terminal as well as opposite on the fertile axis. Each ovule has four broad integumentary lobes, which are extensively fused to each other and also to the nucellus. The cupule is uniovulate, and the five flattened cupule segments of each terminal ovule are elongate cuneate and shorter than the ovule. Associated but not attached pinnules are laminate and Sphenopteris-like, with an entire or lobate margin. Latisemenia is the earliest known plant with ovules borne on the side of the fertile axis and may foreshadow the diverse ovule arrangements found among younger seed plant lineages that emerge in the Carboniferous. Following the telome theory, Latisemenia demonstrates derived features in both ovules and cupules, and the shape and fusion of integumentary lobes suggest effective pollination and protection to the nucellus. Along with other recent discoveries from China, Latisemenia extends the palaeogeographic range of the earliest seed plants.
A review of paleobotanical studies of the Early Eocene Okanagan (Okanogan) Highlands floras of British Columbia, Canada, and Washington, USA
(Canadian Science Publishing, 2016-02) Greenwood, David R.; Pigg, Kathleen B.; Basinger, James F.; DeVore, Melanie L.
The history of plant fossil collecting in the Okanagan (Okanogan) Highlands of British Columbia and northeastern Washington is closely intertwined with the history of geological surveys and mining activities from the 1870s onward. The first descriptions of fossil plants from British Columbia were published in 1870–1920 by J.W. Dawson, G.M. Dawson, and D.P. Penhallow. In the United States, fossil leaves and fish were first recognized at Republic, Washington, by miners in the early 1900s. Many early workers considered these floras to be of Oligocene or Miocene age. C.A. Arnold described Canadian occurrences of conifers and Azolla in the 1950s. Palynological studies in the 1960s by L.V. Hills, G.E. Rouse, and others and those of fossil fish by M.V.H. Wilson in the 1970–1980s provided the framework for paleobotanical research at several key localities. Permineralized plants were first described from the Princeton chert in the 1970s by C.N. Miller, J.F. Basinger, and others, followed by R.A. Stockey and her students. W.C. Wehr and K.R. Johnson revitalized the study of fossils at Republic with the discovery of a diverse assemblage in 1977. In 1987, J.A. Wolfe and Wehr produced a United States Geological Survey monograph on Republic, and Wehr cofounded the Stonerose Interpretive Center as a venue for public collecting. Systematic studies of the Okanagan Highlands plants, as well as paleoecological and paleoclimate reconstructions from palynomorphs and leaf floras, continue to expand our understanding of this important Early Eocene assemblage.
The Miocene Red Lake macroflora of the Deadman River Formation (Chilcotin Group), Interior Plateau, British Columbia, Canada
(W. Szafer Institute of Botany, Polish Academy of Sciences, 2020) Greenwood, David; West, Christopher K.; Basinger, James F.
Despite early interest in Neogene floras, primarily Miocene sites associated with Mio–Pliocene volcanic deposits of the Interior Plateau of British Columbia, few systematic accounts of the Miocene macrofloras of British Columbia – or elsewhere in non-Arctic Canada – have been published since the pioneering studies of J.W. Dawson and his contemporaries in the late 19th century. In this report, the Red Lake macroflora from sediments of the middle Miocene Deadman River Formation exposed in the Red Lake diatomite mine north of Kamloops, British Columbia, is illustrated, and a preliminary assessment presented, along with a brief review of Miocene floras from British Columbia and the U.S. Pacific Northwest. The Red Lake macroflora contains rare Ginkgo leaves, shoots of Cupressaceae (Cupressinocladus, Metasequoia, Taxodium) and shoots and seeds of Pinaceae (Pseudotsuga, Tsuga), maple (Acer) seeds and leaves, Liquidambar (fruit), Trochodendraceae (Zizyphoides auriculata leaves, Nordenskioeldia interglacialis fruits), leaves of 4 species of red and white oaks (Quercus columbiana, Q. prelobata, Q. pseudolyrata, Quercus sp.), leaves of an alder (Alnus harneyana) and birch (Betula thor), chestnut (Castanea spokanensis), beech (Fagus pacifica), sycamore (Platanus dissecta), elm (Ulmus speciosa), leaves of unidentified taxa, fruits of Tilia pedunculata (Malvaceae) and fruits and inflorescences of other unidentified taxa, and leaves of a reed or rush (indet. monocot). The Red Lake middle Miocene climate reconstructed from leaf physiognomy was temperate and mesic, with mean annual temperature ~11–13°C, mild winters (coldest month mean temperature ~3°C), mean annual precipitation 170 −51/+73 cm/yr, and growing season precipitation ~92 cm, with moderate seasonality of precipitation (three wettest months ~51 cm vs. three driest months ~25 cm). The Red Lake flora shows similarities to middle to late Miocene floras from the U.S. Pacific Northwest (i.e., richness in oaks) but is of much lower diversity and lacks key elements common to many of the contemporaneous U.S. Miocene floras (e.g., foliage of Pinaceae esp. Pinus), and is missing taxa detected in the microflora, a pattern likely due to sampling effectiveness at the Red Lake Mine and sampling of different lithofacies for macro- and microfloras.
Dietary palaeoecology of an Early Cretaceous armoured dinosaur (Ornithischia; Nodosauridae) based on floral analysis of stomach contents
(The Royal Society Publishing, 2020-06) Brown, Caleb M.; Greenwood, David; Kalyniuk, Jessica E.; Braman, Dennis R.; Henderson, Donald M.; Greenwood, Cathy L.; Basinger, James F.
The exceptionally well-preserved holotype of the armoured dinosaur Borealopelta markmitchelli (Ornithischia; Nodosauridae) from the Early Cretaceous (Clearwater Formation) of northern Alberta preserves a distinct mass within the abdominal cavity. Fourteen independent criteria (including: co-allochthony, anatomical position, gastroliths) support the interpretation of this mass as ingested stomach contents—a cololite. Palynomorphs in the cololite are a subset of the more diverse external sample. Analysis of the cololite documents well-preserved plant material dominated by leaf tissue (88%), including intact sporangia, leaf cross-sections and cuticle, but also including stems, wood and charcoal. The leaf fraction is dominated (85%) by leptosporangiate ferns (subclass Polypodiidae), with low cycad–cycadophyte (3%) and trace conifer foliage. These data represent the most well-supported and detailed direct evidence of diet in an herbivorous dinosaur. Details of the dietary palaeoecology of this nodosaur are revealed, including: selective feeding on ferns; preferential ingestion of leptosporangiate ferns to the exclusion of Osmundaceae and eusporangiate ferns such as Marattiaceae; and incidental consumption of cycad–cycadophyte and conifer leaves. The presence of significant (6%) charcoal may represent the dietary use of recently burned conifer forest undergoing fern succession, early evidence of a fire succession ecology, as is associated with many modern large herbivores.
Paleobotanical proxies for early Eocene climates and ecosystems in northern North America from middle to high latitudes
(European Geosciences Union, 2020) West, Christopher K.; Greenwood, David R.; Reichgelt, Tammo; Lowe, Alexander J.; Vachon, Janelle M.; Basinger, James F.
Early Eocene climates were globally warm, with ice-free conditions at both poles. Early Eocene polar landmasses supported extensive forest ecosystems of a primarily temperate biota but also with abundant thermophilic elements, such as crocodilians, and mesothermic taxodioid conifers and angiosperms. The globally warm early Eocene was punctuated by geologically brief hyperthermals such as the Paleocene–Eocene Thermal Maximum (PETM), culminating in the Early Eocene Climatic Optimum (EECO), during which the range of thermophilic plants such as palms extended into the Arctic. Climate models have struggled to reproduce early Eocene Arctic warm winters and high precipitation, with models invoking a variety of mechanisms, from atmospheric CO2 levels that are unsupported by proxy evidence to the role of an enhanced hydrological cycle, to reproduce winters that experienced no direct solar energy input yet remained wet and above freezing. Here, we provide new estimates of climate and compile existing paleobotanical proxy data for upland and lowland midlatitude sites in British Columbia, Canada, and northern Washington, USA, and from high-latitude lowland sites in Alaska and the Canadian Arctic to compare climatic regimes between the middle and high latitudes of the early Eocene – spanning the PETM to the EECO – in the northern half of North America. In addition, these data are used to reevaluate the latitudinal temperature gradient in North America during the early Eocene and to provide refined biome interpretations of these ancient forests based on climate and physiognomic data.
A new Late Devonian flora from Sonid Zuoqi, Inner Mongolia, northeastern China
(Cambridge University Press, 2021-10) Bai, Lingqi; Huang, Pu; Yang, Ning; Ju, Wenxin; Liu, Jianbo; Basinger, James F.; Xu, Honghe; Xue, Jinzhuang
The Silurian and Devonian plant fossil record is the basis for our understanding of the early evolution of land plants, yet our appreciation of early global phytogeographic evolution has been constrained by the focus of most studies on deposits from Europe, North America, and, more recently, South China. Devonian plants have been recorded rarely from northeastern China, and among previous records, few plants have been illustrated and formally described. In this article, megafossil plants representing a Late Devonian-aged (probably Famennian) flora are described from a locality at northern Sonid Zuoqi, Inner Mongolia, NE China. The flora includes Melvillipteris sonidia new species, Archaeopteris sp., and fragments of some other plants. The new plant shows main axes and two orders of lateral branches. The first-order branches of this plant show a typical zigzag appearance and are borne in pairs on main axes. Second-order branches are straight or slightly flexed, and are borne helically or alternately on first-order branches. Sterile ultimate appendages and fertile structures of M. sonidia n. sp. are borne alternately on second-order branches. An associated palynological assemblage, as well as U-Pb ages of detrital zircon grains from adjacent horizons, are also reported, indicating a Late Devonian age in accord with the megafossil plants. The present study contributes to our appreciation of the Devonian floristic diversity of the Xing'an Block, and, through our review of the record of early vascular plants from NE China, more broadly to the understanding of the mid-latitude vegetation of the Northern Hemisphere during the Late Devonian.
The Albian vegetation of central Alberta as a food source for the nodosaurid Borealopelta markmitchelli
(Elsevier, 2022-12) Kalyniuk, Jessica E.; West, Christopher K.; Greenwood, David R.; Basinger, James F.; Brown, Caleb M.
During the Cretaceous, large herbivorous dinosaurs (megaherbivores) acted as keystone species—just as large mammals do today (e.g., elephants)—yet despite their significance in Cretaceous ecosystems, what plant taxa these dinosaurs ate is unclear. The Albian armoured dinosaur Borealopelta markmitchelli (Ornithischia; Nodosauridae) was discovered in northern Alberta, Canada and has well-preserved stomach contents dominated by fern leaf tissues, with low amounts of gymnosperm material, implying selective feeding. The lower Albian Gates Formation (Grande Cache Member) macroflora of central Alberta is contemporaneous and spatially proximal with B. markmitchelli and therefore provides information on local vegetation available to this nodosaurid and other megaherbivores in this area. In this study we provide census-sampled abundance data for the Gates Formation macroflora. These data also provide the means to further investigate the feeding ecology of Borealopelta by summarizing the vegetation and local food options available. Census collections at five sites within the Grande Cache Member exposed in the Grande Cache Coal Mine reveal that the local vegetation there was dominated by conifers (44–70%) across all sites. Athrotaxites, Elatides, and Pityocladus were the most common conifers. Other gymnosperms present were ginkgophytes (e.g., Ginkgoites; 11%) and Taeniopteris (9%). Caytoniales (Sagenopteris) were found at one study site but uncommon (2%). Ferns (e.g., Cladophlebis, Coniopteris, Gleichenites) accounted for 14% of the total site counts while cycadophytes (Bennettitales; 4%) and Equisetites (1%) were less common. When comparing the Gates Formation macroflora to the stomach contents of Borealopelta, these data suggest that B. markmitchelli was selectively feeding on ferns, or in a recently disturbed fern-dense area within the local landscape.
Paleogene Paleohydrology of Ellesmere and Axel Heiberg Islands (Arctic Canada) From Palustrine Carbonates
(Advancing Earth and Space Sciences, 2023-10) Padgett, Ashly B.; Hyland, Ethan; West, Christopher K.; Greenwood, David; Basinger, James F.
Ancient greenhouse periods are useful analogs for predicting effects of anthropogenic climate change on regional and global temperature and precipitation patterns. A paucity of terrestrial data from polar regions during warm episodes challenges our understanding of polar climate responses to natural/anthropogenic change and therefore our ability to predict future changes in precipitation. Ellesmere and Axel Heiberg Islands in the Canadian Arctic preserve terrestrial deposits spanning the late Paleocene to middle Eocene (59–45 Ma). Here we expand on existing regional sedimentology and paleontology through the addition of stable (δ13C, δ18O) and clumped (Δ47) isotope analyses on palustrine carbonates. δ13C isotope values range from −4.6 to +12.3‰ (VPDB), and δ18O isotope values range from −23.1 to −15.2‰ (VPDB). Both carbon and oxygen isotope averages decrease with increasing diagenetic alteration. Unusually enriched carbon isotope (δ13C) values suggest that analyzed carbonates experienced repeated dissolution-precipitation enrichment cycles, potentially caused by seasonal fluctuations in water availability resulting in summer carbonate dissolution followed by winter carbonate re-precipitation. Stable isotopes suggest some degree of precipitation seasonality or reduction in winter water availability in the Canadian Arctic during the Paleogene. Clumped (Δ47) temperature estimates range from 52 to 121°C and indicate low temperature solid-state reordering of micritic samples and diagenetic recrystallization in sparry samples. Average temperatures agree with vitrinite reflectance data for Eureka Sound Group and underlying sediments, highlighting structural complexity across the region. Broadly, combined stable and clumped isotope data from carbonates in complex systems are effective for describing both paleoclimatic and post-burial conditions.
Paleobotanical Evidence for Mediterranean Climates in the Western Canadian Paleoarctic During the Late Middle Eocene
(Advancing Earth and Space Sciences, 2024-10) West, Christopher K.; Reichgelt, Tammo; Reyes, Alberto; Buryak, Serhiy D.; Staniszewska, Kasia; Basinger, James F.
Paleogene age deposits east of the Fifteenmile River, northwest of Dawson City, Yukon, Canada preserve a diverse high-latitude fossil flora. Here, we provide new data on the age of the fossil site based on laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U-Pb dating of tephra zircons, paleobotanical paleoclimate reconstructions, and growing season length estimates based on photoperiod. These new data indicate an age of the Fifteenmile River fossil locality as late middle Eocene and likely within the Middle Eocene Climatic Optimum episode. The paleoflora-based paleoclimate reconstruction indicates the region was relatively wet and warm with non-freezing winters, but also experienced seasonal dryness, with an approximate 7 months long growing season as suggested by photoperiod. We interpret this paleoclimate as summer dry and winter wet—a climate analogous to modern day warm Mediterranean climates in the Köppen-Geiger climate classification system. These findings provide a new perspective on the past climate and environment of high-latitude ecosystems during warm greenhouse intervals and contribute to our understanding of the Earth's climate history and its potential future changes.
Spatial and temporal changes in small-strain shear modulus of geogrid-stabilized crushed aggregate materials
(Elsevier, 2025-01-16) Yesnik, Chelsey; Soliman, Haithem; Morozov, Igor; Fleming, Ian; Landry, Ethan
Geogrid stabilization can be used by transportation agencies to build durable roadways over soft subgrade soil. The performance of geogrid stabilization is highly dependent on the properties of the geogrid material, the aggregate material, and the interaction between the two materials when combined. Therefore, transportation agencies need to perform their own studies to assess the performance of geogrid stabilization for their local materials. Additionally, the current knowledge base needs to be continually expanded to a variety of aggregate-geosynthetic composites to develop performance-based design methods for geosynthetic-stabilization. This study evaluates the long-term performance of two geogrids used to stabilize a crushed aggregate material. A full-scale traffic loading system was built to simulate a full half-axle (40kN) traffic load for thousands of load cycles. Two trials were completed using the same crushed aggregate material. For each trial, two geogrid-stabilized sections, and one control section were evaluated. The performance of the test sections was monitored for 4000 load cycles by measuring surface rutting and completing multichannel analysis of surface waves (MASW) to measure aggregate stiffness. Results showed that the geogrid-stabilized sections had better long-term performance than the control sections with lower degradation of the as-built aggregate stiffness. There was good agreement amongst the MASW results, rutting measurements, and Shakedown analysis. It has been concluded that MASW is an effective method for evaluating the long-term performance of geogrid stabilization in aggregate layers with a customized instrumentation plan according to the targeted measurements.
Metal Mobilization from Thawing Permafrost Is an Emergent Risk to Water Resources
(ACS Publications, 2024-12-10) Skierszkan, Elliott; Dockrey, John W.; Lindsay, Matthew B. J.
Metals are ubiquitous in Earth’s Critical Zone and play key roles in ecosystem function, human health, and water security. They are essential nutrients at low concentrations, yet some metals are toxic at a high dose.Permafrost thaw substantially alters all the physical and chemical processes governing metal mobility, including water movement and solute transport and(bio)geochemical interactions involving water, organic matter, minerals, and microbes. The outcomes of these interconnected changes are nonintuitive yet hold global implications for water resources and ecosystem health. This Perspective outlines the primary factors affecting metal mobility in thawing permafrost and underscores the urgent need and priorities for interdisciplinary research to better understand this emerging issue.
Thickness of the stratigraphic record of Britain: How the fidelity of geological and fossil data is unrelated to rock quantity
(Earth-Science Reviews, 2025-01) Craig, James A.; Battle, Ralph J.; Veenma, Yorick P.; McMahon, William J.; Slater, Ben J.; Shillito, Anthony; Davies, Neil S.
The sedimentary-stratigraphic record is the principal repository of empirical historic evidence for evolution and deep time environments. However, the record has a temporal incompleteness and inconsistency to its extensive quantity, driven by the spatial heterogeneity of deposition and erosion. This is argued to bias intensive fossil records, with correlations apparent between fossil diversity and mapped rock area from different intervals. However, mapped rock area is a poor proxy for strata accessible for fossil studies because most is concealed. Additionally, spatially diminutive older rocks commonly sample a greater stratigraphic transect per unit exposure area than widespread younger rocks because the tectonic forces that drive recycling additionally result in tilting. We calculate observable vertical stratigraphic thickness throughout geologic history for southern Britain and show that potential sample availability increases with age, in contrast to general models of rock survivorship. Using this subsample of the sedimentary-stratigraphic record as a calibration sample for the global record, we find no correlation between available stratigraphic thickness and palaeobiodiversity, except in flat-lying strata. We demonstrate instances where the first occurrences of fossil genera appear robust because there is high availability of suitable host rock pre-dating them. Our work suggests that preservation biases induced by variability in rock quantity have been significantly overstated and that local tectonic history renders different regions as stratigraphic hotspots for specific intervals, in which intensive high-veracity fossil records have exceptional value for elucidating global trends and timing in evolutionary history. The British non-marine Palaeozoic record is highlighted as such an example, with high-fidelity palynological records of plant evolution and ichnological records of animal terrestrialization.
Time, space and synoptic topography: how to read outcrops as a granular record of Earth history
(Geological Society, London, Special Publications, 2025-01) Davies, Neil; Veenma, Yorick P.; Craig, James A.; Allport, Hamilton A.; McMahon, William J.; Shillito, Anthony
Siliciclastic strata commonly preserve chronostratigraphic surfaces that record the ancient interface of sediment and water/air, in the form of true substrates on bedding planes and sampled topography in stratigraphic profiles. Such surfaces are commonly a reflection of sedimentary stasis, a sedimentation state where neither deposition or erosion was occurring. Sedimentary stasis may be instantaneous, temporary or prolonged, and may also be considered to occur when the constituent grains of a substrate remain in motion as the surface active layer, when the elevation of the lithic surface does not change. The preservation of patches of synoptic topography requires only that sedimentation states of deposition, erosion and stasis fluctuate, but is more common in lower energy parts of a depositional environment. Certain sedimentary features associated with true substrates and sampled topography can, through modern analogy, be used to determine the likely duration of sedimentary stasis. Here we use original case studies to show how the duration of this stasis can be variable depending on facies and stratal age, but that at outcrop scale it is always a very short interval relative to the longevity of a depositional environment. With examples from several siliciclastic facies and geological periods, we show that stratigraphic time preserved at outcrop scale can be very short, indicating that the total stratigraphic record is built brick by brick of many lower hierarchy snapshots. This understanding shifts perspectives on the stratigraphic record as an archive, with implications for the meaning of sedimentary signatures at outcrop and the construction of narratives to understand Earth history.
Exploring the significance of true substrates in a Pennsylvanian fluvio-estuarine tidal flat
(Geological Society Special Publications, 2025-01-25) Buatois, Luis; Mángano, M. Gabriela; Maples, Christopher G.
The Pennsylvanian Tonganoxie Sandstone of Kansas contains examples of true substrates in tidal rhythmites formed in a tidal flat at the fluvio-estuarine transition of a macrotidal valley. These surfaces are characterized by an impressive preservation of biogenic and physical sedimentary structures, indicative of the coexistence of low-energy tidal currents and freshwater conditions together with brief periods of subaerial exposure. Biogenic activity corresponds to a time of stasis during or immediately after accumulation of ebb-phase clay followed by low tide. Deposition-stasis-deposition (D-S-D) was involved in the formation and preservation of these true substrates, with only a few instances of deposition-stasis-erosiondeposition (D-S-E-D). Crosscutting relationships among biogenic structures and of these with physical sedimentary structures suggest a tidally controlled taphonomic pathway, which indicates that these true substrates represent short-term time-averaged surfaces at the scale of a few hours, rather than snapshots. True substrates preserved in tidal rhythmites are widespread in other late Palaeozoic tide-dominated estuarine deposits of the North American Midcontinent. The likelihood and quality of preservation seem to show spatial and temporal trends at various scales that ultimately reflect a complex interplay of abiotic factors (e.g. sedimentary dynamics) and biotic factors (e.g. secular changes in intensity and depth of bioturbation).
An anomalous shallow-marine ichnofacies gradient from the Lower Devonian Talacasto Formation of the Argentine Precordillera
(Palaeogeography, Palaeoclimatology, Palaeoecology, 2025-01) Wenger, Federico D.; Buatois, Luis A.; Mángano, M. Gabriela; Muñoz, Diego F.; Rustán, Juan J.
The Lower Devonian Talacasto Formation in western Argentina records deposition in wave-dominated shallow-marine environments. This unit comprises a large-scale progradational succession, transitioning from black, parallel-laminated mudstone in the lower interval to siltstone and very fine- to medium-grained sandstone in the upper interval. The succession spans environments ranging from the shelf to the upper shoreface. Three trace-fossil assemblages have been identified: (1) Palaeophycus assemblage, including Palaeophycus heberti, P. tubularis, and Helminthopsis isp., corresponding to the shelf; (2) Phycosiphon-Zoophycos assemblage with Zoophycos isp., Phycosiphon incertum, Nereites missouriensis, and Chondrites isp., ranging from the lower offshore to the lower/middle shoreface; and (3) Rosselia assemblage containing Rosselia socialis, Skolithos isp., Arenicolites isp., Palaeophycus tubularis, and escape trace fossils, corresponding to the offshore transition and the lower/middle shoreface. Two ichnofacies have been identified: distal Cruziana and Skolithos Ichnofacies. Unlike the traditional ichnofacies model, the Talacasto Formation shows an onshore expansion of the distal Cruziana Ichnofacies, which is present not only in the lower offshore, but in the upper offshore, offshore transition, and lower shoreface as well. In contrast, the archetypal Cruziana Ichnofacies is not present. This anomalous distribution is attributed to an interplay of ecologic and taphonomic factors combined with the restricted topography of the southern portion of the Precordillera Basin. Low-energy conditions and high food supply for prolonged times allowed for the obliteration of shallow-tier trace fossils by deeper and widely distributed burrows, favoring the onshore expansion of the distal Cruziana Ichnofacies and preventing the preservation of the typical elements of the archetypal Cruziana Ichnofacies. Areas subjected to greater storm influence provided favorable conditions for the development of the Skolithos Ichnofacies.

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