Continuous Core Research Articles

Predicting trends in atmospheric CO2 across the Mid-Pleistocene Transition using existing climate archives

Abstract. During the Mid-Pleistocene Transition (MPT), ca. 1200–800 000 years ago (ka), the Earth's glacial cycles changed from 41 to 100 kyr periodicity. The emergence of this longer ice age periodicity was accompanied by higher global ice volume in glacial periods and lower global ice volume in interglacial periods. Since there is no known change in external orbital forcing across the MPT, it is generally agreed that the cause of this transition is internal to the Earth system. Resolving the climate, carbon cycle, and cryosphere processes responsible for the MPT remains a major challenge in Earth and palaeoclimate science. To address this challenge, the international ice core community has prioritised recovery of an ice core record spanning the MPT interval. Here we present results from a simple generalised least-squares (GLS) model that predicts atmospheric CO2 out to 1.8 Myr. Our prediction utilises existing records of atmospheric carbon dioxide (CO2) from Antarctic ice cores spanning the past 800 kyr along with the existing LR04 benthic δ18Ocalcite stack (Lisiecki and Raymo, 2005; hereafter “benthic δ18O stack”) from marine sediment cores. Our predictions assume that the relationship between CO2 and benthic δ18O over the past 800 000 years can be extended over the last 1.5 million years. The implicit null hypothesis is that there has been no fundamental change in feedbacks between atmospheric CO2 and the climate parameters represented by benthic δ18O, global ice volume, and ocean temperature. We test the GLS-model-predicted CO2 concentrations against observed blue ice CO2 concentrations, δ11B-based CO2 reconstructions from marine sediment cores, and δ13C of leaf-wax-based CO2 reconstructions (Higgins et al., 2015; Yan et al., 2019; Yamamoto et al., 2022). We show that there is no clear evidence from the existing blue ice or proxy CO2 data to reject our predictions or our associated null hypothesis. A definitive test and/or rejection of the null hypothesis may be provided following recovery and analysis of continuous oldest ice core records from Antarctica, which are still several years away. The record presented here should provide a useful comparison for the oldest ice core records and an opportunity for further constraints on the processes involved in the MPT.

A Comparison of Passive Rewarming Systems Following Cold Water Immersion.

We studied field rewarming using a typical winter sleeping bag versus two heated hypothermia wrap systems in a semi-realistic lab simulation. 10 participants (8 M, 2 F) were cooled to 36.1°C core temperature through 10.5-11.5°C water immersion, then performed 60 min of passive rewarming in 0°C air. The rewarming methods tested were: 1) a -9°C rated mummy-style Sleeping Bag; 2) Doctor Down Rescue Wrap; and 3) Thermal Yielding Vascular Airway Capsule (TYVAC) system; the latter two methods included vapor barriers and two heating pads. Rectal and skin temperatures, along with metabolic heat production calculated via indirect calorimetry, were measured throughout rewarming. One male participant was removed from analysis due to lack of sufficient cooling. Rectal temperature decreased in the remaining participants by ∼1.1-1.2°C to 36.1°C during the initial immersion phase. Over the 60 min of rewarming, rectal temperature changes were Δ0.0 ± 0.6°C in a sleeping bag, Δ+0.2 ± 0.3°C in Doctor Down, and Δ+0.2 ± 0.3°C in TYVAC, with no significant differences across methods. Mean skin temperatures, metabolic heat production, and perceptual measures were also similar across methods with no method×time interactions. After 60 min of passive rewarming in cold conditions, all three rewarming methods were able to stall continued core cooling to levels at or slightly above post-immersion temperatures. With no differences in any physiological measures, it appears that all three rewarming methods are equally viable options for wilderness responders, and the choice should come down to environmetal conditions, availability, convenience, and ergonomics rather than rewarming efficacy.

Core body temperature estimation model with thermal contact resistance compensation

Continuous and accurate monitoring of core body temperature (CBT) is crucial for personal healthcare, clinical disease diagnosis, and enhancing athletic performance. Current CBT measurement methods typically ignore contact interface variation at the sensor-body interface, resulting in insufficient CBT measurement accuracy under daily wearable scenarios with varying sensor contact pressure. This study proposed a core temperature estimation model with thermal contact resistance (TCR) compensation, introducing the TCR factor into the computational equation to improve estimation accuracy in daily wearable scenarios. A numerical simulation of the temperature field between the human forehead and sensor was developed for model performance evaluation. Given the inconvenience of TCR measurement, this study proposed a method based on pressure/optical photoplethysmography (PPG) signals for updating thermal contact resistance. The mean absolute error of CBTER model under varying thermal contact resistance conditions was 0.26 °C, which was 27 % compared to traditional model errors in simulation. Using pressure updating methods, the result of human trials was 0.01±0.23 °C (with 95 % limits of agreement). Overall, the proposed method effectively compensated for errors in core body temperature estimation due to thermal contact resistance, holding potential for continuous core body temperature monitoring to meet healthcare needs scenarios.

Lotsberg Formation: lithological and geochemical constraints for a prime H2 cavern target in Alberta, Canada

Abstract Homogenous and thick (approximately 40–170 m) halite intervals in the upper part of the Lotsberg Formation are most favored targets for hydrogen (H2) storage caverns in Alberta. However, repurposing cavern-making technologies for H2 storage must consider higher diffusivity and higher reactivity of H2, including its known dissolving effect on sulfate minerals and intense production of H2S through bacterial sulfate reduction. New core observations, geochemical and XRD data made on a continuous core through the upper informal member of the Lotsberg Formation and overlying red beds elucidate high content of anhydrite nodules and partings in these red beds, whereas the thick (42.9 m in our test well), exceptionally clean and homogeneous upper halite in this succession contains anhydrite only in trace amounts. A dolomarl-rich interval at 1894.0–1899.45 m, traced regionally as the L2 marker, represents a solution-collapse breccia, thus indicating an intraformational unconformity and an episode of meteoric salt removal prior to deposition of the upper-most halite of the Lotsberg Formation. If the cavern roof is made close to the overlying anhydritic dolostone of the Ernestina Lake Formation, reactivity of H2 may cause rapid dissolution of anhydrites leading to roof collapse, as well as accumulation of H2S through bacterial sulfate reduction. We infer that preserving a thick salt roof during cavern making may be a solution to prevent these damaging effects. Reactivity of H2 with carbonates in the caprock should also be considered. Anhydrite nodules also occur in the basal one-third of the upper Lotsberg, the interval containing more non-halite impurities than the upper salt unit of this member. In this part of the section, anhydrites do not seem to represent the same concern as they will be exposed to cavern-floor sump and cushion gas, whereas H2 reservoir can be operated within the limits of the clean and homogeneous upper halite of the upper Lotsberg Formation. Emplacement of horizontally elongated two-well caverns may represent an adequate way to overcome cavern size limitations, especially in overlying, thinner-bedded halites of the Prairie Evaporite Formation. Résumé Des intervalles homogènes et épais (d’environ 40 m à 170 m) d’halite dans la partie supérieure de la Formation de Lotsberg sont parmi les plus ciblés pour stocker l’hydrogène (H2) dans des cavités en Alberta. Cependant, adapter les technologies pour créer des cavernes de stockage de H2 doit considérer la diffusivité et la réactivité plus élevées de l’H2, y compris son effet dissolvant connu sur les minéraux sulfatés et son intense production de H2S par la sulfatoréduction bactérienne. De nouvelles observations sur les carottes avec données géochimiques et diffractions de rayon X faites sur une carotte continue à travers le membre supérieur officieux de la Formation de Lotsberg et des lits rouges sus-jacents élucident le contenu élevé de nodules et d’inclusions stériles dans ces lits rouges, tandis que le plan d’halite (de 42,9 m d’épaisseur de notre puits d’essai) de la partie supérieure de cette succession se révèle exceptionnellement propre et homogène et ne contient que des traces d’anhydrite. Un intervalle riche en marne dolomitique dans la partie comprise de 1894,0 m à 1899,45 m est l’horizon marqueur L2 au niveau régional. Celui-ci représente une brèche d’effondrement par dissolution, ce qui indique par conséquent une discordance intraformationnelle et un épisode d’élimination saline par météorisation avant le dépôt d’halite le plus élevé de la Formation de Lotsberg. Si le toit de la cavité est créé près de la dolomie anhydritique sus-jacente de la Formation d’Ernestina Lake, la réactivité de l’H2 pourrait causer une dissolution rapide des anhydrites et entraîner l’effondrement du toit, ainsi qu’à l’accumulation de H2S par la sulfatoréduction bactérienne. Nous supposons que la préservation d’un épais toit salin durant la création de cavités serait la solution pour prévenir ces effets dommageables. Nous devrions également considérer la réactivité de l’H2 avec les carbonates de la roche couverture. De plus, les nodules d’anhydrite se présentent également dans la tierce partie basale de la Formation de Lotsberg, l’intervalle contenant plus d’impuretés non liées à l’halite que l’halite de la partie supérieure de Lotsberg. Dans la partie de cette section, l’anhydrite ne semble pas représenter les mêmes préoccupations puisqu’elle sera exposée au puisard du fond de la cavité et au gaz-coussin, tandis que le réservoir H2 peut être exploité dans les limites de l’halite supérieure propre et homogène de la Formation de Lotsberg supérieure. L’emplacement de cavités à deux puits horizontaux allongés peut représenter un moyen adéquat pour résoudre les limites quant à la grandeur des cavités, en particulier lorsqu’il s’agit de minces lits d’halites sus-jacents de la Formation d’halite des Prairies. Michel Ory ACRONYMY AB Alberta AIHA Alberta’s Industrial Heartland Association CRM Critical Raw Minerals EPG Elk Point Group LNG Liquefied Natural Gas LPG Liquefied Petroleum Gas R&D Research and Development SK Saskatchewan UHS Underground Hydrogen Storage XRD X-ray diffraction WCSB Western Canada Sedimentary Basin

A New Correlation for Estimating Static Elastic Properties of Sandstone Formations: Case Study from Rumaila Oilfield

Evaluating the elastic characteristics of reservoir's rocks is crucial for the oil and gas sector to reduce risks throughout drilling and production operations. Elastic parameters are essential for prediction of wellbore stability, estimation of in-situ stresses, optimization of drilling performance and design of hydraulic fracturing. Depending on the type of formation, Elastic parameter is varied dramatically. Thus, a precise way to identify these characteristics is needed. Inaccurate assessment of elastic characteristics can result in excessive expenditure and inappropriate field development plans. Static elastic modulus (Est) can be determined through laboratory testing. Although laboratory measurement is the most precise approach to determine the elastic modulus, it requires a continuous core sample to acquire a complete profile of the formation's elastic characteristics. However, just a portion of the well is typically sampled for cores. On the other hand, wireline log data is applied to determine the dynamic modulus (Edyn), allowing for continuous assessment of elastic properties. Numerous characteristics of the rock, including consolidation, pore pressure and lithology affect the dynamic modulus. Thus, it needs to be converted to Static elastic modulus by empirical formulae. Several empirical equations have been proposed to convert dynamic Young's modulus to static Elastic modulus. Nevertheless, the validity of these relationships is restricted and exclusive to certain areas. This research seeks to establish a relationship between Dynamic modulus and static Elastic modulus for sandstone formation of Rumaila oil field. The suggested correlation provides accurate predictions of the static elastic modulus for the complete sandstone segment. The newly created correlation performed better than the previous correlations in predicting static elastic modulus with average absolute error of 8.69 %, and correlation coefficient of 0.9848. The newly established empirical correlation can assist geo-mechanical engineers in estimating continuous profile of the sandstone formation's static modulus.

Play fairway analysis of geothermal resources across the state of Hawai‘i: 5. Slim hole drilling on Lāna‘i island

This paper builds on four earlier papers detailing the results of the Hawai‘i Play Fairway (PF) project's first two phases. In Phase 3 the project deepened a water well on the rim of the caldera of Lāna‘i Volcano to a maximum depth of just over 1 km. Due to funding constraints, the project deepened an already existing water well that was proximal to our area of highest resource probability within the caldera. Drilling preparation included: completion of an Environmental Assessment, lowering a camera down the well, deviation logging, coordinating site preparation, procure and shipping, and participating in multiple community meetings. Drilling occurred 24/7 the entire month of June 2019. The project deepened Lāna‘i Well 10 from 427 m to 1057 m, while collecting continuous core, and measured a roughly linear temperature gradient averaging 42 °C/km and a maximum bottom hole temperature of 66 °C. This gradient is more than twice the background for Hawai‘i and within a range of gradients measured in this depth range for some exploration wells within the volcanically active East Rift Zone of Kīlauea Volcano. Geothermal gradient determinations and computed chemical geothermometer temperatures indicate that accessible temperatures within Lāna‘i Well 10 are 130–200 °C between 2 and 3 km depth. This paper includes a summary of detailed core logging, which found pervasive hydrothermal alteration. We recommend drilling a slim hole within Lāna‘i's caldera to ∼2 km, where considerably higher temperatures may be encountered. The positive implications this project's results have for the island of O‘ahu are substantial. The shield stage of O‘ahu's volcanoes ended 1–2 Million years earlier, however O'ahu uses more electricity than the rest of the islands combined.

Compression and energy absorption of wood-based reinforced 3D Kagome lattice structures

3D Kagome lattice sandwich structure is recognized as the most excellent lattice configuration. However, the preparation method of 3D Kagome is complicated and the raw materials for its preparation are limited to materials with high plasticity. In this study, we developed a wood-based 3D Kagome lattice structure that combines discrete rods into a continuous core using reinforcement. Orthogonal tests, theoretical analysis, and finite element simulations were performed to investigate the correlation between the dimensional parameters, the mechanical properties, and the energy absorption capacity. The damage modes were found to be mainly bending fracture, core shear, and panel rupture, with the use of reinforcement affecting the damage modes. Compressive properties of the 3D Kagome lattice structure are increased by increasing core diameter and inclination degree, decreasing core in-cut diameter, and using high-strength reinforcements. Finite element simulations further confirm that the use of high-strength reinforcements changes the stress distribution of the lattice structure. The 3D Kagome lattice structure with an inclination degree of 65°, a core diameter of 10 mm, a reinforcement wall thickness of 2 mm, and a core in-cut diameter of 2 mm has the optimal compression performance and energy absorption capacity.

Continuity and Evolution in Vermeule on Legal Interpretation

Abstract This article is a constructive interpretation of Adrian Vermeule’s thought on legal interpretation, putting his previous work on these issues in conversation with his explicit embrace of the classical legal tradition so prominently on display in Common Good Constitutionalism. What emerges is a picture of Vermeule’s contemporary thinking on interpretation that has an interesting core of continuity, one running concurrently with several significant conceptual and normative evolutions brought about by his more explicit embrace of a classical legal framework. Part I offers a synthesis of Vermeule’s treatment of core questions of legal interpretation pre-Common Good Constitutionalism. Part II begins by outlining Vermeule’s express turn to the classical legal tradition and how this tradition approaches important public law issues linked to interpretation. Part II then proceeds to pick out and elaborate on themes of continuity and evolution. I argue here that while Vermeule’s embrace of the classical legal tradition has involved several significant conceptual and normative shifts in his thinking, this has not involved repudiation of his prior work on legal interpretation. Rather, the thrust and insights of much of his previous public law thought on interpretation retain vibrancy within the explicitly classical framework he has now adopted. Overall, I suggest Common Good Constitutionalism, and the works accompanying and building upon it, can be profitably read as providing a form of retroactive coherence to Vermeule’s long-standing arguments concerning legal interpretation, offering them a unifying conceptual framework. From the perspective of a classical natural law jurist at least, Vermeule’s embrace of the classical tradition provides his extensive body of scholarship in this area a more explicit and robust conceptual and normative anchor.

Enhanced mechanical properties of sandwich panels via integrated 3D printing of continuous fiber face sheet and TPMS core

Sandwich panel structures have widespread applications in various components, owing to their excellent lightweight properties. However, conventional manufacturing methods involve multiple steps, which limits the exploration of innovative sandwich panel structure. In this study, an integrated 3D printing method for continuous fibers reinforced sandwich panel with Triply Periodic Minimal Surface (TPMS) core structure is proposed via Fused Deposition Modelling (FDM). A bridging layer and a continuous basalt fiber pre-impregnated by stiff thermoset epoxy resin are utilized to address the issue of overhanging printing for the upper face sheet. Two kinds of TPMS are employed as the core, as well as two kinds of honeycomb. Multi-step printed samples using a bonding process and counterpart samples without fiber were prepared for the comparison. 3-point bending tests were conducted and a finite element model which can represent the structure characteristic is proposed to investigate the mechanical properties. The results show that the integrated printed sample exhibits better performance in terms of printing quality, flexural modulus, strength and energy absorption (EA) compared with the multi-step printed sample. It has an excellent ability to avoid the catastrophic damage which is usually encountered in the multi-step printed sample due to the introduction of brittle epoxy resin, showing a notable 162.88 % augmentation in specific energy absorption (SEA). The significant improvement lies in that it uses the reinforcement of fiber and the energy absorption capacity of core to full advantage via the strong binding. In addition, as one kind of TPMS, Schwarz Primary structure exhibits the maximum flexural modulus, strength and energy absorption among the four cores. The proposed design and fabrication methodology pave the way for the creation of high-performance sandwich panels with different core structures.

Interaction between basement detachment fault, rift onset unconformity, and overlying basin fills: An example from the Songliao basin of a Cretaceous active continental margin volcanic rift in northeast Asia

How does a giant rift basin begin? No precise examples describe this issue. Based on 7108 m of continuous coring data recovered from the whole stratigraphy of the Songliao Basin (SLB), an attempt has been made to answer this question. Through comprehensive geological, geochemical and seismic research it has been found that there is a triangular extensional domain (TED) beneath the sedimentary cover in the basement at the rift center, from where the initial rupture of the giant rift was created. The basement detachment fault (DF), rift onset unconformity (ROU), and overlying basin fills are interrelated elements of a sedimentary basin and are the key to interpreting the geological archives recorded in the basin. The interaction processes between them determine the location of the basin center and the style of basement subsidence, which reflect the tectonic properties of the basin. This interaction may have a coevolutionary relationship with the deep magmatic activities beneath the basin. The basement of a basin typically consists of a series of strata that the lower strata age older. The uppermost basement sequence of the Triassic in the SLB is particularly important for the overlying basin formation and evolution. The surface topography controlled the thickness of the overlying Cretaceous cover. An ROU and DF developed at the top and bottom of the Triassic, respectively.The long-term uplift, denudation, and subsequent volcanic deposition may be common features of an ROU in a volcanic rift basin. More so, DF is the controlling factor for basin subsidence in the syn-rift stage of basin evolution. The frequent intrusive association with graben faults suggests that sublithospheric mantle flow may affect the accommodation space of the overlying basin by cutting the basement blocks via feeder dykes and shaping the graben pattern on top of the basement.

Manufacturing of Continuous Core–Shell Hydrated Salt Fibers for Room Temperature Thermal Energy Storage

The encapsulation ofsalt hydrate phase change materials (PCMs) in uniform microscale bodies has yetbeen reported in research due in part to the delicate relationship betweenthermal performance and water‐to‐salt ratios which are easily altered duringmanufacturing. Herein, core–shell composite fibers comprised of a salt hydratePCM core and a poly(acrylonitrile) (PAN) shell are wet spun in a continuousprocess using a syringe pump and coaxial die. The PCM phase comprises calciumchloride hexahydrate (CaCl2·6H2O) with strontium chloride hexahydrate(SrCl2·6H2O) (3 wt%) and fumed silica(SiO2) (2 wt%) as additive, acomposition that is prepared from homogenous melt at 40 °C. 15 wt% PAN indimethylsulfoxide solvent is used to prepare the shell‐forming polymer gel. PCM and polymer gel injectionrates of 10–40 mL h−1 are used tospin coaxial fibers through a coagulation bath, yielding continuousmicrotubules with diameters in the range of 850–1500 μm. Cyclic testing showsthat after 1000 cycles, melting enthalpies incurred only a 3.5% decline from 131.46 to 126.9 J g−1. Success hereovercomes several coincidental drawbacks of PCM fiber performance andmanufacturing and delivers the first example of scalable roll‐to‐roll PCM fiber produced by wet spinning forbuilding material applications.

Comparison of Wireless Continuous Axillary and Core Temperature Measurement after Major Surgery.

Temperature is considered one of the primary vital signs for detection of complications such as infections. Continuous wireless real-time axillary temperature monitoring is technologically feasible at the general ward, but no clinical validation studies exist. This study compared axillary temperature with a urinary bladder thermometer in 40 major abdominal postoperative patients. The primary outcome was changes in axillary temperature registrations. Secondary outcomes were mean bias between the urinary bladder and the axillary temperatures. Intermittent frontal and tympanic temperature recordings were also collected. Forty patients were monitored for 50 min with an average core temperature of 36.8 °C. The mean bias was -1.0 °C (LoA -1.9 to -0) after 5 min, and -0.8 °C (LoA -1.6 to -0.1) after 10 min when comparing the axillary temperature with the urinary bladder temperature. After 20 min, the mean bias was -0.6 °C (LoA -1.3-0.1). During upper arm abduction, the axilla temperature was reduced to -1.6 °C (LoA -2.9 to -0.3) within 1 min. Temporal skin temperature measurement had a resulted in a mean bias of -0.1 °C (LOA -1.1 to -1.0) compared with central temperature. Compared with the mean tympanic temperature, it was -0.1 °C (LoA -0.9 to -1.0) lower than the urinay bladder temperature. Axillary temperature increased with time, reaching a mean bias of 1 °C between axillary and core temperature within 5 min. Opening the axillary resulted in rapidly lower temperature recordings. These findings may aid in use and designing corrections for continuous axillary temperature monitoring.

Evaluating marine dust records as templates for optical dating of Oldest Ice

Abstract. The continuous ice core record extends 800 000 years into the past, covering the period of 100 000-year glacial cycles but not the transition from 40 000-year glacial cycles (the mid-Pleistocene transition, 1.2–0.7 million years ago). A primary goal of the International Partnerships in Ice Core Sciences is therefore to retrieve a 1.5-million-year-old continuous ice core, increasing our understanding of this major change in the climate system and thus of fundamental climate forcings and feedbacks. However, complex glacial processes, limited bedrock data, and young basal ice in previous cores necessitate careful reconnaissance studies before extracting a full core. Ice borehole optical logging reflects the ice dust content and may be used to date ice quickly and inexpensively if a reference record is known. Here we explore the relationship between ice dust records and well-dated marine dust records from sediment cores in the southern Atlantic and Pacific oceans, which lie along paths of dust sources to Antarctica. We evaluate how representative these records are of Antarctic dust both through the existing ice core record and during the older target age range, suggesting that a newly published 1.5-million-year record from Site U1537 near South America is likely the most robust predictor of the Oldest Ice dust signal. We then assess procedures for rapid dating of potential Oldest Ice sites, noting that the ability to detect dating errors is an essential feature. We emphasize that ongoing efforts to identify, recover, date, and interpret an Oldest Ice core should use care to avoid unfounded assumptions about the 40 kyr world based on the 100 kyr world.

Depositional processes in a shale-dominated Devonian succession: Sedimentary facies and trace fossil integrated analysis

Fine-grained rocks have historically been interpreted as a product of the settling of fine fractions in low-energy environments. However, recent studies have suggested that in these environments, more dynamic and complex processes operate. These processes involve a much more diverse set of sedimentary processes than those previously assumed. The lithological homogeneity of clayey successions, associated with the obliteration of their primary characteristics by diagenetic and/or weathering processes, makes it difficult to interpret depositional processes and understand the paleoenvironment. To contribute to a better comprehension of the mechanisms of transport and deposition of fine-grained rocks in a siliciclastic mud-dominated succession, as well as their depositional site, the present study aims at the detailed analysis of a continuous drill core. This core contains a thick Devonian succession consisting essentially of shale from the Ponta Grossa Formation (Paraná Basin, Brazil). Throughout the analyzed succession, a wide variety of sedimentary structures have been identified, such as parallel laminations, wave-ripple cross-stratification, hummocky cross-stratification, normal grading, and gutter casts. These structures show the constant performance of high-energy flows, which are configured as important deposition and/or rework agents. The integrated analysis of facies and trace fossils has proven to be more efficient for paleoenvironmental characterization than isolated approaches. This is because facies and ichnofacies (e.g., Cruziana, with its proximal, impoverished, archetypal, and distal expressions; Skolithos and Glossifungites) can be easily correlated, facilitating the identification of facies associations. This approach not only allows for the interpretation of a shallow marine platform with a gentle slope (ramp shelf) paleoenvironment of moderate to high energy, subject to storm wave action, but also enables the identification of the particular characteristics of deposits from different sub-environments (proximal to distal offshore, offshore transition, shoreface to offshore transition, and prodelta) and their deposition mechanisms. Furthermore, the facies associations are useful for highlighting the variations formed in response to oscillations of the relative sea level and changes in sedimentary input.

Validity and reproducibility of the CALERA Research Sensor to estimate core temperature at different intensities of a cycling exercise in the heat

Recent heatwaves have highlighted the importance of accurate and continuous core temperature (TCORE) monitoring in sports settings. For example, accentuated rises in TCORE caused by physical exercises under environmental heat stress increase the risk of heat illnesses. Thus, using valid and reproducible devices is essential to ensure safe sports practice. In this study, we assessed the validity and reproducibility of the Calera Research Sensor (CRS) in estimating the TCORE of male and female participants during cycling exercise in a hot environment. Seven male (age: 36.2 ± 10.1 years) and eight female cyclists (age: 30.1 ± 5.0 years) underwent two identical cycling trials in a dry-bulb temperature of 32 °C and relative humidity of 60%. The protocol consisted of an initial 10-min rest followed by a 60-min exercise comprising 10 min at 20%, 25 min at 55%, and 25 min at 75% of maximal aerobic power, and an additional 25 min of post-exercise recovery. TCORE was recorded simultaneously every minute using a gastrointestinal capsule (TGi) and the CRS (TSENSOR). Bland–Altman analysis was performed to calculate bias, upper (LCS) and lower (LCI) concordance limits, and the 95% confidence interval (95%CI). The maximum acceptable difference between the two devices was predetermined at ±0.4 °C. A mixed linear model was used to assess the paired differences between the two measurement systems, considering the participants, trials, and environmental conditions as random effects and the cycling stages as fixed effects. An intra-class correlation coefficient (ICC) of 0.98 was recorded when analyzing data from the entire experiment. A non-significant bias value of 0.01 °C, LCS of 0.38 °C, LCI of −0.35 °C, and CI95% of ±0.36 °C were found. When analyzing data according to the participants’ sex, CRS reproducibility was high in both sexes: ICC values of 0.98 and 0.99 were reported for males and females, respectively. CI95% was 0.35 °C in experiments with males and 0.37 °C with females, thereby falling within the acceptable margin of difference. Therefore, CRS was considered valid (compared to TGi) and reproducible in estimating TCORE in both sexes at various intensities of cycling exercise in the heat.

BASE (Barberton Archean Surface Environments) – drilling Paleoarchean coastal strata of the Barberton Greenstone Belt

Abstract. The BASE (Barberton Archean Surface Environments) scientific drilling project aimed at recovering an unweathered continuous core from the Paleoarchean Moodies Group (ca. 3.2 Ga), central Barberton Greenstone Belt (BGB), South Africa. These strata comprise some of the oldest well-preserved sedimentary strata on Earth, deposited within only a few million years in alluvial, fluvial, coastal-deltaic, tidal, and prodeltaic settings. They represent a very-high-resolution record of Paleoarchean surface conditions and processes. Moodies Group strata consist of polymict conglomerates, widespread quartzose, lithic and arkosic sandstones, siltstones, shales, and rare banded-iron formations (BIFs) and jaspilites, interbedded with tuffs and several thin lavas. This report describes objectives, drilling, and data sets; it supplements the operational report. Eight inclined boreholes between 280 and 495 m length, drilled from November 2021 through July 2022, obtained a total of 2903 m of curated core of variable quality through steeply to subvertically dipping, in part overturned stratigraphic sections. All drilling objectives were reached. Boreholes encountered a variety of conglomerates, diverse and abundant, mostly tuffaceous sandstones, rhythmically laminated shale-siltstone and banded-iron formations, and several horizons of early-diagenetic silicified sulfate concretions. Oxidative weathering reached far deeper than expected. Fracturing was more intense, and BIFs and jaspilites were thicker than anticipated. Two ca. 1 km long mine adits and a water tunnel, traversing four thick stratigraphic sections within the upper Moodies Group in the central BGB, were also sampled. All boreholes were logged by downhole wireline geophysical instruments. The core was processed (oriented, slabbed, photographed, described, and archived) in a large, publicly accessible hall in downtown Barberton. A geological exhibition provided background explanations for visitors and related the drilling objectives to the recently established Barberton Makhonjwa Mountains World Heritage Site. A substantial education, outreach, and publicity program addressed the information needs of the local population and of local and regional stakeholders.

Evidence for low sulfate and anoxic deep waters in early Cambrian

The role of environmental change as a significant force driving biological evolution during the Ediacaran–Cambrian transition remains a subject of extensive debate. In this study, we present high-resolution C-isotope data of organic matter (δ13Corg) and multiple S-isotope compositions of pyrite (δ34Spy and Δ33Spy) obtained from a continuous drill core (ZK1505) in South China, spanning the interval from the Ediacaran to Cambrian Stage 2. Our δ13Corg and δ34Spy data, combined with published data from four sections deposited across a shelf-to-basin transect, reveal substantial gradient from shallow to deep water in δ13Corg and sustained positive δ34Spy values in the early Cambrian. The vertical δ13Corg gradient suggests chemical stratification of the early Cambrian ocean, characterized by oxic shallow water and anoxic deep water. The sustained positive δ34Spy values in the same period suggest low seawater sulfate concentrations. Furthermore, we observed intermittent occurrences of negative Δ33Spy values coupled with positive δ34Spy, suggesting a dominant deep-water anoxia during early Cambrian in the Yangtze Block. We propose that protracted deep-water anoxia may have contributed to the extinction of the Ediacaran biota and played a significant role in the evolution of Cambrian animals.

Correlation and response of astronomical forcing in lacustrine deposits of the middle jurassic, sichuan basin, southwest China

The astronomical cycle characteristics of Mesozoic lacustrine fine-grained sedimentary rocks play a crucial role in understanding the formation environment of such sediments. The fine-grained sedimentary rocks of the Middle Jurassic Lianggaoshan Formation in the Sichuan Basin, China, constitute a significant lacustrine deposit. Previous research has primarily focused on its reservoir characteristics, with limited understanding of the relationship between lithofacies changes and astronomical cycles. To fill this knowledge void, we provide a continuous lacustrine core record of approximately 260 m from the XY-4 well, spanning the Lianggaoshan Formation in the Eastern Sichuan Basin. Initially, we categorized it into eight lithofacies types and established a lithologic ranking sequence based on this classification. Through time-series analysis, we identified the 405 Kyr long eccentricity cyc lecycle, 125 Kyr short eccentricity cycle, obliquity, and precession cycle. We emphasize the significance of the 125 Kyr short eccentricity cycle as the primary controlling factor during the deposition of the Lianggaoshan Formation. Subsequently, based on the 405 Kyr long eccentricity cycle, we established an age model for astronomical tuning, creating an astronomical age scale. The calculated sedimentation interval for the Lianggaoshan Formation ranges from 170.00 Ma to 172.74 Ma, spanning a total duration of 2.74 Ma. Meanwhile, the sedimentation interval for the Lower Liang 2 Submember is determined to be from 171.54 Ma to 172.52 Ma, lasting 0.98 Ma. Further comparison of TOC content and mineral composition with the orbital cycles reveals that TOC content and clay mineral content exhibit in-phase variations with the 125 Kyr short eccentricity. This characteristic contradicts the features of Cenozoic continental basins but aligns consistently with the characteristics of the Middle Triassic in North China. In contrast, silica minerals and carbonate minerals display anti-phase variations with the 125 Kyr short eccentricity. Different lithofacies demonstrate distinct responses to orbital cycles. Lithofacies characterized by higher organic matter content generally develop during the half-period with the maximum eccentricity. In contrast, lithofacies with lower organic matter content tend to occur during the half-cycle associated with the minimum eccentricity. Finally, based on the integrated analysis of lithological characteristics and astronomical cycles, we established two sedimentary modes: “Seasonally Pronounced Type” corresponding to the maximum eccentricity and “Seasonally Obscure Type” corresponding to the minimum eccentricity.

Sedimentary Paleoenvironment and Organic Matter Enrichment Characteristics of Lacustrine Shahezi Shale in Songliao Basin: Insights from the Continental Scientific Drilling.

The lacustrine shale of the Shahezi Formation in the Songliao Basin has obvious organic matter enrichment characteristics and great potential for oil and gas resources. At present, the understanding of the sedimentary paleoenvironment and organic matter enrichment characteristics of the lacustrine shale of the Shahezi Formation is relatively weak. Therefore, taking the international continental scientific drilling Program (ICDP) borehole Songke-2 (SK-2) with continuous and whole Shahezi cores as the research object, combined with organic geochemistry, elemental geochemistry, and logging data, the sedimentary paleoenvironment and organic matter enrichment mechanism were studied. The results show that the organic matter of Shahezi shale is generally in the high to over mature stage. The kerogen type of organic matter is mainly II2-III. The organic matter is mainly derived from the lake basin's own algae and terrestrial higher plants. The total organic carbon (TOC) content of Shahezi shale is relatively high, and the TOC is mainly distributed between 1% and 2%. The Shahezi Formation is dominated by clay shale and siliceous shale, and experienced moderate chemical weathering during deposition. According to the analysis of organic geochemistry and elemental geochemistry data, the paleoenvironment of organic matter deposition in Shahezi shale was dominated by warm and humid climate in the early stage, and then experienced multiple cooling and arid periods. The climate type turned to semihumid-semiarid, with stable terrigenous debris input, low deposition rate, brackish water salinity and oxygen-rich-oxygen-poor water environment. The sedimentary period of Shahezi Formation is in the Cretaceous oceanic anoxic Aptian-Albian stage. During the oceanic anoxic event, the anoxic sedimentary environment and the frequent volcanic activity have an important impact on the organic matter enrichment. The oceanic anoxic event and volcanic activity are the main causes of water body hypoxia in the lake basin. The nutrients brought by volcanic activity are also one of the reasons for promoting the growth of lake basin organisms, creating good conditions for organic matter enrichment. The enrichment of organic matter in Shahezi Formation is the result of the interaction and coupling of various factors such as paleoclimate, paleoenvironment, paleoproductivity, water environment, terrestrial input, and major geological events. And, the organic matter enrichment model of Shahezi Formation shale is established.

Bayesian inference of electron density and ion temperature profiles from neutral beam and halo Balmer-α emission at Wendelstein 7-X

By employing Bayesian inference techniques, the full electron density profile from the plasma core to the edge of Wendelstein 7-X (W7-X) is inferred solely from neutral hydrogen beam and halo Balmer-α (Hα) emission data. The halo is a cloud of neutrals forming in the vicinity of the injected neutral beam due to multiple charge exchange reactions. W7-X is equipped with several neutral hydrogen beam heating sources and an Hα spectroscopy system that views these sources from different angles and penetration depths in the plasma. As the beam and halo emission form complex spectra for each spatial point that are non-linearly dependent on the plasma density profile and other parameters, a complete model from the neutral beam injection and halo formation through to the spectroscopic measurements is required. The model is used here to infer electron density profiles for a range of common W7-X plasma scenarios. The inferred profiles show good agreement with profiles determined by the Thomson scattering and interferometry diagnostics across a broad range of absolute densities without any changes to the input or fitting parameters. The time evolution of the density profile in a discharge with continuous core density peaking is successfully reconstructed, demonstrating sufficient spatial resolution to infer strongly shaped profiles. Furthermore, it is shown as a proof of concept that the model is also able to infer the main ion temperature profile using the same data set.