bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sedimentology and integrated chronostratigraphy of the lower Heatherdale Shale (Cambrian, stages 2–3), Stansbury Basin, South Australia
Authors: Chen Feiyang , Brock Glenn A. , Betts Marissa J. , Zhang Zhiliang , Yun Hao , Klaebe Robert Matthew , Laing Brittany , Zhang Zhifei 
Published: December 2020

AbstractMajor progress has recently been made regarding the biostratigraphy, lithostratigraphy and isotope chemostratigraphy of the lower Cambrian successions in South Australia, in particular of the Arrowie Basin, which has facilitated robust global stratigraphic correlations. However, lack of faunal and sedimentological data from the lower Cambrian Normanville Group in the eastern Stansbury Basin, South Australia – particularly the transition from the Fork Tree Limestone to the Heatherdale Shale – has prevented resolution of the age range, lithofacies, depositional environments and regional correlation of this succession. Here we present detailed sedimentologic, biostratigraphic and chemostratigraphic data through this transition in the eastern Stansbury Basin. Three lithofacies are identified that indicate a deepening depositional environment ranging from inner-mid-shelf (Lithofacies A and B) to outer shelf (Lithofacies C). New δ13C chemostratigraphic data capture global positive excursion III within the lower Heatherdale Shale. Recovered bradoriid Sinskolutella cuspidata supports an upper Stage 2 (Micrina etheridgei Zone). The combined geochemistry and palaeontology data reveal that the lower Heatherdale Shale is older than previously appreciated. This integrated study improves regional chronostratigraphic resolution and interbasinal correlation, and better constrains the depositional setting of this important lower Cambrian package from the eastern Stansbury Basin, South Australia.
Newsround
Authors: Parikh Tulsi 
Published: December 2020

Abstract‘Newsround’ offers a platform for new discoveries that do not appear within the specialist contributions of this year’s Archaeological Reports, but which nevertheless warrant emphasis, either as a result of their particular characteristics or for the contribution they make to broader archaeological narratives. This section is not intended to be exhaustive but rather an overview of archaeological research in Greece. It comprises largely preliminary reports (results of excavations that took place up to and including August 2020 where possible) that complement the digital content made available through Archaeology in Greece Online (https://chronique.efa.gr). Due to the diachronic nature of a number of the sites and for ease of reference, the material is organized geographically in the first instance and then chronologically (earliest to latest) within each section as far as possible.
The nadir of vital interests: Hannah Arendt and the Franco-German Armistice 1940
Authors: Whitehall Deborah 
Published: December 2020

AbstractIllusions of common interest and joint purpose falter when states choose to break up, as with the recent changes to the European Union, or according to more dangerous precipitants such as those which shaped the Franco-German Armistice 1940, 80 years ago as a detail of war. The latter bares the sudden end of the Franco-British alliance and holds an invitation from history to re-examine the troubling political, social and legal layers of the concept of the vital interests of states. That category opened to radically different interpretations for political and legal thinkers who witnessed the fall of France yet did not respond directly or immediately. Hannah Arendt’s theory of politics, conceived in the aftermath of war as a corrective to the internal fragmentation of the European nation-state, elucidates the instability of the concept of vital interests which underpinned international legal and political thought in the 1930s and 1940s and frustrates the co-operative relations between states. The problem pairs back, she says, to whether interests signify an associative technique or sword. Her invitation for legal thought is to challenge the expectation of rupture implicit in the juridical category by outlining an alternative that recovers the pacifistic function of law and implicates the international lawyer.
Peritectic Melting of Mica in Fault‐Related Pseudotachylite Melts and Potassium Mass Balance as an Indicator of Fluid‐Absent Source Conditions.
Authors: Dobson David P. , Montheil Leny , Paine Joseph J. , Thomson Andrew R. 
Published: December 2020

AbstractPseudotachylites are generally considered to be produced by flash melting of the most fusible minerals, with compositions often dominated by biotite mica. We present phase fraction calculations for 237 pseudotachylite analyses from 28 localities spanning a range of host rock compositions from granites to peridotites. Pseudotachylite matrix compositions cannot be reproduced by a simple linear mixture of the minerals in their host rocks and commonly show a potassium deficit in pseudotachylites which contain significant contributions from biotite or muscovite. This is strongly indicative of peritectic melting of mica under fluid‐absent conditions. Occasionally, a negative contribution from an aluminosilicate phase is required but with a positive contribution from potassium feldspar. This is most consistent with peritectic melting of micas under fluid present conditions. The present data therefore suggest that, while fluid absent flash melting might be the most common mode of formation of pseudotachylite, in some instances pseudotachylites can be produced in the presence of a free fluid. Potassium mass balance of pseudotachylites might therefore be a diagnostic indicator of fluid‐absent conditions in their source regions during seismogenic rupture. We give some examples of observational evidence of peritectic liquidus phases in pseudotachylites and suggest that the significance of these phases might have been overlooked in previous studies.
An Unknown Maximum Lag‐Correlation Between Rainfall and Aerosols at 140–160 Minutes
Authors: Alpert Pinhas , Shafir Haim , Elhacham Emily 
Published: December 2020

AbstractRainfall and aerosols play major roles in the Earth climate system and substantially influence our life. Here, the focus is on the local near‐surface aerosol/rainfall correlations with time scales of minutes to days. We investigated 29 experiments including 14 specific rain events, with time resolutions of daily and 60, 30, and 10 min at 10 stations in Israel and California. The highest negative correlations were consistently at a positive lag of about 140–160 min where a positive lag means that the aerosol time series follows that of the rain. The highest negative value is suggested to be the probable outcome of immediate scavenging along with the rise in aerosol concentration after rain depending on aerosol sources, hygroscopic growth, and transport. The scavenging dominance is expressed by the mostly negative lag‐correlation values in all experiments. In addition, the consistent lack of significant correlation found at negative lags suggests a weak aerosol effect on precipitation.
Sustained Changes in Well Water Levels Following a Large Earthquake: Possible Evidence of Permeability Decreases in a Shallow Groundwater System
Authors: Liao Xin , Wang Guangcai , Shi Zheming 
Published: December 2020

AbstractObservation of earthquake‐induced changes in well water levels provides an opportunity to study the effects of seismic activity on the groundwater system. In this study, we used data from a well network in the alluvial Canterbury Plain of New Zealand’s South Island to document sustained and complex changes in well water levels following the 2010 Darfield earthquake. Sustained increases in well water levels in midstream areas, as well as sustained decreases in downstream areas, resulted from decreases in permeability. These decreases in permeability were possibly caused by consolidation of liquefied sediments following the earthquake.
Soil Organic Carbon Development and Turnover in Natural and Disturbed Salt Marsh Environments
Authors: Luk Sheron Y. , Todd‐Brown Katherine , Eagle Meagan , McNichol Ann P. , Sanderman Jonathan , Gosselin Kelsey , Spivak Amanda C. 
Published: December 2020

AbstractSalt marsh survival with sea‐level rise (SLR) increasingly relies on soil organic carbon (SOC) accumulation and preservation. Using a novel combination of geochemical approaches, we characterized fine SOC (≤1 mm) supporting marsh elevation maintenance. Overlaying thermal reactivity, source (δ13C), and age (F14C) information demonstrates several processes contributing to soil development: marsh grass production, redeposition of eroded material, and microbial reworking. Redeposition of old carbon, likely from creekbanks, represented ∼9%–17% of shallow SOC (≤26 cm). Soils stored marsh grass‐derived compounds with a range of reactivities that were reworked over centuries‐to‐millennia. Decomposition decreases SOC thermal reactivity throughout the soil column while the decades‐long disturbance of ponding accelerated this shift in surface horizons. Empirically derived estimates of SOC turnover based on geochemical composition spanned a wide range (640–9,951 years) and have the potential to inform predictions of marsh ecosystem evolution.
Particle‐In‐Cell Modeling of Martian Magnetic Cusps and Their Role in Enhancing Nightside Ionospheric Ion Escape
Authors: Poppe A. R. , Brain D. A. , Dong Y. , Xu S. , Jarvinen R. 
Published: December 2020

AbstractAmongst various escape channels, ion outflow is a major contributor to atmospheric loss at Mars over geologic time. On Mars' nightside, observations have indicated that cusp regions within crustal magnetic fields are associated with phenomena such as accelerated particle populations, discrete auroral emissions, and ionospheric outflow; however, the kinetic physics occurring within crustal magnetic cusps is poorly understood. Here, we present 1.5‐dimensional particle‐in‐cell simulations of magnetospheric‐ionospheric interactions within martian crustal magnetic cusp regions of varying strength. Simulation results demonstrate the formation of quasi‐static, field‐aligned potentials pointing away from Mars that accelerate electrons into the martian atmosphere while accelerating ions away, thereby enhancing ionospheric escape. Escaping ionospheric flux scales with crustal field strength, with 160 nT crustal fields yielding >2× the ion escape flux than in the case with no crustal fields. We discuss these results and conclude that magnetic cusp regions may be significant sources of ion loss at Mars.
Remote Influence of the Midlatitude South Atlantic Variability in Spring on Antarctic Summer Sea Ice
Authors: Zhang Li , Gan Bolan , Li Xichen , Wang Hong , Wang Chuan‐Yang , Cai Wenju , Wu Lixin 
Published: December 2020

AbstractRelationship between Antarctic sea ice and the Southern Annular Mode and tropical climate variability has been widely studied. Focusing on the midlatitude oceanic frontal zones, this study identifies a fingerprint of South Atlantic (SA) variability in the Antarctic summer sea ice. The interaction between spring SA sea surface temperature (SST) and summer storm‐track activity modulates the hemispheric atmospheric circulation, which in turn alters Antarctic summer sea ice concentration (SIC) through thermal and wind‐driven forcing. Specifically, warm SST anomalies in the western SA frontal zone, corresponding to the strengthened SST front, cause the increased SIC in the eastern Ross Sea via anomalous cold air advection and offshore drift of sea ice. The opposite effect (i.e., warm air advection and onshore ice drift) results in the decreased SIC in the northwestern Weddell Sea. The findings also imply a potential impact of the midlatitude SA variability to the South Pole air temperature variability.
A Machine‐Learning Approach to Classify Cloud‐to‐Ground and Intracloud Lightning
Authors: Zhu Yanan , Bitzer Phillip , Rakov Vladimir , Ding Ziqin 
Published: December 2020

AbstractTo know if a lightning discharge reaches the ground or remains within the thundercloud is critical for lightning safety as cloud‐to‐ground lightning poses the greatest threat to life and property. The current classification methods for most lightning detection networks, which are based on the classification of electromagnetic pulses produced by lightning, still have plenty of room to improve, including some known issues to be addressed. We present a machine‐learning approach to classify lightning discharges. The classification model used in this study is based on Support Vector Machines (SVMs). Compared with traditional multiparameter methods, our algorithm does not require extraction of individual pulse parameters and additionally provides a probability for each prediction. Using a representative lightning pulse data collected by the Cordoba Marx Meter Array in Argentina, we found the classification accuracy of our machine‐learning algorithm to be 97%, which is higher than that for the existing lightning detection networks.
Intensified Humid Heat Events Under Global Warming
Authors: Wang Pinya , Yang Yang , Tang Jianping , Leung L. Ruby , Liao Hong 
Published: December 2020

AbstractBased on the Coupled Model Intercomparison Project Phase 5 multimodel simulations, this paper investigates the future changes in extreme wet‐bulb temperatures (TWs) and extreme dry‐bulb temperatures (Ts) globally under both low‐emission and high‐emission scenarios (Representative Concentration Pathways of 4.5 [RCP4.5] and 8.5 [RCP8.5]). Under a warming climate, T and TW exhibit a higher absolute increase in their mean values over the mid–high latitudes while they show higher relative increases in their mean values and variability over tropics. Humid and dry heat events which consist of consecutive extreme TWs and Ts show higher occurrences over tropics, governed by the joint increases in mean values and variability of TW and T therein. Humid heat events show intensifications to dry heat events with higher frequency, duration, and intensity, driven by the lower variability of TW than T. In the mid–high latitudes, heat events will start earlier and last longer in warm season under RCP8.5 than RCP4.5, motivating the need for global warming mitigation.
Processes in the Current Disruption Region: From Turbulence to Dispersion Relation
Authors: Kozak L. V. , Petrenko B. A. , Lui A. T. Y. , Kronberg E. A. , Daly P. W. 
Published: December 2020

AbstractUsing measurements from Cluster‐II space mission, we compared the characteristics of the fluctuations of the magnetic field magnitude and the Bz component in the current disruption (CD) regions. We used fast Fourier transform, statistical, and wavelet analysis, and wave surveyor technique on the multispacecraft measurements. Among the obtained results one can note the presence of spectral breaks in both the magnetic field magnitude and the Bz component at frequencies smaller or equal to the proton gyrofrequency. The numerical values of the spectral index for the magnetic field magnitude and for the Bz component are similar, and the nature of the turbulent processes is close to that of the homogeneous magnetohydrodynamic (MHD) (the spectral index varies from −2.00 to −1.31) on the large time scale and resembles Hall‐MHD (the spectral index varies from −2.33 to −2.99) on the smaller time scales. The kurtosis results are consistent with those of the spectral analysis. From wavelet technique, we detected powerful Pc4 and Pi1 pulsations, along with cascade features both for the magnetic field magnitude and for its z‐component. The dispersion ratios also indicate the presence of nonlinear energy cascade processes in CD regions. We have found that the pulsations observed for magnetic pressure are also present in thermal proton and electron pressures although their powers differ considerably. For the dynamic helium and oxygen pressures, and also for the thermal pressures of these components, only pulsations in the high‐frequency region are revealed.
Comparative Analysis of the Various Generalized Ohm's Law Terms in Magnetosheath Turbulence as Observed by Magnetospheric Multiscale
Authors: Stawarz J. E. , Matteini L. , Parashar T. N. , Franci L. , Eastwood J. P. , Gonzalez C. A. , Gingell I. L. , Burch J. L. , Ergun R. E. , Ahmadi N. , Giles B. L. , Gershman D. J. , Le Contel O. , Lindqvist P.‐A. , Russell C. T. , Strangeway R. J. , Torbert R. B. 
Published: December 2020

AbstractDecomposing the electric field (E) into the contributions from generalized Ohm's law provides key insight into both nonlinear and dissipative dynamics across the full range of scales within a plasma. Using high‐resolution, multispacecraft measurements of three intervals in Earth's magnetosheath from the Magnetospheric Multiscale mission, the influence of the magnetohydrodynamic, Hall, electron pressure, and electron inertia terms from Ohm's law, as well as the impact of a finite electron mass, on the turbulent E spectrum are examined observationally for the first time. The magnetohydrodynamic, Hall, and electron pressure terms are the dominant contributions to E over the accessible length scales, which extend to scales smaller than the electron gyroradius at the greatest extent, with the Hall and electron pressure terms dominating at sub‐ion scales. The strength of the nonideal electron pressure contribution is stronger than expected from linear kinetic Alfvén waves and a partial antialignment with the Hall electric field is present, linked to the relative importance of electron diamagnetic currents in the turbulence. The relative contribution of linear and nonlinear electric fields scale with the turbulent fluctuation amplitude, with nonlinear contributions playing the dominant role in shaping E for the intervals examined in this study. Overall, the sum of the Ohm's law terms and measured E agree to within ∼20% across the observable scales. These results both confirm general expectations about the behavior of E in turbulent plasmas and highlight features that should be explored further theoretically.
Compaction Banding in High‐Porosity Carbonate Rocks: 1. Experimental Observations
Authors: Abdallah Youssouf , Sulem Jean , Bornert Michel , Ghabezloo Siavash , Stefanou Ioannis 
Published: December 2020

AbstractIdentifying the mechanisms that control the formation of compaction bands is of high interest in reservoir mechanics since these structures may drastically affect the performance of geosystems operations. Considering the difficulty to identify compaction bands in carbonate samples tested in the laboratory, the Digital Volume Correlation technique is applied here and proves to be a relevant method. X‐Ray Computed Tomography (XRCT) images of Saint‐Maximin limestone centimetric samples are recorded before and after several triaxial loading stages and deformation maps are built. A new postprocessing method based on the analysis of the kinematics throughout the observed localization bands is proposed to identify their type. Compaction bands are identified at relatively high‐confining pressures, while shear bands are observed at lower confinements. The brittle‐ductile transitional regime reveals the formation of compactive shear bands, while a diffuse compaction is observed under hydrostatic loading. The effect of porosity heterogeneities on strain localization is explored by computing 3D porosity maps from calibrated XRCT images. Compaction bands are found to dominantly lay inside high‐porosity zones, while shear bands can cross both high‐ and low‐porosity zones. The band orientation is found to be controlled primarily by the confining pressure. Moreover, the porosity heterogeneity strongly affects the volumetric behavior inside the deformation bands, with a dilatant behavior identified in low‐porosity zones in contrast to a compactive behavior observed in high‐porosity zones. Finally, Scanning Electron Microscopy observations reveal that calcite grain crushing is dominant in high‐porosity zones, while intergranular cement cracking occurs in denser zones.
Formation of Tridymite and Evidence for a Hydrothermal History at Gale Crater, Mars
Authors: Yen A. S. , Morris R. V. , Ming D. W. , Schwenzer S. P. , Sutter B. , Vaniman D. T. , Treiman A. H. , Gellert R. , Achilles C. N. , Berger J. A. , Blake D. F. , Boyd N. I. , Bristow T. F. , Chipera S. , Clark B. C. , Craig P. I. , Downs R. T. , Franz H. B. , Gabriel T. , McAdam A. C. , Morrison S. M. , O’Connell‐Cooper C. D. , Rampe E. B. , Schmidt M. E. , Thompson L. M. , VanBommel S. J. 
Published: December 2020

AbstractIn August 2015, the Curiosity Mars rover discovered tridymite, a high‐temperature silica polymorph, in Gale crater. The existing model for its occurrence suggests erosion and detrital sedimentation from silicic volcanic rocks in the crater rim or central peak. The chemistry and mineralogy of the tridymite‐bearing rocks, however, are not consistent with silicic volcanic material. Using data from Curiosity, including chemical composition from the Alpha Particle X‐ray Spectrometer, mineralogy from the CheMin instrument, and evolved gas and isotopic analyses from the Sample Analysis at Mars instrument, we show that the tridymite‐bearing rocks exhibit similar chemical patterns with silica‐rich alteration halos which crosscut the stratigraphy. We infer that the tridymite formed in‐place through hydrothermal processes and show additional chemical and mineralogical results from Gale crater consistent with hydrothermal activity occurring after sediment deposition and lithification.
Coral Record of Younger Dryas Chronozone Warmth on the Great Barrier Reef
Authors: Brenner Logan D. , Linsley Braddock K. , Webster Jody M. , Potts Donald , Felis Thomas , Gagan Michael K. , Inoue Mayuri , McGregor Helen , Suzuki Atsushi , Tudhope Alexander , Esat Tezer , Thomas Alex , Thompson William , Fallon Stewart , Humblet Marc , Tiwari Manish , Yokoyama Yusuke 
Published: December 2020

AbstractThe Great Barrier Reef (GBR) is an internationally recognized and widely studied ecosystem, yet little is known about its sea surface temperature (SST) evolution since the Last Glacial Maximum (LGM) (~20 kyr BP). Here, we present the first paleo‐application of Isopora coral‐derived SST calibrations to a suite of 25 previously published fossil Isopora from the central GBR spanning ~25–11 kyr BP. The resultant multicoral Sr/Ca‐ and δ18O‐derived SST anomaly (SSTA) histories are placed within the context of published relative sea level, reef sequence, and coralgal reef assemblage evolution. Our new calculations indicate SSTs were cooler on average by ~5–5.5°C at Noggin Pass (~17°S) and ~7–8°C at Hydrographer's Passage (~20°S) (Sr/Ca‐derived) during the LGM, in line with previous estimates (Felis et al., 2014, https://doi.org/10.1038/ncomms5102). We focus on contextualizing the Younger Dryas Chronozone (YDC, ~12.9–11.7 kyr BP), whose Southern Hemisphere expression, in particular in Australia, is elusive and poorly constrained. Our record does not indicate cooling during the YDC with near‐modern temperatures reached during this interval on the GBR, supporting an asymmetric hemispheric presentation of this climate event. Building on a previous study (Felis et al., 2014, https://doi.org10.1038/ncomms5102), these fossil Isopora SSTA data from the GBR provide new insights into the deglacial reef response, with near‐modern warming during the YDC, since the LGM.