High-energy Events Research Articles

Simulating Coronal Loop Implosion and Compressible Wave Modes in a Flare Hit Active Region

Abstract There is considerable observational evidence of implosion of magnetic loop systems inside solar coronal active regions following high-energy events like solar flares. In this work, we propose that such collapse can be modeled in three dimensions quite accurately within the framework of ideal magnetohydrodynamics. We furthermore argue that the dynamics of loop implosion is only sensitive to the transmitted disturbance of one or more of the system variables, e.g., velocity generated at the event site. This indicates that to understand loop implosion, it is sensible to leave the event site out of the simulated active region. Toward our goal, a velocity pulse is introduced to model the transmitted disturbance generated at the event site. Magnetic field lines inside our simulated active region are traced in real time, and it is demonstrated that the subsequent dynamics of the simulated loops closely resemble observed imploding loops. Our work highlights the role of plasma β in regards to the rigidity of the loop systems and how that might affect the imploding loops’ dynamics. Compressible magnetohydrodynamic modes such as kink and sausage are also shown to be generated during such processes, in accordance with observations.

Boulder emplacement and remobilisation by cyclone and submarine landslide tsunami waves near Suva City, Fiji

The characteristics of a reef-top boulder field created by a local submarine landslide tsunami are presented for the first time. Our examination of large reef-derived boulders deposited by the 1953 tsunami near Suva City, Fiji, revealed that shorter-than-normal-period tsunami waves generated by submarine landslides can create a boulder field resembling a storm boulder field due to relatively short boulder transport distances. The boulder-inferred 1953 tsunami flow velocity is estimated at over 9ms−1 at the reef edge. Subsequent events, for example Cyclone Kina (1993), appear to have remobilised some large boulders. While prior research has demonstrated headward retreat of Suva Canyon in response to the repeated occurrence of earthquakes over the past few millennia, our results highlight the lingering vulnerability of the Fijian coastlines to high-energy waves generated both in the presence (tsunami) and absence (storm) of submarine failures and/or earthquakes. To explain the age discrepancies of U-Th dated coral comprising the deposited boulders, we introduce a conceptual model showing the role of repeated episodes of tsunamigenic submarine landslides in removing reef front sections through collapse. Subsequent high-energy wave events transport boulders from exposed older sections of the reef front onto the reef where they are deposited as ‘new’ boulders, alongside freshly detached sections of the living reef. In similar situations where anachronistic deposits complicate the deposition signal, age-dating of the coral boulders should not be used as a proxy for determining the timing of the submarine landslides or the tsunamis that generated them.

Storm-related sedimentation influenced by coastal configuration in the stratigraphic record of a tectonically active shelf (Upper Pleistocene Le Castella terrace, Italy)

Analysis of patterns of coastal circulation and sediment dispersal is an essential step for the study of controlling factors influencing the long-term dynamics of coastal systems. Modern settings offer the possibility to monitor relevant parameters over relatively short time spans. However, geological examples complement this perspective by providing a time-averaged record where longer trends and stratigraphically significant processes can be evaluated. This study investigates the shallow marine deposits of Le Castella terrace (Upper Pleistocene, southern Italy) to document how patterns of circulation influenced by coastline configuration can affect the preserved millennial-scale depositional record of a progradational shoreline system. The regressive portion of the Le Castella terrace deposits, developed during a relative sea-level highstand and falling stage, consists of a progradational wedge mainly composed of redistributed skeletal particles of a coeval shallow water carbonate factory. Preservation of the morphology of the paleocoastline and abundant current-related sedimentary structures allow reconstruction of the predominant sediment dispersal dynamics responsible for the formation of this sedimentary wedge. Facies and paleocurrent analysis indicate offshore and alongshore sediment transport modes, consistent with coastal circulation driven by storms normally incident to the shoreline and a sharp change in coastline orientation. This coastal inflection influenced circulation patterns causing flow separation and eddy formation in the lee of the curved coastline. Syndepositional tectonic deformation also affected the architecture of the preserved deposits, controlling the nucleation and development of a clinostratified body and determining localized lateral stratigraphic variability. This study illustrates how transient but recurrent circulation patterns associated with changes in coastal orientation and related to high-energy storm events can leave a predominant signature in the stratigraphic record of microtidal shallow-marine successions.

Early to mid-Holocene spatiotemporal vegetation changes and tsunami impact in a paradigmatic coastal transitional system (Doñana National Park, southwestern Europe)

Abstract The southern European Donana wetlands host a highly biodiverse landscape mosaic of complex transitional ecosystems. It is one of the largest protected natural sites in Europe, nowadays endangered by intensive agricultural practices, and more recently tourism and human-induced fires. Its present-day spatial heterogeneity has been deeply investigated for the last three decades. However, a long-term perspective has not been applied systematically to this unique landscape. In this new study, a palaeoecological approach was selected in order to unravel patterns of landscape dynamism comparing dry upland and aquatic ecosystems. A 709 cm-long sediment core was retrieved and a multi-proxy approach applied (palynological, microcharcoal, grain size, magnetic susceptibility, loss-on-ignition and multivariate statistical analyses). Pollen signatures show how sensitive aquatic wetland vegetation was to environmental changes while terrestrial vegetation was stable at millennial scale. The impact of several high energy events punctuates the Early and Middle Holocene sequence, two of which relate to the local tsunami record (~ 6.6 and ~ 9.1 cal. kyr BP). Contrasting impacts of these two events in the aquatic and upland ecosystems show the importance of landscape configuration and the contingent history as key elements for coastal protection.

Analysis of electrical tree inception in silicone gels

This work assesses the initial and crucial part of electrical treeing degradation, the inception stage, focusing on its dependence on applied voltage waveform and frequency. Tests have been performed on needle-plane configuration samples in solids and gels. A physical model has been formulated through an adaptation of an established theory for solids in which electrical tree inception is related to damage-producing injection currents. The voltage rise time appeared to be the most important parameter influencing the tree inception in the gel, while in the solid material the frequency is more relevant. The analysis leads to the conclusion that tree inception in gels is due to a single high-energy event, in contrast to what is commonly known for solids where damage accumulation takes place. A tree inception model is proposed for the gel, in which initiation is driven by a pressure wave generated by the electric field and the space charge injected into the sample. The model fits the experimental data and may be used to predict the tree initiation for different waveforms and voltage values.

Trace fossils of an amalgamated storm-bed succession from the Jurassic of the Kachchh Basin, India: The significance of time-averaging in ichnology

The uppermost part of the Upper Bathonian Sponge Limestone member, Patcham Formation, of the Jhura Dome of Kachchh Mainland is a thickening- and shallowing-upward succession topped by medium- to thick-bedded hummocky cross-stratified grainstones deposited by storm waves. Occasionally, thin, commonly lenticular, intraclastic–bioclastic silty marl intercalations between the grainstones are highly bioturbated, in contrast to the grainstones, in which, for the most part, trace fossils occur scattered. Large exposures of bedding planes of the grainstones allow the detailed investigation of ichnological features, whereas the high density of traces in the soft marls precludes the identification of any ichnotaxa. Eighteen ichnotaxa have been recorded including Ophiomorpha, Thalassinoides, Taenidium, Gyrophyllites, Chondrites, Dactyloidites, Teichichnus, Bolonia, and Ancorichnus. Except for Ophiomorpha nodosa and Thalassinoides, which generally indicate moderate to high energy conditions and are the dwelling burrows of suspension-feeding to omnivorous crustaceans, the ichnotaxa represent a deposit-feeding behaviour of their producers and thus are characteristic of low-energy environments. The trace fossils form three ichnoassemblages characterized by (1) Ophiomorpha nodosa and Thalassinoides suevicus, (2) ?Thalassinoides isp. A, Taenidium, and Bolonia lata, and (3) Ancorichnus. The dominance of traces of deposit-feeders in rocks indicative of high-energy events is counterintuitive and points to their non-contemporaneity. The sediments were deposited during brief high-energy events, whereas the trace fossils were produced when, after waning of storms low-energy conditions prevailed. This time-averaging is particularly pronounced in trace fossils that extend vertically downwards and may reach strata deposited under distinctly different conditions. Thus, environmental interpretations based on trace fossils should refer to colonisation surfaces rather than to the sediment surrounding the trace fossils. In the latter case, interpretations may be erroneous, especially when erosion subsequently destroyed sedimentary evidence of their original environment.

The effect of tides and storms on the sediment transport across a Dutch barrier island

AbstractUnder natural conditions, barrier islands might grow vertically and migrate onshore under the influence of long‐term sea level rise. Sediment is transported onshore during storm‐induced overwash and inundation. However, on many Dutch Wadden Islands, dune openings are closed off by artificial sand‐drift dikes that prevent the influx of sediment during storms. It has been argued that creating openings in the dune row to allow regular flooding on barrier islands can have a positive effect on the sediment budget, but the dominant hydrodynamic processes and their influence on sediment transport during overwash and inundation are unknown. Here, we present an XBeach model study to investigate how sediment transport during overwash and inundation across the beach of a typical mesotidal Wadden Sea barrier island is influenced by wave, tide and storm surge conditions. Firstly, we validated the model XBeach with field data on waves and currents during island inundation. In general, the XBeach model performed well. Secondly, we studied the long‐term sediment transport across the barrier island. We distinguished six representative inundation classes, ranging from frequently occurring, low‐energy events to infrequent, high‐energy events, and simulated the hydrodynamics and sediment transport during these events. An analysis of the model simulations shows that larger storm events cause larger cross‐shore sediment transport, but the net sediment exchange during a storm levels off or even becomes smaller for the largest inundation classes because it is counteracted by larger mean water levels in the Wadden Sea that oppose or even reverse sediment transport during inundation. When taking into account the frequency of occurrence of storms we conclude that the cumulative effect of relatively mild storms on long‐term cross‐shore sediment transport is much larger than that of the large storm events. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

Evaluation and Management of Blunt Solid Organ Trauma

Trauma is a leading cause of death in patients under the age of 45 and generally associated with a high kinetic energy event such as a motor vehicle accident or fall from extreme elevations. Blunt trauma can affect every organ system and major vascular structure with potentially devastating effect. When we consider abdominal solid organ injury from blunt trauma, we usually think of the liver, spleen, and kidneys. However, all of the abdominal organs, including the pancreas and adrenal glands, may be involved. Blunt hepatic trauma is more commonly associated with venous bleeding rather than arterial injury. Stable venous injury is often managed conservatively; when the patient is hemodynamically unstable from venous hepatic injury, operative management should be first-line therapy. When the injury is arterial, endovascular therapy should be initiated. Blunt trauma to the spleen is the most common cause of traumatic injury to the spleen. Management is controversial. In our institution unstable patients are taken to the operating room, and stable patients with Grades IV-V injuries and patients with active arterial injury are taken for endovascular treatment. Renal injuries are less common, and evidence of arterial injury such as active extravasation or pseudoaneurysm is warranted before endovascular therapy. Pancreatic trauma is uncommon and usually secondary to steering wheel/handlebar mechanism injuries. Adrenal injuries are rare in the absence of megatrauma or underlying adrenal abnormality.

Reworking processes and deposits in coral reefs during (very) high-energy events: Example from a Pleistocene coral formation (125 ka), La Désirade Island, Lesser Antilles

Abundant literature has documented the ecological impact of very high-energy (hurricane-type) events and high-energy (storm-type) events on modern coral reefs and sediment transport. In previous studies, sedimentary processes are often deduced from geophysical image analysis and scuba diving observations. Few field-based studies have been devoted to the impact of (very) high-energy disturbance on the structure and ecology of Holocene and Pleistocene coral reefs, and very few to the sedimentary processes acting around these reefs.This research examines the structure of the late Pleistocene (end of MIS5e stage) reefs of La Désirade Island, Guadeloupe Archipelago, Lesser Antilles, and focuses on the poorly known reworking processes and related coral-breccia sedimentation surrounding these reefs. Fieldwork was performed to document two coral-fragment-rich breccia interbedded with coral patches. The breccia predominantly show the same petrography but differ in their internal structure, showing a “massive breccia” type and a “stratified breccia” type. This work infers that these breccia are the result of gravity-induced high-density mass flows triggered by high to very-high energy events such as storms and hurricanes. Damage and reworking vary according to the type of (very) high-energy event. Prior to transport, storms are thought to have broken the heads of branching and columnar coral colonies, and broken and overturn isolated lamellar and massive colonies. Hurricanes (particularly their eye walls) may have reworked much more sediment than storms, and may have also destabilised entire several metre-sized columnar colonies from the flank of coral patch reefs. We propose the name “coral debrite” for these coral breccia deposits caused by gravity-induced debris flows.The reworked deposits are interbedded between two coral reef levels, of which the main coral-species vertical succession should record the end of Marine Isotope Stage 5e sea-level rise. Thus, reworking is believed to occur during the transitional stage between a glacial and an interglacial period.

Solar Energetic Particle Forecasting Algorithms and Associated False Alarms

Solar energetic particle (SEP) events are known to occur following solar flares and coronal mass ejections (CMEs). However, some high-energy solar events do not result in SEPs being detected at Earth, and it is these types of event which may be termed “false alarms”.We define two simple SEP forecasting algorithms based upon the occurrence of a magnetically well-connected CME with a speed in excess of 1500~mbox{km},mbox{s}^{-1} (a “fast” CME) or a well-connected X-class flare and analyse them with respect to historical datasets. We compare the parameters of those solar events which produced an enhancement of {>},40~mbox{MeV} protons at Earth (an “SEP event”) and the parameters of false alarms.We find that an SEP forecasting algorithm based solely upon the occurrence of a well-connected fast CME produces fewer false alarms (28.8%) than an algorithm which is based solely upon a well-connected X-class flare (50.6%). Both algorithms fail to forecast a relatively high percentage of SEP events (53.2% and 50.6%, respectively).Our analysis of the historical datasets shows that false-alarm X-class flares were either not associated with any CME, or were associated with a CME slower than 500~mbox{km},mbox{s}^{-1}; false-alarm fast CMEs tended to be associated with flare classes lower than M3.A better approach to forecasting would be an algorithm which takes as its base the occurrence of both CMEs and flares. We define a new forecasting algorithm which uses a combination of CME and flare parameters, and we show that the false-alarm ratio is similar to that for the algorithm based upon fast CMEs (29.6%), but the percentage of SEP events not forecast is reduced to 32.4%.Lists of the solar events which gave rise to {>},40~mbox{MeV} protons and the false alarms have been derived and are made available to aid further study.

On the compatibility of the IceCube results with a universal neutrino spectrum

There is mounting evidence that the IceCube findings cannot be described simply invoking a single power-law spectrum for cosmic neutrinos. We discuss which the minimal modifications are of the spectrum that are required by the existing observations and we obtain a universal cosmic neutrino spectrum, i.e. valid for all neutrino flavors. Our approach to such task can be outlined in three points: (1) we rely on the throughgoing muon analysis above 200 TeV and on the high-energy starting events (HESE) analysis below this energy, requiring the continuity of the spectrum; (2) we assume that cosmic neutrinos are subject to three-flavor neutrino oscillations in vacuum; (3) we make no assumption on the astrophysical mechanism of production, except for no nu _tau (overline{nu }_tau ) component at the source. We test our model using the information provided by HESE shower-like events and by the lack of double pulses and resonant events. We find that a two-component power-law spectrum is compatible with all observations. The model agrees with the standard picture of pion decay as a source of neutrinos, and indicates a slight preference for a pgamma mechanism of production. We discuss the tension between the HESE and the “throughgoing muons” datasets around few tens TeV, focussing on the angular distributions of the spectra. The expected number of smoking-gun signatures of nu _tau -induced events (referred to as double pulses) is quantified: in the baseline model we predict 0.65 double pulse events in 5.7 years. Uncertainties in the predictions are quantified.

The impact of Cyclone Nargis on the Ayeyarwady (Irrawaddy) River delta shoreline and nearshore zone (Myanmar): Towards degraded delta resilience?

The Ayeyarwady River delta (Myanmar) is exposed to tropical cyclones, of which the most devastating has been cyclone Nargis (2–4 May 2008). We analysed waves, flooded area, nearshore suspended sediments, and shoreline change from satellite images. Suspended sediment concentrations up to 40% above average during the cyclone may reflect fluvial mud supply following heavy rainfall and wave reworking of shoreface mud. Massive recession of the high-water line resulted from backshore flooding by cyclone surge. The shoreline showed a mean retreat of 47m following Nargis. Erosion was stronger afterwards (−148m between August 2008 and April 2010), largely exceeding rates prior to Nargis (2000–2005: −2.14m/year) and over 41 years (1974–2015: −0.62m/year). This implies that resilience was weak following cyclone impact. Consequently, the increasingly more populous Ayeyarwady delta, rendered more and more vulnerable by decreasing fluvial sediment supply, could, potentially, become more severely impacted by future high-energy events.

Numerical simulation of wave conditions in nearshore island area for sea-crossing bridge using spectral wave model

The assessment of wave conditions is a primary task for the design, construction, and structural analysis of sea-crossing bridge. This article presents a numerical simulation and a field measurement to study the wave conditions in the nearshore island area for sea-crossing bridges. Pingtan Strait sea-crossing bridge site was selected as an example of nearshore island area. A 3-day high-energy wave event was measured and simulated using spectral wave model. The parameters of the numerical model were calibrated through the comparison with the field measured wave data. The spatial pattern of wave conditions along the bridge and the wave-breaking zone were analyzed based on the calibrated model. The analytical procedures suggested in the Chinese Code for nearshore wave prediction were finally testified through the comparison with numerical results. The research showed that (1) spectral wave model predicts the wave conditions in bridge site reasonably; (2) seabed terrain and islands significantly influence wave conditions, wave spatial pattern, and breaking wave zones; and (3) analytical wave simulation procedure recommended in the Code is not suitable to island area for sea-crossing bridge. This research allows a better understanding of wave conditions for sea-crossing bridge site and could provide useful reference for engineering practice.

CHANGE ANALYSIS OF LASER SCANS OF LABORATORY ROCK SLOPES SUBJECT TO WAVE ATTACK TESTING

Abstract. For better understanding how coastal structures with gentle slopes behave during high energy events, a wave attack experiment representing a storm of 3000 waves was performed in a flume facility. Two setups with different steepness of slope were compared under the same conditions. In order to quantify changes in the rock slopes after the wave attack, a terrestrial laser scanner was used to obtain 3D coordinates of the rock surface before and after each experiment. Next, through a series of processing steps, the point clouds were converted to a suitable 2D raster for change analysis. This allowed to estimate detailed and quantitative change information. The results indicate that the area around the artificial coast line, defined as the intersection between sloped surface and wave surface, is most strongly affected by wave attacks. As the distances from the sloped surface to the waves are shorter, changes for the mildly sloped surface, slope 1 (1 : 10), are distributed over a larger area compared to the changes for the more steeply sloped surface, slope 2 (1 : 5). The results of this experiment show that terrestrial laser scanning is an effective and feasible method for change analysis of rock slopes in a laboratory setting. Most striking results from a process point of view is that the transport direction of the rocks change between the two different slopes: from seaward transport for the steeper slope to landward transport for the milder slope.

The Bruneau Woodpile: A Miocene Phosphatized Fossil Wood Locality in Southwestern Idaho, USA

The Bruneau Woodpile site has long been popular among fossil collectors; however, the deposit has received scant attention from scientists. Our research reveals that the fossilized wood was deposited ca. 6.85 Ma, within the Chalk Hills Formation, and was mineralized with carbonate-fluorapatite. The diverse assemblage of conifers and hardwoods is representative of the warm temperate forests that flourished in southwest Idaho, USA during the late Miocene. Limb and trunk fragments preserved in a single thin sandstone bed appear to represent woody debris that was transported by streams. One possible explanation is that wood, pumice, and sandy volcaniclastic sediment arrived separately as a result of ordinary stream action, and later were combined into a single assemblage during a subsequent high-energy sedimentation event. We favor an alternate hypothesis: a catastrophic event (e.g., a windstorm) damaged trees on slopes bordering the ancient lake. Branches and small trunk fragments were carried by wind and rain into local streams and ponds where they became waterlogged. After a delay that allowed pumice and wood to become saturated, storm water transported these materials, along with finer volcaniclastic sediment, into a lake. The resulting density current produced a fining-upward sedimentary cycle where wood was preserved in the lowest, coarsest stratum.

INTEGRAL Observations of GW170104

Abstract We used data from the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) to set upper limits on the γ-ray and hard X-ray prompt emission associated with the gravitational-wave event GW170104, discovered by the Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo collaboration. The unique omnidirectional viewing capability of the instruments on board INTEGRAL allowed us to examine the full 90% confidence level localization region of the LIGO trigger. Depending on the particular spectral model assumed and the specific position within this region, the upper limits inferred from the INTEGRAL observations range from F γ = 1.9 × 10−7 erg cm−2 to F γ = 10−6 erg cm−2 (75 keV–2 MeV energy range). This translates into a ratio between the prompt energy released in γ-rays along the direction to the observer and the gravitational-wave energy of E γ /E GW < 2.6 × 10−5. Using the INTEGRAL results, we cannot confirm the γ-ray proposed counterpart to GW170104 by the Astro—Rivelatore Gamma a Immagini Leggero (AGILE) team with the mini-Calorimeter (MCAL) instrument. The reported flux of the AGILE/MCAL event, E2, is not compatible with the INTEGRAL upper limits within most of the 90% LIGO localization region. There is only a relatively limited portion of the sky where the sensitivity of the INTEGRAL instruments was not optimal and the lowest-allowed fluence estimated for E2 would still be compatible with the INTEGRAL results. This region was also observed independently by Fermi/Gamma-ray Burst Monitor and AstroSAT, from which, as far as we are aware, there are no reports of any significant detection of a prompt high-energy event.

All flavour point-source search with the ANTARES neutrino telescope

ANTARES is the largest neutrino telescope in the Northern Hemisphere. The detector has established excellent pointing resolution for muon neutrinos (0.4 degrees) and a degree-level resolution also for contained shower events (about 2 degrees). Together with its geographical location, the good angular resolution makes ANTARES an excellent tool to test for the presence of cosmic sources in the Southern Hemisphere and in particular the area around the Galactic Centre, where IceCube reports a number of high-energy events. In this contribution, we present a search for cosmic neutrino sources using ANTARES data taken from early 2007 until the end of 2013. Such sources are identified as a cluster of events in the combined track and shower channels. In addition to the all-flavour full-sky and candidate list searches, we focus on a restricted region around the Galactic Centre. Different spectral indices for the neutrino energy spectrum have been investigated as well as possible extended sources.

The Impact of Hydrodynamics, Authigenesis, and Basin Morphology On Sediment Accumulation In An Upwelling Environment: The Miocene Monterey Formation At Shell Beach and Mussel Rock (Pismo and Santa Maria Basins, Central California, U.S.A.)

ABSTRACT: In the sections at Shell Beach (Pismo Basin) and Mussel Rock (Santa Maria Basin)—both along the central California coast—the Miocene Monterey Formation is composed of laminated, biosiliceous, organic-rich and phosphate-rich sediments, which are intercalated with carbonates and volcanogenic deposits. The presence of small- and large-scale scours, conglomerates, gravity-flow deposits, slumps, and condensed intervals reveals the importance of sediment reworking, which is related to the presence of bottom currents, the general morphology of the basins, and recurrent high-energy events of likely seismic origin. The lithologies reflect strong upwelling, enhanced primary productivity, and the presence of an oxygen-minimum zone, which is indicated by ubiquitous lamination, a general absence of bioturbation (with the rare exception of traces related to the gravity-flow displacement of trace makers), high pyrite, Mo, and U concentrations, and molar ratios of total organic carbon and organic phosphorus (TOC/P org ) of up to 2000. Oxygen depletion was particularly severe during the early Langhian, and the late Serravallian and early Tortonian, and favored the preservation of organic matter. Episodes of deposition of organic-rich sediment were followed by longer phases of subdued sediment accumulation and early diagenetic phosphogenesis, which resulted in the formation of a low-porosity, less permeable “lid” in the near-surface sediments that assisted in preserving organic matter. Phosphogenesis occurred throughout the time interval considered (approximately 17.5–6.5 Ma), and phosphate-rich sediments formed especially during periods of sedimentary condensation in the Langhian and earliest Serravallian, and the latest Tortonian and early Messinian. A comparison of temporal trends in the type and quantity of deposited sediments between the two sections at Shell Beach and Mussel Rock, and three sections of the Santa Barbara Basin (El Capitan State Beach, Naples Beach, and Haskell Beach) confirms that towards the top of the Monterey Formation, sediments become enriched in biosilica in all three basins. The transition into this lithology occurred diachronously, during the Serravallian in the Pismo and Santa Maria basins and Tortonian in the Santa Barbara Basin, and was probably related to a diachronous shift to more intense upwelling in all three basins. A phase of important condensation and phosphogenesis terminated Monterey-“type” sedimentation during the latest Tortonian and early Messinian in both the Santa Maria and Santa Barbara basins. The uniform expression of this phase is interpreted as the result of improved connections between the two basins.

High-energy flood events recorded in the Mesoproterozoic Meall Dearg Formation, NW Scotland; their recognition and implications for the study of pre-vegetation alluvium

The Mesoproterozoic–Neoproterozoic Torridonian Sandstone of NW Scotland has renewed sedimentological significance following recent advances in the understanding of pre-vegetation alluvium, as it is one of the most extensive and easily accessible successions of such strata worldwide. This paper presents the first modern sedimentological analysis of the unit's constituent Meall Dearg Formation (late Mesoproterozoic), recognizing a dominance of alluvial facies, with subordinate aeolian facies. Alluvial strata within the Meall Dearg Formation contain direct evidence for event deposition by high-energy floods, including the following: (1) widespread upper and transitional upper flow regime elements; (2) frequent stacking of successively lower flow regime elements; (3) common subcritical subaqueous dune fields with superimposed ripple marks; (4) occasional thin, desiccated mudstones; (5) evidence that microbial mats colonized substrates during intervals of sedimentary stasis. Together these strands of primary sedimentary geological evidence indicate that the alluvial deposition of the Meall Dearg Formation was typified by supercritical flows during high-energy floods, punctuated by prolonged intervals of sedimentary stasis. The preservation potential of all of the features was boosted by highly aggradational sedimentary conditions. These primary observations have implications for the ‘norm’ in pre-vegetation alluvium and confirm that, despite increasing recognition of diversity within Precambrian fluvial systems, classical pre-vegetation motifs of high-energy alluvial flood deposits preserved as ‘sheet-braided’ alluvium are still an archetypal sedimentary signature in some instances. Using supportive evidence from the Meall Dearg Formation, we recommend that the term ‘sheet-braided’ be used in inverted commas in future studies; this emphasizes the polygenetic depositional nature of the 20:1 width:thickness fluvial style, while maintaining the value of the term in the isolation of a key characteristic of pre-vegetation sedimentary architecture.

A phenomenological study on the production of Higgs bosons in the cSMCS model at the LHC

In the present work, we intend to predict the production rates of the Higgs bosons in the simplest extension of the Standard Model (SM) by a neutral complex singlet (cSMCS). This model has an additional source of CP violation and provides strong enough first-order electroweak phase transition to generate the baryon asymmetry of universe (BAU). The scalar spectrum of the cSMCS includes three neutral Higgs particles with the lightest one considered to be the 125 GeV Higgs boson found at LHC. The SM-like Higgs boson comes mostly from the SM-like SU(2) doublet, with a small correction from the singlet. To predict the production rates of the Higgs bosons, we use a conventional effective LO QCD framework and the unintegrated parton distribution functions (UPDF) of Kimber–Martin–Ryskin (KMR). We first compute the SM Higgs production cross-section and compare the results to the existing theoretical calculations from different frameworks as well as the experimental data from the CMS and ATLAS collaborations. It is shown that our framework is capable of producing sound predictions for these high-energy QCD events in the SM. Afterwards we present our predictions for the Higgs boson production in the cSMCS.