Tectonic Consequences of a Uniformly Hot Backarc and Why is the Cordillera Mountain Belt High?

SUMMARYWhy is the North American Cordilleran mountain belt high? We expect a thick crust to support high elevations by isostasy but, remarkably, the Cordilleran crust is thin. There is no crustal root. An important recent recognition is that the high elevation is supported by thermal expansion rather than by thickened crust. The elevation of the Cordillera is only one consequence of the Cordillera being uniformly hot and having a thin lithosphere, in common with most current or recent backarcs. Some other consequences of the high temperatures compared to the adjacent cool craton include: (1) The Cordillera and other backarcs are hot, weak mobile belts that can be deformed by available plate-tectonic forces, in contrast to stable cratons that cannot; (2) Most continental seismicity is concentrated in backarcs; (3) In the Cordillera there is widespread sporadic ‘backarc’ volcanism; (4) The high temperatures result in very low strength in the lower crust that allows lower-crust detachment; (5) The lower crust weakness facilitates large-scale crustal oroclines that may be independent of the upper mantle; (6) The lower crust in the Cordillera and other backarcs is in amphibolite- to granulite-facies conditions, ~800–900°C at the Moho; (7) In ancient backarcs globally, regional Barrovian metamorphism is concluded to be the result of high temperatures that predate the orogenic collision and deformation. No "heat of orogeny" is required. Following the termination of subduction, backarcs cool with a time constant of 300–500 m.y.RÉSUMÉPourquoi la chaîne de montagnes de la Cordillère nord-américaine est-elle si haute? On comprend qu’une croûte sur-épaisse puisse expliquer une grande élévation, mais voilà, la croûte de la Cordillère est mince. Il n’existe pas de racine crustale. Or, récemment, une conclusion importante s’est imposée, soit que cette haute élévation s’explique par l’expansion thermique plutôt que par l’existence d’une croûte sur-épaisse. L’élévation de la Cordillère n’est qu’une des conséquences d’une Cordillère uniformément chaude flottant sur une lithosphère mince, caractéristiques communes aux zones d’arrière-arc actuelles ou récentes. Quelques unes des autres conséquences de cette haute température, par opposition aux froids cratons adjacents, comprennent: (1) La Cordillère et d’autres zones d’arrières-arcs sont des zones chaudes et facilement déformables par les forces tectoniques ambiantes, contrairement aux cratons stables; (2) La majorité de l’activité sismique continentale est concentrée dans le zones d’arrière-arc; (3) Dans la Cordillère l’activité volcanique sporadique est généralisé; (4) Ces températures élevées explique la très faible rigidité de la croûte inférieure et les décollements qu’elle subit; (5) La flaccidité de la croûte inférieure facilite la formation d’oroclinaux de grandes magnitudes qui peuvent être indépendants du manteau supérieur; (6) La croûte inférieure de la Cordillère et d’autres zones d’arrière-arc sont dans la zone de faciès amphibolite à granulite, soit 800 à 900oC à la discontinuité Moho; (7) Globalement dans les anciennes zones d’arrière-arc, le métamorphisme régional barrovien s’explique alors comme étant le résultat des hautes températures antérieures à la collision et à la déformation orogénique. Aucune « chaleur orogénique » n’est nécessaire. Après la période de subduction, les zones d’arrière-arc se refroidissent à l’intérieur d’un intervalle de temps de 300 à 500  millions d’années

The Challenge of Deep Ocean Drilling for Natural Gas Hydrate

Large reservoirs of natural gas hydrate have been sampled extensively by past DSDP, ODP, and other scientific ocean drilling. Gas hydrate is an ice-like solid consisting of gas molecules, commonly methane, trapped in a cage of water molecules. Global estimates of the methane content of natural gas hydrate are very large, potentially enormous. Such large quantities of gas hydrate could be important as a clean energy source, as a control in global climate, and as a factor in seafloor slumps and slides. Gas hydrate occurs only in water depths greater than about 600 m at temperate latitudes, but occurs on land and in shallow water in the Arctic. The formation mechanisms of gas hydrates are only partly understood. Gas hydrate appears to be formed usually by migrating fluids carrying biologically generated methane upward to regions of sufficiently low temperature and high pressure where the hydrate is stable. Quantitative aspects of this formation model need testing, however, and questions remain about the sources and sinks for methane, and the amount that can reach the atmosphere. In Canada, gas hydrates are found on most of its continental margins, notably on the continental slope off Vancouver Island and in the Mackenzie Delta-Beaufort Sea region. A drilling program off Vancouver Island would examine gas hydrates in a well-studied accretionary sedimentary wedge; such sediments appear to be the most common environment in which hydrates are found globally. Drilling for gas hydrate offshore in the Canadian Arctic, perhaps using an alternative drilling platform, would complement a current onshore Arctic gas hydrate drilling program in the permafrost environment. The Arctic land and shallow sea hydrate are important because such hydrate is especially susceptible to global climate change. Résumé De vastes réservoirs d'hydrate de gaz naturel ont été amplement échantillonnés par le DSDP, l'ODP et d'autres programmes de forage scientifiques. L'hydrate de gaz est un solide semblable à la glace, constitué de molécules de gaz, généralement du méthane, piégées dans une cage de molécules d'eau. Les estimations des volumes planétaires d'hydrate de gaz naturel sont très grandes, voire énormes. De telles quantités d'hydrate de gaz pourraient s'avérer important comme source d'énergie, comme tampon de régulation du climat de la planète, et comme facteur dans les mouvements et les glissements de terrains des fonds marins. Sous l'eau, les hydrate de gaz n'existent qu'à des profondeurs de plus de 600 m aux latitudes tempérées, mais ils existent sur terre et en eaux peu profondes dans les régions arctiques. Le mécanisme de formation des hydrates de gaz n'est que partiellement élucidé. Il semble que l'hydrate de gaz se forme généralement par la migration ascendante de fluides porteurs de méthane biologique vers des zones de température suffisamment basse et de pression suffisamment élevée, là où l'hydrate est stable. Cependant, les aspects quantitatifs de ce modèle de formation doivent être vérifiés, et certaines questions demeurent sans réponse quant aux sources et aux pièges du méthane, et à la quantité pouvant atteindre l'atmosphère. Au Canada, on trouve de l'hydrate de gaz sur la plupart de ses marges continentales, notamment sur la pente continentale au large de l'île de Vancouver de même que dans la zone du delta du Mackensie-mer de Beaufort. Un programme de forage au large de l'île de Vancouver permettrait d'étudier les hydrates de gaz au sein d'un biseau sédimentaire d'accrétion bien étudié; il semble que ce type de sédiments soit l'environnement le plus commun où l'on trouve des hydrates de gaz sur la planète. Le forage de prospection en mer pour l'hydrate de gaz dans l'Arctique canadien, peut-être avec une autre plateforme de forage, permettrait de compléter un programme de forage sur les hydrates de gaz en cours dans une région arctique du continent, dans un environnement de pergélîsol. L'hydrate de gaz des terres de l'Arctique et des mers peu profondes est important à cause de sa susceptibilité aux changements climatiques planétaires

Ambient seismic noise tomography of Canada and adjacent regions: Part I. Crustal structures

This paper presents the first continental-scale study of the crust and upper mantle shear velocity (V_s) structure of Canada and adjacent regions using ambient noise tomography. Continuous waveform data recorded between 2003 and 2009 with 788 broadband seismograph stations in Canada and adjacent regions were used in the analysis. The higher primary frequency band of the ambient noise provides better resolution of crustal structures than previous tomographic models based on earthquake waveforms. Prominent low velocity anomalies are observed at shallow depths (<20 km) beneath the Gulf of St. Lawrence in east Canada, the sedimentary basins of west Canada, and the Cordillera. In contrast, the Canadian Shield exhibits high crustal velocities. We characterize the crust-mantle transition in terms of not only its depth and velocity but also its sharpness, defined by its thickness and the amount of velocity increase. Considerable variations in the physical properties of the crust-mantle transition are observed across Canada. Positive correlations between the crustal thickness, Moho velocity, and the thickness of the transition are evident throughout most of the craton except near Hudson Bay where the uppermost mantle V_s is relatively low. Prominent vertical V_s gradients are observed in the midcrust beneath the Cordillera and beneath most of the Canadian Shield. The midcrust velocity contrast beneath the Cordillera may correspond to a detachment zone associated with high temperatures immediately beneath, whereas the large midcrust velocity gradient beneath the Canadian Shield probably represents an ancient rheological boundary between the upper and lower crust

Governmentality

Peer reviewe

EON-ROSE and the Canadian Cordillera Array – Building Bridges to Span Earth System Science in Canada

EON-ROSE (Earth-System Observing Network - Réseau d’Observation du Système terrestrE) is a new initiative for a pan-Canadian research collaboration to holistically examine Earth systems from the ionosphere into the core. The Canadian Cordillera Array (CC Array) is the pilot phase, and will extend across the Cordillera from the Beaufort Sea to the U.S. border. The vision for EON-ROSE is to install a network of telemetered observatories to monitor solid Earth, environmental and atmospheric processes. EON-ROSE is an inclusive, combined effort of Canadian universities, federal, provincial and territorial government agencies, industry, and international collaborators. Brainstorming sessions and several workshops have been held since May 2016. The first station will be installed at Kluane Lake Research Station in southwestern Yukon during the summer of 2018. The purpose of this report is to provide a framework for continued discussion and development.RÉSUMÉEON-ROSE (Earth-System Observing Network - Réseau d’Observation du Système terrestrE) est une nouvelle initiative de collaboration de recherche pancanadienne visant à étudier de manière holistique les systèmes terrestres, depuis l’ionosphère jusqu’au noyau. Le Réseau canadien de la cordillère (CC Array) en est la phase pilote, laquelle couvrira toute la Cordillère, de la mer de Beaufort jusqu’à la frontière étasunienne. L’objectif d’EON-ROSE est d’installer un réseau d’observatoires télémétriques pour suivre en continu les processusterrestres, environnementaux et atmosphériques. EON-ROSE est un effort combiné et inclusif des universités canadiennes, des organismes gouvernementaux fédéraux, provinciaux et territoriaux, de l’industrie et de collaborateurs internationaux. Des séances de remue-méninges et plusieurs ateliers ont été tenus depuis mai 2016. La première station sera installée à la station de recherche du lac Kluane, dans le sud-ouest du Yukon, au cours de l’été 2018. Le but du présent rapport est de fournir un cadre de discussion et de développement continu

The October 2012 magnitude (Mw) 7.8 earthquake offshore Haida Gwaii, Canada

Alison L. Bird et al. report on the Mw 7.8 earthquake offshore Haida Gwaii, Canada, from 2012 for the Summary of the Bulletin of the International Seismological Centre

Has management accounting research been critical?

This paper examines the contributions Management Accounting Research (MAR) has (and has not) made to social and critical analyses of management accounting in the twenty-five years since its launch. It commences with a personalised account of the first named author’s experiences of behavioural, social and critical accounting in the twenty-five years before MAR appeared. This covers events in the UK, especially the Management Control Workshop, Management Accounting Research conferences at Aston, the Inter-disciplinary Perspectives on Accounting Conferences; key departments and professors; and elsewhere the formation of pan-European networks, and reflections on a years’ visit to the USA. Papers published by MAR are analysed according to year of publication, country of author and research site, research method, research subject (type of organization or subject studied), data analysis method, topic, and theory. This revealed, after initial domination by UK academics, increasing Continental European influence; increasing use of qualitative methods over a wide range of topics, especially new costing methods, control system design, change and implementation, public sector transformation, and more recently risk management and creativity. Theoretical approaches have been diverse, often multi-disciplinary, and have employed surprisingly few economic theories relative to behavioural and social theories. The research spans mainly large public and private sector organisations especially in Europe. Seven themes perceived as of interest to a social and critical theory analysis are evaluated, namely: the search for ‘Relevance Lost’ and new costing; management control, the environment and the search for ‘fits’; reconstituting the public sector; change and institutional theory; post-structural, constructivist and critical contributions; social and environmental accounting; and the changing geography of time and space between European and American research. The paper concludes by assessing the contributions of MAR against the aspirations of groups identified in the opening personal historiography, which have been largely met. MAR has made substantial contributions to social and critical accounting (broadly defined) but not in critical areas endeavouring to give greater voice and influence to marginalised sectors of society worldwide. Third Sector organisations, politics, civil society involvement, development and developing countries, labour, the public interest, political economy, and until recently social and environmental accounting have been neglected

Recent Developments in Peptide-Based Nucleic Acid Delivery

Despite the fact that non-viral nucleic acid delivery systems are generally considered to be less efficient than viral vectors, they have gained much interest in recent years due to their superior safety profile compared to their viral counterpart. Among these synthetic vectors are cationic polymers, branched dendrimers, cationic liposomes and cell-penetrating peptides (CPPs). The latter represent an assortment of fairly unrelated sequences essentially characterised by a high content of basic amino acids and a length of 10–30 residues. CPPs are capable of mediating the cellular uptake of hydrophilic macromolecules like peptides and nucleic acids (e.g. siRNAs, aptamers and antisense-oligonucleotides), which are internalised by cells at a very low rate when applied alone. Up to now, numerous sequences have been reported to show cell-penetrating properties and many of them have been used to successfully transport a variety of different cargos into mammalian cells. In recent years, it has become apparent that endocytosis is a major route of internalisation even though the mechanisms underlying the cellular translocation of CPPs are poorly understood and still subject to controversial discussions. In this review, we will summarise the latest developments in peptide-based cellular delivery of nucleic acid cargos. We will discuss different mechanisms of entry, the intracellular fate of the cargo, correlation studies of uptake versus biological activity of the cargo as well as technical problems and pitfalls

2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales.

Correction to: 2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales. Archives of Virology (2021) 166:3567–3579. https://doi.org/10.1007/s00705-021-05266-wIn March 2021, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by four families (Aliusviridae, Crepuscuviridae, Myriaviridae, and Natareviridae), three subfamilies (Alpharhabdovirinae, Betarhabdovirinae, and Gammarhabdovirinae), 42 genera, and 200 species. Thirty-nine species were renamed and/or moved and seven species were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.This work was supported in part through Laulima Government Solutions, LLC prime contract with the US National Institute of Allergy and Infectious Diseases (NIAID) under Contract No. HHSN272201800013C. J.H.K. performed this work as an employee of Tunnell Government Services (TGS), a subcontractor of Laulima Government Solutions, LLC under Contract No. HHSN272201800013C. This work was also supported in part with federal funds from the National Cancer Institute (NCI), National Institutes of Health (NIH), under Contract No. 75N91019D00024, Task Order No. 75N91019F00130 to I.C., who was supported by the Clinical Monitoring Research Program Directorate, Frederick National Lab for Cancer Research. This work was also funded in part by Contract No. HSHQDC-15-C-00064 awarded by DHS S&T for the management and operation of The National Biodefense Analysis and Countermeasures Center, a federally funded research and development center operated by the Battelle National Biodefense Institute (V.W.); and NIH contract HHSN272201000040I/HHSN27200004/D04 and grant R24AI120942 (N.V., R.B.T.). S.S. acknowledges partial support from the Special Research Initiative of Mississippi Agricultural and Forestry Experiment Station (MAFES), Mississippi State University, and the National Institute of Food and Agriculture, US Department of Agriculture, Hatch Project 1021494. Part of this work was supported by the Francis Crick Institute which receives its core funding from Cancer Research UK (FC001030), the UK Medical Research Council (FC001030), and the Wellcome Trust (FC001030).S