Plate tectonics of the Altaids

Abstract: The Altaids consist in a huge accretionary-type belt extending from Siberia through Mon-golia, northern China, Kyrgyzstan and Kazakhstan. They were formed from the Vendian through the Jurassic by the accretion of numerous displaced and exotic terranes (e.g. island arc, ribbon microcontinent, seamount, basaltic plateau, back-arc basin). The number, nature and origin of the terranes differ according to the palaeotectonic models of the different authors. Thanks to a geo- dynamic study (i.e. definition of tectonic settings and elaboration of geodynamic scenarios) and plate tectonics modelling, this work aims to present an alternative model explaining the Palaeozoic palaeotectonic evolution of the Altaids. Based on a large set of compiled geological data related to palaeogeography and geodyna¬mic (e.g. sedimentology, stratigraphy, palaeobiogeography, palaeomagnetism, magmatism, me- tamorphism, tectonic...), a partly new classification of the terranes and sutures implicated in the formation of the Altaids is proposed. In the aim to elaborate plate tectonics reconstructions, it is necessary to fragment the present arrangement of continents into consistent geological units. To avoid confusion with existing terminology (e.g. tectonic units, tectono-stratigraphic units, micro- continents, terranes, blocks...), the new concept of "Geodynamic Units (GDU)" was introduced. A terrane may be formed by a set of GDUs. It consists of a continental and/or oceanic fragment which has its own kinematic and geodynamic evolution for a given period. With the same ap-proach, the life span and type of the disappeared oceans is inferred thanks to the study of the mate-rial contained in suture zones. The interpretation of the tectonic settings within the GDUs comple-ted by the restoration of oceans leads to the elaboration of geodynamic scenarios. Since the Wilson cycle was presented in 1967, numerous works demonstrated that the continental growth is more complex and results from diverse geodynamic scenarios. The identification of these scenarios and their exploitation enable to elaborate plate tectonics models. The models are self-constraining (i.e. space and time constraints) and contest or confirm in turn the geodynamic scenarios which were initially proposed. The Altaids can be divided into three domains: (1) the Peri-Siberian, (2) the Kazakhstan, and (3) the Tarim-North China domains. The Peri-Siberian Domain consists of displaced (i.e. Sayan Terrane Tuva-Mongolian, Lake-Khamsara Terrane) and exotic terranes (i.e. Altai-Mongolian and Khangai-Argunsky Terrane) accreted to Siberia from the Vendian through the Ordovician. Fol-lowing the accretion of these terranes, the newly formed Siberia active margin remained active un-til its part collision with the Kazakhstan Superterrane in the Carboniferous. The eastern part of the active margin (i.e. East Mongolia) continued to act until the Permian when the North-China Tarim Superterrane collided with it. The geodynamic evolution of the eastern part of the Peri-Siberian Domain (i.e. Eastern Mongolia and Siberia) is complicated by the opening of the Mongol-Okhotsk Ocean in the Silurian. The Kazakhstan Domain is composed of several continental terranes of East Gondwana origin amalgamated together during the Ordovician-Silurian time. After these different orogenic events, the Kazakhstan Superterrane evolved as a single superterrane until its collision with a Tarim-North China related-terrane (i.e. Tianshan-Hanshan Terrane) and Siberian Continent during the Devonian. This new organisation of the continents imply a continued active margin from Siberia, to North China through the Kazakhstan Superterrane and the closure of the Junggar- Balkash Ocean which implied the oroclinal bending of the Kazakhstan Superterrane during the entire Carboniferous. The formation history of the Tarim-North China Domain is less complex. The Cambrian northern passive margin became active in the Ordovician. In the Silurian, the South Tianshan back-arc Ocean was open and led to the formation of the Tianshan-Hanshan Terrane which collided with the Kazakhstan Superterrane during the Devonian. The collision between Siberia and the eastern part of the Tarim-North China continents (i.e. Inner Mongolia), implied by the closure of the Solonker Ocean, took place in the Permian. Since this time, the major part of the Altaids was formed, the Mongol-Okhotsk Ocean only was still open and closed during the Jurassic. Résumé: La chaîne des Altaïdes est une importante chaîne d'accrétion qui s'étend en Sibérie, Mon-golie, Chine du Nord, Kirghizstan et Kazakhstan. Elle s'est formée durant la période du Vendian au Jurassique par l'accrétion de nombreux terranes déplacés ou exotiques (par exemple arc océa-nique, microcontinent, guyot, plateau basaltique, basin d'arrière-arc...). Le nombre, la nature ou encore l'origine diffèrent selon les modèles paléo-tectoniques proposés par les différents auteurs. Grâce à une étude géodynamique (c'est-à-dire définition des environnements tectoniques et éla-boration de scénarios géodynamiques) et à la modélisation de la tectonique des plaques, ce travail propose un modèle alternatif expliquant l'évolution paléo-tectonique des Altaïdes. Basé sur une large compilation de données géologiques pertinentes en termes de paléo-géographie et de géodynamique (par exemple sédimentologie, stratigraphie, paléo-biogéographie, paléomagnétisme, magmatisme, métamorphisme, tectonique...), une nouvelle classification des terranes et des sutures impliqués dans la formation des Altaïdes est proposée. Dans le but d'élabo¬rer des reconstructions de plaques tectoniques, il est nécessaire de fragmenter l'arrangement actuel des continents en unités tectoniques cohérentes. Afin d'éviter les confusions avec la terminolo¬gie existante (par exemple unité tectonique, unité tectono-stratigraphique, microcontinent, block, terrane...), le nouveau concept d' "Unité Géodynamique (UGD)" a été introduit. Un terrane est formé d'une ou plusieurs UGD et représente un fragment océanique ou continental défini pas sa propre cinétique et évolution géodynamique pour une période donnée. Parallèlement, la durée de vie et le type des océans disparus (c'est-à-dire principal ou secondaire) est déduite grâce à l'étude du matériel contenu dans les zones de sutures. L'interprétation des environnements tectoniques des UGD associés à la restauration des océans mène à l'élaboration de scénarios géodynamiques. Depuis que le Cycle de Wilson a été présenté en 1967, de nombreux travaux ont démontré que la croissance continentale peut résulter de divers scénarios géodynamiques. L'identification et l'ex-ploitation de ces scénarios permet finalement l'élaboration de modèles de tectonique des plaques. Les modèles sont auto-contraignants (c'est-à-dire contraintes spatiales et temporelles) et peuvent soit contester ou confirmer les scénarios géodynamiques initialement proposés. Les Altaïdes peuvent être divisées en trois domaines : (1) le Domaine Péri-Sibérien, (2) le Domaine Kazakh, et (3) le Domaine Tarim-Nord Chinois. Le Domaine Péri-Sibérien est composé de terranes déplacés (c'est-à-dire Terrane du Sayan, Tuva-Mongol et Lake-Khamsara) et exotiques (c'est-à-dire Terrane Altai-Mongol et Khangai-Argunsky) qui ont été accrétés au craton Sibérien durant la période du Vendien à l'Ordovicien. Suite à l'accrétion de ces terranes, la marge sud-est de la Sibérie nouvellement formée reste active jusqu'à sa collision partielle avec le Superterrane Ka-zakh au Carbonifère. La partie est de la marge active (c'est-à-dire Mongolie de l'est) continue son activité jusqu'au Permien lors de sa collision avec le Superterrane Tarim-Nord Chinois. L'évolu¬tion géodynamique de la partie est du Domaine Sibérien est compliquée par l'ouverture Silurienne de l'Océan Mongol-Okhotsk qui disparaîtra seulement au Jurassique. Le Domaine Kazakh est composé de plusieurs terranes d'origine est-Gondwanienne accrétés les uns avec les autres avant ou pendant le Silurien inférieur et leurs evolution successive sous la forme d'un seul superterrane. Le Superterrane Kazakh collisione avec un terrane Tarim-Nord Chinois (c'est-à-dire Terrane du Tianshan-Hanshan) durant le Dévonien et le continent Sibérien au Dévonien supérieur. Ce nouvel agencement des plaques induit une marge active continue le long des continents Sibérien, Kazakh et Nord Chinois et la fermeture de l'Océan Junggar-Balkash qui provoque le plissement oroclinal du Superterrane Kazakh durant le Carbonifère. L'histoire de la formation du Domaine Tarim-Nord Chinois est moins complexe. La marge passive nord Cambrienne devient active à l'Ordovicien et l'ouverture Silurienne du bassin d'arrière-arc du Tianshan sud mène à la formation du terrane du Tianshan-Hanshan. La collision Dévonienne entre ce dernier et le Superterrane Kazakh provoque la fermerture de l'Océan Tianshan sud. Finalement, la collision entre la Sibérie et la partie est du continent Tarim-Nord Chinois (c'est-à-dire Mongolie Intérieure) prend place durant le Permien suite à la fermeture de l'Océan Solonker. La majeure partie des Altaïdes est alors formée, seul l'Océan Mongol-Okhotsk est encore ouvert. Ce dernier se fermera seulement au Jurassique.

Paediatric end-of-life care needs in Switzerland: current practices, and perspectives from parents and professionals. A study protocol.

AIM: To present a protocol for a multi-phase study about the current practice of end-of-life care in paediatric settings in Switzerland. BACKGROUND: In Switzerland, paediatric palliative care is usually provided by teams, who may not necessarily have specific training. There is a lack of systematic data about specific aspects of care at the end of a child's life, such as symptom management, involvement of parents in decision-making and family-centred care and experiences and needs of parents, and perspectives of healthcare professionals. DESIGN: This retrospective nationwide multicentre study, Paediatric End-of-LIfe CAre Needs in Switzerland (PELICAN), combines quantitative and qualitative methods of enquiry. METHODS: The PELICAN study consists of three observational parts, PELICAN I describes practices of end-of-life care (defined as the last 4 weeks of life) in the hospital and home care setting of children (0-18 years) who died in the years 2011-2012 due to a cardiac, neurological or oncological disease, or who died in the neonatal period. PELICAN II assesses the experiences and needs of parents during the end-of-life phase of their child. PELICAN III focuses on healthcare professionals and explores their perspectives concerning the provision of end-of-life care. CONCLUSION: This first study across Switzerland will provide comprehensive insight into the current end-of-life care in children with distinct diagnoses and the perspectives of affected parents and health professionals. The results may facilitate the development and implementation of programmes for end-of-life care in children across Switzerland, building on real experiences and needs. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01983852.

Development and initial validation of the Parental PELICAN Questionnaire (PaPEQu) - an instrument to assess parental experiences and needs during their child's end-of-life care.

AIM: To develop and test the Parental PELICAN Questionnaire, an instrument to retrospectively assess parental experiences and needs during their child's end-of-life care. BACKGROUND: To offer appropriate care for dying children, healthcare professionals need to understand the illness experience from the family perspective. A questionnaire specific to the end-of-life experiences and needs of parents losing a child is needed to evaluate the perceived quality of paediatric end-of-life care. DESIGN: This is an instrument development study applying mixed methods based on recommendations for questionnaire design and validation. METHOD: The Parental PELICAN Questionnaire was developed in four phases between August 2012-March 2014: phase 1: item generation; phase 2: validity testing; phase 3: translation; phase 4: pilot testing. Psychometric properties were assessed after applying the Parental PELICAN Questionnaire in a sample of 224 bereaved parents in April 2014. Validity testing covered the evidence based on tests of content, internal structure and relations to other variables. RESULTS: The Parental PELICAN Questionnaire consists of approximately 90 items in four slightly different versions accounting for particularities of the four diagnostic groups. The questionnaire's items were structured according to six quality domains described in the literature. Evidence of initial validity and reliability could be demonstrated with the involvement of healthcare professionals and bereaved parents. CONCLUSION: The Parental PELICAN Questionnaire holds promise as a measure to assess parental experiences and needs and is applicable to a broad range of paediatric specialties and settings. Future validation is needed to evaluate its suitability in different cultures.