• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 10
  • 4
  • 2
  • 1
  • Tagged with
  • 15
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The tectonic significance of the Kazerun fault zone, Zargos fold-thrust belt, Iran

Sepehr, Mohammad January 2000 (has links)
The N-S trending Kazerun Fault zone obliquely crosses the NW-SE trending Zagros fold thrust belt in southwest of Iran. This still active fault zone is an ancient structural lineament, which has controlled the structure, sedimentation and subsidence of part of the Zagros mountain belt since the Cambrian. This study presents a new interpretation of the Kazerun Fault zone, and recognises it to be made up of four north-south trending segments, termed from north to south the Sisakht, Yasuj, Kamarij and Burazjan segments respectively. The Kazerun Fault limited the distribution of the Cambrian Hormuz salt with considerable thickness forming to the east of the fault (i.e. in the Fars region) and little or none to the west (i.e. in the Dezful Embayment). This thick salt layer decouples the cover rocks from the basement structures. The salt significantly reduces the cohesion and frictional resistance at the base of the sedimentary cover and enables deformation to the east of the fault to propagate 100km further to the southwest than in the Dezful Embayment to the west. This basal decollement and the rheological differences in the cover rocks each side of the Kazerun Fault is the reason for the arcuate plan view of the fold-thrust belt in the Fars region. There is a remarkable difference in the distribution of deformation in the cover rocks in the two regions which are separated from each other by the Kazerun Fault zone. The Sisakht, Kamarij and Burazjan segments of the Kazerun Fault acted as lateral ramps linking the three major Zagros deformation fronts, the High Zagros, the Mountain Front and the Zagros Frontal Faults respectively. These segments are characterised by huge vertical displacements with downthrow to the west. However, it is argued that the Yasuj segment only became active relatively lately, during the folding and unlike the other segments did not control the post collision sedimentation of the Zagros. A study of the digital elevation model of the Sarbalesh anticline (formed by combination of aerial photographs, the TM satellite image and topographic maps) and field data were used to analyse this anticline and its associated structures. It is suggested that synchronous folding and faulting (both thrusting and normal faulting) occurred during the formation of this boomerang shaped anticline which is situated in the junction between the Kamarij segment of the Kazerun Fault and a segment of the Mountain Front Fault. A detailed review of the sedimentation of the Iranian sector of the Zagros fold-thrust belt reveals the structural evolution of the Kazerun Fault and other major structural elements of the Zagros and shows the intimate interplay between sedimentation and tectonics. The Zagros basin experienced rifting during the Permo-Trias and the resulting horsts and grabens had a NW-SE trend i.e. parallel to the present mountain belt. These structures controlled the subsidence of the basin during this period. During the Jurassic-Early Cretaceous the area corresponding to the present day Kazerun and Izeh Fault zones was the site of transition between the two entirely different basins which occupied the Fars and Lurestan regions. Important movements along the Kazerun-Izeh Fault zone in the Mid-Cretaceous produced a series of N-S trending horst and graben structures which are marked by significant sedimentary change across them. During the Tertiary the NW-SE trending Mountain Front Fault (i.e. introduced in this study) was the major deformation front, controlling the deposition and geometry of the Zagros foreland and piggyback basins to the southwest and northeast of the fault respectively. The different deformational styles of the cover rocks in the Zagros (e.g. on either side of the Kazerun Fault zone), relates to inherited basement structures, the different rheological profiles and particularly, the presence and position of the detachment horizons within the cover rocks. In fact, these differences are mainly the result of activity along the Kazerun Fault in the Cambrian, the Kazerun-Izeh Fault in the Jurassic- Cretaceous and the Mountain Front Fault in the Tertiary. It is also argued that Zagros anticlines (the major hydrocarbon traps in the Zagros) are the result of different mechanisms. These include classical buckle folds, en echelon folds along strike-slip faults and fault related folds above thrusts and reactivated normal faults. These differences related directly to the rheological profile of the cover rocks which was controlled by activity along the Kazerun, Jzeh, Bala Rud and Mountain Front Faults. Based on this study a clearer picture of the interplay between structures, sedimentation and deformation of the Zagros fold-thrust belt has emerged. This makes it appropriate to revise the entire Zagros belt from the point of view of new hydrocarbon targets, which include folds, faults and sedimentary traps.
2

Metamorphism, melting and extension at the top of the high Himalayan slab, Mount Everest region, Nepal and Tibet

Simpson, Robert Luke January 2002 (has links)
No description available.
3

Syllable-based constraints on properties of English sounds

January 1990 (has links)
Mark A. Randolph. / Also issued as Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1989. / Includes bibliographical references (p. 169-174). / Work sponsored in part by the Office of Naval Research. N00014-82-K-0727
4

傅奕《道德經古本篇》硏究. / 傅奕道德經古本篇硏究 / Fu Yi "Dao de jing gu ben pian" yan jiu. / Fu Yi Dao de jing gu ben pian yan jiu

January 2002 (has links)
黃俊文. / "2002年7月" / 論文 (哲學碩士)--香港中文大學, 2002. / 參考文獻 (leaves 158-175) / 附中英文提要. / "2002 nian 7 yue" / Huang Junwen. / Lun wen (zhe xue shuo shi)--Xianggang Zhong wen da xue, 2002. / Can kao wen xian (leaves 158-175) / Fu Zhong Ying wen ti yao. / 緒論 --- p.1-2 / Chapter 第一章: --- 傅奕生平考訂 --- p.3-24 / Chapter 1. --- 籍貫 / Chapter 2. --- 生卒年 / Chapter 3. --- 家貧及爲道士 / Chapter 4. --- 仕宦 / Chapter 5. --- 小結 / Chapter 第二章: --- 《道德經古本篇》成書考 --- p.25-36 / Chapter 1. --- 傅奕所見的《道德經》版本 / Chapter 2. --- 《道德經古本篇》成書考 / Chapter 第三章: --- 傅奕本的流傳 --- p.37-44 / Chapter 第四章: --- 《道德經古本篇》避諱考 --- p.45-79 / Chapter 1. --- 引言 / Chapter 2. --- 隋唐諱 / Chapter 3. --- 魏晉南北朝諱 / Chapter 4. --- 漢諱 / Chapter 5. --- 秦諱 / Chapter 第五章: --- 《道德經古本篇》異文硏究 --- p.80-130 / Chapter 第六章: --- 傅、范本關係硏究 --- p.131-155 / 總結 --- p.156-157 / 參考書目 --- p.158-175 / 附錄 --- p.176-178
5

Paléodrainage, paléoenvironnements et paléoclimats de l'Éocène birman : implications sur l'origine et l'évolution précoce des anthropoïdes asiatiques / Paleodrainage, paleoenvironments and paleoclimate of the Burmese Eocene series : implications on the origin and the early evolution of Asian anthropoids

Licht, Alexis 26 November 2013 (has links)
Les plus anciens anthropoïdes fossiles sont issus de plusieurs formations géologiques asiatiques de l'Eocène moyen à tardif (47 à 34 millions d'années), parmi lesquelles la formation de Pondaung (Birmanie) a délivré la faune la plus diverse. L'objectif de cette thèse est de reconstituer la paléogéographie, l'environnement et le climat de l'Eocène birman afin de mieux comprendre leur histoire évolutive. Dans un premier temps, l'évolution de la provenance du sédiment de Birmanie centrale a été étudiée par une approche alliant pétrographie, lithostratigraphie et géochimie isotopique. L'étude montre que la Birmanie centrale est restée à l'écart de tout apport sédimentaire himalayen et tibétain et formait, à l'Eocène, une bande côtière connectant l'avant-pays indien avec la région de la Sonde. Les paléoenvironnements de la formation de Pondaung ont ensuite été reconstitués par une approche combinant sédimentologie fluviale, pédologie et paléobotanique. Ces approches révèlent un paysage de marécages saisonniers, de forêts ripariennes et d'espaces ouverts, développés sous un climat tropical à forte saisonnalité. Les bois fossiles identifiés représentent différents écotones forestiers similaires à ceux des forêts de mousson actuelles. L'étude en isotope stable de gastéropodes fossiles et de dents de mammifères confirme un régime de précipitation semblable à la mousson moderne. Les paléoenvironnements de Pondaung contrastent avec l'idée d'épaisses forêts primaires comme habitat préférentiel des premiers anthropoïdes et lient leur biodiversité aux zones tropicales saisonnières, où les plus grosses espèces, comme les amphipithécidés, étaient particulièrement compétitives. / The fossil record of the first anthropoids is currently fed by several Middle to Late Eocene Asian strata (47 to 34 millions years ago), of which the Pondaung Formation in Myanmar has yielded the most diverse and prolific fauna. The aim of this PhD is to reconstruct the paleogeography, paleoenvironments, and paleoclimate of the Eocene Burmese successions in order to better constrain the early evolutionary history of the anthropoids. The sediment provenance of central Myanmar was first studied using a multi-proxy approach, combining petrography, sedimentology and isotope geochemistry. Results show that central Myanmar was isolated from any Himalayan or Tibetan input and additionally formed a narrow coastal band linking the Indian foreland with the Sunda area during the Eocene. Alluvial palaeoenvironments of the Pondaung Formation were then reconstructed through a combined sedimentological, pedological and paleobotanical approach. Results revealed a mosaic landscape with seasonal swamps, riparian forests, and open areas, expanding under a tropical climate with significant seasonality. Fossil woods form different ecotones similar to those of modern days monsoonal forests. Paleoclimate reconstruction through stable isotope geochemistry on mammalian fossil teeth and fossil gastropods confirms a monsoonal, modern-like rainfall regime in the Eocene. Pondaung paleoenvironments contrast with the idea of Eocene evergreen rainforests as a preferential living environment for the first anthropoids and link the Eocene biodiversity of anthropoid fauna to the tropical seasonal areas, where the biggest species, such as the amphipithecids, were particularly competitive.
6

Acute Effects Of Local Vibration On Muscle Performance At Different Durations And Frequencies

Yildirim, Ahmet 01 September 2010 (has links) (PDF)
The purpose of the present study was to investigate the acute effects of local vibration on muscle performance at different durations and frequencies. Fifteen male handball players participated in the study voluntarily. University&rsquo / s Ethics Committee approved the study and the informed consent forms were filled by all participants. Different vibration durations, (10 sec, 1 min, 10 min), different frequencies (40 and 80 Hz), dominancy (dominant and non-dominant) and conditions (vibration and no-vibration) were independent variables of study. Dependent variables were maximum isometric strength measures under different situations. One way Repeated measures ANOVA, Bonferoni adjusted paired sample t-tests and Two way Repeated ANOVA was used for statistical analyses. Result of this study demonstrated that local vibration (LV) induced significantly higher muscle activity than no vibration (NV) condition. Strength improvements were obtained in quadriceps muscles of dominant and non-dominant legs for 40 Hz and 80 Hz. When 40 Hz vibration was applied to dominant leg with different durations (10 sec, 1 min, 10 min), significantly higher strength measures were found than no vibration. When 80 Hz vibration was applied to dominant leg with different durations (10 sec, 1 min, 10 min), only 10-sec vibration duration revealed significant increase in strength measures. When 40 Hz vibration was applied to non-dominant leg with different durations, (10 sec, 1 min, 10 min) significantly higher strength measures were found than no vibration. When 80 Hz vibration was applied to non-dominant leg with different durations (10 sec, 1 min, 10 min), 10-sec and 1 min vibration durations revealed significant increase in strength measures. However, no significant difference was obtained when the different vibration durations were compared between 40 Hz and 80 Hz.
7

Origine sédimento-diagénétique de réservoirs carbonatés microporeux : exemple de la formation Mishrif (Cénomanien) du Moyen-Orient / Sedimento-diagenetic origin of microporos carbonate reservoirs : example of the Mishrif (Fm) -Cenomanian of the Middle-East

Deville de Periere, Matthieu 30 June 2011 (has links)
La microporosité représente jusqu'à 95% de la porosité totale des réservoirs à hydrocarbures et des aquifères dans les calcaires crétacés du Moyen-Orient. Dans ces sédiments microporeux, la porosité est modérée à excellente (jusqu'à 35%), tandis que la perméabilité est faible à modérée (jusqu'à 190mD). A l'inverse, mes faciès microporeux peuvent former des niveaux denses, avec de très faibles porosité et perméabilité (respectivement 2–8% et 0,01–2mD). Dans ce travail, les échantillons proviennent essentiellement de la Formation Mishrif (Cénomanien), mais aussi de la Formation Habshan (Berriasien/Valanginien), afin d'examiner les grandes différences verticales et latérales des propriétés pétrophysiques. Le MEB a été utilisé pour étudier deux contrôles potentiels des qualités réservoir : (1) la morphologie des particules micritiques (forme et contacts intercristallins), et (2) la cristallométrie des micrites, définie comme la taille médiane des particules mesurées sur les clichés MEB. Les données morphométriques ont été comparées avec trois paramètres pétrophysiques (porosité, perméabilité, distribution des rayons de seuil de pore). Les résultats montrent que les matrices micritiques peuvent être subdivisées en trois classes pétrophysiques. La Classe C (micrites strictement microporeuses avec des cristaux grossiers ayant des contacts punctiques à partiellement coalescents) est composée de particules grossières (>2µm), polyhédrales à arrondies. Elle présente des porosités bonnes à excellentes (8-28%), des perméabilités faibles à modérées (0,2-190mD), et des rayons de seuils de pores (PTR) moyens supérieurs à 0,5µm. Cette Classe C est généralement observée dans les shoals bioclastiques riches en rudistes, où de nombreux facteurs sédimentaires (hydrodynamisme…) peuvent défavoriser le dépôt des particules les plus fines. L'étude diagénétique montre que ces micrites grossières peuvent aussi être expliquées par une dissolution précoce des fines particules d'aragonite et de HMC dans des fluides météoriques oxydants, permettant la formation in-situ de surcroissances sur les particules de LMC au sommet de la nappe phréatique météorique. Ces processus induisent une augmentation de la taille des particules micritiques, une lithification précoce de la boue carbonatée, et donc une stabilisation minéralogique précoce des micrites grossières de la Classe C. La Classe F (micrites strictement microporeuses avec des cristaux fins ayant des contacts punctiques à partiellement coalescents, est composée de particules fines (<2µm), polyhédrales à arrondies. Elle présente des porosités bonnes à excellentes (3-35%), mais des valeurs de perméabilité souvent inférieures à 10mD, et des PTR inférieurs à 0,5µm. Cette Classe F est souvent observée dans les sédiments déposés en domaine de plate-forme interne boueuse. La formation de ces micrites fines est aussi expliquée par une stabilisation minéralogique précoce des particules micritiques dans des eaux météoriques confinées, favorisant les processus de néomorphisme, pouvant continuer au cours de l'enfouissement. Plus tard, au cours de l'enfouissement de la série, les qualités réservoirs des Classes C et F sont localement améliorées par de la dissolution mésogénétique (probablement liée à des acides organiques) affectant la matrice micritique durant la mise en charge des réservoirs. La Classe D est formée par des matrices micritiques denses, composées de cristaux anhédraux ou subhédraux avec des contacts fusionnés. Elle présente de très faibles données de porosité et de perméabilité. Ces micrites sont uniquement observées dans les niveaux de plate-forme interne et forment des intervalles inter-réservoirs, généralement en association avec des stylolites et un contenu argileux important, pouvant dépasser 10%. Quelque soit leur mode de formation, ces trois classes peuvent être incorporées dans les futures études de rock-typing portant sur les réservoirs carbonatés microporeux du Moyen-Orient / Microporosity may account for as much as 95% of the total porosity of hydrocarbon and water reservoirs in Cretaceous limestones of the Arabian Gulf. In these microporous facies porosity is moderate to excellent (up to 35%) while permeability is poor to moderate (up to 190mD). Conversely, microporous facies may form dense inter-reservoir or cap rock layers with very low porosity and permeability values (2–8% and 0.01–2mD, respectively). For this study, samples were mainly collected from the Cenomanian Mishrif Formation, but also from the Berriasian-Valanginian Habshan Formation, so as to examine the wide vertical and lateral discrepancies in their petrophysical parameters. Scanning Electron Microscopy was used to investigate two potential controls of reservoir properties: (1) micrite particle morphology (shape and inter-crystal contacts); and (2) micrite crystallometry, defined as the median size of micrite particles measured on SEM photomicrographs. The morphometric data are compared with three petrophysical parameters (porosity, permeability and pore threshold radius distribution). Results reveal that micrite matrixes can be subdivided into three petrophysical classes each with its own distinctive crystallometry, morphology and reservoir properties. Class C (strictly microporous limestones with coarse punctic-to-partially coalescent micrites) is made up of coarse (>2µm) polyhedral to rounded micritic crystals, it has good to excellent porosity (8–28%), poor to moderate permeability (0.2–190mD) and a mean pore threshold radius of more than 0.5µm. The class C is usually observed in rudist-rich bioclastic shoal facies where several sedimentary factors (hydrodynamism, bioproduction …) would disfavour deposition of the finer micritic crystals. Diagenetic study shows that the development of coarse micrites (Class C) must also be explained by the early dissolution of fine aragonite and high magnesium calcite particles in oxygenated meteoric fluids leading to a simultaneous in-situ overgrowth on LMC particles at the top of the meteoric phreatic lens. These processes induce an increase of the crystallometry of micritic particles, an early lithification of the carbonate mud, and so the mineralogical stabilization of coarse Class C micrites. Class F (strictly microporous limestones with fine punctic-to-partially coalescent micrites) is composed of fine (<2µm) polyhedral to rounded micrites with poor to excellent porosity (3–35%), but permeability values of less than 10mD and a mean pore threshold radius of less than 0.5µm. It is mostly observed in sediments deposited in a low energy muddy inner platform setting. The formation of fine micrites (Class F) is also explained by an early mineralogical stabilization of micritic particles in confined meteoric waters, favoring neomorphism processes, which may proceeds during burial. Later, during burial, reservoir properties of classes C and D strictly microporous samples where locally enhanced by mesogenetic dissolution (probably due to organic acids) affecting the microporous matrix during the oil emplacement. Class D (strictly microporous mud-dominated facies with compact anhedral to fused dense micrites) comprises subhedral to anhedral crystals with sutured to fused contacts forming a dense matrix. It has very low porosity and permeability. Class D is only found in low energy muddy inner platform facies and forms inter-reservoir or caps rock layers usually in association with stylolites and clay contents that exceed 10%. Regardless of how they formed, though, the three classes can be usefully incorporated into future rock-typing of the microporous carbonate reservoirs of the Middle East
8

Variability of the precipitation and moisture sources of the Tianshan Mountains, Central Asia

Guan, Xuefeng 15 August 2023 (has links)
Das Tianshan-Gebirge, als „Wasserturm“ Zentralasiens, hat entscheidenden Einfluss auf die Wasserressourcen der Region. Untersuchungen von 1950 bis 2016 zeigen, dass der Jahresniederschlag in den meisten Teilen des Gebirges zunahm, außer im westlichen Tianshan, wo er abnahm. Es gibt hoch- und niedrigfrequente Schwankungen im Niederschlag mit 3-, 6-, 12- und 27-jährigen Quasiperioden. Auf Dekadenskala gab es zwei Trockenperioden (1950–1962, 1973–1984) und zwei Feuchtperioden (1962–1972, 1985–2016). Seit 2004 ist eine kontinuierliche Feuchtezunahme zu verzeichnen. Zusammenhänge wurden zwischen Zirkulationsmustern und dem Niederschlag identifiziert. Das East Atlantic-West Russia (EATL/WRUS)-Muster korreliert positiv mit dem Winter-Niederschlag. Das Scandinavia (SCAND)-Muster beeinflusst den Sommerniederschlag. Das Silk Road-Muster (SRP) war im Zeitraum 1964-1984 relevant. Die Feuchtigkeitsquellen für den Tianshan-Niederschlag stammen zu 93,2% von kontinentalen Quellen und nur begrenzt aus dem Ozean. Zentralasien ist die Hauptfeuchtequelle für das Gebirge. Im westlichen Tianshan kommt die Feuchtigkeit hauptsächlich von Zentralasien von April bis Oktober und von Westasien von November bis März. Im östlichen Tianshan tragen Ost- und Südasien sowie Sibirien konstant zur Feuchtigkeit im Sommer bei. Der Beitrag der Feuchtigkeit aus dem Nordatlantik zum Sommerniederschlag im nördlichen, zentralen und östlichen Tianshan zeigt einen abnehmenden Trend, obwohl dieser Beitrag ohnehin begrenzt ist. In Monaten mit extremem Winterniederschlag stammt die größte Zunahme der Feuchtigkeit im westlichen Tianshan aus Westasien, während Europa einen wichtigen Beitrag zu den extremen Winterniederschlägen im nördlichen Tianshan leistet. Im östlichen Tianshan ist die Feuchtigkeitszufuhr aus Ost- und Südasien sowie aus Sibirien während der extremen Niederschlagsmonate sowohl im Winter als auch im Sommer erhöht. / The Tianshan Mountains, the "water tower" of Central Asia, are crucial water sources. Precipitation variability and water vapor transport impact water distribution. The study assessed 1950-2016 precipitation using Mann-Kendall tests and EEMD on GPCC data. Multi-timescale precipitation variations were analyzed with NCEP/NCAR reanalysis, and moisture sources during 1979–2017 with ERA–Interim data. Most of Tianshan had increasing annual precipitation, except Western Tianshan, which experienced a downtrend. Precipitation exhibited 3- and 6-year cycles and 12- and 27-year cycles. On the decadal scale, two dry and two wet periods occurred, with continuous humidification since 2004. A significant positive correlation was found between East Atlantic-West Russia EATL/WRUS circulation pattern and winter precipitation. SCAND influenced Tianshan's summer precipitation, with a wet period after 1988 due to enhanced water vapor flux. SCAND and EAP strengthened water vapor fluxes to Tianshan. SRP impacted Tianshan's summer precipitation during 1964–1984. About 93.2% of Tianshan's moisture comes from continental sources. Central Asia dominates moisture supply. Western Tianshan receives moisture mainly from Central Asia (April to October) and Western Asia (November to March). Almost 13.0% of Eastern Tianshan's summer moisture originates from East and South Asia and Siberia, with steady contributions. Moisture from the North Atlantic Ocean to summer precipitation in Northern, Central, and Eastern Tianshan shows a decreasing trend, but limited overall contribution. Extreme winter precipitation in Western Tianshan is linked to moisture from West Asia. Europe significantly contributes to extreme winter precipitation in Northern Tianshan. Eastern Tianshan sees enhanced moisture from East and South Asia and Siberia during extreme precipitation months in winter and summer.
9

L'évolution tectonique du Paléozoïque supérieur de la ceinture orogénique de l'Asie centrale du Centre-Oriental de la Mongolie intérieure / The Late Paleozoic tectonic evolution of Central Asian orogenic belt in Central-Eastern inner Mongolia

Zhao, Pan 17 October 2014 (has links)
Le Centre-Est de la Mongolie intérieure, faisant la partie sud-est de la Ceinture Orogénique de l'Asie Centrale (CAOB), est une zone de clé pour étudier l'histoire de l’accrétion-collision entre la Chine du Nord (NCC) et les blocs continentaux du Nord. Les contraintes du cadre tectonique et de la connaissance de l’évolution tectonique sont importantes pour comprendre l’accrétion de la CAOB car il n’y a pas de consensus sur le mode et la période de l'accrétion entre NCC et les blocs du Nord. Par conséquent, des études pluridisciplinaires ont été effectuées sur les roches sédimentaires et magmatiques du Paléozoïque supérieur dans le centre-oriental de la Mongolie Intérieure. Sur la base de nos études sédimentologiques, géochronologiques, géochimiques et paléomagnétiques, et compte tenu des résultats précédents en pétrographie, géochimie et paléontologie, l'évolution sédimentaire et tectonique du Paléozoïque supérieur du Centre-Oriental de la Mongolie Intérieure a été bien établie. Les études détaillées en sédimentologie et géochimie montrent une transition entre les dépôts molassiques du Dévonien à la dénudation du Carbonifère inférieur et les sédiments marins du Carbonifère supérieure vers les dépôts de bassin d'extension au Permien. D’après nos analyses détaillées des faciès sédimentaires, des caractéristiques géochimiques des roches magmatiques et nos données paléomagnétiques, nous proposons un modèle géodynamique de subduction-collision-extension post-orogénique pour le Paléozoïque au Centre-Oriental de la Mongolie Intérieure. / Central-eastern Inner Mongolia, located in the southeastern part of the Central Asian Orogenic Belt (CAOB), is a key area to study the collisional-accretionary history between the North China Craton (NCC) and the northern continental blocks. The establishment of precise constraints of this tectonic framework and evolutional history are important to understand the accretion of CAOB. However, no any consensus has been achieved about the way and the timing of the accretion between NCC and the northern blocks. Therefore, multidisciplinary studies have been carried out on the Late Paleozoic strata and magmatic rocks in central-eastern Inner Mongolia. Based on our sedimentological analyses, detrital zircon geochronological constraints, geochemical studies and paleomagnetic investigations, integrating the previous results in petrology, geochemistry and paleontology, the Late Paleozoic sedimentary-tectonic evolution of the central-eastern Inner Mongolia has been established. Detailed sedimentological and geochemical studies show a transition from the Devonian molassic deposits to the Early Carboniferous denudation and from the Late Carboniferous inland-sea sediments to the Permian extensional basin deposits. According to the comprehensive analyses on sedimentary facies, geochemical characteristics and paleomagnetic data, we propose a Paleozoic subduction-collision- post-orogenic extension tectonic model for central-eastern Inner Mongolia.
10

Magnétisme des villes circulaires du troisième millénaire avant J.C dans les marges arides de la Syrie / Magnetism of circular cites trom the third millenia B.C. in the dryland ot Syria

Alkhatib-Alkontar, Rozan 04 September 2015 (has links)
À l’heure actuelle, la prospection magnétique est reconnue comme une méthode efficace pour répondre à des problématiques archéologiques en partie du fait de sa capacité à détecter les structures enfouies (bâtiments, fosses, canaux, etc,…). Elle permet de mettre en évidence et de localiser avec précision les structures et elle est donc une aide précieuse avant le début des opérations de fouilles. Notre travail rend compte de cartographies magnétiques effectuées sur trois sites archéologiques en Syrie (Al-Rawda, Sh’airat, Malhat Ed-Deru) en utilisant deux méthodes de cartographie magnétique à différents niveaux de résolution. La première méthode (à la perche) permet de couvrir de grandes surfaces rapidement et la deuxième méthode (à la luge), plus lente, permet de mieux imager les structures enfouies. Ces méthodes fournissent des plans urbanistiques des villes circulaires du troisième millénaire avant J.C. Les opérateurs de méthodes potentielles et la modélisation ont permis de caractériser la géométrie des structures aimantées. / Currently, magnetic surveying is recognized as an effective method to address archaeological issues in part because of its ability to detect buried structures (buildings, pits, channels, etc ...). It allows identifying and accurately locating structures and is therefore a valuable aid before the commencement of excavation. Our work reports on magnetic mapping done at three archaeological sites in Syria (Al-Rawda, Sh’airat, Malhat Ed-Deru) using two methods of magnetic mapping at different levels of resolution, The first method (Backpack) allows to cover large areas quickly and the second method (Sledge), slower, allows better imaging of buried structures. These methods have provided urban planning circular cities of the third millennium BC. The modeling method swapped to characterize the magnetic sources.

Page generated in 0.4129 seconds