Introduktion: Sjukfrånvaron i Sverige är hög och kunskap om vad som påverkar återgång i arbete efter sjukskrivning behöver utvecklas. I processen kring återgång i arbete är bedömning av arbetsförmåga en viktig del. Bristen på valida, reliabla och teoretiskt förankrade bedömningsinstrument inom området är dock ett bekymmer eftersom tillförlitliga bedömningar av arbetsförmåga är en förutsättning för utformning och genomförande av interventioner för att stödja återgång i arbete. Denna typ av interventioner kräver multidisciplinär kompetens där arbetsterapeuter utgör en viktig funktion. Vid bedömning av arbetsförmåga bör personens subjektiva uppfattning om sin situation beaktas, då den har betydelse för utfallet av återgång i arbete. Worker Role Interview (WRI) och Work Environment Impact Scale (WEIS) är två arbetsrelaterade intervjuinstrument, som har utvecklats i syfte att bedöma subjektiva psykosociala och miljömässiga faktorers påverkan på arbetsförmåga. Den teoretiska grunden till WRI och WEIS är Model of Human Occupation, som är en modell med fokus på aktivitetsutförande i relation till psykosociala faktorer. Inledande prövningar av WRI och WEIS reliabilitet och validitet har genomförts. Bedömningsinstrumenten har bearbetats och översatts till svenska och används främst av arbetsterapeuter, som arbetar med personer med arbetsrelaterad problematik. Syfte: Det övergripande syftet med avhandlingen är att undersöka användbarheten av bedömningsinstrumenten Worker Role Interview och Work Environment Impact Scale för identifiering av psykosociala och miljömässiga rehabiliteringsbehov av betydelse för återgång i arbete. Metod: Avhandlingen består av fem empiriska studier. I samtliga studier har erhållen information bearbetats kvantitativt. I studie IV har även kvalitativ bearbetning genomförts. Studie I, II och IV är tvärsnittsstudier och studie II och V är två års longitudinella studier. I studie I samlades information in via enkät. I studie II, III och V bestod den huvudsakliga informationen av skattningar utifrån WRI variabler och i studie IV var bedömningar utifrån WEIS i form av skattningar och nedskrivna kommentarer till skattningarna den huvudsakliga informationen. Resultat: I studie I undersöktes vilka teoretiska utgångspunkter och professionsspecifika modeller arbetsterapeuter i Sverige ansåg påverka den psykiatriska vården och den psykiatriska arbetsterapin. Det psykosociala perspektivet var den teoretiska utgångspunkt som hade störst påverkan både på psykiatrisk vård och på psykiatrisk arbetsterapi. Den arbetsterapeutiska modell som flest identifierade var Model of Human Occupation. Detta resultat indikerar att Model of Human Occupation verkar vara användbar inom arbetsterapi och motiverade vidare användning av modellen i denna avhandling. Det som dock också framkom i studie I var att arbetsterapeuter inom psykiatrisk vård använde professionsspecifika modeller i en relativt liten utsträckning. Ett sätt att öka tillämpningen av teori i praktik är att använda teoretiskt grundade bedömningsinstrument. I studie II, III, IV och V har endera av de Model of Human Occupation- baserade bedömningsinstrumenten WRI och WEIS använts och värderats. I studie II och V prövades WRI:s förmåga att predicera återgång i arbete efter långvarig sjukskrivning. Det område i WRI som uppvisade bäst prediktivitet var området ”Självuppfattning” vars variabler beaktar personens motivation för återgång i arbete i form av personens upplevelse av kompetens och effektivitet för att utföra arbetsuppgifter och hantera utmaningar i arbetet. De två WRI variabler som bäst kunde predicera vilka som skulle återgå respektive inte återgå i arbete vid uppföljning efter två år var: ”Tro på sin arbetsförmåga”, och ”Dagliga vanor och rutiner”. Resultaten tyder på att kunskap om hur tro på den egna förmågan stärks och kunskap om dagliga vanor och rutiners påverkan på utförande av arbete är central vid genomförande av interventioner i syfte att stödja personer att återgå till arbete efter sjukskrivning. I studie III prövades WRI:s konstrukturella validitet i en internationell studie. Samtliga variabler i WRI, förutom de som tillhör miljöområdet, uppvisade en god konstrukturell validitet dvs mätte psykosociala faktorers påverkan på arbetsförmågan. WRI:s skattningsskala verkar stabil och valid mellan olika länder och för personer med olika diagnoser. I analysen framkom att WRI kunde särskilja mellan personers psykosociala arbetsförmåga på tre olika nivåer. I studie IV undersöktes hur personer med erfarenhet av långtidssjukskrivning uppfattar att faktorer i arbetsmiljön stödjer respektive hindrar personens utförande av arbete och välbefinnande genom bedömningar utifrån WEIS. De faktorer som uppfattades som mest stödjande var olika former av sociala interaktioner på arbetet samt uppfattningen om arbetets värde och mening. De faktorer som uppfattades som mest hindrande var olika krav i relation till arbetsgenomförandet samt den belöning som erhålls för arbetet. Konklusion: Sammanfattningsvis så kan WRI användas för bedömning av psykosociala faktorers påverkan på arbetsförmågan. I WRI ingår variabler som kan predicera återgång till arbete upp till två år efter genomförd bedömning. WEIS verkar användbart för att identifiera arbetsmiljöfaktorer som stödjer respektive hindrar personers välbefinnande och utförande av arbete. Att komplettera olika datainsamlingsmetoder är en förutsättning för att uppnå en så god bedömning av arbetsförmåga som möjligt. Den information som WRI- och WEISintervjuer genererar är värdefull, då den kan utgöra en viktig grund för planering av individspecifika rehabiliteringsinsatser. Bedömningsinstrumenten WRI och WEIS med sin teoretiska förankring i Model of Human Occupation kan anses vara användbara för att identifiera psykosociala och miljömässiga rehabiliteringsbehov i syfte att stödja personer i processen åter till arbete efter sjukskrivning. / Introduction: In Swedish society the sick-leave rate is high and a better understanding is required of the factors that facilitate return to work. In the return to work process, assessments of peoples’ work ability play an important role. However, the lack of usable, valid, reliable, and theoretically sound assessment instruments for assessing work ability is a concern. Credible and theoretically sound assessment methods for assessing clients’ work ability strengthen the possibilities for making valid interpretations and obtaining important information for composing further intervention strategies which can guide suitable interventions in the process of returning to work. Such interventions need multi-professional expertise. In this area occupational therapists can offer valuable contribution. In the overall assessment of work ability the unique individual’s subjective perception of the situation needs to be considered since this has been found greatly relevant for return to work. The Worker Role Interview (WRI) and the Work Environment Impact Scale (WEIS) are two work-related interview assessment instruments that have been developed to assess subjective psychosocial and environmental factors of work ability. The WRI and the WEIS have been primarily tested for reliability and validity and are theoretically founded in the Model of Human Occupation (MOHO), which is an occupation-focused model addressing psychosocial factors. They have been adapted and translated to Swedish and are used among Swedish occupational therapists working with clients experiencing work-related problems. Aim: The overall aim of this thesis was to evaluate the usefulness of the assessment instruments the Worker Role Interview and the Work Environment Impact Scale for identifying psychosocial and environmental rehabilitation needs essential for returning to work. Methods: Five empirical studies were performed, all of which were analysed quantitatively, with the exception of study IV in which both qualitative and quantitative analysing methods were used. Studies I, III and IV were cross-sectional while studies II and V were two-year longitudinal studies. In study I, data were collected by a questionnaire, in studies II, III and V the primary data constituted of ratings on the WRI items. In study IV the primary data were ratings of the WEIS items and the written notes beside the rating on each item. Results: In study I, theoretical approaches and professional models that influenced psychiatric care and psychiatric occupational therapy practice among occupational therapists in Sweden was investigated. The most common approach in psychiatric care was the psychosocial approach, and the practice model which was most often used was the Model of Human Occupation. The results indicated that the psychosocial approach and the Model of Human Occupation seemed applicable in occupational therapy, motivating further use of that model. However, it was also found that occupational therapists in psychiatric care used professional practice models to a rather low extent. One way to enhance the application of theory into practice is the use of theory- based assessment instruments. Consequently, the Model of Human Occupation- based assessment instruments, the WRI and the WEIS, have been evaluated and used in the other studies in the present thesis The value of the WRI for predicting return to work after long term sick-leave was investigated in studies II and V. The content area in the WRI with best overall predictive validity for return to work was ‘Personal causation’. Its items focus on the individual’s motivation for return to work in relation to the individual’s feeling of competence and effectiveness in doing work tasks and facing challenges at work. The two WRI items which best predicted whether the participants would be in the working or the non-working groups at the two-year follow up were ‘Expectations of job success’, which concerns beliefs in personal abilities in relation to returning to work, and the item ‘Daily routines’ which concerns the individual’s routines and organisation of time outside work. These results suggest that knowledge about how to strengthen the person’s belief in his or her abilities, how routines impact occupational performance, and how to support the individual in structuring his or her daily doings are needed in interventions aiming at supporting the individual to return to work. In study III the construct validity of the WRI was investigated in an international study. All the WRI items except those related to the environment area seemed to capture the intended construct of the WRI, namely psychosocial ability for return to work. The construct of the WRI seems to be stable and valid across different countries and populations, and the WRI showed an ability to separate clients into three distinct levels of psychosocial ability for return to work. In study IV the impact of the work environment was investigated by using the WEIS among people with experiences of sick-leave. Social interactions at work and the meaning of the work had the most supportive impact and different work demands and the rewards received for the work were perceived as most interfering with work performance, well-being, and satisfaction. Conclusion: The WRI seems to be suitable for estimating psychosocial work ability. In addition it contains items which can predict return to work up to two years after the assessment is conducted. The use of the WEIS revealed supportive and interfering factors for work performance, well-being, and satisfaction among people with experiences of long term sick-leave. The interview format of the WRI and the WEIS seems valuable since it provides comprehensive information which can contribute to the planning of rehabilitation interventions for the unique client. Thus, the WRI and the WEIS, which are theoretically founded in the Model of Human Ocupation are juged to be useful for identifying psychosocial and environmental rehabilitation needs in order to support the individual in returning to work after sick-leave.

Les surfaces à très faible relief localisées en altitude, observées dans un certain nombre de chaîne de montagnes, sont classiquement interprétées comme des reliques de pénéplaines post-tectoniques. Leur altitude est souvent interprétée comme une quantification directe du soulèvement de la surface terrestre. Une interprétation alternative récente propose que ces surfaces soient les reliques d’une pénéplaine qui se développe en altitude en raison de la remontée progressive du niveau de base efficace du système de drainage des chaînes de montagnes et de l’inhibition consécutive de l’érosion de celles-ci au cours de leur construction. Les deux interprétations impliquent des dynamiques lithosphériques radicalement différentes. Cette étude porte sur l’exemple emblématique de la chaîne des Pyrénées, où ces deux hypothèses du développement de la pénéplaine pyrénéenne du Miocène moyen sont toujours confrontées. Dans un premier temps, une nouvelle méthodologie de cartographie a été développée pour reconstituer la morphologie de la chaîne à cette époque à partir des surfaces à faible relief et haute altitude actuelles. Dans un second temps, les épaisseurs crustale et lithosphérique ont été déterminées à partir d'une approche simple qui tient compte des densités et des paramètres thermiques de la lithosphère et suppose que la chaîne est en équilibre isostatique et thermique. La comparaison entre la pénéplaine reconstituée et les épaisseurs crustale et lithosphérique sous la chaîne montre que la racine crustale est préservée sous la pénéplaine dans l'ensemble des Pyrénées, et que la croûte épaissie s’amincit de façon progressive jusqu'à disparaître en Méditerranée, entraînant une diminution proportionnelle de l’altitude de la pénéplaine. La comparaison des épaisseurs crustales modélisées avec des densités normales et les épaisseurs résultant des données sismiques montrent que l'altitude actuelle de la chaîne est compensée isostatiquement au niveau de la lithosphère. Ces résultats écartent l’hypothèse d'une surcompensation de la racine crustale des Pyrénées ainsi que celle d'un soulèvement post-tectonique de 2000 m, de Miocène supérieur au Plio-Quaternaire, de la chaîne tel que proposé précédemment. Ils confirment par contre l’hypothèse d’un développement en altitude de la pénéplaine pyrénéenne Miocène moyen. / High-elevation, low-relief surfaces in mountain belts is classically interpreted as remnants of post-tectonic peneplains. Their elevation is often used to quantify the uplift of the Earth’s surface. A recent alternative interpretation propose that these surfaces are the remnants of a peneplain that develops at high elevation, due to the progressive rise of the efficient base level of the drainage system in mountain belts, and to the resulting inhibition of erosion during the mountain belts building. The two interpretations involve radically different lithosphere dynamics. The present study is concerned with the emblematic case of the Pyrenees, where the two hypotheses concerning the development of the mid-Miocene Pyrenean peneplain are opposed. First, a new mapping methodology has been developed to restore the morphology of the chain during the mid-Miocene from the present-day high-elevation, low-relief surfaces. Second, the crust and lithosphere thicknesses have been determined using a simple approach that takes into account the densities and the thermal parameters within the Pyrenean lithosphere, and assuming local isostasy and thermal equilibrium. The comparison of the restored peneplain with the crustal and lithosphere thicknesses below the Pyrenees shows that the crustal root is preserved beneath the peneplain in the whole Pyrenees, and that the crust thickness progressively decreases to the east, up to its complete disappearance of the in the Mediterranean, and resulting in the proportional lowering of the peneplain elevation. The comparison of the crust and lithosphere thicknesses, using normal densities, with the crust and lithosphere thicknesses deduced from seismic data shows that the presented elevation of the chain is isostatically compensated at lithosphere level. These results refute the previous hypothesis of an overcompensation of the crustal root beneath the Pyrenees, as well as the previous hypothesis of a 2000 m post-tectonic, upper Miocene to Plio-Quaternary of the chain. They favor in return the interpretation of the development of the mid-Miocene Pyrenean peneplain at high elevation.

No description available.

The region of West Bohemia is one of the most geodynamically active areas of Central Europe. The activity is characterized by many natural phenomena such as recurrent seismic swarms. The crustal structure of the region was subject of many geophysical investigations that revealed increased reflectivity of the lower crust. In this thesis, we adapt the multi-azimuthal approach for the detection of crustal discontinuities developed by Hrubcov'a et al. (2013). We apply the ap- proach on waveforms of the 2000 and 2008 swarms that occurred in the Nov'y Kos- tel focal area registered by several German stations. Analysis of the data of more distant German stations allowed expanding of the information about the depth and character of the crust/mantle transition in a broader area of the West Bo- hemia region. The results show a thickening of the zone in Germany with in- creasing distance from the epicentral area. Such findings are in agreement with previous active and passive seismic experiments.

Dense array seismic techniques can be applied to multiple types of seismic data to understand regional tectonic processes via analysis of crustal velocity structure, imaging reflection surfaces, and calculating high-resolution hypocenter locations. The two regions presented here include an intraplate seismogenic fault zone in Virginia and a steep cratonic margin in eastern Oregon and Idaho. The intraplate seismicity study in Virginia consisted of using 201 short-period vertical-component seismographs, which recorded events as low as magnitude -2 during a period of 12 days. Dense array analysis revealed almost no variation in the seismic velocity within the hypocentral zone, indicating that the aftershock zone is confined to a single crystalline-rock terrane. The 1-2 km wide cloud of hypocenters is characterized by a 29° strike and 53° dip consistent with the focal mechanism of the main shock. A 5° bend along strike and a shallower dip angle below 6 km points toward a more complex concave shaped fault zone. The seismic study in Idaho and Oregon was centered on the inversion of controlled-source wide-angle reflection and refraction seismic P- and S-wave traveltimes to determine a seismic velocity model of the crust beneath this part of the U.S. Cordillera. We imaged a narrow, steep velocity boundary within the crust that juxtaposes the Blue Mountains accreted terranes and the North American craton at the western Idaho shear zone. We found a 7 km offset in Moho depth, separating crust with different seismic velocities and Poisson's ratios. The crust beneath the Blue Mountains terranes is consistent with an intermediate lithology dominated by diorite. In the lower crust there is evidence of magmatic underplating which is consistent with the location of the feeder system of the Columbia River Basalts. The cratonic crust east of the WISZ is thicker and characterized by a felsic composition dominated by granite through most of the crust, with an intermediate composition layer in the lower crust. This sharp lithologic and rheologic boundary strongly influenced subsequent deformation and magmatic events in the region. / Ph. D. / Dense array seismic techniques involve using many instruments deployed closely together to record natural or man-made ground shaking. These techniques can be applied to different types of seismic data to understand the regional composition and behavior of the Earth’s crust, and identify locations where earthquakes have occurred. The two regions presented here include a zone in Virginia known to have small earthquakes and a location in eastern Oregon and Idaho where younger crust meets older crust across a very steep boundary. The seismicity study in Virginia consisted of using 201 instruments to record earthquake aftershocks with very small magnitudes during a period of 12 days. Dense array analysis techniques revealed almost no variation in the speed that seismic waves travel within the zone of aftershocks, indicating that the aftershocks are confined to a single crystalline-rock region. The 1-2 km wide zone of sub-surface aftershock locations is consistent with the rupture orientation of the main earthquake on 23 August 2011. The zone’s slightly concave shape indicates a complex region of rock movement. The seismic study in Idaho and Oregon was centered on analyzing seismic waves that are generated by explosions and travel through the crust, bending and reflecting when they pass through variations in the rock. We imaged a narrow, steep boundary that juxtaposes the younger Blue Mountains crust and the older North American craton at the western Idaho shear zone (WISZ). We found a sharp ~7 km step between the thicknesses of the two regions and different seismic velocities on either side of the boundary. The crust beneath the Blue Mountains terranes is consistent with an intermediate rock type dominated by diorite. In the lower crust there is evidence of a layer that is consistent with un-erupted material from the Columbia River Basalts. The continental crust east of the WISZ is thicker and dominated by granite through most of the crust, with an intermediate composition layer in the lower crust. This sharp boundary strongly influenced subsequent deformation and magmatic events in the region.

Isostasy is a key concept in geoscience to interpret the state of mass balance between the Earth’s crust and mantle. There are four well-known isostatic models: the classical models of Airy/Heiskanen (A/H), Pratt/Hayford (P/H), and Vening Meinesz (VM) and the modern model of Vening Meinesz-Moritz (VMM). The first three models assume a local and regional isostatic compensation, whereas the latter one supposes a global isostatic compensation scheme. A more satisfactory test of isostasy is to determine the Moho interface. The Moho discontinuity (or Moho) is the surface, which marks the boundary between the Earth’s crust and upper mantle. Generally, the Moho interface can be mapped accurately by seismic observations, but limited coverage of seismic data and economic considerations make gravimetric or combined gravimetric-seismic methods a more realistic technique for imaging the Moho interface either regional or global scales. It is the main purpose of this dissertation to investigate an isostatic model with respect to its feasibility to use in recovering the Moho parameters (i.e. Moho depth and Moho density contrast). The study is mostly limited to the VMM model and to the combined approach on regional and global scales. The thesis briefly includes various investigations with the following specific subjects: 1) to investigate the applicability and quality of satellite altimetry data (i.e. marine gravity data) in Moho determination over the oceans using the VMM model, 2) to investigate the need for methodologies using gravimetric data jointly with seismic data (i.e. combined approach) to estimate both the Moho depth and Moho density contrast over regional and global scales, 3) to investigate the spherical terrain correction and its effect on the VMM Moho determination, 4) to investigate the residual isostatic topography (RIT, i.e. difference between actual topography and isostatic topography) and its effect in the VMM Moho estimation, 5) to investigate the application of the lithospheric thermal-pressure correction and its effect on the Moho geometry using the VMM model, 6) Finally, the thesis ends with the application of the classical isostatic models for predicting the geoid height. The main input data used in the VMM model for a Moho recovery is the gravity anomaly/disturbance corrected for the gravitational contributions of mass density variation due in different layers of the Earth’s crust (i.e. stripping gravity corrections) and for the gravity contribution from deeper masses below the crust (i.e. non-isostatic effects). The corrections are computed using the recent seismic crustal model CRUST1.0. Our numerical investigations presented in this thesis demonstrate that 1) the VMM approach is applicable for estimating Moho geometry using a global marine gravity field derived by satellite altimetry and that the possible mean dynamic topography in the marine gravity model does not significantly affect the Moho determination, 2) the combined approach could help in filling-in the gaps in the seismic models and it also provides good fit to other global and regional models more than 90 per cent of the locations, 3) despite the fact that the lateral variation of the crustal depth is rather smooth, the terrain affects the Moho result most significantly in many areas, 4) the application of the RIT correction improves the agreement of our Moho result with some published global Moho models, 5) the application of the lithospheric thermal-pressure correction improves the agreement of VMM Moho model with some other global Moho models, 6) the geoid height cannot be successfully represented by the classical models due to many other gravitational signals from various mass variations within the Earth that affects the geoid. / <p>QC 20160317</p>

Orientador: Roberto Berton de Angelo / Acompanha 1 CD-ROM: acervo Moholy Nagy / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-12T13:18:59Z (GMT). No. of bitstreams: 1 Castral_PauloCesar_D.pdf: 28061578 bytes, checksum: c96d8994b2af4fc5919d0c0ce28e4924 (MD5) Previous issue date: 2007 / Resumo: Pretende-se discutir através das formulações dos conceitos de criação ótica absoluta e criação ótica representativa elaborados por László Moholy-Nagy, tendo como recorte de análise sua produção de imagens fotográficas, o desenho dos contornos das relações de reciprocidade entre os meios de expressão fotográfica e os meios de expressão espacial, estabelecidas na primeira metade do século XX. Dessa maneira, procura-se resgatar a contribuição do campo específico da linguagem fotográfica no debate e definição do espaço dito moderno. Busca-se redirecionar as abordagens antes focadas nos diferentes níveis de figuração empregados na elaboração dos discursos sobre o espaço, para a discussão então do processo de constituição das possíveis proposições de novas configurações espaco-temporais, elaboradas através da própria imagem fotográfica. / Abstract: Through the concept formulation of 'absolute optical creation' and 'representative optical creation' created by László Moholy-Nagy, It Intend to discuss, having as a cutting out of analysis his production of photographic images, the sketch contours of the reciprocities relations between photographic expression media and espacial expression media, estabilished in the first half of twentieth century. In this way, it intend to rescue the contribution of the specific field of photographic language in the debate and definitions of the modern space. One searchs to redirect the approach previously focus on different levels of figuration used to elaborate space's speeches, for the discussion of the constitution process of possible proposals of new configurations space-time, elaborated through photographic image. / Doutorado / Doutor em Multimeios

Les dômes métamorphiques extensifs associés à des zones de détachement ont été identifiés dans le Basin & Range (U.S.A.) à la fin des années 70. Ces structures résultent de l'extension d'un domaine crustal épaissi et thermiquement relaxé, autrement dit d'une extension post-orogénique. Les détachements présents en surface sont considérés comme des failles normales ou des zones de cisaillement à faible pendage séparant le dôme métamorphique d'une unité de croûte supérieure cassante. En profondeur, ces dômes se caractérisent par une géométrie planaire du Moho. Pour comprendre les relations entre l'exhumation du dôme, la formation d'un détachement et la géométrie planaire du Moho, des modèles numériques et analogiques ont été réalisés en se basant sur l'idée simple d'une extension post-orogénique, comme condition générale favorable à la formation des dômes métamorphiques. Le développement des dômes se caractérise par deux étapes majeures : une instabilité en striction de la croûte supérieure fragile et l'amplification du dôme, accommodée par l'écoulement de la croûte ductile en profondeur. Le processus d'exhumation et d'écoulement en profondeur s'étend sur de larges distances (de l'ordre de la centaine de km), impliquant une extension régionale. L'analyse de la déformation des dômes montre que les détachements ne sont pas créés en tant que tels dès le début de l'extension, mais qu'ils résultent d'un processus de localisation de la déformation, lors de l'amplification du dôme. Il est donc proposé que les détachements ne soient donc pas la cause mais plutôt la conséquence de l'exhumation des dômes métamorphiques. La détermination de l'épaisseur crustale à partir des données gravimétriques du domaine égéen a permis d'analyser les effets du comportement de la croûte ductile sur un exemple concret. Trois provinces se distinguent en termes d'épaisseur crustale : le Nord Egée, la Mer de Crête et les Cyclades avec une moyenne de 25 km à l'échelle régionale. Depuis l'Oligo-Miocène, l'extension du domaine égéen résulte d'un effondrement gravitaire post-orogénique, dû au retrait vers le sud de la zone de subduction sud-hellénique. Cette extension est responsable d'un amincissement proche de 100% de la croûte continentale, par écoulement de la croûte ductile à grande échelle, et de la formation des dômes métamorphiques observés en particulier dans les Cyclades. L'extrusion récente de l'Anatolie, depuis 5 Ma, a modifié le style de déformation dans le Nord Egée, tandis qu'en Mer de Crête, l'extension semble toujours principalement contrôlée par la migration de la zone de subduction. Entre ces deux zones d'extension récente, le domaine des Cyclades se comporte comme un bloc rigide.

The Gulf of Mexico Basin Opening project (GUMBO) is a study of the lithological composition and structural evolution of the Gulf of Mexico (GoM) that uses Ocean Bottom Seismometer (OBS) data from four transects in the Northern GoM. I examine 39 OBS shot records in the easternmost transect for shear wave arrivals and pick shear wave travel times from the 11 usable records. I then carry out a tomographic inversion of seismic refraction travel times. I use the resulting shear-wave velocity model in conjunction with a previously constructed P-wave model to examine the relationship between Vp and Vs. I compare velocities in the sediment and basement with empirical velocities from previous studies for the purpose of constraining lithological composition below the transect and make an interpretation of the structural evolution of the eastern GoM. The seismic velocities for crust landward of the Florida Escarpment are consistent with normal continental crust. Seaward of the Escarpment, velocities in the upper oceanic crust are anomalously high (Vp = 6.5 – 7 km/sec; Vs = 4.0 – 4.6 km/sec). A possible explanation for this observation is that GoM basalt formation consisted of basaltic sheet flows, forming oceanic crust that does not contain the vesicularity and lower seismic velocities found in typical pillow basalts. Increased magnesium and iron content could also account for these high velocities. Seismic refraction and reflection data provide a means of investigating the nature of the Moho in the northeastern GoM. I use a finite difference method to generate synthetic record sections for data from eight instruments that are part of the two easternmost GUMBO seismic lines (lines 3 & 4). I then vary the thickness of the Moho in these synthetic models and compare the results with the original receiver gather to examine the effects this variability has on amplitudes. The data from the instruments chosen for these two lines are representative of continental and transitional crust. The finite difference models indicate that the Moho beneath GUMBO 3 is ~1500 m thick based on the onset and amplitudes of PmP arrivals. All five instruments display consistent results. The instruments along GUMBO 4 suggest a Moho almost twice as thick as GUMBO 3 on the landward end of the transect that grades into a Moho of similar thickness (1750 m) in the deep water GoM. The three instruments used to model the Moho in this area show that the Moho ranges from ~1750 to 3500 m in thickness. The sharper boundary beneath continental crust in GUMBO Line 3 supports other evidence that suggests magmatic underplating and volcanism in the northern GoM during the mid-Jurassic. The thicker Moho seen on the landward end of GUMBO Line 4 that is overlain by continental crust was likely unaffected by GoM rifting. Therefore, the Moho beneath the Florida Platform might be as old as the Suwannee Terrane, and complex Moho structure is not uncommon for ancient continental crust. / text

No description available.