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Across the world we observe spectacular mountain belts that formed as a result of two colliding plates. Frequently this process is disturbed by the influence of neighbouring geological processes, such as the formation of adjacent mountain belts, adding significant kinematic and geometric complexities to the collisional systems. To understand the relative contributions of the processes involved it is essential to identify the individual interfering processes and to quantify their influence on the evolution of the mountain system. The Eastern Alps (Europe) is such a complex mountain belt and is the prime target of this research with particular interest in the transitions to the neighbouring Dinaric mountain belt and the Pannonian Basin. These transitions provide a unique opportunity to unravel the effects of interfering tectonic processes based on field studies, low temperature geochronology and physical analogue modelling. The geological evolution of the Eastern Alps and Dinarides is largely related to the motion of the African continental plate towards the European plate, with the microcontinent Adria located in between the two. The plate motion of the latter plays a key role in driving the deformation of the Eastern Alps as well as the Dinaric mountain chain. With respect to the Eastern Alps the Adriatic plate is traditionally viewed as a bulldozer that deforms, uplifts and laterally displaces the Eastern Alps. However, we show that these geological processes are also compatible with a tectonic scenario in which the Adriatic plate subducts below the Alps. The subduction also provides a crucial mechanism to create the formation of the Southern Alps, which affects at the same time the geological evolution of the northern Dinarides. The experimental results also strongly suggest that the geological evolution of the Eastern Alps during the last 30 Ma is best explained by phases of oblique and subsequent orthogonal Alps-Adria convergence. This has led to the characteristic deformation patterns of the Eastern Alps: significant crustal thickening in the west and dominant lateral displacements of crustal units in the east. These differences in deformation style are confirmed by our new field observations and low temperature age data which also emphasize a tectonic link to the contemporaneous opening of the Pannonian Basin and associated extension. The data thereby disclose that the coeval collision and extension is critical for the rapid exhumation of metamorphosed rocks around 17 Ma at the transition from the Alps to the Dinarides. At the same time, a recorded phase of accelerated uplift during the last 10 Ma is rather related to the absence of extension in combination with ongoing Alps-Adria collision and deep seated processes. The integrated results of this thesis demonstrate that subduction/collision processes related to Alps-Adria convergence are strongly influenced by neighbouring and far-fielded processes, which has significant implications for the structural and topographic evolution of the studied region.

Swiss Journal of Geosciences, 106 (1), ISSN:1661-8734, ISSN:1661-8726

Se presentan en esta tesis los resultados del estudio del sector andino de los Andes Patagónicos Septentrionales ubicados entre los 41º30´ y los 42º30´S, en las provincias de Río Negro y Chubut. La región estudiada no contaba, hasta el momento, con levantamientos geológicosdetallados debido a la dificultad de acceso que presenta este sector de los Andes. El análisisestratigráfico y morfoestructural del área constituyen los ejes principales del trabajo deinvestigación realizado. Las imágenes satelitales disponibles, así como los datos gravimétricos yrelevamientos magnéticos con los que se pudo contar, complementan la información disponibley contribuyen a dar solidez a las interpretaciones realizadas. Además, se llevaron a cabo análisispetrográficos, geoquímicos y radimétricos. El análisis estratigráfico ha permitido realizar una caracterización de las unidades volcánicas yplutónicas jurásico-cretácicas que resulta considerablemente más precisa que las descripcionespreexistentes. En particular, se ha reconocido además la existencia de una unidad volcánicamiocena, previamente desconocida, que aflora en el sector interno de los Andes entre los 41º 30´ y los 41º 50´S. El análisis morfoestructural revela, a escala local, el carácter sinextensionalde estas rocas y, a escala regional, la existencia de un importante evento de extensión. Lasprecisas dataciones radimétricas (U-Pb LAICPMS en circones) que se presentan en esta tesispermiten asignar este evento al Mioceno Medio a Superior. El análisis morfoestructural realizado permite postular que la faja plegada y corrida desarrolladaa estas latitudes estuvo sometida a condiciones de evolución singulares que no han sidoreconocidas en otros segmentos andinos. A la etapa compresiva que se inició durante el Mioceno Inferior a Medio, y continuó desarrollándose al menos hasta el Mioceno Superior en lazona de antepaís, se sobreimpusieron fenómenos extensionales en el sector occidental interno,de modo que ambos fenómenos podrían incluso haber coexistido durante una parte del procesode estructuración de los Andes. El análisis morfoestructural aporta, por lo tanto, datos valiososque permiten evaluar, en un sentido más amplio, el desarrollo de la deformación en el tiempo yel espacio. Adicionalmente, se discuten una serie de indicios que podrían indicar la existencia deuno o más eventos de deformación desarrollados durante el Jurásico-Cretácico, que deberán serinvestigados a futuro. This thesis is focused on the study of the Andean sector of the North Patagonian Andeslocated between 41º30´ and 42º30´S, in Río Negro and Chubut provinces. This area ischaracterized by a difficult access, reason by which no previous detailed geological surveyswere done. A stratigraphical and morphostructural analysis of the study area was done on thebasis of field mapping and interpretation of satellite images. The interpretations presented inthis thesis were also complemented with gravity and magnetic data, and also withpetrographical, geochemical and geochronological analysis. The stratigraphical analysis allowed a precise characterization of the Jurassic-Cretaceous to Cenozoic volcanic and plutonic units. Additionally, a previously unknown, Miocene volcanicunit outcropping at the inner sector of the Andes, between 41º30´ and 41º50´S, was recognized. A morphostructural analysis reveals, at a local scale, the synextensional character of these rocks. The new radiometric ages presented in this work constrain this event to the middle to late Miocene. The morphostructural analysis allows us to postulate that the fold and thrust belt wassubjected to unique conditions during its evolution, which are not recognized through otherneighbor Andean segments. After the beginning of the compression in the late Miocene, andduring its progression to the foreland zone, middle to late Miocene extensional phenomenaoccurred in the inner Andean sector. Additionally, morphostructural analysis provides valuableinformation in order to evaluate spatial and temporal development of the deformation. Finally,the existence of one or more deformational events acting in Jurassic-Cretaceous times isdiscussed. Fil: Tobal, Jonathan Elías. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

The Australian continent records c. 1860-1800 Ma orogenesis associated with rapid accretion of several ribbon micro-continents along the southern and eastern margins of the proto-North Australian Craton during Nuna assembly. The boundaries of these accreted micro-continents are imaged in crustal-scale seismic reflection data, and regional gravity and aeromagnetic datasets. Continental growth (c. 1860-1850 Ma) along the southern margin of the proto-North Australian Craton is recorded by the accretion of a micro-continent that included the Aileron Terrane (northern Arunta Inlier) and the Gawler Craton. Eastward growth of the North Australian Craton occurred during the accretion of the Numil Terrane and the Abingdon Seismic Province, which forms part of a broader zone of collision between the northwestern margins of Laurentia and the proto-North Australian Craton. The Tickalara Arc initially accreted with the Kimberley Craton at c. 1850 Ma and together these collided with the proto-North Australian Craton at c. 1820 Ma. Collision between the West Australian Craton and the proto-North Australian Craton at c. 1790-1760 Ma terminated the rapid growth of the Australian continent.

Convergent plate margins occur when two adjoining tectonic plates come together to form either a subduction zone, where at least one of the converging plates is oceanic and plunges beneath the other into the mantle, or a collision zone, where two continents or a continent and a magmatic arc collide. Convergent plate margins are arguably the most complicated and dynamic plate boundaries on Earth and have been the subject of many investigations and discussions since the advent of plate tectonic theory. This paper provides a historical background and a review of the development of geological and geodynamic theories on convergent plate margins. Furthermore, it discusses some of the recent advances that have been made in the fields of structural geology, geophysics and geodynamics, which are fundamental to our understanding of this phenomenon. These include: (1) the finding that plates and plate boundaries move at comparable velocities across the globe; (2) the emerging consensus that subducted slabs are between two to three orders of magnitude stronger than the ambient upper mantle; (3) the importance of lateral slab edges, slab tearing and toroidal mantle flow patterns for the evolution of subduction zones; and (4) clear evidence from mantle tomography that slabs can penetrate into the lower mantle. Still, many first-order problems regarding the geodynamic processes that operate at convergent margins remain to be solved. These include subduction zone initiation and the time of inception of plate tectonics, and with it convergent plate margins, on Earth. Fundamental problems in orogenesis include the mechanism that initiated Andean mountain building at the South American subduction zone, the potential episodicity of mountain building with multiple cycles of shortening and extension, and the principal driving force behind the construction of massive mountain belts such as the Himalayas–Tibet and the Andes. Fundamental questions in subduction dynamics regard the partitioning of subduction into a trench and plate component, and the distribution of energy dissipation in the system. In seismic imaging, challenges include improving resolution at mid to lower mantle depth in order to properly understand the fate of slabs, and better constraining the 3-D flow-related anisotropic structure in the surrounding mantle. Future insights into such fundamental problems and into the regional and global dynamics of convergent plate margins will likely be obtained from integrating spatio-temporal data, structural geological data, geophysical data and plate kinematic data into plate tectonic reconstructions and three-dimensional geodynamic models of progressive deformation.

Evidence of two burial–exhumation cycles that took place during a single orogeny has been found in rocks belonging to the Piemonte unit of the Western Alps. An early high pressure event, which resulted from tectonic burial down to pressures of 1.5 GPa, was followed by exhumation to ca. 0.20–0.35 GPa as a result of extensional deformation. Renewed shortening culminated in a second burial episode down to pressures of 0.65–0.80 GPa, before the final exhumation took place. Existing geochronological data allow only ca. 13–19 Ma for the completion of both burial–exhumation cycles. Therefore, we suggest that the evolution of orogens is characterized by multiple short-lived burial–exhumation cycles related to orogen-scale alternance between shortening and extensional deformation.

6 p., mapa col., [EN]This paper discusses the issue of the origin and maintenance of biodiversity on tropical mountains, with emphasis on the Neotropics, and concludes that present-day biodiversity patterns of highland biotas cannot be understood without the combined action of Neogene tectonics and Pleistocene climatic changes., [ES]En este artículo se discute el origen y mantenimiento de la biodiversidad en las montañas tropicales, con énfasis en el Neotrópico, y se concluye que los patrones de biodiversidad de las biotas de gran altura no pueden ser explicados sin la acción combinada de la tectónica neógena y los cambios climáticos del Pleistoceno., Funding was provided by the BBVA Foundation (projects BIOCON 2004-90 and BIOCON 2008-031) and the Higher Council for Scientific Research (CSIC, project 201430E007).

[cat] Aquesta tesi doctoral descriu la cinemàtica dels Pirineus Basco-Cantàbrics, més concretament de la Plataforma Burgalesa, mitjançant la integració de i) geologia de superfície; ii) interpretació de línies sísmiques i pous; i iii) estudis paleomagnètics de rotacions d'eix vertical. La integració d'aquest conjunt de dades permet comprendre la relació entre la Plataforma Burgalesa i les conques d'avantpaís de l'Ebre i del Duero durant la orogènia Pirenaica. Les principals contribucions de la tesi són: i) Presentar un model estructural, el qual honora tots les restriccions imposades per l'estratigrafia, la preconfiguració de l'àrea prèvia a la deformació contractiva i les dades tant superficials com profundes. Aquest model permet comprendre com és la transició entre la deformació pel·licular present a l'est de la zona d'estudi i la deformació no pel·licular present a l'oest. ii) Reinterpretació de l'estructura de Zamanzas localitzada al nord de la Plataforma Burgalesa mitjançant el treball combinat entre geologia de superfície i les dades aportades per els pous d'exploració. iii) Aportar noves dades de vint-i-sis estacions de paleomagnetisme repartides per a la zona d'estudi i que permeten caracteritzar el patró de rotacions d'eix vertical. El resultat final és el de proposar un nou model per a l'evolució de la Plataforma Burgalesa que honra les restriccions imposades tant per la geologia de superfície com les dades d'exploració profunda disponibles fins a la data. Aquest model està caracteritzat per presentar deformació no pel·licular al sector oest mentre que quan el nivell de desenganxament augmenta de potència els encavalcaments es desenganxen i deformen la cobertora presentant un estil estructural pel·licular. Aquesta tesi ha demostrat que la pre-configuració tant de la conca extensiva pròpiament dita com la del seu voltant, tenen una forta implicació en el desenvolupament i estructuració de la Plataforma Burgalesa durant la Orogènia Pirenaica. És durant aquesta etapa en la qual es produeixen rotacions tant horàries com antihoràries en els diferents sectors mostrejats., [eng] This PhD Thesis describes the kinematics of the Burgalesa Platform in the Basque-Cantabrian Pyrenees by the integration of i) surface geology; ii) seismic and well data; and iii) vertical axis rotation paleomagnetic studies. The integration of all the data allow to understand the relationship between the Burgalesa Platform and the Ebro and Duero foreland basins during the Pyrenean Orogeny. The principal contribution of the Thesis is to present a new structural model, that fits all the constraints imposed by the stratigraphy, the pre-configuration of the area prior to the contractive deformation and both the deep and the surface data. This model allows to understand the transition between thin-skinned and the thick-skinned tectonics. The combined work between surface geology and well data has allowed to reinterpret the Zamanzas structure located at the northern boundary of the Burgalesa Platform. Previously, this structure had been interpreted as a set of extensional faults. This Thesis pointed out the mismatches and reinterpret the Zamanzas structure as a popup generated during the Pyrenean Orogeny. The combined interpretation of wells and seismic sections allow to partially comprehend the structure of the area during the extensional event as well as the result of the Pyrenean Orogeny occurred later. This study allowed to determine the distribution of the Lower Cretaceous depocenters during the North Atlantic and the Bay of Biscay opening. Moreover, during this stage salt mobilisation triggered by extension generated areas where the Triassic salt layer was thickened as demonstrated by the well data and the outcropping diapirs. This process accentuated the development of the depocenters. The extensional event also generated the onlap sedimentary geometries in the syn-rift sediments. The extensional model proposed is a combined model with the development of cover forced folding with salt migration at the southern boundary. The Triassic salt decoupled the extension between the basement and the cover and contractional structures were developed such as the back-thrust in the Huidobro area that produced the duplication of the Mesozoic. The early stages of the Pyrenean Orogeny resulted in the development of the San Pedro Structure, with north-directed and basement-involved thrusts, later fossilised by the Duero foreland sediments. To the north, the Burgalesa Platform, characterised by south-directed thrusts rooted into the Triassic salts, was southwards displaced until the San Pedro act as a backstop forcing the Burgalesa Platform to extrude laterally towards the southeast overriding the Ebro Foreland Basin. The paleomagnetic study focussed on determine the possible vertical axis rotations along the Pyrenees, denotes that the amount of sites that some areas have is not present in the Burgalesa Platform and vicinities that lack of sites. For that reason, another objective of this Thesis is to provide new paleomagnetic sites for the study area. The study carried out is made up of twenty-six new sites widely distributed and that allow to characterise the vertical axis rotation pattern. The results obtained reveals that i) the magnetisation of the Cenozoic sediments is prior to deformation and that ii) clockwise and counter clockwise rotation occurred in the Burgalesa Platform and adjacent areas. The evolution models previously proposed for the Burgalesa Platform were based either from surface geology of from geophysical data thus fitting some of the constraints. Because any model integrated all the observations and available data, a new model explaining the Burgalesa Platform evolution has been proposed. This model is characterised by presenting thick-skinned deformation at the western sector whereas, thin-skinned at the eastern one when the Triassic salt layer thickens point in which the thrusts are detach the cover from the basement. The results of this Thesis demonstrate that the pre-configuration of the extensional basin and its vicinities have a strong implication in the development and evolution of the Burgalesa Platform during the Pyrenean Orogeny. Finally, during this evolution, clockwise and counter clockwise rotations occurred in the different sectors as shown by the paleomagnetic studies carried out during this Thesis.

[spa] Los experimentos de multi-sísmicas realizados en el marco de la iniciativa del proyecto ALCUDIA incluyen una incidencia normal y sísmica gran angular de los conjuntos de datos de reflexión sísmica. Estos limitan las estructuras internas, la estructura detallada de la corteza y litosfera y, proporcionan el conocimiento necesario de las propiedades físicas a lo largo de la Zona Central Ibérica. Las imágenes sísmicas de incidencia normal se presentan de Sur a Norte: las estructuras de la Zona Ossa-Morena (Unidad Central), el ondulante domino Ibérico Central, los cuerpos intrusivos graníticos (Granitos de Mora, complejo Anatético de Toledo, etc.) hasta la falla de Toledo, justo al Sur de la cuenca del Tajo. La zona de estudio está caracterizada por una topografía ondulada debido a una serie de sinclinales y anticlinales. La imagen muestra una corteza inferior débilmente reflectante, ~13-18 km de espesor. La topografía sinodal refleja los pliegues, los sistemas de cabalgamientos imbricados, y fallas extensionales lístricas observados por los datos de sísmica de incidencia normal. A niveles más profundos las imágenes revelan estructuras arqueadas y laminares que sugieren estructuras como boundinage. Estas características son interrumpidas hacia el Sur, muy probablemente debido a la existencia de la zona de sutura. La expresión más profunda del afloramiento de la zona de sutura, está ligeramente desplazada hacia el Norte con respecto a su localización en superficie y, esta es vista como un cabalgamiento profundo de una fina capa de corteza inferior. Hacia el límite norte del perfil, debajo la falla de Toledo, una banda de reflectividad buzando hacia norte sugiere un adelgazamiento de la corteza inferior hacia el Norte. La discontinuidad de Mohorovicic se delimita como una fuerte disminución de la reflectividad a la base de la corteza inferior, localizada a unos ~31-33 km de profundidad (10.5 s tempo doble). Los datos de gran ángulo de sísmica de reflexión adquiridos a principios de mayo de 2012, tenían como objetivo proporcionar las distribuciones de las propiedades físicas (velocidades P y S, densidades, y el coeficiente de Poisson) de la corteza bajo la zona de estudio. Este perfil fue diseñado para ser casi coincidente con el perfil de incidencia normal. Los modelos de velocidad de P y S obtenidos revelan importantes variaciones laterales de velocidad en la corteza superior, que son coherentes con la observación de los afloramientos en superficie. La corteza inferior se identifica por un fuerte aumento de la velocidad a ~13 km y ~20 km de profundidad en Zona Central Ibérica y en la Cuenca del Tajo, respectivamente. La base de la corteza está fuertemente limitada por grandes amplitud de las llegadas de PmP y SmS y se encuentra a ~31 km en el extremo sur y a ~35,5 km por debajo del extremo norte del perfil de sísmica de gran ángulo. La sísmica de gran ángulo también se utilizó para producir low-fold stacks para las ondas P y las S. Esto se hizo para tomar una mirada más cercana a la discontinuidad de Moho, y para ser capaces de estimar la estructura interna y generar sismogramas sintéticos donde las fases PmP y SmS serían cualitativamente comparables a las fases observadas en los registros sísmicos. Esto dio lugar restricciones clave en la estructura de la discontinuidad de Moho bajo la Zona Central Ibérica y la Cuenca del Tajo en el orógeno Varisco del Macizo Central Ibérico. Las imágenes revelan una profundización gradual de ~31 km (10,2 s) en la Zona Central Ibérica a ~35,5 km (11,8 s) debajo de la cuenca del Tajo para la discontinuidad de Moho. Los datos sísmicos de gran ángulo y los resultados derivados de ellos son compatibles con las imágenes de incidencia normal., [eng] The multi-seismic experiments carried out under the ALCUDIA research initiative include a normal incidence and a wide-angle seismic reflection datasets. These constrain the internal architecture, the detailed crustal and lithospheric structure and, provide the necessary knowledge on physical properties across the Central Iberia Zone. The normal incidence seismic images from south to north: the suture zone of Ossa-Morena Zone (the Central Unit), the undulating Central Iberian domain, the intruded granitic bodies (the Mora Granite, the Toledo Anatectic complex, etc) up to the Toledo Fault, just south of the Tajo Basin. The study area is characterized by undulating topography characterized by a series of synclines and anticlines. The image shows a weakly reflective upper crust, ~13-18 km thick. The sinusoidal topography reflects the folding, the imbricate thrust systems, and listric extensional faults imaged by the normal incidence data. At deeper levels the image reveals arcuate and laminated events suggesting boudinage like structures. These features are disrupted in the south most probably due to the existence of the suture zone. The deep expression of the outcropping suture zone, is slightly displaced to the north with respect to its surface position and, it is imaged as an under-thrusting of a thin slice of lower crust. Towards the northern end of the transect, beneath the Toledo fault, a north dipping band of reflectivity suggest a significant thinning of the lower crust to the north. The Mohorovicic discontinuity is delineated as a sharp decrease in reflectivity at the base of the lower crust, located at ~31-33 km depth (10.5 s two-way travel-time). The wide-angle seismic reflection data acquired in early May 2012, was aimed to provide the distributions of the physical properties (P- and and S-wave velocities, densities, and Poisson’s ratio) of the crust beneath the study area. It was designed to be nearly coincident with the normal incidence profile. The obtained P- and S- wave velocity models reveal significant lateral velocity variations in the upper crust, which are consistent with the observation from the surface outcrops. The lower crust is identified by a sharp increase in velocity at ~13 km and ~20 km beneath the Central Iberian Zone and the Tajo Basin, respectively. The base of the crust is strongly constrained by the high amplitude PmP and SmS arrivals and it is located at ~31 km in the southern end and at ~35.5 km below the northern end of the wide-angle transect. The wide-angle was also used to produce low-fold P- and S-wave wide-angle stacks. This was done to take a closer look to the Moho discontinuity, and to be able to estimate the internal structure and generate synthetic seismograms in which the PmP and SmS would be qualitatively comparable to the phases observed in the shot records. This place key constraints on the structure of the Moho discontinuity beneath the Central Iberian Zone and the Tajo Basin in the Variscan orogen of the central Iberian Massif. The images reveal gradual deepening from ~31 km (10.2 s) in the Central Iberian Zone to ~35.5 km (11.8 s) beneath the Tajo Basin for the Moho discontinuity. The wide-angle seismic data and the results derived from it are compatible with the normal incidence images.

The surface expression of a lateral polarity change of continental mantle lithosphere subduction has been studied by using lithosphere-scale physical models. Key parameters investigated were: the degree of lateral coupling between adjacent domains of opposing subduction polarity, the width of the zone separating the domains, and the lithosphere geometry and rheology. The model results illustrate an asymmetric lithospheric structure induced by deformation of the downgoing plates, which have been separated by a narrow transition zone. A wide and symmetric orogenic wedge overlying a region of thickened mantle lithosphere and hampered subduction characterizes this transition zone. In addition, interaction between the neighboring subduction domains caused downbending of the upper plates and resulted in the lateral termination of crustal structures and lowering of surface topography. The lateral extent of interaction between the domains strongly depends on the degree of coupling between the domains, the rheology of the mantle lithosphere and the amount of bulk shortening. The modelling results have major implications on the interpretation of seismic and tomographic data from the European Alps in terms of the crust and lithosphere geometries. It appears that an observed lateral change of subduction polarity at mantle depth can explain the variations of wedge build-up between the Western/Central and Eastern Alps.

This thesis investigates the tectonic histories of igneous and metamorphic rocks exposed in the Mérida Andes, Venezuela, and Santander Massif, Colombia from the Late Cambrian to the present day. Zircon U-Pb ages from 52 igneous and metamorphic rocks constrain the main periods of arc magmatism on the north-western corner of Gondwana from ~500 to ~413 Ma and from ~294 Ma to ~196 Ma. Peak Barrovian metamorphic conditions are recorded by anatexis at ~477 Ma and the intrusion of synkinematic granitoids until ~472 Ma. Back-arc extension is recorded at ~453 Ma. High exhumation rates constrained by 40Ar/39Ar and apatite U-Pb data suggest a second orogenic phase at ~250 Ma. Combined isotopic data show that the basement rocks of the studied regions are autochthonous to north-western Gondwana, and that arc magmatism sampled more juvenile sources during extension than during orogenesis. Low temperature thermochronology suggests that the Santander Massif started exhuming at ~40 Ma.

Составлен профиль МСЗ в Осетинском секторе Большого Кавказа. Получена информация о глубинном строении складчатого сооружения. По результатам геолого-геофизического изучения сделаны за- ключения о глубинном строении Большого Кавказа, The MSZ profile of the ossetic sector of the large Caucasus is composed. Information about the deep structure of plicated construction is obtained. The conclusions about the deep structure of the large Caucasus are made according to the results of geological-geophysical study, Геология и геофизика Юга России, Выпуск 4 2013