Los efectos producidos por la aproximación, colisión y subducción de dorsales pacíficas en los Andes Patagónicos

Los Andes Patagónicos Septentrionales son una cordillera formada inicialmente por la subducción de las placas de Phoenix-Farallón y posteriormente por la de Nazca, que muestran rastros de deformación polifásica desde el Jurásico superior hasta el Neógeno, con posterioridad a la ruptura del Gondwana. El objetivo principal del trabajo es agrupar en dos ciclos esta secuencia compleja de eventos deformativos, los cuales sean dependientes de la distribución de edades en la trinchera oceánica durante la subducción. Al sur del paralelo 38° S, la génesis de los Andes Patagónicos Septentrionales está ligada a los efectos producidos por la colisión de dorsales oceánicas. La situación actual permite ilustrar cómo se produce la distribución de la deformación, durante una subducción oblicua, en un sistema con baja partición de la deformación. En los Andes Centrales Australes, al norte de los 38° S, la corteza se imbrica en el retroarco a partir de una distancia crítica de la dorsal oceánica de Chile. Cuando esta distancia es menor, el sistema de corrimientos en el retroarco se detiene, tal como ocurre en los Andes Patagónicos Septentrionales, donde subduce una corteza oceánica relativamente joven. Los cambios en el tiempo de la configuración oceánica a lo largo de la trinchera debido a la subducción, determinan que los modelos de deformación descritos varíen en el tiempo, pudiéndose definir dos modelos extremos: tipo Andes Patagónicos vs. Andes Centrales Australes. Durante los últimos 120 millones de años, en los Andes Patagónicos se han podido documentar, a partir de la interpretación del registro geológico, dos ciclos de apilamiento orogénico cortical con manifestación en sistemas de acortamiento en el retroarco y posterior fosilización del mismo, relacionados con el acercamiento, la colisión y la posterior subducción de una dorsal oceánica orientada oblicuamente con relación al margen occidental de la placa Sudamericana.The Northern Patagonian Andes are an orogenic belt, which were formed by the subduction of the Phoenix-Farallón plates first and the Nazca plate latter and they present a series of deformational phases since the Late Jurassic to the Neogene. The main objective is to group this complex sequence of deformational events in two cycles, which are related to the age distribution of the subducted oceanic plates. South of 38°S, the origin of the Northern Patagonian Andes is linked to the effects produced by oceanic ridge collision. The present picture shows how strain is distributed in the upper plate, in a low strain partitioned setting, during oblique subduction. The continental crust stacks in the retroarc area, as in the present Central Andes to the north, under a certain critical length between the Chilean trench and the oceanic ridge. When this distance reaches that threshold length the thrust systems stop, as in the Northern Patagonian Andes, where very young oceanic crust is being subducted. As the oceanic configuration changed in time along the trench because of ridge subduction, the described strain crustal types also shifted depicting two contrasting styles such as the present Central Andes vs. Patagonian Andes. For the last 120 million years, at least two cycles of crustal thrusting and retroarc orogenic quiescence have been documented, recording the different tectonic settings in the geological record, associated with the approaching, collision and subduction of seismic oceanic ridges, obliquely oriented with respect to the South American border. Keywords: Patagonian Andes. Oceanic Ridges. Strain Partitioning. Andean mountain building. Argentina. Chile

The matrix Kadomtsev--Petviashvili equation as a source of integrable nonlinear equations

A new integrable class of Davey--Stewartson type systems of nonlinear partial differential equations (NPDEs) in 2+1 dimensions is derived from the matrix Kadomtsev--Petviashvili equation by means of an asymptotically exact nonlinear reduction method based on Fourier expansion and spatio-temporal rescaling. The integrability by the inverse scattering method is explicitly demonstrated, by applying the reduction technique also to the Lax pair of the starting matrix equation and thereby obtaining the Lax pair for the new class of systems of equations. The characteristics of the reduction method suggest that the new systems are likely to be of applicative relevance. A reduction to a system of two interacting complex fields is briefly described.Comment: arxiv version is already officia

El terremoto del último 7 de septiembre : tiembla, todo tiembla

Fil: Folguera, Andrés. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Laboratorio de Tectónica Andina; Argentina.Fil: Triep, Enrique. Instituto de Sismología Volponi; Argentina.Fil: González Díaz, Emilio M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil: Ramos, Víctor A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Laboratorio de Tectónica Andina; Argentina.Los terremotos no son un fenómeno del pasado y las placas que conforman los niveles móviles más\nsuperficiales de la Tierra están aún en pleno movimiento. Con respecto a la intensidad de los mismos y\nsus desplazamientos asociados, la actividad actual, en especial la deformación permanente asociada\na estos terremotos, se ha mantenido en el mismo orden de magnitud que en los últimos 10 millones de\naños. La frecuencia con la que ocurren estos movimientos está también dentro del mismo orden,\nsiendo quizás la diferencia más significativa el avance de la tecnología y las comunicaciones de este\nmundo global que nos permiten conocer al instante este tipo de eventos en cualquier parte del planeta,\npareciendo de esta forma un fenómeno más periódico en la actualidad

Gradients from GOCE reveal gravity changes before Pisagua Mw = 8.2 and Iquique Mw = 7.7 large megathrust earthquakes

Considerable improvements in the measurement of the Earth gravity field from GOCE satellite mission have provided global gravity field models with homogeneous coverage, high precision and good spatial resolution. In particular, the vertical gravity gradient (Tzz), in comparison to the classic Bouguer anomaly, defines more accurately superficial mass heterogeneities. Moreover, the correction of these satellitederived data from the effect of Earth topographic masses by means of new techniques taking into account the Earth curvature, improves results in regional analyses. In a recent work we found a correlation between Tzz and slip distribution for the 2010 Maule Mw= 8.8 earthquake. In the present work, we derive the vertical gravity gradient from the last GOCE only model, corrected by the topographic effect and also by the sediments on depocenters of the offshore region at the PerueChile margin, in order to study a spatial relationship between different lobes of the gravity derived signal and the seismic sources of large megathrust earthquakes. In particular, we analyze this relation for the slip models of the 1996 Mw = 7.7 Nazca, 2001 Mw = 8.4 Arequipa, 2007 Mw = 8.0 Pisco events and for the slip models of the 2014 Mw = 8.2 Pisagua and Mw = 7.7 Iquique earthquakes from Schurr et al. (2014), including the previously analyzed 2010 Mw = 8.8 Maule event. Then we find a good correlation between vertical gravity gradients and main rupture zones, correlation that becomes even stronger as the event magnitude increases. Besides this, a gravity fall in the gravity gradient was noticed over the area of the main slip patches at least for the two years before 2014 Mw = 8.2 Pisagua and Mw = 7.7 Iquique earthquakes. Additionally, we found temporal variations of the gravity field after 2010 Mw = 8.8 Maule event, related to the main patches of the slip distribution, and coseismic deformation. Therefore, we analyzed vertical gravity gradient field variations as an indirect measure of the variable seismic coupling finding a potential relationship between Tzz and the seismic b-value. These relationships exemplify the strong potential of the satellite only derived models as a predictive tool to determine potential seismic energy released in a subduction segment, determining the potential size of a potential rupture zone, and in particular internal slip distribution that allows inferring coseismic displacement field at surface

New evidence about the subduction of the Copiap\uf2 ridge beneath South America, and its connection with the Chilean-Pampean flat slab, tracked by satellite GOCE and EGM2008 models

Satellite-only gravity measurements and those integrated with terrestrial observations provide global gravity field models of unprecedented precision and spatial resolution, which allow analyzing lithospheric structure allowing the analysis of the lithospheric structure. We used the model EGM2008 (Earth Gravitational Model) to calculate the gravity anomaly and the vertical gravity gradient in the South Central Andes region, correcting these quantities by the topographic effect. Both quantities show a spatial relationship between the projected subduction of the Copiap\uf3 aseismic ridge (located at 33 about 27\uba 30\u2019 S), its potential deformational effects in the overriding plate, and the Ojos del Salado-San Buenaventura volcanic lineament. This volcanic lineament constitutes a projection of the volcanic arc towards the retroarc zone, whose origin and development were not clearly understood. The analysis of the gravity anomalies, at the extrapolated zone of the Copiap\uf3 ridge beneath the continent, shows a change in the general NNE38 trend of the Andean structures to an ENE-direction coincident with the area of the Ojos del Salado-San Buenaventura volcanic lineament. This anomalous pattern over the upper plate is interpreted to be linked with the subduction of the Copiap\uf3 ridge. We explore the relation between deformational effects and volcanism at the northern Chilean-Pampean flat slab and the collision of the Copiap\uf3 ridge, on the basis of the Moho geometry and elastic thicknesses calculated from the new satellite GOCE data. Neotectonic deformations interpreted in previous works associated with volcanic eruptions along the Ojos del Salado-San Buenaventura volcanic lineament is interpreted as caused by crustal doming, imprinted by the subduction of the Copiap\uf3 ridge, evidenced by crustal thickening at the sites of ridge inception along the trench. Finally, we propose that the Copiap\uf3 ridge could have controlled the northern edge of the Chilean-Pampean flat slab, due to higher buoyancy, similarly to the control that the Juan Fernandez ridge exerts in the geometry of the flat slab further south

Cretaceous deformation of the southern Central Andes: synorogenic growth strata in the Neuquén Group (35° 300–37° S)

The Neuquén Group is an Upper Cretaceous continental sedimentary unit exhumed during the latest Miocene contractional phase occurred in the southern Central Andes, allowing a direct field observation and study of the depositional geometries. The identification of growth strata on these units surrounding the structures of the frontal parts of the Andes, sedimentological analyses and U–Pb dating of detrital components, allowed the definition of a synorogenic unit that coexisted with the uplift of the early Andean orogen since ca. 100 Ma, maximum age obtained in this work, compatible with previous assignments and constrained in the top by the deposition of the Malarg€ue Group, in the Maastrichtian (ca. 72 Ma). The definition of a wedge top area in this foreland basin system, where growth strata were described, permitted to identify a Late Cretaceous orogenic front and foredeep area, whose location and amplitude contrast with previous hypotheses. This wedge top area was mostly fed from the paleo-Andes with small populations coming from sources in the cratonic area that are interpreted as a recycling in Jurassic and Lower Cretaceous sections, which contrasts with other analyses performed at the foredeep zone that have mixed sources. In particular, Permian sources are interpreted as coming directly from the cores of the basement structures, where Neopaleozoic sections are exposed, next to the synorogenic sedimentation, implying a strong incision in Late Cretaceous times with an exhumation structural level similar to the present. The maximum recognised advance for this Late Cretaceous deformation in the study area is approximately 500 km east of the Pacific trench, which constitutes an anomaly compared with neighbour segments where Late Cretaceous deformations were found considerably retracted. The geodynamic context of the sedimentation of this unit is interpreted as produced under the westward fast moving of South America, colliding with two consecutive mid-ocean ridges during a period of important plate reorganisation. The subduction of young, anhydrous, buoyant lithosphere would have produced changes in the subduction geometry, reflected first by an arc waning/gap and subsequently by an arc migration that coexisted with synorogenic sedimentation. These magmatic and deformational processes would be the product of a shallow subduction regime, following previous proposals, which occurred in Late Cretaceous times, synchronous to the sedimentation of the Neuqu en Group.Facultad de Ciencias Naturales y Muse

Accelerated geroncogenesis in hereditary breast-ovarian cancer syndrome

The geroncogenesis hypothesis postulates that the decline in metabolic cellular health that occurs naturally with aging drives a "field effect" predisposing normal tissues for cancer development. We propose that mutations in the cancer susceptibility genes BRCA1/2 might trigger "accelerated geroncogenesis" in breast and ovarian epithelia. By speeding up the rate at which the metabolic threshold becomes "permissive" with survival and expansion of genomically unstable pre-tumoral epithelial cells, BRCA haploinsufficiency-driven metabolic reprogramming would operate as a bona fide oncogenic event enabling malignant transformation and tumor formation in BRCA carriers. The metabolic facet of BRCA1 one-hit might involve tissue-specific alterations in acetyl-CoA, α-ketoglutarate, NAD +, FAD, or S-adenosylmethionine, critical factors for de/methylation or de/acetylation dynamics in the nuclear epigenome. This in turn might induce faulty epigenetic reprogramming at the "install phase" that directs cell-specific differentiation of breast/ovarian epithelial cells, which can ultimately determine the penetrance of BRCA defects during developmental windows of susceptibility. This model offers a framework to study whether metabolic drugs that prevent or revert metabolic reprogramming induced by BRCA haploinsufficiency might displace the "geroncogenic risk" of BRCA carriers to the age typical for those without the mutation. The identification of the key nodes that directly communicate changes in cellular metabolism to the chromatin in BRCA haploinsufficient cells may allow the epigenetic targeting of genomic instability using exclusively metabolic means. The validation of accelerated geroncogenesis as an inherited "one-hit" metabolic "field effect" might offer new strategies to therapeutically revisit the apparently irreversible genetic-hereditary fate of women with hereditary breast-ovarian cancer syndrome

Geometry of Middle to Late Triassic extensional deformation pattern in the Cordillera del Viento (Southern Central Andes): A combined field and geophysical study

Combined field and gravimetric-magnetic data reveal a complex pattern of extensional structures superimposed to the late Carboniferous – Early Permian Gondwanan orogen at the inner sectors of the Southern Central Andes, in the westernmost part of the Chos Malal fold and thrust belt at the cordillera del Viento area. W-NW, NW basement structures of regional significance, segmented by minor NE structures are bounding Late Triassic depocenters and structural highs corresponding to the cordillera del Viento rifting, equivalent to the Precuyo cycle. A pattern of roughly N-S trending structures recognized in the field associated with Andean thrusts do not show evidences of previ­ous structural controls, as they cut the magnetic anomalies. Field observations show that W-NW, NW and NE normal structures control changes in Late Triassic sedimentary thicknesses and are associated with synextensional geometries. Our model indicates that Late Triassic rifting in the area would have had a regional W-NW to NW trend being segmented by minor NE structures. Both sets were reactivated dur­ing Andean times, acting W-NW and NW structures as transfer zones between decoupled contractional panels and NE structures as frontal contractional structures. N-S contractional structures did not respect rifting architecture cutting through the depocenters and occasionaly exhuming synextensional geometries.La combinacion de datos de campo, junto con magnéticos y gravimétricos, revelan un patrón complejo de estructuras sobreimpuestas al orógeno gondwánico (Carbonífero superior– Pérmico) en el sector interno de la faja plegada y corrida de los Andes Centrales australes, en el área de la cordillera del Viento. Estructuras de basamento W-NW, NW de significancia regional, segmentadas por estruturas menores NE están limitando depocentros y altos estructurales correspondientes al rifting del Triásico Superior de la cordillera del Viento, equivalente de las unidades del ciclo Precuyo. En el campo se reconoce además un patrón de estructuras de rumbo N, asociadas a fallas andinas que no muestran evidencias de un control estrutural previo, ya que las anomalías magnéticas están cortadas por éstas. Las observaciones de campo demuestran que tanto las estructuras W-NW y NW como las NE controlan cambios de espesor de los sedimentos del Triásico Superior y se asocian a geometrías sinextensionales. El modelo propuesto indica que el rifting del Triásico Superior podría haber tenido una geometría elongada según el patrón de estructuras identificadas W-NW a NW, segmentado por estructuras menores NE. Ambas muestran reactivación durante tiempos andinos, las primeras actuando como zonas de transferencia entre sectores que muestran diferentes grados y mecánicas de contracción y las últimas como estructuras frontales contraccionales. Las estructuras contraccionales de orientación N-S no respetan la arquitectura del rift triásico, cortando los depocentros y eventualmente exhumando geometrías sinextensionales

In silico clinical trials for anti-aging therapies

Altres ajuts: CERCA Programme/Generalitat de CatalunyaAltres ajuts: Fundació Oncolliga Girona (Lliga catalana d'ajuda al malalt de càncer, Girona)Altres ajuts: Obra Social La Caixa Foundation on Collaborative Mathematics awarded to the Centre de Recerca Matemàtica (CRM)Therapeutic strategies targeting the hallmarks of aging can be broadly grouped into four categories, namely systemic (blood) factors, metabolic manipulation (diet regimens and dietary restriction mimetics), suppression of cellular senescence (senolytics), and cellular reprogramming, which likely have common characteristics and mechanisms of action. In evaluating the potential synergism of combining such strategies, however, we should consider the possibility of constraining trade-off phenotypes such as impairment in wound healing and immune response, tissue dysfunction and tumorigenesis. Moreover, we are rapidly learning that the benefit/risk ratio of aging-targeted interventions largely depends on intra- and inter-individual variations of susceptibility to the healthspan-, resilience-, and/or lifespan-promoting effects of the interventions. Here, we exemplify how computationally-generated proxies of the efficacy of a given lifespan/healthspan-promoting approach can predict the impact of baseline epigenetic heterogeneity on the positive outcomes of ketogenic diet and mTOR inhibition as single or combined anti-aging strategies. We therefore propose that stochastic biomathematical modeling and computational simulation platforms should be developed as in silico strategies to accelerate the performance of clinical trials targeting human aging, and to provide personalized approaches and robust biomarkers of healthy aging at the individual-to-population levels

Model for Andean orogenic volume variation and shortening in the 20°-46°S sector

El volumen orogénico levantado en los Andes es el resultado del delicado equilibrio entre el levantamiento y la erosión. Los diferentes grados de acortamiento sufridos por el borde occidental del continente americano, desde el codo de Arica hasta Tierra del Fuego, han definido contrastantes rasgos morfotectónicos, desde extensas altiplanicies endorreicas hasta reducidas y simples divisorias. El volumen orogénico a través de los Andes Centrales Australes y Patagónicos Septentrionales (20º-46ºS) disminuye linealmente de norte a sur. Esta linealidad experimenta un drástico cambio de pendiente, a los 38ºS, en la zona de transición entre los Andes Centrales Australes y los Patagónicos Septentrionales. La zona norte (20º-38ºS) presenta mayor velocidad de variación que la sur (38º-46ºS). Este quiebre coincide con un cambio relativo en el gradiente de edades de fondo oceánico, sugiriendo un control en el acortamiento, al menos parcial, por parte de la flotabilidad de la placa oceánica subducida. Esto se contrapone con las hipótesis que postulan que el factor climático sería el principal condicionante de estos contrastes morfológicos. Se presentan además dos ecuaciones empíricas para la obtención de volúmenes orogénicos a una latitud dada, fuera del ámbito de dos anomalías centradas en 27º y 33ºS respectivamente. A estas latitudes, otros factores adicionales al acortamiento orogénico están definiendo el relieve observado. Adicionalmente se discute una ley de variación del acortamiento en función de la latitud, calculado a partir de datos gravimétricos, fuera de los entornos de estas anomalías alrededor de las cuales se observan fluctuaciones equivalentes al caso anterior.The orogenic volume of the Andes is the result of the equilibrium between the tectonic uplift and erosion. The different rates of shortening along the western margin of the South American continent have defined contrasting morphostructural settings. The orogenic volume along the southern Central Andes and northern Patagonian Andes (20°-46°S) decreases linearly, from north to south. At 38°S, we have separated two segments with different rates of variation in the Andean volume. The northern sector (20°-38°S) shows a steeper linear law than the southern sector. Even though the Andean volume varies together with the decrease from north to south of the subducted oceanic slab age, latitude 38°S coincides with a sudden change related to this late parameter. This observation has led us to propose a linkage between subducted parameters and variation of Andean volume, which contrasts with other hypotheses that assume that climate, is the principal cause for the variations in the observed orogenic volume. We also present two empiric equations to calculate the orogenic volume at determined latitude, beyond the area of influence of two anomalies centered around 27°S and 33°S respectively. Those sectors are considered to be influenced by other factors related to isostatic rebounds, superposed to shortening. Additionally, we discuss a law for the latitudinal variation of the orogenic shortening away from the location of the mentioned anomalies.Fil: Pose, Fernando A.. No especifica;Fil: Spagnuolo, Mauro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin