Chasma Boreale, Mars: A Sapping and Outflow Channel with a Tectono-thermal Origin

A detailed geomorphological study of Chasma Boreale, a widely known feature of Mars’ north polar cap, has been carried out for the first time, along with a quantitative paleohydro logical model. It is concluded that the chasma was eroded by a flow whose discharge was on the order of magnitude of 109 m sec21. This catastrophic flow is thought to have been preceded by a powerful sapping process, caused by a tectonic control in the distribution and present aspect of most of the polar troughs. This tectonic forcing probably played a major role in the inception of not only Chasma Boreale but also other polar reentrants as wel

Evidence of gully formation by regional groundwater flow in the Gorgonum–Newton region (Mars)

The discovery of gullies on Mars suggests liquid water activity near the surface of the planet in recent times. Since liquid water is unstable under the present-day P–T martian conditions, the formation mechanisms of the gullies, and the source of the putative water, have been a matter of debate for the last years. To provide new insights into these matters, we have approached the problem studying the gullies in relation to their regional setting. A major point in our study relates to the geographic orientation of gullies, an aspect that has been previously regarded as a crucial matter in different models, and has profound implications regarding their origin. We present a comprehensive and detailed survey of the Gorgonum–Newton region, and a study of the Dao and Nirgal Vallis regions. The survey was carried out with the aid of 965 high-resolution MOC images (752 for Gorgonum–Newton, 102 for Nirgal Vallis and 111 for Dao Vallis regions), and MOLA-derived DEMs.We found that gullies display a clear regional pattern, geographically and topographically consistent with a decreasing regional slope. We interpret the results in terms of the existence of several groundwater flow systems operating at different scales, which ultimately may have led to gully formation by seepage at the slopes of craters and canyons. We suggest that aquifers discharging at gully systems may have recharged from the surface, in response to the melting of young partially eroded ice-rich deposits

Depth of faulting and ancien theat flows in the Kuiper region of Mercury from lobate scarp topography

Mercurian lobate scarp sare interpreted to be the surface expressions of thrust faults formed by planetary cooling and contraction, which deformed the crust downto the brittle–ductile transition (BDT) dep that the time of faulting. In this work we have used a for ward modeling procedure in order to analyze the relation be tweens carptopography and fault geometrie sand dep thsas sociated with a group of prominent lobate scarps (Santa Maria Rupes and twoun named scarps) located inthe Kuiper region of Mercury for which Earth-based radar altimetry is available. Also aback thrust associated with one of the lobate scarps has been included in this study. We have obtained best fits for depthsof faul ting between 30 and 39 km; the results are consistent with the previous results for o ther lobate scarps on Mercury. The so-derived fault depths have been used to calculate surface heat flows for the time of faulting, taking into account crustal heat source sand a heterogeneous surface temperature due to the variable in solation pattern. Deduced surface heat flow sare be tween 19 and 39m Wm-2 for the Kuiper region, and between 22 and 43 mWm-2 for Discovery Rupes. Both BDT depth sand heat flows are consistent with the predictions of thermal history models for the range of time relevant for scarp formation

Contrasting catastrophic eruptions predicted by different intrusion and collapse scenarios

Catastrophic volcanic eruptions triggered by landslide collapses can jet upwards or blast sideways. Magma intrusion is related to both landslide-triggered eruptive scenarios (lateral or vertical), but it is not clear how such different responses are produced, nor if any precursor can be used for forecasting them. We approach this problem with physical analogue modelling enhanced with X-ray Multiple Detector Computed Tomography scanning, used to track evolution of internal intrusion, and its related faulting and surface deformation. We find that intrusions produce three different volcano deformation patterns, one of them involving asymmetric intrusion and deformation, with the early development of a listric slump fault producing pronounced slippage of one sector. This previously undescribed early deep potential slip surface provides a unified explanation for the two different eruptive scenarios (lateral vs. vertical). Lateral blast only occurs in flank collapse when the intrusion has risen into the sliding block. Otherwise, vertical rather than lateral expansion of magma is promoted by summit dilatation and flank buttressing. The distinctive surface deformation evolution detected opens the possibility to forecast the possible eruptive scenarios: laterally directed blast should only be expected when surface deformation begins to develop oblique to the first major fault

Tissue response to dental implants with platform switching

La evolución en los diseños de los sistemas de implantes y en la configuración de los pilares protési- cos ha desarrollado el concepto de plataforma reducida que comprende la colocación de un pilar más estrecho que la plataforma del implante para aumentar su distancia de la interfase hueso-implante. La plataforma reducida es considerada un factor importante para preservar la estabilidad del hueso crestal y de los tejidos blandos y asegurar el éxito de los implantes dentales a largo plazo. La plataforma redu- cida reduce las fuerzas oclusales y la contaminación bacteriana en la interfase entre el hueso crestal y el implante. Los estudios experimentales en animales y clínicos en pacientes muestran su eficacia para prevenir la pérdida ósea y de los tejidos blandos periimplantarios Conclusiones. La introducción de la plataforma reducida constituye un importante campo en la investi- gación experimental en implantología oral y en el tratamiento clínico con implantes para mantener los tejidos periimplantarios.The evolution of designs of implant systems and abutments configurations has developed the concept of platform-switching that involves the connection of a narrower abutment to the platform implant to allow horizontal distance of the interface bone-implant. Platform-switching is considered an important factor to preserve the stability of crestal bone and soft tissue ensuring the success of dental implants in the long-term follow-up. Platform-switching reduces the forces of occlusal loading and bacterial conta- mination in the interface between the crestal bone and the implant. Experimental studies in animals and clinical studies in patients showed that implants with platform-switching have demonstrated the effecti- veness to prevent peri-implant bone loss and subsequent soft tissue loss. Conclusions. The platform-switching constitute an important field for research of experimental implant dentistry and clinical implant treatment in the maintenance of peri-implant tissue

Composition of the lava associated with the flank collapses of the western sector of the La Orotava (Tenerife)

Se han analizado las lavas de dos galerías de agua excavadas en el valle de La Orotava que cortan la secuencia de relleno de la depresión generada tras el gran colapso de flanco de La Orotava (OL) y los dos colapsos de flancos menores (WOL-1 y WOL-2). Especialmente las lavas situadas inmediatamente encima y debajo de lo depósitos de avalancha asociados al WOL-2 (el U-DAD). Se trata mayoritariamente de basanitas, con algunos términos algo más evolucionados (traquibasaltos y traquiandesitas basálticas). Por sus características químicas parecen pertenecer todas a un mismo sistema magmático y ligadas entre sí por procesos sencillos de fraccionación de clinopiroxeno y, en menor medida, de olivino.Tras el colapso de flanco WOL-2 se aprecia que las rocas son, en general, menos evolucionadas, algo más alcalinas y, con frecuencia, muy ricas en fenocristales máficos.The lava flows from two water galleries excavated in the La Orotava valley that drill the infilling sequence of the depression generated after the massive flank collapse of La Orotava (OL) and the two smaller flank collapses (WO-1 and WOL-2) have been analyzed. Especially the lava flows located immediately above and below the avalanche deposits associated with the WOL-2 (the U-DAD). They are mostly basanites, with some more evolved rocks (trachybasalts and basaltic trachyandesites). From their chemical characteristics, they all seem to belong to the same magmatic system and linked together by simple fractionation processes of clinopyroxene and, to a lesser extent, olivine.After the WOL-2 flank collapse, the rocks are, in general, less evolved, somewhat more alkaline, and often very rich in mafic phenocrysts.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEMinisterio de Economía y Competitividad (MINECO)Universidad Complutense de Madridpu

Evidencias mineralógicas y geoquímicas de mezcla incompleta de magmas en la Sierra de las Cruces, Cinturón Volcánico Mexicano

Received: 19/05/2011 / Accepted: 12/04/2013.Pliocene – Pleistocene lava flows, mainly of dacitic composition, are exposed in the Sierra de las Cruces (SC) volcanic range within the Mexican Volcanic Belt (MVB). SC volcanic rocks are porphyritic, generally containing an assemblage of plagioclase + amphibole + orthopyroxene ± clinopyroxene ± quartz ± Fe-Ti oxides. Most of them exhibit diverse mineralogical and geochemical features that attest a magma mixing and mingling processes with concomitant fractional crystallization in which a small volume of hot andesite magma injects into dacitic magma. Both rock types are probably derived from partial melting of continental crust at different levels. The evidences of magma mixing and mingling include: (a) normal and sieved plagioclases in the same sample, rounded and embayed crystals, and armoured rims over the dissolved crystal surfaces; (b) subrounded, vesicular magmatic enclaves, ranging from a few millimeters to ~20 centimeters in size, with plagioclase + orthopyroxene + amphibole + quartz ± olivine ± Fe-Ti-oxides assemblage; (c) mineral chemistry evidence such as crystals with reaction rims or heterogeneous plagioclase compositions (inverse and oscillatory zoning or normally and inversely zoned crystals) in the same sample; and (d) elemental geochemical variations and trace-element ratio more akin to magma mixing and to some extent diffusion process. These andesitic enclaves could be considered as portions of the intermediate magma that did not mix completely (mingling) with the felsic host lavas, confirming the major role of magma mixing and mingling processes in the overall evolution of the MVB.En la Sierra de las Cruces (SC), Cinturón Volcánico Mexicano (CVM), se encuentran expuestos flujos de lava, principalmente de composición dacítica, del Plioceno-Pleistoceno. Las rocas volcánicas de la SC son de textura porfirítica, conteniendo plagioclasa + anfibol + ortopiroxeno ± clinopiroxeno ± cuarzo ± óxidos de Fe-Ti. La mayor parte de ellas exhiben diversas características que indican un proceso de mezcla incompleta de magmas, con una cristalización fraccionada concomitante, en la que un pequeño volumen de un magma andesítico caliente es inyectado a un magma dacítico. Es probable que ambos tipos de roca se hayan generado por fusión parcial a diferentes niveles de la corteza continental. Las evidencias de la mezcla incompleta de magmas incluyen: (a) plagioclasas con texturas normal y anubarrada en la misma muestra, cristales redondeados y corroídos, y bordes de reacción en superficies de cristal disueltas; (b) enclaves magmáticos subredondeados y vesiculares, que ocurren en dimensiones de un pocos milímetros a ~20 centímetros de diámetro, con plagioclasa + ortopiroxeno + anfíbol + cuarzo ± olivino ± óxidos de Fe-Ti; (c) química de minerales, que incluye cristales con bordes de reacción o plagioclasas de composición heterogénea (zonación inversa y oscilatoria o cristales con zonación normal e inversa) en la misma muestra; y (d) variaciones geoquímicas de elementos y relaciones de elementos traza explicables por una mezcla de magmas y por un proceso de difusión. Los enclaves andesíticos podrían considerarse como porciones de magma intermedio que no se mezcló con los líquidos dacíticos receptores, lo que confirma la importancia de los procesos de mezcla incompleta de magmas en la evolución magmática del CVM.Universidad Autónoma de Nuevo LeónDepto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Aprendizaje cooperativo e integrado de Ingeniería Química mediante el juego del Cluedo

Memoria ID-045 Ayudas de la Universidad de Salamanca para la innovación docente, curso 2020-2021