Technological and infrastructure collaborative seismic research in Western Mexico

In February and March 2014, Spanish, Mexican and British scientists and technicians explored the western margin of Mexico, a region with a high occurrence of large earthquakes (> Mw = 7.5) and tsunami generation, on board the British Royal Research Ship James Cook. This successful joint cruise, named TSUJAL, was made possible thanks to a cooperative agreement between NERC and CSIC as part of the Ocean Facilities Exchange Group (OFEG), a major forum of European oceanographic institutions for the exchange of ship time, equipment and personnel. A dense geophysical data set was acquired using for the first time 6 km length seismic streamer facilities from Spain’s Consejo Superior de Investigaciones Cientificas (CSIC), usually operating in the Spanish RV Sarmiento de Gamboa, onboard the British RRS James Cook by solving all mechanical, electrical and electronic problems. The RRS James Cook in turn provides the seismic source and the acoustic, hullmounted echosounder operated by the British Natural Environment Research Council (NERC). Multiscale seismic and echosounder images unravel the subduction geometry, nature of the crust, and evidence faults and mass wasting processes. The data are crucial to estimating fault seismic parameters, and these parameters are critical to carrying out seismic hazard in Mexico, especially when considering largemagnitude earthquakes (Mw 8.0), and to constrain tsunami models.Peer Reviewe

Carbon remineralization by small mesopelagic and bathypelagic Stomiiforms in the Northeast Atlantic Ocean

The organic carbon resulting from photosynthesis in the upper ocean is transferred downward through the passive sinking of organic particles, physical mixing of particulate and dissolved organic carbon as well as active flux transported by zooplanktonic and micronektonic migrants. Several meso- and bathypelagic organisms feed in shallower layers during the nighttime and respire, defecate, excrete and die at depth. Recent studies suggest that migrant micronekton transport similar amounts of carbon to migrant zooplankton. However, there is scarce information about biomass and carbon flux by non-migratory species in the mesopelagic and bathypelagic zones. The non-migratory bristlemouth fishes (Cyclothone spp.) and partial migrator (A. hemigymnus) remineralise organic carbon at depth, and knowledge about this process by this fauna is lacking despite them having been referred to as the most abundant vertebrates on Earth. Here we show the vertical distribution of biomass and respiration of non-migratory mesopelagic fishes, during day and night, using the enzymatic activity of the electron transfer system (ETS) as a proxy for respiration rates. The study is focused on five Cyclothone species (C. braueri, C. pseudopallida, C. pallida, C. livida and C. microdon) and Argyropelecus hemigymnus. The samples were taken on a transect from the oceanic upwelling off Northwest Africa (20° N, 20° W) to the south of Iceland (60° N, 20° W). Cyclothone spp. showed, by far, the largest biomass (126.90 ± 86.20 mg C·m⁻²) compared to A. hemigymnus (0.54 ± 0.44 mg C·m⁻²). The highest concentrations of Cyclothone spp. in the water column were observed between 400 and 600 m and from 1000 to 1500 m depths, both during day and night. For the different species analysed, ETS activity did not show significant differences between diurnal and nocturnal periods. The total average specific respiration of Cyclothone spp. (0.02 ± 0.01 d⁻¹) was lower than that observed for A. hemigymnus (0.05±0.02 d⁻¹). The average carbon respiration of Cyclothone spp. was 2.22 ± 0.81 mg C·m⁻²·d⁻¹, while it was much lower for A. hemigymnus (0.04 ± 0.03 mg C·m⁻²·d⁻¹). The respiration of Cyclothone spp. was lower in the bathypelagic than in the mesopelagic zone (0.84 ± 0.48 vs 1.36 ± 1.01 mg C·m⁻²·d⁻¹, respectively). These results, to our knowledge, provide the first account of remineralisation by this community in the meso and bathypelagic zones of the ocean.En prens

Micronekton groups contributing to the night scattering layers in the Western Mediterranean

40th CIESM Congress: The largest Forum on Mediterranean and Black Sea Research, 28 October - 1 November 2013, Marseille, France.-- 1 page, 1 figureIn the present study the biomass and numerical contribution of micronekton organisms responsible of the night Scattering Layers of the upper water column were investigated. Relative abundance in weight and number of individuals of the different groups collected using midwater trawls performed concurrently with the detection of the scattering layers by echosounders are presentedPeer Reviewe

Vertical distribution, diversity and assemblages of mesopelagic fishes in the western Mediterranean

Publicado

Multichannel Seismic Imaging of the Rivera Plate Subduction at the Seismogenic Jalisco Block Area (Western Mexican Margin)

During the TSUJAL marine geophysical survey, conducted in February and March 2014, Spanish, Mexican and British scientists and technicians explored the western margin of Mexico, considered one of the most active seismic zones in America. This work aims to characterize the internal structure of the subduction zone of the Rivera plate beneath the North American plate in the offshore part of the Jalisco Block, to link the geodynamic and the recent tectonic deformation occurring there with the possible generation of tsunamis and earthquakes. For this purpose, it has been carried out acquisition, processing and geological interpretation of a multichannel seismic reflection profile running perpendicular to the margin. Crustal images show an oceanic domain, dominated by subduction–accretion along the lower slope of the margin with a subparallel sediment thickness of up to 1.6 s two-way travel time (approx. 2 km) in the Middle American Trench. Further, from these data the region appears to be prone to giant earthquake production. The top of the oceanic crust (intraplate reflector) is very well imaged. It is almost continuous along the profile with a gentle dip (<10°); however, it is disrupted by normal faulting resulting from the bending of the plate during subduction. The continental crust presents a well-developed accretionary prism consisting of highly deformed sediments with prominent slumping towards the trench that may be the result of past tsunamis. Also, a bottom simulating reflector (BSR) is identified in the first half a second (twtt) of the section. High amplitude reflections at around 7–8 s twtt clearly image a discontinuous Moho, defining a very gentle dipping subduction plane.Consejo Nacional de Ciencia y Tecnología (México)Ministerio de Economia y Competitividad (España)Universidad Nacional Autonoma de MexicoGeneralitat de CatalunyaDepto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasTRUEpu

Physical oceanography and productivity in the Weddell-Scotia Confluence: A spanish contribution to the DOVETAIL international project

García, Marc A.... et al.-- 5 pages, 3 figures[EN] The aim of the project "Physical oceanography and productivity in the Weddell-Scotia Confluence: A spanish contribution to the DOVETAIL international project" is to carry out a multidisciplinary oceanographic study of the physical and chemical characteristics of the Weddell-Scotia Confluence waters. [...][ES] La campaña oceanográfica E-DOVETAIL (HE 47) realizada por el BIO Hespérides en enero-febrero de 1998 se inscribe en el marco del proyecto internacional "Deep Ocean Ventilation Though Antarctic Intermediate Layers", auspiciado por el programa International Antarctic Zone del Scientific Committe on Oceanic Research (SCOR). [...]Peer reviewe

. 29. Arqueología

En el presente número, hemos intentado reunir propuestas que reflejen una variabilidad geográfica, cronológica y de enfoques teórico-metodológicos, donde prevalezcan las tipologías y la historia regional. Nuestra intención es que las colaboraciones se vayan enriqueciendo, diversificando y que, sobre todo, se mantenga y se eleve cada vez más la calidad académica. Las dos primeras contribuciones recuperan la investigación y la discusión sobre la Prehistoria de México, que sigue viva y ofrece un estimulante campo de debate. El artículo sobre “Sonora precerámica”, nos muestra que los territorios de las sociedades prehistóricas intersectan las fronteras actuales y requieren de un conocimiento compartido para tratar de entender las evidencias mexicanas. Los datos que se proporcionan revierten las reconstrucciones anteriores, básicamente tipológicas y permiten replantear algunos procesos tempranos sociales y ambientales, referentes a cazadores-recolectores y agricultores incipientes. El segundo trabajo, “El pasado del pasado”, se inicia con el hallazgo de un bifacial de tipología temprana ofrendado en una tumba de El Opeño, en Michoacán, hace una recopilación crítica de los elementos de tipología análoga encontrados en México y reflexiona sobre su presencia eventual en contextos más tardíos, que evidencian una reinterpretación no circunstancial en el ámbito ideológico. Continuando con Michoacán, les ofrecemos la aportación de una cantidad considerable de información obtenida en un “Salvamento arqueológico de dos carreteras”, en las zonas de Maravatío-Zapotlanejo y Morelia-Lázaro Cárdenas. Los datos, de por sí novedosos, en lo inmediato contienen información básica para una propuesta de secuencia cultural y abren la posibilidad de plantear investigaciones a largo plazo. El análisis tipológico tradicional es el tema del trabajo sobre “Comercio durante el Posclásico de la cerámica decorada”. A partir de la distribución espacial en grandes áreas, sobre todo del altiplano, de ciertos estilos cerámicos del Posclásico, el autor reinterpreta su génesis y significado cultural. Además plantea mecanismos de circulación y consumo, en una recopilación bibliográfica acuciosa. Para continuar con el altiplano en el Posclásico, el artículo sobre el “Cerro de los Magueyes: un centro funerario”, además de enriquecer nuestro conocimiento sobre tratamientos funerarios y características poblacionales de matlatzincas y nahuas, nos permite reconocer la importancia que tuvieron las unidades multiétnicas y sus complejos sistemas de interacción. Quedando en el tema de los contextos funerarios, muy socorrido en este número, les presentamos un hallazgo mortuorio en “Balcón de Montezuma”, sitio aún poco conocido, a pesar de ser uno de los más interesantes del estado de Tamaulipas y fronterizo entre los territorios de grupos agricultores y cazadores- recolectores. Para seguir con la “esfera” huasteca en esta misma porción del noreste de México, el trabajo sobre la “Cerámica Huasteca Negro sobre Blanco”, arrancando de consideraciones iconográficas en tres regiones clave, Pánuco, Oxitipa y Tuxpan, realiza correlaciones con estilos escultóricos y soluciones arquitectónicas y propone que esta cerámica es una manifestación tardía y de influencia foránea. El último artículo es una síntesis geográfico-histórica y arqueológica sobre la región de “Los Reyes Metzontla en el sureste de Puebla”. Por medio de la revisión documental y arqueológica, se discuten algunos rasgos de los señoríos del Posclásico y de sus transformaciones durante la colonia temprana. El número contiene las acostumbradas noticias y reseñas. Además, en reconocimiento a la labor de colegas y colaboradores, se incluye la sección de Archivo Técnico en donde se recuperan dos informes emblemáticos de la poco conocida labor del arqueólogo Héctor Gálvez, resultados de sus investigaciones en Chimalhuacán, Estado de México y en Culiacán, Sinaloa. Por último, insistiendo en nuestro propósito de impulsar la discusión académica, los invitamos a apoyar el mejoramiento de la revista a través de contribuciones originales, comentarios y críticas fundamentadas de los artículos.</p