Dense shelf water cascades and sedimentary furrow formation in the Cap de Creus Canyon,northwestern Mediterranean Sea   总被引：1，自引：0，他引：1  

P. Puig  A. Palanques  D.L. Orange  G. Lastras  M. Canals 《Continental Shelf Research》2008

To investigate the processes by which sediment is transported through a submarine canyon incised in a continental margin affected by recurrent dense shelf water cascading events, several instrumented moorings were deployed in the Cap de Creus Canyon from September 2004 to September 2005. This was done as part of the EuroSTRATAFORM Program that investigated sediment transport and accumulation processes in the Gulf of Lions. Results obtained in this observational study confirm that major cascading events can effectively contribute to the rapid export of sediment from the shelf and upper slope to deeper environments, and suggest that the associated strong currents carrying coarse particles are able to erode the canyon floor and generate sedimentary furrows. During winter 2004–2005, persistent northerly winds and the absence of river floods contributed to decrease the buoyancy of coastal waters and to dramatically enhance the intensity of dense shelf water cascades in the Gulf of Lions. Under such conditions, cascading continuously affected the entire Cap de Creus upper canyon section for more than a month and sustained cold temperatures and down-canyon steady currents >60 cm/s (up to 100 cm/s), showing periodic fluctuations that lasted between 3 and 6 days. Increases in suspended sediment concentrations were associated with dense shelf water cascading outbursts, but the magnitude of the concentration peaks decreased with time, suggesting a progressive exhaustion of the resuspendable sediments from the shelf and canyon floor. Grain size analyses of the particles caught by a near-bottom sediment trap show that dense shelf water cascades are able to transport coarse sediments (up to 65% sand) in suspension (and presumably as bed load), which have the potential to abrade the seafloor and generate erosive bed forms. The orientation of a large field of “wide” (i.e., widths about 1/2 spacing indicative of erosive formation) sedimentary furrows recently observed in the Cap de Creus Canyon clearly coincides with the preferential direction of highest velocities measured by the moored current meters, indicating a causative relationship between contemporary dense shelf water cascades and furrow formation.  相似文献   

Comparison of horizontal and downward particle fluxes across canyons of the Gulf of Lions (NW Mediterranean): Meteorological and hydrodynamical forcing     

J. Bonnin  S. Heussner  A. Calafat  J. Fabres  A. Palanques  X. Durrieu de Madron  M. Canals  P. Puig  J. Avril  N. Delsaut 《Continental Shelf Research》2008

In the framework of the European project Eurostrataform, an array of six near-bottom mooring lines was deployed in the heads of the major submarine canyons incising the continental slope of the Gulf of Lions (NW Mediterranean). All moorings were equipped with sediment traps, current meters and turbidity Optical Backscatters Sensors (OBS) situated at few meters above the bottom. Particulate mass fluxes were recorded weekly by the sediment traps between November 2003 and May 2004 and compared with horizontal export fluxes obtained from the turbidity and current meters.  相似文献   

LEGRI Science Operation Center. Architecture and Operations     

Pere Blay  Julia Suso  Almudena Robert  Jose Luis Requena  Jorge Alamo  Victor Reglero  Chris J. Eyles 《Astrophysics and Space Science》2001,276(1):311-323

The LEGRI Science Operation Center (SOC) is the single contact pointbetween the MINISAT-01 Centro de Operaciones Científicas (COC)located at Villafranca del Castillo (Madrid) and the LEGRI Consortium.Its architecture, operational procedures and associated software hasbeen developed at the Universities of Valencia and Birmingham on thescope to define a integrated Data Analysis System, able to perform thedaily follow-up of the instrument health, raw data files decompressionand archiving activities (on-line and historical). Pointing and telecommandfiles generation is also a SOC responsibility.The aim of this paper is to report the SOC activities during the two yearsof LEGRI operations. Conclusions about the SOC architecture and proceduresevolution on how to handle the operations for space-borne instrumentation,are also presented.Special attention has been paid to the operative evaluation of the pointingreconstruction solutions from the MINISAT-01 Attitude Control System bycomparing them with those obtained with the LEGRI Star Sensor. The analysisof one year of observations shows the good agreement between both sets ofdata. No systematic deviations have been found with an averaged standarddeviation of 1 degree in alpha and delta coordinates. For most of the timethe MINISAT pointing system is working slightly better than expected andwithin specifications.  相似文献   

Time-series measurements of Th in water column and sediment trap samples from the northwestern Mediterranean Sea     

J. Kirk Cochran  Juan Carlos Miquel  Robert Armstrong  Scott W. Fowler  Pere Masqu  Beat Gasser  David Hirschberg  Jennifer Szlosek  Alessia M. Rodriguez y Baena  Elisabet Verdeny  Gillian M. Stewart 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(18):1487-1501

Disequilibrium between ²³⁴Th and ²³⁸U in water column profiles has been used to estimate the settling flux of Th (and, by proxy, of particulate organic carbon); yet potentially major non-steady-state influences on ²³⁴Th profiles are often not able to be considered in estimations of flux. We have compared temporal series of ²³⁴Th distributions in the upper water column at both coastal and deep-water sites in the northwestern Mediterranean Sea to coeval sediment trap records at the same sites. We have used sediment trap records of ²³⁴Th fluxes to predict temporal changes in water column ²³⁴Th deficits and have compared the predicted deficits to those measured to determine whether the time-evolution of the two coincide. At the coastal site (327 m water depth), trends in the two estimates of water column ²³⁴Th deficits are in fairly close agreement over the 1-month deployment during the spring bloom in 1999. In contrast, the pattern of water column ²³⁴Th deficits is poorly predicted by sediment trap records at the deep-water site (DYFAMED, 2300 m water depth) in both 2003 and 2005. In particular, the transition from a mesotrophic to an oligotrophic system, clearly seen in trap fluxes, is not evident in water column ²³⁴Th profiles, which show high-frequency variability. Allowing trapping efficiencies to vary from 100% does not reconcile the differences between trap and water column deficit observations; we conclude that substantial lateral and vertical advective influences must be invoked to account for the differences.Advective influences are potentially greater on ²³⁴Th fluxes derived from water column deficits relative to those obtained from traps because the calculation of deficits in open-ocean settings is dominated by the magnitude of the “dissolved” ²³⁴Th fraction. For observed current velocities of 5–20 cm s⁻¹, in one radioactive mean-life of ²³⁴Th, the water column at the DYFAMED site can reflect ²³⁴Th scavenging produced tens to hundreds of kilometers away. In contrast, most of the ²³⁴Th flux collected in shallow sediment traps at the DFYFAMED site was in the fraction settling >200 m d⁻¹; in effect the sediment trap can integrate the ²³⁴Th flux over distances 40-fold less than water column ²³⁴Th distributions. In some sense, sediment trap and water column sampling for ²³⁴Th provide complementary pictures of ²³⁴Th export. However, because the two methods can be dominated by different processes and are subject to different biases, their comparison must be treated with caution.  相似文献   

The phase 0/A study of the ESA M3 mission candidate EChO     

Ludovic Puig  Kate Isaak  Martin Linder  Isabel Escudero  Pierre-Elie Crouzet  Roger Walker  Matthias Ehle  Jutta Hübner  Rainer Timm  Bram de Vogeleer  Pierre Drossart  Paul Hartogh  Christophe Lovis  Giusi Micela  Marc Ollivier  Ignasi Ribas  Ignas Snellen  Bruce Swinyard  Giovanna Tinetti  Paul Eccleston 《Experimental Astronomy》2015,40(2-3):393-425

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Aragonite stromatolitic buildups from Santorini (Aegean Sea,Greece): Geochemical and palaeontological constraints of the caldera palaeoenvironment prior to the Minoan eruption (ca 3600 yr bp)     

Pere Anadón  Carles Canet  Walter L. Friedrich 《Sedimentology》2013,60(5):1128-1155

The pyroclastic deposits of the Minoan eruption (ca 3600 yr bp ) in Santorini contain abundant xenoliths. Most of these deposits are calcareous blocks of laminated‐botryoidal, stromatolite‐like buildups that formed in the shallow waters of the flooded pre‐Minoan caldera; they consist of (i) light laminae, of fibrous aragonite arranged perpendicular to layering, and (ii) dark laminae, with calcified filaments of probable biological origin. These microstructures are absent in the light laminae, suggesting a predominant inorganic precipitation of aragonite on substrates probably colonized by microbes. Internal cavities contain loose skeletal grains (molluscs, ostracods, foraminifera and diatoms) that comprise taxa typical of shallow marine and/or lagoon environments. Most of these forms are typical of warm water environments, although no typical taxa from hydrothermal vents have been observed. Past gasohydrothermal venting is recorded by the occurrence of barite, pyrolusite and pyrite traces. The most striking features of the stable isotopic data set are: (i) an overall wide range in δ¹³C_PDB (0·16 to 12·97‰) with a narrower variation for δ¹⁸O_PDB (?0·23 to 4·33‰); and (ii) a relatively uniform isotopic composition for the fibrous aragonite (δ¹³C = 12·40 ± 0·43‰ and δ¹⁸O = 2·42 ± 0·77‰, n = 21). The δ¹³C and δ¹⁸O values from molluscs and ostracods display a covariant trend, which reflects a mixing between sea water and a fluid influenced by volcano‐hydrothermal activity. Accordingly, ⁸⁷Sr/⁸⁶Sr from the studied carbonates (0·708758 to 0·709011 in fibrous aragonite and 0·708920 to 0·708991 in molluscs) suggests that the aragonite buildups developed in sea water under the influence of a hydrothermal/volcanic source. Significant differences in trace elements have been detected between the fibrous aragonite and modern marine aragonite cements. The caldera water from which the fibrous aragonite crusts formed received an input from a volcano‐hydrothermal system, probably producing diffuse venting of volcanogenic CO₂ gas and of a fluid enriched in Ca, Mn and Ba, and depleted in Mg and probably in Sr.  相似文献   

Bilan,fonctionnement et protection du système karstique de la Fontaine de Vaucluse (sud-est de la France)     

Bernard Blavoux  Jacques Mudry  Jean-Michel Puig 《Geodinamica Acta》2013,26(3):153-172

Résumén

L’aquifère karstique de la célèbre Fontaine de Vaucluse a fait l’objet de nouvelles investigations hydrogéologiqurs dont les résultats portent sur la définition et le fonctionnement du système.

Les données géologiques (lithologie, structure) nous ont permis la délimitation d’un impluvium de 1115 km² dont l’altitude moyenne. 870 m, est confirmée par les traceurs naturels physico-chimiques et isotopiques.

Le bilan hydrique, faute d’un réseau météorologique représentatif, a été calculé à partir d’un modèle climatique par tranches d’altitude, qui utilise les gradients pluviométriques et thermiques régionaux. On montre alors que les 3/4 des pluies efficaces proviennent des zones situées au-dessus de l’altitude moyenne de l’impluvium.

Les études hydrodynamiques et physico-chimiques nous ont permis de démontrer la faible inertie du système malgré sa taille, donc sa bonne karstification, ce qui confirme à l’échelle de l’ensemble les observations spéléologiques ponctuelles du plateau et de l’émergence.

Malgré leur faible apport au débit total, les précipitations estivales marquent la chimie de l’émergence et interrompent ainsi la phase de tarissement.

La contribution de l’eau des réserves au débit est prépondérante : respectivement les 3/4 et les 2/3 des volumes annuels écoulés en 1981 et 1982.

Compte tenu de l’absence de sols et de terrains poreux de couverture, ainsi que du développement de la karstification, la vulnérabilité du système est grande. Aussi une attention particulière doit-elle être portée à l’aménagement de la zone montagnarde de l’impluvium dont le rôle est prépondérant dans l’alimentation du système.  相似文献   

Increased predation of juvenile European spiny lobster (Palinurus elephas) in a marine protected area     

David Díaz  Mikel Zabala  Cristina Linares  Bernat Hereu  Pere Abelló 《新西兰海洋与淡水研究杂志》2013,47(2):447-453

One of the aims of Mediterranean marine protected areas (MPAs) is to increase populations of exploited species, such as the European spiny lobster (Palinurus elephas), which is considered a key species for its commercial and ecological value. Monitoring of temporal patterns in abundance of early benthic stages of P. elephas indicated that predation may be higher inside the Medes Islands MPA relative to adjacent control sites. Tethering experiments were performed to test whether predation rates actually differed within and outside the MPA. Relative mortality of recently‐settled juveniles inside the MPA was much higher than in control sites in adjacent non‐protected areas. Treatments with and without shelter indicated that predation on recently‐settled juvenile spiny lobsters was moderated by the availability of suitable shelter. The decline or absence of fish predators in the fished area may be the reason why juvenile lobsters outside the MPA experience lower predation than within the MPA.  相似文献   

Holocene intramontane lake development: A new model in the Jáchal River Valley, Andean Precordillera, San Juan, Argentina     

Ferran Colombo  Pere Busquets  Nuria Sole de Porta  Carlos Oscar Limarino  Nemesio Heredia  Luis Roberto Rodriguez-Fernandez  Joaquina Alvarez-Marron 《Journal of South American Earth Sciences》2009,28(3):229-238

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Basic magmas in the early evolution of the Southernmost Patagonian Batholith,Chile     

Dr. M. Suárez  Dr. M. Hervé  Dr. A. Puig 《International Journal of Earth Sciences》1985,74(2):337-342

Basic magmas played an important role in the early evolution of a segment of the Patagonian Batholith (141 to 34 m.y.) exposed south of Tierra del Fuego, Chile. The basic magmatism lasted 40 m.y. to possibly 60 m.y. (141 to 84 m.y.). It is represented by early gabbros and hornblendites (141 to 103 m.y.) and by synplutonic dikes and some of the numerous basic inclusions in the granitoids of a Cretaceous (113 to 84 m.y.) plutonic group. Some of the inclusions are interpreted as the disrupted portions of synplutonic dikes.Available data indicate that basaltic to rhyolitic volcanism which took place in the area during the Early Cretaceous was contemporaneous with the basic magmatism reported here and during its latest stage, with granitoid magmas. Therefore, gabbros apparently formed part of the roots of the island arc during the early stages of its evolution, whilst granitoids may have had a greater participation at a later stage in the root system.

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Zusammenfassung Basische Magmen spielten eine bedeutende Rolle bei der frühen Entwicklung eines Abschnittes des Patagonischen Batholithen (141-34 Mio. J.), der südlich Tierra del Fuego, Chile, aufgeschlossen ist. Der basische Magmatismus dauerte 40 bis etwa 60 Millionen Jahre (141-84 Mio. J.). Er besteht aus frühen Gabbros und Hornblenditen (141-103 Mio. J.) und aus synplutonischen Gängen und einigen der zahlreichen basischen Einschlüsse in dem Granitkomplex der kretazischen Plutonit-Gruppe (113-84 Mio. J.). Einige der Einschlüsse werden als isolierte Anteile von synplutonischen Gängen gedeutet.Die zur Verfügung stehenden Daten belegen, daß der basaltische bis rhyolitische Vulkanismus, der sich in diesem Gebiet während der frühen Kreide ereignete, gleichzeitig mit dem hier vorgestellten basischen Magmatismus und in dessen letztem Stadium zusammen mit granitischen Magmen ereignete. Daher waren offensichtlich Gabbros an den Wurzeln des Inselbogens während der frühen Entwicklungsstadien beteiligt, während Granotioide mit größerem Anteil an dem späterem Stadium des Wurzelsystems beteiligt waren.

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Resumen Magmas básicos tuvieron un importante rol en la historia temprana del segmento del Batolito Patagónico (141 a 34 M a) que se expone al sur de Tierra del Fuego, Chile. El magmatismo básico tuvo una duración de unos 40 Ma y hasta unos 60 Ma (141 a 84 Ma). Este magmatismo está representado por gabros y hornblenditas (141 a 103 Ma), por diques sinplutónicos y por algunas de las numerosas inclusiones básicas en los granitoides pertenecientes a un grupo plutónico del Cretácico (113 a 84 Ma). Algunas de las inclusiones se interpretan como partes de diques sinplutónicos.La información existente permite indicar que el volcanismo basáltico y riolítico que tuvo lugar en la región, durante el Cretácico Inferior, fue contemporáneo con el magmatismo básico del que se informa en este artículo. Aparentemente, la etapa final de este volcanismo habría sido coetáneo con un importante magmatismo granítico. En consecuencia, aparentemente, en las etapas iniciales de la evolución de la cadena volcánica, los gabros habrían constituído parte de su raíz, mientras que posteriormente habría habido mayor participación de granitoides.

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