Detrital zircon geochronology in the Dora‐Maira and Zone Houillère: a record of sediment travel paths in the Carboniferous          下载免费PDF全文

Paola Manzotti  Michel Ballvre  Marc Poujol 《地学学报》2016,28(4):279-288

In the internal zone of the European Alps, late Carboniferous to Permian sediments have been detached from their basement (e.g. the Zone Houillère in the Briançonnais Zone). The Pinerolo Unit (Dora‐Maira Massif) is the deepest unit exposed in the stack of the Western Alps and is considered to be Carboniferous in age based on lithological considerations. Detrital zircon grains from the Pinerolo Unit and the Zone Houillère display similar age patterns, with the youngest and largest population being Carboniferous (340–330 Ma). The distribution of Carboniferous magmatism in the Alps and surrounding areas suggests that the detritus was transported from Maures‐Corsica and possibly from the Helvetic Zone into the Zone Houillère and the Pinerolo basin. Our results highlight the potential of detrital zircon geochronology for deciphering the sources of detrital material in meta‐sediments, even if they have been affected by metamorphic overprints.  相似文献   

Size Fraction Effects on Planktonic Foraminifera Assemblages: A Compositional Contribution to the Golden Sieve Rush     

Valentino Di Donato  Josep Daunis-i-Estadella  Josep A. Martín-Fernández  Paola Esposito 《Mathematical Geosciences》2015,47(4):455-470

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Diagnosis of physical and biological controls on phytoplankton distribution in the Sargasso Sea     

WANG Caixia  and Paola Malanotte-Rizzoli 《中国海洋大学学报(英文版)》2014,13(1):32-44

The linkage between physical and biological processes is studied by applying a one-dimensional physical-biological coupled model to the Sargasso Sea. The physical model is the Princeton Ocean Model and the biological model is a five-component system including phytoplankton, zooplankton, nitrate, ammonium, and detritus. The coupling between the physical and biological model is accomplished through vertical mixing which is parameterized by the level 2.5 Mellor and Yamada turbulence closure scheme. The coupled model investigates the annual cycle of ecosystem production and the response to external forcing, such as heat flux, wind stress, and surface salinity, and the relative importance of physical processes in affecting the ecosystem. Sensitivity experiments are also carried out, which provide information on how the model bio-chemical parameters affect the biological system. The computed seasonal cycles compare reasonably well with the observations of the Bermuda Atlantic Time-series Study (BATS). The spring bloom of phytoplankton occurs in March and April, right after the weakening of the winter mixing and before the establishment of the summer stratification. The bloom of zooplankton occurs about two weeks after the bloom of phytoplankton. The sensitivity experiments show that zooplankton is more sensitive to the variations of biochemical parameters than phytoplankton.  相似文献   

Source location of long period seismicity at Volcàn de Colima,México   总被引：1，自引：0，他引：1  

Simona Petrosino  Paola Cusano  Mario La Rocca  Danilo Galluzzo  Justo Orozco-Rojas  Mauricio Bretón  Jesus Ibáñez  Edoardo Del Pezzo 《Bulletin of Volcanology》2011,73(7):887-898

This paper presents an analysis of seismicity associated with the volcanic activity of Volcàn de Colima (México) and recorded in the period November 2005–April 2006 during a field survey by the Istituto Nazionale di Geofisica e Vulcanologia (INGV)–Osservatorio Vesuviano, the Observatorio Vulcanologico de Colima of Colima University and the Instituto Andaluz de Geofisica, University of Granada. Three different types of volcanic earthquakes have been identified on the basis of their spectral properties: Type A (0.3–1 Hz), Type B (1–5 Hz) and Type C (3–4 Hz). Results of polarization analysis applied to Type A events show a predominance of radial motion, indicating that the wavefield comprises compressional waves (P) and shear waves polarized in the vertical plane (SV), while the signal always begins with a negative polarity. Type A, B and C earthquakes have been located using both a flat layered model and a 3D model including topography. Hypocentre distributions indicate that the source of Type A signals is very shallow and confined to a small volume lying about 1 km below the crater. In contrast, the source of Type B and C events is significantly deeper, with most hypocentres located in a volume of about 1 km³ centred at 2.5–3 km depth. A cluster analysis based on the cross-correlation among the waveforms of different events recorded at the same station was applied to Type A earthquakes. Only two clusters, which include only a small percentage of events were found, indicating that earthquake families were uncommon during the period of our survey.  相似文献   

Analysis of the liquefaction phenomena in the village of Vittorito (L��Aquila)     

Paola Monaco  Filippo Santucci de Magistris  Salvatore Grasso  Silvano Marchetti  Michele Maugeri  Gianfranco Totani 《Bulletin of Earthquake Engineering》2011,9(1):231-261

This paper describes a case-history of liquefaction occurred near the village of Vittorito after the April 6, 2009 L’Aquila earthquake (moment magnitude M_w = 6.3), approximately 45 km far from the epicentre. In the document, first, an estimation of the seismic motion in the area has been made. Thereafter, the performed geotechnical investigation is described, followed by the application of some fast assessment criteria for the occurrence of liquefaction, recently proposed by the new Italian Building Code. A careful assessment of all the parameters involved in conventional Seed and Idriss (1971) liquefaction analyses is considered. The cyclic resistance ratio CRR is evaluated by cone penetration tests CPT and by in situ seismic dilatometer tests SMDT; in the latter case CRR is evaluated by different empirical correlations with shear wave velocity V_s and horizontal stress index K_D. Analytical data confirmed the observed occurrence of the liquefaction in Vittorito, even if the acceleration field in the area, produced by the L’Aquila earthquake, was very low.  相似文献   

Using Lightning Data to Better Understand and Predict Flash Floods in the Mediterranean     

C. Price  Y. Yair  A. Mugnai  K. Lagouvardos  M. C. Llasat  S. Michaelides  U. Dayan  S. Dietrich  F. Di Paola  E. Galanti  L. Garrote  N. Harats  D. Katsanos  M. Kohn  V. Kotroni  M. Llasat-Botija  B. Lynn  L. Mediero  E. Morin  K. Nicolaides  S. Rozalis  K. Savvidou  B. Ziv 《Surveys in Geophysics》2011,32(6):733-751

One of the costliest natural hazards around the globe is flash floods, resulting from localized intense convective precipitation over short periods of time. Since intense convective rainfall (especially over the continents) is well correlated with lightning activity in these storms, a European Union FP6 FLASH project was realized from 2006 to 2010, focusing on using lightning observations to better understand and predict convective storms that result in flash floods. As part of the project, 23 case studies of flash floods in the Mediterranean region were examined. For the analysis of these storms, lightning data were used together with rainfall estimates in order to understand the storms?? development and electrification processes. In addition, these case studies were simulated using mesoscale meteorological models to better understand the local and synoptic conditions leading to such intense and damaging storms. As part of this project, tools for short-term predictions (nowcasts) of intense convection across the Mediterranean and Europe, and long-term forecasts (a few days) of the likelihood of intense convection, were developed and employed. The project also focused on educational outreach through a special Web site http://flashproject.org supplying real-time lightning observations, real-time experimental nowcasts, medium-range weather forecasts and educational materials. While flash floods and intense thunderstorms cannot be prevented, long-range regional lightning networks can supply valuable data, in real time, for warning the public, end-users and stakeholders of imminent intense rainfall and possible flash floods.  相似文献   

Salt Waters of the Northern Apennine Foredeep Basin (Italy): Origin and Evolution     

Tiziano Boschetti  Lorenzo Toscani  Orfan Shouakar-Stash  Paola Iacumin  Giampiero Venturelli  Claudio Mucchino  Shaun K. Frape 《Aquatic Geochemistry》2011,17(1):71-108

The salt waters from the Emilia-Romagna sector of the Northern Apennine Foredeep have been investigated using major and trace element and stable isotope (δ²H, δ¹⁸O, δ³⁷Cl, δ⁸¹Br and ⁸⁷Sr/⁸⁶Sr ratio). Ca, Mg, Na, K, Sr, Li, B, I, Br and SO₄ vs. Cl diagrams suggest the subaerial evaporation of seawater beyond gypsum and before halite precipitation as primary process to explain the brine’s salinity, whereas saline to brackish waters were formed by mixing of evaporated seawater and water of meteoric origin. A diagenetic end-member may be a third component for mud volcanoes and some brackish waters. Salinization by dissolution of (Triassic) evaporites has been detected only in samples from the Tuscan side of the Apennines and/or interacting with the Tuscan Nappe. In comparison with the seawater evaporation path, Ca–Sr enrichment and Na–K–Mg depletion of the foredeep waters reveal the presence of secondary processes such as dolomitization–chloritization, zeolitization–albitization and illitization. Sulfate concentration, formerly buffered by gypsum-anhydrite deposition, is heavily lowered by bacterial and locally by thermochemical reduction during burial diagenesis. From an isotopic point of view, data of the water molecule confirm mixing between seawater and meteoric end-members. Local ¹⁸O-shift up to +11‰ at Salsomaggiore is related to water–rock interaction at high temperature (≈150°C) as confirmed by chemical (Mg, Li, Ca distribution) and isotopic (SO₄–H₂O) geothermometers. ³⁷Cl/³⁵Cl and ⁸¹Br/⁷⁹Br ratios corroborate the marine origin of the brines and evidence the diffusion of halogens from the deepest and most saline aquifers toward the surface. The ⁸⁷Sr/⁸⁶Sr ratio suggests a Miocene origin of Sr and rule out the hypothesis of a Triassic provenance of the dissolved components for the analyzed waters issuing from the Emilia-Romagna sector of the foredeep. Waters issuing from the Tuscan side of the Apennines and from the Marche sector of the foredeep show higher ⁸⁷Sr/⁸⁶Sr ratios because of the interaction with siliciclastic rocks.  相似文献   

Salinity and Chlorophyll a as Performance Measures to Rehabilitate a Mangrove-Dominated Deltaic Coastal Region: the Ci��naga Grande de Santa Marta�CPajarales Lagoon Complex, Colombia     

Victor H. Rivera-Monroy  Robert R. Twilley  J. Ernesto Mancera-Pineda  Christopher J. Madden  Ariel Alcantara-Eguren  E. Barry Moser  Bror F. Jonsson  Edward Casta?eda-Moya  Oscar Casas-Monroy  Paola Reyes-Forero  Jorge Restrepo 《Estuaries and Coasts》2011,34(1):1-19

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Searching for the physical drivers of eigenvector 1: influence of black hole mass and Eddington ratio     

Paola Marziani  Radoslav K. Zamanov †  Jack W. Sulentic  Massimo Calvani 《Monthly notices of the Royal Astronomical Society》2003,345(4):1133-1144

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Introduction to the special issue of the Consortium of Organizations for Strong Motion Observation Systems (COSMOS) international guidelines for applying noninvasive geophysical techniques to characterize seismic site conditions     

Yong  Alan  Askan  Aysegul  Cassidy  John  D’Amico  Sebastiano  Parolai  Stefano  Pilz  Marco  Stephenson  William 《Journal of Seismology》2022,26(4):557-566

Journal of Seismology -  相似文献