Leucogranite intruding the South Tibetan Detachment in western Nepal: implications for exhumation models in the Himalayas   总被引：1，自引：0，他引：1  

Rodolfo Carosi  Chiara Montomoli  Daniela Rubatto  Dario Visonà 《地学学报》2013,25(6):478-489

The most popular models regarding the exhumation of the Greater Himalayan Sequence (GHS), such as extrusion, channel flow, critical taper and wedge extrusion, require prolonged activity of the two bounding shear zones and faults, the Main Central Thrust (MCT) and the South Tibetan Detachment (STD). We present the crystallization age of an undeformed leucogranite that intrudes both the GHS and the Tethyan Himalaya Sequence (THS). Zircon and monazite U‐Pb ages in the leucogranite give ages between 23 and 25 Ma constraining, at that time, the end of shearing along the STD. Our results limit the contemporaneous activity of the MCT and STD to a short period of time (~1–2 Ma) and thus argue against exhumation models requiring prolonged contemporaneous activity of the MCT and STD.  相似文献   

Solar-Terrestrial Signal Record in Tree Ring Width Time Series from Brazil     

Nivaor Rodolfo Rigozo  Cláudio Sergio Lisi  Mário Tomazello Filho  Alan Prestes  Daniel Jean Roger Nordemann  Mariza Pereira de Souza Echer  Ezequiel Echer  Heitor Evangelista da Silva  Valderez F. Rigozo 《Pure and Applied Geophysics》2012,169(12):2181-2191

This work investigates the behavior of the sunspot number and Southern Oscillation Index (SOI) signal recorded in the tree ring time series for three different locations in Brazil: Humaitá in Amaz?nia State, Porto Ferreira in S?o Paulo State, and Passo Fundo in Rio Grande do Sul State, using wavelet and cross-wavelet analysis techniques. The wavelet spectra of tree ring time series showed signs of 11 and 22?years, possibly related to the solar activity, and periods of 2–8?years, possibly related to El Ni?o events. The cross-wavelet spectra for all tree ring time series from Brazil present a significant response to the 11-year solar cycle in the time interval between 1921 to after 1981. These tree ring time series still have a response to the second harmonic of the solar cycle (5.5?years), but in different time intervals. The cross-wavelet maps also showed that the relationship between the SOI x tree ring time series is more intense, for oscillation in the range of 4–8?years.  相似文献   

Benthic foraminifera as bio-indicators of trace element pollution in the heavily contaminated Santa Gilla lagoon (Cagliari, Italy)     

Fabrizio Frontalini  Carla Buosi  Rodolfo Coccioni  Carla Bucci 《Marine pollution bulletin》2009,58(6):858-877

In order to assess the response of benthic foraminifera to trace element pollution, a study of benthic foraminiferal assemblages was carried out into sediment samples collected from the Santa Gilla lagoon (Sardinia, Italy). The lagoon has been contaminated by industrial waste, mainly trace elements, as well as by agricultural and domestic effluent. The analysis of surficial sediment shows enrichment in trace elements, including Cr, Cu, Hg, Ni, Pb and Zn. Biotic and abiotic data, analyzed with multivariate techniques of statistical analysis, reveal a distinct separation of both the highly polluted and less polluted sampling sites. The innermost part of the lagoon, comprising the industrial complex at Macchiareddu, is exposed to a high load of trace elements which are probably enhanced by their accumulation in the finer sediment fraction. This area reveals lower diversity and higher percentages of abnormalities when compared to the outermost part of the lagoon.  相似文献   

A prehistoric lahar-dammed lake and eruption of Mount Pinatubo described in a Philippine aborigine legend     

Kelvin S. Rodolfo  Jesse V. Umbal 《Journal of Volcanology and Geothermal Research》2008

The prehistoric eruptions of Mount Pinatubo have followed a cycle: centuries of repose terminated by a caldera-forming eruption with large pyroclastic flows; a post-eruption aftermath of rain-triggered lahars in surrounding drainages and dome-building that fills the caldera; and then another long quiescent period. During and after the eruptions lahars descending along volcano channels may block tributaries from watersheds beyond Pinatubo, generating natural lakes. Since the 1991 eruption, the Mapanuepe River valley in the southwestern sector of the volcano has been the site of a large lahar-dammed lake. Geologic evidence indicates that similar lakes have occupied this site at least twice before. An Ayta legend collected decades before Mount Pinatubo was recognized as a volcano describes what is probably the younger of these lakes, and the caldera-forming eruption that destroyed it.  相似文献   

Late Pleistocene flank collapse of Zempoala volcano (Central Mexico) and the role of fault reactivation     

José Luis Arce  Rodolfo Macías  Armando García Palomo  Lucia Capra  José Luis Macías  Paul Layer  Hernando Rueda 《Journal of Volcanology and Geothermal Research》2008

Zempoala is an extinct Pleistocene (∼ 0.7–0.8 Ma) stratovolcano that together with La Corona volcano (∼ 0.9 Ma) forms the southern end of the Sierra de las Cruces volcanic range, Central Mexico. The volcano consists of andesitic and dacitic lava flows and domes, as well as pyroclastic and epiclastic sequences, and has had a complex history with several flank collapses. One of these collapses occurred during the late Pleistocene on the S–SE flank of the volcano and produced the Zempoala debris avalanche deposit. This collapse could have been triggered by the reactivation of two normal fault systems (E–W and NE–SW), although magmatic activity cannot be absolutely excluded. The debris avalanche traveled 60 km to the south, covers an area of 600 km² and has a total volume of 6 km³, with a calculated Heim coefficient (H/L) of 0.03. Based on the textural characteristics of the deposit we recognized three zones: proximal, axial, and lateral distal zone. The proximal zone consists of debris avalanche blocks that develop a hummocky topography; the axial zone corresponds with the main debris avalanche deposit made of large clasts set in a sandy matrix, which transformed to a debris flow in the lateral distal portion. The deposit is heterolithologic in composition, with dacitic and andesitic fragments from the old edifice that decrease in volume as bulking of exotic clasts from the substratum increase. Several cities (Cuernavaca, Jojutla de Juárez, Alpuyeca) with associated industrial, agricultural, and tourism activities have been built on the deposit, which pose in evidence the possible impact in case of a new event with such characteristics, since the area is still tectonically active.  相似文献   

Organic matter characterisation of the Selli Level (Umbria-Marche Basin, central Italy)     

François Baudin  Nicolas Fiet  Rodolfo Coccioni  Simone Galeotti 《Cretaceous Research》1998,19(6):701-714

The Selli Level is a marker-bed in the Umbria-Marche Apennines that represents the regional sedimentary expression of the Lower Aptain Oceanic Anoxic Event 1a. This one to three-metre-thick interval shows a remarkable uniformity on a regional scale, with a green to grey marly lower part overlain by black shales. Bulk geochemical studies and an examination of palynofacies were carried out on three sections in order to characterise the distribution and nature of the organic matter in the Selli Level which has been poorly known hitherto. The organic content is medium (0.5 to 2.9% TOC) in the basal part and higher (4.5% on average, and up to 18% TOC) in the black shales. Pyrolysis and palynological data indicate that the organic matter is mainly of marine origin. The geochemical characteristics of the Selli Level are compared to other, more or less organic-rich marker-beds in the Cretaceous succession of the Umbria-Marche Apennines.

Abstract

Le Niveau Selli est un niveau-repère des Apennins d'Ombrie-Marches qui correspond à l'enregistrement régional de l'événement anoxique océanique 1a. Ce niveau, épais de un à trois mètres, présente une remarquable uniformité à l'échelle régionale avec une partie inférieure argileuse, verdâtre à grise, surmontée par des black shales. Des analyses géochimiques et l'examen des palynofacies ont été entreprises sur trois coupes afin de caractériser le contenu en matière organique du niveau Selli, jusqu'à présent mal connu. Les teneurs en carbone organique sont moyennes (0,5 à 2,9% COT) dans la partie basale et élevées (4,5% en moyenne et jusque 18% COT) dans les black shales. Les résultats de pyrolyse et des observations palynologiques indiquent que la matière organique est essentiellement d'origine marine. Les caractéristiques géochimiques du niveau Selli sont comparées aux autres niveaux repères, plus ou moins riches en carbone organique, qui émaillent la série du Crétacé du basin d'Ombrie-Marches.  相似文献   

An integrated stratigraphic record of the Palaeocene–lower Eocene at Gubbio (Italy): new insights into the early Palaeogene hyperthermals and carbon isotope excursions     

Rodolfo Coccioni  Giuseppe Bancalà  Rita Catanzarit  Eliana Fornaciari  Fabrizio Frontalini  Luca Giusberti  Luigi Jovane  Valeria Luciani  Jairo Savian  Mario Sprovieri 《地学学报》2012,24(5):380-386

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Automatic inspection and analysis of digital waveform images by means of convolutional neural networks     

Pignatelli  Alessandro  D’Ajello Caracciolo  Francesca  Console  Rodolfo 《Journal of Seismology》2021,25(6):1347-1359

Journal of Seismology - Analyzing seismic data to get information about earthquakes has always been a major task for seismologists and, more in general, for geophysicists. Recently, thanks to the...  相似文献   

UAV RGB,thermal infrared and multispectral imagery used to investigate the control of terrain on the spatial distribution of dryland biocrust     

Javier Blanco-Sacristán  Cinzia Panigada  Rodolfo Gentili  Giulia Tagliabue  Roberto Garzonio  M. Pilar Martín  Mónica Ladrón de Guevara  Roberto Colombo  Thomas P. F. Dowling  Micol Rossini 《地球表面变化过程与地形》2021,46(12):2466-2484

Biocrusts (topsoil communities formed by mosses, lichens, bacteria, fungi, algae, and cyanobacteria) are a key biotic component of dryland ecosystems. Whilst climate patterns control the distribution of biocrusts in drylands worldwide, terrain and soil attributes can influence biocrust distribution at landscape scale. Multi-source unmanned aerial vehicle (UAV) imagery was used to map and study biocrust ecology in a typical dryland ecosystem in central Spain. Red, green and blue (RGB) imagery was processed using structure-from-motion techniques to map terrain attributes related to microclimate and terrain stability. Multispectral imagery was used to produce accurate maps (accuracy > 80%) of dryland ecosystem components (vegetation, bare soil and biocrust composition). Finally, thermal infrared (TIR) and multispectral imagery was used to calculate the apparent thermal inertia (ATI) of soil and to evaluate how ATI was related to soil moisture (r² = 0.83). The relationship between soil properties and UAV-derived variables was first evaluated at the field plot level. Then, the maps obtained were used to explore the relationship between biocrusts and terrain attributes at ecosystem level through a redundancy analysis. The most significant variables that explain biocrust distribution are: ATI (34.4% of variance, F = 130.75; p < 0.001), Elevation (25.8%, F = 97.6; p < 0.001), and potential solar incoming radiation (PSIR) (52.9%, F = 200.1; p < 0.001). Differences were found between areas dominated by lichens and mosses. Lichen-dominated biocrusts were associated with areas with high slopes and low values of ATI, with soil characterized by a higher amount of soluble salts, and lower amount of organic carbon, total phosphorus (P_tot) and total nitrogen (N_tot). Biocrust-forming mosses dominated lower and moister areas, characterized by gentler slopes and higher values of ATI with soils with higher contents of organic carbon, P_tot and N_tot. This study shows the potential to use UAVs to improve our understanding of drylands and to evaluate the control that the terrain has on biocrust distribution.  相似文献   

Extensive characterization of Italian accelerometric stations from single-station ambient-vibration measurements     

Rodolfo Puglia  Dario Albarello  Antonella Gorini  Lucia Luzi  Sandro Marcucci  Francesca Pacor 《Bulletin of Earthquake Engineering》2011,9(6):1821-1838

This paper describes the analyses of the single-station ambient-vibration measurements performed on the Italian accelerometric network to detect site resonance phenomena potentially affecting earthquake recordings. The use of low cost, high quality microtremor measurement can be helpful to discriminate among soil classes, since several classification schemes based on resonance frequencies were proposed in the last decades. Operatively, in the framework of the Italian Strong Motion Database project (DPC-INGV 2007–2009 S4; ), soil resonance frequencies have been evaluated from more than 200 ambient vibration measurements in correspondence of accelerometric stations included in ITACA (). The noise recordings have been analyzed using the same numerical protocol in order to standardize the results. Particular attention has been paid to evaluate the quality of measurements and to develop an on-purpose mathematical tool to automatically estimate the peaks in the horizontal-to-vertical spectral ratio (HVSR) curve. The reliability of the resonance frequencies from HVSR has been tested by comparing estimates provided by independent methods (modeling or earthquake recordings). The test confirmed the reliability of the microtremor HVSR for assessing the resonance frequencies of the examined sites.  相似文献