3D modeling of large urban areas with stereo VHR satellite imagery: lessons learned     

Daniela Poli  Ivano Caravaggi 《Natural Hazards》2013,68(1):53-78

This paper discusses the potentials of very high-resolution (VHR) stereo imagery for automatic generation of digital surface models (DSM) and 3D information extraction on large metropolitan cities. Stereo images acquired by GeoEye-1 on Dakar (Senegal) and Guatemala City (Guatemala) and by WorldView-2 on Panama City (Panama), Constitucion (Chile), Kabul (Afghanistan), Teheran (Iran), Kathmandu (Nepal), and San Salvador (El Salvador) were processed following a rigorous photogrammetric approach. The work focuses on evaluating the quality of the DSMs in relation to the image and terrain characteristics. The size of the datasets, the variety of case studies, and the complexity of the scenarios allow to critically analyze the potentials of VHR stereo imagery for 3D landscape modeling for natural hazards assessment.  相似文献   

Using Mg Isotopes to Trace Cyanobacterially Mediated Magnesium Carbonate Precipitation in Alkaline Lakes   总被引：1，自引：0，他引：1  

Liudmila S. Shirokova  Vasileios Mavromatis  Irina A. Bundeleva  Oleg S. Pokrovsky  Pascale B��n��zeth  Emmanuelle G��rard  Christopher R. Pearce  Eric H. Oelkers 《Aquatic Geochemistry》2013,19(1):1-24

This study assesses the potential use of Mg isotopes to trace Mg carbonate precipitation in natural waters. Salda Lake (SW Turkey) was chosen for this study because it is one of the few modern environments where hydrous Mg carbonates are the dominant precipitating minerals. Stromatolites, consisting mainly of hydromagnesite, are abundant in this lake. The Mg isotope composition of incoming streams, groundwaters, lake waters, stromatolites, and hydromagnesite-rich sediments were measured. Because Salda Lake is located in a closed basin, mass balance requires that the Mg isotopic offset between Lake Salda water and precipitated hydromagnesite be comparable to the corresponding offset between Salda Lake and its water inputs. This is consistent with observations; a ??²⁶Mg offset of 0.8?C1.4??? is observed between Salda Lake water and it is the incoming streams and groundwaters, and precipitated hydromagnesite has a ??²⁶Mg 0.9?C1.1??? more negative than its corresponding fluid phase. This isotopic offset also matches closely that measured in the laboratory during both biotic and abiotic hydrous Mg carbonate precipitation by cyanobacteria (Mavromatis, V., Pearce, C., Shirokova, L. S., Bundeleva, I. A., Pokrovsky, O. S., Benezeth, P. and Oelkers, E.H.: Magnesium isotope fractionation during inorganic and cyanobacteria-induced hydrous magnesium carbonate precipitation, Geochim. Cosmochim. Acta, 2012a. 76, 161?C174). Batch reactor experiments performed in the presence of Salda Lake cyanobacteria and stromatolites resulted in the precipitation of dypingite (Mg₅(CO₃)₄(OH)₂·5(H₂O)) and hydromagnesite (Mg₅(CO₃)₄(OH)₂·4H₂O) with morphological features similar to those of natural samples. Concurrent abiotic control experiments did not exhibit carbonate precipitation demonstrating the critical role of cyanobacteria in the precipitation process.  相似文献   

Einstein Gravity Explorer–a medium-class fundamental physics mission     

S. Schiller  G. M. Tino  P. Gill  C. Salomon  U. Sterr  E. Peik  A. Nevsky  A. Görlitz  D. Svehla  G. Ferrari  N. Poli  L. Lusanna  H. Klein  H. Margolis  P. Lemonde  P. Laurent  G. Santarelli  A. Clairon  W. Ertmer  E. Rasel  J. Müller  L. Iorio  C. Lämmerzahl  H. Dittus  E. Gill  M. Rothacher  F. Flechner  U. Schreiber  V. Flambaum  Wei-Tou Ni  Liang Liu  Xuzong Chen  Jingbiao Chen  Kelin Gao  L. Cacciapuoti  R. Holzwarth  M. P. Heß  W. Schäfer 《Experimental Astronomy》2009,23(2):573-610

The Einstein Gravity Explorer mission (EGE) is devoted to a precise measurement of the properties of space-time using atomic clocks. It tests one of the most fundamental predictions of Einstein’s Theory of General Relativity, the gravitational redshift, and thereby searches for hints of quantum effects in gravity, exploring one of the most important and challenging frontiers in fundamental physics. The primary mission goal is the measurement of the gravitational redshift with an accuracy up to a factor 10⁴ higher than the best current result. The mission is based on a satellite carrying cold atom-based clocks. The payload includes a cesium microwave clock (PHARAO), an optical clock, a femtosecond frequency comb, as well as precise microwave time transfer systems between space and ground. The tick rates of the clocks are continuously compared with each other, and nearly continuously with clocks on earth, during the course of the 3-year mission. The highly elliptic orbit of the satellite is optimized for the scientific goals, providing a large variation in the gravitational potential between perigee and apogee. Besides the fundamental physics results, as secondary goals EGE will establish a global reference frame for the Earth’s gravitational potential and will allow a new approach to mapping Earth’s gravity field with very high spatial resolution. The mission was proposed as a class-M mission to ESA’s Cosmic Vision Program 2015–2025.

S. SchillerEmail:

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Geochemical characteristics of potassic volcanics from Mts. Ernici (Southern Latium,Italy)   总被引：1，自引：0，他引：1  

L. Civetta  F. Innocenti  P. Manetti  A. Peccerillo  G. Poli 《Contributions to Mineralogy and Petrology》1981,78(1):37-47

Major elements, trace elements and ⁸⁷Sr/⁸⁶Sr data are reported for the Quaternary potassic alkaline rocks from the Mts. Ernici volcanic area (Southern Latium — Italy). These rocks are represented by primitive types which display high Mg_v, low D.I., variable degrees of silica undersaturation and different K₂O contents which allowed the distinction of a potassium series (KS) and a high potassium series (HKS). All the analyzed samples have high LIL element contents and high ⁸⁷Sr/⁸⁶Sr which ranges between 0.707–0.711. They also have fractionated REE patterns. The KS rocks have lower LIL element concentrations and ⁸⁷Sr/⁸⁶Sr ratios than the HKS rocks with a large compositional gap between the two series. Minor but still significant isotopic and trace element variations are also observed within both KS and HKS. The genesis cannot be completly explained either by crystal liquid fractionation, mixing or assimilation processes or by different degrees of equilibrium partial melting from a homogeneous source, thus indicating that both the KS and HKS consist of several geochemically and isotopically distinct magma types. The data suggest that the KS and HKS magmas originated by low degrees of melting of a garnet peridotite mantle heterogeneously enriched in LIL elements and radiogenic strontium, possibly accompanied by disquilibrium melting of some accessory phases. The occurrence of a geochemical anomaly within the mantle is believed to be due to fluid metasomatism probably generated by dehydration of a lithospheric slab subducted during the Late Tertiary development of the Apennine Chain.  相似文献   

The Vedrette di Ries (rieserferner) plutonic complex: Petrological and geochemical data bearing on its genesis   总被引：2，自引：0，他引：2  

G. Bellieni  A. Peccerillo  G. Poli 《Contributions to Mineralogy and Petrology》1981,78(2):145-156

Data on Co, Sc, Rb, Sr, Th, Zr, Ta, Hf and REE contents are reported for tonalites, granodiorites, granites and one diorite from the Alpine plutonic complex of Vedrette di Ries in the Eastern Alps. Co and Sc range respectively between 19.6-1.2 ppm and 32-3.3 ppm showing a good negative correlation with the Differentiation Index (D.I.). Rb values range between 61–197 ppm displaying a positive correlation with D.I. All the samples have variably fractionated light and heavy REE with La_N/Sm_N=1.7–5.55 and Tb_N/Yb_N=0.58–1.65 and no important europium anomalies. On the basis of the HREE fractionation two groups of rocks can be distinguished: one showing higher Tb_N/Yb_N values which range between 1.27–1.65 and are positively correlated with the D.I. and a second group with Tb_N/Yb_N values less than unity which decrease with the differentiation. The rocks with high Tb_N/Yb_N ratio also display a positive Sr versus D.I. variation whereas the samples with flat or upward concave HREE patterns (i.e. with Tb_N/Yb_N<1) define negative Sr versus D.I. trends. Th, Ta, Hf, Zr and LREE show an overall tendecy to increase and then to decrease with the differentiation, with a large scattering of values.The data obtained fit the hypothesis that the entire rock series under study is the product of a two-stage crystal/liquid fractionation process starting from one parent magma of tonalitic or dioritic composition. During the first stage, which occurred at high pressure, the separation of hornblende+garnet produced the liquids displaying the positve Tb_N/Yb_N and Sr versus D.I. correlation. These liquids during their rise through the crust would have undergone a second stage fractionation with separation of hornblende and plagioclase evolving toward low-Tb_N/Yb_N and Sr-poor composition.  相似文献   

Effet de la turbidité sur la dégradation des pigments phytoplanctoniques dans l'estuaire de la GirondeEffect of turbidity on phytoplanktonic pigments degradation in the Gironde Estuary     

Emmanuelle Lemaire  Gwenaël Abril  Rutger De Wit  Henri Etcheber 《Comptes Rendus Geoscience》2002,334(4):251-258

In the Gironde Estuary, most part of phytoplanktonic material carried by the rivers is mineralised in the maximum turbidity zone (MTZ). In order to follow the degradation of the phytoplanktonic material into the MTZ, we developed an in vitro approach based on the monitoring of phytoplanktonic pigments. Algal material from two chlorophytes (Scenedesmus suspicatus Chaudat and Chlamydomonas sp.) was incubated in the dark during 28 days into water samples from the Gironde estuary MTZ, at variable suspended solid concentrations (SPM) as well as in a sterilised turbid sample. First order decay constants of chlorophylls a and b and lutein increased by a factor 3 to 5 between SPM of 0 and $\text{3 }\text{g}\text{l}{}^{\mathrm{?1}}$. The production of pheophytin a in the presence of particles and the lack of degradation in the sterilised turbid sample confirmed the effect of attached bacteria on the particles. To cite this article: E. Lemaire et al., C. R. Geoscience 334 (2002) 251–258.  相似文献   

Non-linear and chaotic dynamics in igneous petrology     

G. Poli  D. Perugini 《Lithos》2002,65(3-4):vii-viii

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Petrology,geochemistry and Sr-isotope characteristics of lavas from the area of Commenda (Mts. Vulsini,Italy)     

L. Civetta  P. Del Carmine  P. Manetti  A. Peccerillo  G. Poli 《Bulletin of Volcanology》1984,47(3):581-595

Major, trace element and Sr-isotope compositions are reported for a suite of lavas coming from the area of Commenda in the SE Vulsinian district. The analyzed samples have all low silica contents and variable but generally high CaO, MgO and FeO_t. Based on K₂O% and K₂O/Na₂O ratio, the rocks from Commenda can be classified as belonging to the Potassic Series (KS) and the High-potassium Series (HKS). The HKS rocks appear to have derived by cristal/liquid fractionation from the most mafic types with separation of olivine and clinopyroxene and then of clinopyroxene + leucite. The most primitive HKS rocks have aphyric texture and high Mg-values, Cr and Ni contents which are close or within the range of values of magmas formed by partial melting of periodititic mantle sources. The KS rocks have lower incompatible element contents as the HKS rocks with similar degree of evolution.The variations of Sr-isotopic ratios of the analyzed rocks and of other Vulsinian lavas, indicate that the basic HKS Vulsinian rocks did not interact significantly with the continental crust. Instead, the KS appears to have evolved by combined crystal fractionation and assimilation processes, starting from parental magmas which had⁸⁷Sr/⁸⁶Sr ratio not significantly lower than that found in the less evolved rocks of the suite.The most primitive HKS rocks from Commenda have hygromagmatophile element distribution pattern characterized by high ratio of LILE/HFSE with negative anomalies of Ta and Ti, resembling closely those of other Roman mafic volcanics. The primitive geochemical characteristics of the Commenda rocks exclude that these features are the products of interaction with the crust and provide a further support to the hypothesis of a genesis within a subduction-modified mantle source.  相似文献   

Tourmaline nodules from Capo Bianco aplite (Elba Island,Italy): an example of diffusion limited aggregation growth in a magmatic system   总被引：1，自引：0，他引：1  

Diego Perugini  Giampiero Poli 《Contributions to Mineralogy and Petrology》2007,153(5):493-508

The morphology of tourmaline nodules occurring in the Capo Bianco aplite (Elba Island, Italy) is studied. Outcrop features indicate that tourmaline nodules are the product of magmatic crystallization, as they are aligned along flow fields developed within the magmatic hosting mass. Mesoscopic observations indicate that nodule morphologies are very variable, from rounded to dendritic. Morphometric analyses show that tourmaline nodules are fractals and that fractal dimension quantifies their degree of irregularity. Numerical simulations of nodule growth are performed by using a Diffusion-Limited Aggregation process. The presence in natural samples of nodules with different morphologies is explained by considering a chaotic magmatic system characterized by a complex interplay between growth rate in different dynamical regions, latent heat of crystallization, and local convection dynamics. It is suggested that higher growth rates correspond to growth of tourmaline nodules in dynamical regions where the transfer of nutrients is very efficient. In such conditions, the latent heat released by the growing nodule is high, inducing strong local convection dynamics, destabilizing the nodule interface, and promoting the formation of dendritic morphologies. On the contrary, the growth of nodules in dynamical regions characterized by weak transfer of nutrients is inhibited leading to weak local convection dynamics and, consequently, to the formation of rounded morphologies.  相似文献   

Experimental determination of magnesia and silica solubilities in graphite-saturated and redox-buffered high-pressure COH fluids in equilibrium with forsterite + enstatite and magnesite + enstatite     

Carla?TiraboschiEmail authorView author&#;s OrcID profile  Simone?Tumiati  Dimitri?Sverjensky  Thomas?Pettke  Peter?Ulmer  Stefano?Poli 《Contributions to Mineralogy and Petrology》2018,173(1):2

We experimentally investigated the dissolution of forsterite, enstatite and magnesite in graphite-saturated COH fluids, synthesized using a rocking piston cylinder apparatus at pressures from 1.0 to 2.1 GPa and temperatures from 700 to 1200 °C. Synthetic forsterite, enstatite, and nearly pure natural magnesite were used as starting materials. Redox conditions were buffered by Ni–NiO–H₂O (ΔFMQ = ??0.21 to ??1.01), employing a double-capsule setting. Fluids, binary H₂O–CO₂ mixtures at the P, T, and fO₂ conditions investigated, were generated from graphite, oxalic acid anhydrous (H₂C₂O₄) and water. Their dissolved solute loads were analyzed through an improved version of the cryogenic technique, which takes into account the complexities associated with the presence of CO₂-bearing fluids. The experimental data show that forsterite?+?enstatite solubility in H₂O–CO₂ fluids is higher compared to pure water, both in terms of dissolved silica (mSiO₂?=?1.24 mol/kg_H2O versus mSiO₂?=?0.22 mol/kg_H2O at P?=?1 GPa, T?=?800 °C) and magnesia (mMgO?=?1.08 mol/kg_H2O versus mMgO?=?0.28 mol/kg_H2O) probably due to the formation of organic C–Mg–Si complexes. Our experimental results show that at low temperature conditions, a graphite-saturated H₂O–CO₂ fluid interacting with a simplified model mantle composition, characterized by low MgO/SiO₂ ratios, would lead to the formation of significant amounts of enstatite if solute concentrations are equal, while at higher temperatures these fluid, characterized by MgO/SiO₂ ratios comparable with that of olivine, would be less effective in metasomatizing the surrounding rocks. However, the molality of COH fluids increases with pressure and temperature, and quintuplicates with respect to the carbon-free aqueous fluids. Therefore, the amount of fluid required to metasomatize the mantle decreases in the presence of carbon at high P–T conditions. COH fluids are thus effective carriers of C, Mg and Si in the mantle wedge up to the shallowest level of the upper mantle.  相似文献