Experimental Melting of Carbonated Peridotite at 6-10 GPa   总被引：2，自引：0，他引：2  

Brey  Gerhard P.; Bulatov  Vadim K.; Girnis  Andrei V.; Lahaye  Yann 《Journal of Petrology》2008,49(4):797-821

Partial melting of magnesite-bearing peridotites was studiedat 6–10 GPa and 1300–1700°C. Experiments wereperformed in a multianvil apparatus using natural mineral mixesas starting material placed into olivine containers and sealedin Pt capsules. Partial melts originated within the peridotitelayer, migrated outside the olivine container and formed poolsof quenched melts along the wall of the Pt capsule. This allowedthe analysis of even small melt fractions. Iron loss was nota problem, because the platinum near the olivine container becamesaturated in Fe as a result of the reaction Fe₂SiO₄^Ol = Fe^Fe–Ptalloy + FeSiO₃^Opx + O₂. This reaction led to a gradual increasein oxygen fugacity within the capsules as expressed, for example,in high Fe³⁺ in garnet. Carbonatitic to kimberlite-like meltswere obtained that coexist with olivine + orthopyroxene + garnet± clinopyroxene ± magnesite depending on P–Tconditions. Kinetic experiments and a comparison of the chemistryof phases occasionally grown within the melt pools with thosein the residual peridotite allowed us to conclude that the meltshad approached equilibrium with peridotite. Melts in equilibriumwith a magnesite-bearing garnet lherzolite are rich in CaO (20–25wt %) at all pressures and show rather low MgO and SiO₂ contents(20 and 10 wt %, respectively). Melts in equilibrium with amagnesite-bearing garnet harzburgite are richer in SiO₂ andMgO. The contents of these oxides increase with temperature,whereas the CaO content becomes lower. Melts from magnesite-freeexperiments are richer in SiO₂, but remain silicocarbonatitic.Partitioning of trace elements between melt and garnet was studiedin several experiments at 6 and 10 GPa. The melts are very richin incompatible elements, including large ion lithophile elements(LILE), Nb, Ta and light rare earth elements. Relative to theresidual peridotite, the melts show no significant depletionin high field strength elements over LILE. We conclude fromthe major and trace element characteristics of our experimentalmelts that primitive kimberlites cannot be a direct productof single-stage melting of an asthenospheric mantle. They rathermust be derived from a previously depleted and re-enriched mantleperidotite. KEY WORDS: multianvil; carbonatite melt; peridotite; kimberlite; element partitioning  相似文献   

Analysis of liquefaction susceptibility of nearly saturated sands     

Ahmad Jafari‐Mehrabadi  Majid Abedinzadegan Abdi  Radu Popescu 《国际地质力学数值与分析法杂志》2007,31(5):691-714

A new constitutive formulation for simulating the behaviour of nearly saturated sands under seismic loads is presented. The formulation is based on combining the Henry's law for dissolution of gas in water, the ideal or perfect gas law and the law of conservation of mass. The effects of transient air dissolution in water on the compressibility of partially saturated soils are also taken into account. The model was calibrated based on numerical simulations of isotropically consolidated cyclic triaxial tests conducted on partially saturated samples of Toyoura sand. A multi‐yield plasticity soil constitutive model implemented in the finite element code DYNAFLOW was used for these numerical simulations. It is shown that the formulation proposed here is able to reasonably predict the soil cyclic undrained behaviour at various degrees of saturation (95% and higher). Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Diversity of the 2014 Iquique’s foreshocks and aftershocks: clues about the complex rupture process of a Mw 8.1 earthquake     

Sergio León-Ríos  Sergio Ruiz  Andrei Maksymowicz  Felipe Leyton  Amaya Fuenzalida  Raúl Madariaga 《Journal of Seismology》2016,20(4):1059-1073

We study the foreshocks and aftershocks of the 1 April 2014 Iquique earthquake of Mw 8.1. Most of these events were recorded by a large digital seismic network that included the Northern Chile permanent network and up to 26 temporary broadband digital stations. We relocated and computed moment tensors for 151 events of magnitude Mw?≥?4.5. Most of the foreshocks and aftershocks of the Iquique earthquake are distributed to the southwest of the rupture zone. These events are located in a band of about 50 km from the trench, an area where few earthquakes occur elsewhere in Chile. Another important group of aftershocks is located above the plate interface, similar to those observed during the foreshock sequence. The depths of these events were constrained by regional moment tensor (RMT) solutions obtained using the records of the dense broad band network. The majority of the foreshocks and aftershocks were associated to the interplate contact, with dip and strike angles in good agreement with the characteristics of horst and graben structures (>2000 m offset) typical of the oceanic Nazca Plate at the trench and in the outer rise region. We propose that the spatial distribution of foreshocks and aftershocks, and its seismological characteristics were strongly controlled by the rheological and tectonics conditions of the extreme erosive margin of Northern Chile.  相似文献   

Removal of Arsenic by Alumina: Effects of Material Size,Additives, and Water Contaminants          下载免费PDF全文

Victor K. Tchieda  Emilio D'Amato  Agostina Chiavola  Mariapaola Parisi  Angelo Chianese  Mohamed Amamra  Andrei Kanaev 《洁净——土壤、空气、水》2016,44(5):496-505

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Reply to “Discussion 2 on ‘Introspection on improper seismic retrofit of Basilica Santa Maria di Collemaggio after 2009 Italian earthquake' by G.P.Cimellaro, A.M.Reinhorn and A.De Stefano” by Enzo Cartapati     

Gian Paolo Cimellaro  Andrei M. Reinhorn  Alessandro De Stefano 《地震工程与工程振动(英文版)》2012,11(2):291-292

The authors thank the discusser for the additional information,which is provided related to the historical interventions of the church through the centuries.This information was known to the authors,however they decided not to include it in the paper because of lack of space.Additional details regarding the retrofit interventions of the church can also be found in the MCEER report regarding the L'Aquila earthquake (Cimellaro et al.,2010).  相似文献   

Reply to “Discussion 2 on ‘Introspection on improper seismic retrofit of Basilica Santa Maria di Collemaggio after 2009 Italian earthquake’ by G.P. Cimellaro, A.M. Reinhorn and A.De Stefano” by Enzo Cartapati     

Gian Paolo Cimellaro  Andrei M. Reinhorn  Alessandro De Stefano 《地震工程与工程振动(英文版)》2012,11(2):291-292

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Dynamic force control with hydraulic actuators using added compliance and displacement compensation     

Mettupalayam V. Sivaselvan  Andrei M. Reinhorn  Xiaoyun Shao  Scot Weinreber 《地震工程与结构动力学》2008,37(15):1785-1800

A new approach to dynamic force control of mechanical systems, applicable in particular to frame structures, over frequency ranges spanning their resonant frequencies is presented. This approach is implemented using added compliance and displacement compensation. Hydraulic actuators are inherently velocity sources, that is, an electrical signal regulates their velocity response. Such systems are therefore by nature high‐impedance (mechanically stiff) systems. In contrast, for force control, a force source is required. Such a system logically would have to be a low‐impedance (mechanically compliant) system. This is achieved by intentionally introducing a flexible mechanism between the actuator and the structure to be excited. In addition, in order to obtain force control over frequencies spanning the structure's resonant frequency, a displacement compensation feedback loop is needed. The actuator itself operates in closed‐loop displacement control. The theoretical motivation, as well as the laboratory implementation of the above approach is discussed along with experimental results. Having achieved a means of dynamic force control, it can be applied to various experimental seismic simulation techniques such as the effective force method and the real‐time dynamic hybrid testing method. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Dynamic properties of the Quaternary sedimentary rocks and their influence on seismic site effects. Case study in Bucharest City,Romania     

Andrei Bala  Bogdan Grecu  Viorica Ciugudean  Victor Raileanu 《Soil Dynamics and Earthquake Engineering》2009

Bucharest is one of the cities most affected by earthquakes in Europe. Situated at 150–170 km distance from Vrancea epicentral zone, Bucharest had suffered many damages due to high energy Vrancea intermediate-depth earthquakes. For example, the 4 March 1977 event produced the collapse of 32 buildings with 8–12 levels, while more than 150 old buildings with 6–9 levels were seriously damaged. The studies done after this earthquake had shown the importance of the surface geological structure upon ground motion parameters. New seismic measurements are performed in Bucharest area aiming at defining better elastic and dynamic properties of the shallow sedimentary rocks. Down-hole seismic measurements were performed in a number of 10 cased boreholes drilled in the Bucharest City area. Processing and interpretation of the data lead to the conclusion that shallow sedimentary rocks can be considered weak in the area, down to 150–200 m depth. Seismic wave velocity values and bulk density values presented in the paper associated with local geology are useful primary data in the seismic microzonation of Bucharest City. They are used as 1D models to derive transfer functions and response spectra for the stack of sedimentary rocks in several parts of Bucharest area, leading to a better knowledge of the local site amplification and associated frequency spectra. In a recent study the H/V spectral ratio using Nakamura’s method was applied on the seismic noise measurements in 22 sites in Bucharest City in order to derive the fundamental period associated with these sites. The values confirm the previous results, showing a dominant resonance in the period range of 1.25–1.75 s. The fundamental periods obtained with Nakamura’s method are in good agreement with those computed on the basis of geological and geotechnical data in boreholes, which show an increase of the fundamental period in the Bucharest area from south to north, in the same direction as the increase of the thickness of the Quaternary deposits above the Fratesti layer which is considered the bedrock in the area.  相似文献   

The occurrence, spatial and temporal distribution, and environmental routes of tetracycline resistance and integrase genes in Crassostrea virginica beds     

Andrei L. Barkovskii  Christen Green  Dorset Hurley 《Marine pollution bulletin》2010,60(12):2215-2224

Rapid spread of antibiotic resistance genes has placed them under consideration as emerging environmental contaminants. The occurrence and distribution of tetracycline resistance genes (TRG) and integrons (INT) have been monitored for 2 years in seven oyster beds located in the Altamaha River (Georgia, USA) estuary. TRG/INT profiles varied both temporally (p < 0.025) and spatially between oysters and their environment (p < 0.005) suggesting shifts in sources of contamination and selection of TRG/INT carriers by oysters. The latter was confirmed via analysis of tet(D) and tet(G) distribution between oysters and their environment. Uncommon class 3 integrons dominated the integrons’ profile in oysters. The frequency of TRG/INT incidents correlated (R² ? 0.9) to (i) dissolved solids, (ii) potential water density, and (iii) turbidity but not to the amount of local precipitation suggesting the watershed as the dominant source of TRG/INT contamination and other than directly rainfall-caused run-offs as its environmental route.  相似文献   

Impact of spatial correlation of ground motions on seismic damage for residential buildings in Bucharest,Romania     

Pavel  Florin  Vacareanu  Radu  Calotescu  Ileana  Sandulescu  Ana-Maria  Arion  Cristian  Neagu  Cristian 《Natural Hazards》2017,87(2):1167-1187

Natural Hazards - This paper focuses on the investigation of seismic risk for residential buildings situated in Bucharest, the capital city of Romania. With a population of nearly 2 million...  相似文献