Plastic deformation of wadsleyite: I. High-pressure deformation in compression     

E. Thurel  P. Cordier 《Physics and Chemistry of Minerals》2003,30(5):256-266

 We have studied the plastic deformation of Mg₂SiO₄ wadsleyite polycrystals. Wadsleyite was synthesized from a forsterite powder in a multianvil apparatus. It was then recovered and placed in a second multianvil assembly designed to induce plastic deformation by compression between two hard alumina pistons. After the deformation experiment, the microstructures are characterized by transmission electron microscopy (TEM) and large-angle convergent beam electron diffraction (LACBED). Deformation experiments have been carried out at 15–19 GPa and at temperatures ranging from room temperature to 1800–2000 °C. Five different dislocation types have been identified by LACBED: [100], 1/2〈111〉, [010], 〈101〉 and [001]. The [001] dislocations result from dislocation reactions and not from activation of a slip system. The [010] dislocations are activated under high stresses at the beginning of the experiments and further relax by decomposition into 1/2〈111〉 dislocations or by dissociation into four 1/4[010] partial dislocations. The following slip systems have been identified: 1/2〈111〉{101}, [100](010), [100](001), [100]{011}, [100]{021}, [010](001), [010]{101} and 〈101〉(010). Received: 15 July 2002 / Accepted: 14 February 2003 Acknowledgements High-pressure experiments were performed at the Bayerisches Geoinstitut under the EU IHP – Access to Research Infrastructures Programme (Contract no. HPRI-1999-CT-00004 to D.C. Rubie). P.C. has benefited from a Congé thématique pour recherche from the University of Lille, and would like to thank warmly all the people in Bayreuth who contributed to this work by daily assistance and discussions: Nathalie Bolfan-Casanova, Daniel Frost, Jed L. Mosenfelder and Brent Poe. The quality of the preparation of the TEM specimens by H. Schultze is greatly appreciated.  相似文献   

Plastic deformation of wadsleyite: II. High-pressure deformation in shear     

E. Thurel  P. Cordier  D. Frost  S.-I. Karato 《Physics and Chemistry of Minerals》2003,30(5):267-270

 We have studied the dislocation microstructures that develop in (Mg_0.9Fe_0.1)₂SiO₄ wadsleyite deformed by simple shear at high pressure. The experiments were performed in a multianvil apparatus with the shear assembly designed by Karato and Rubie (1997). The samples were synthesized in a separate experiment from high-purity oxides. The deformation experiments were carried out at 14 GPa and 1300 °C with time durations ranging from 1 to 8 h leading to plastic shear strains of 60 and 73%, respectively. The microstructures investigated by transmission electron microscopy (TEM) show that dislocation glide is activated under these conditions over the whole experimental time. The easy slip systems at 1300 °C involve 1/2<111> dislocations gliding in {101} as well as [100] dislocations gliding in (010) and {011}. Received: 15 July 2002 / Accepted: 14 February 2003 Acknowledgements High-pressure experiments were performed at the Bayerisches Geoinstitut under the EU IHP — Access to Research Infrastructures Programme (Contract no. HPRI-1999-CT-00004 to D.C. Rubie). The quality of the preparation of the TEM specimens by H. Schultze is greatly appreciated.  相似文献   

复杂构造条件下采煤引起的特殊地表移动现象及其研究新方法     

何满潮 《测绘学报》1991,(3)

迄今，矿山开采沉陷领域的研究者们在采煤引起的地表移动规律研究及共服务于生产方面已经取得了令人膛目的成就，但是在复杂构造条件下采煤引起的特殊地表移动现象研究方面尚无明显进展。本文运用现代工程地质学理论和现代变形力学理论，对一个复杂的摺皱断裂十分发育的条件下采取露天和井下联合开采方式所引起的特殊地表移动现象及其规律作了分析，取得了预测规律与实际情况一致的结果。  相似文献   

Reaction-induced weakening of plagioclase–olivine composites   总被引：1，自引：0，他引：1  

A.A. de Ronde  H. Stünitz  J. Tullis  R. Heilbronner 《Tectonophysics》2005,409(1-4):85-106

The localisation of strain into natural ductile shear zones is often associated with the occurrence of metamorphic reactions. In order to study the effects of solid–solid mineral reactions on plastic deformation of rocks, we have investigated the shear deformation of plagioclase–olivine composites during the reaction plagioclase + olivine → orthopyroxene + clinopyroxene + spinel (± garnet). Microstructures of plagioclase–olivine composites were studied after shear deformation experiments in a Griggs apparatus. Experiments were performed on anorthite–forsterite (An–Fo) and labradorite–forsterite (Lab–Fo) composites at 900 °C, confining pressures between 1000–1600 MPa and with constant shear strain rates of 5 × 10⁻⁵ s⁻¹.In absence of reaction, Lab–Fo composites are stronger than pure olivine and labradorite end-members that deform with a high temperature plasticity mechanism. Lab–Fo composites strain–harden due to the inhibition of extensive recrystallisation by interphase boundaries.In An–Fo composites, the reaction induces strain weakening by a switch from dislocation creep to grain size sensitive deformation mechanisms through the development of fine-grained (size < 0.5 μm) polyphase reaction products. Interconnecting layers of reaction products accommodate most of the applied strain by grain size sensitive creep. Recovery processes are pronounced during syndeformational reaction: original anorthite and olivine dynamically recrystallise by subgrain rotation and bulging recrystallisation. Presumably, the dynamic recrystallisation is caused by reduced stress conditions and partitioning of strain and strain rates between the new reaction products and the relict An–Fo grains. The results of our experiments are in good agreement with natural observations of shear localisation in the lower crust and upper mantle, and imply that anhydrous mineral reactions can be important causes for localisation of deformation.  相似文献   

石化企业工业设备震害经验分析   总被引：3，自引：0，他引：3  

廖旭  项忠权 《东北地震研究》1997,13(1):44-49

在国内外的大地震中，石油化工企业的震害经验是比较少的，过去的记载只是笼统地描述各类设备和构筑物的地震损坏情况，而与地震烈度相联系的定量说明却很少，看不出在各种地震烈度作用下震害的规律，因此整理并归纳内外七，八度地震烈度作用下石油化工设备和构筑物的震害情况，给出与地震烈度相联系的定量说明，使震害预测更有科学的依据。  相似文献   

南极小红蛤生理生态学研究          下载免费PDF全文

洪旭光  陆华  吴宝铃 《极地研究》1997,9(2):49-54

本文在实验室条件下研究了南极小红蛤的摄食、呼吸和排泄。随着小红蛤的个体大小（壳长）和干重的增加，单位个体的摄食率、耗氧率、排氨率、ＭＣＲ、Ｏ／Ｎ增大，而单位干重的耗氧率、ＭＣＲ、Ｏ／Ｎ下降。本文还利用Ｏ／Ｎ比探讨了小红蛤的代谢能源机制。  相似文献   

干旱地区春小麦耗水量和节水措施的探讨   总被引：3，自引：0，他引：3  

李守谦谢忠奎  兰念军雷波 马忠明 《高原气象》1993,12(2):209-216

本文研究了春小麦耗水量与产量的关系及其耗水规律，分析了土壤湿度、耗水量对春小麦生长发育的影响。结果表明：拔节至抽穗是春小麦的水分临界期，抽穗至成熟期耗水量最多，耗水模系数最大；产量与耗水量呈二次曲线关系，适宜土壤水分下限为：出苗至拔节期为田间持水量的70％-75％，拔节至抽穗期为60％-65％、抽穗至灌浆初期为55％-60％．灌浆初期至成熟期为50％-55％，本文还对春小麦覆盖地膜的节水增产原因及效果进行了探讨，提出了黑河流域春小麦节水增产的技术措施及进一步研究的意见。  相似文献   

橄榄石晶格优选方位和上地幔地震波速各向异性   总被引：20，自引：5，他引：20       下载免费PDF全文

金振民 Ji  SC 《地球物理学报》1994,37(4):469-477

根据福建省明溪幔源包体（二辉橄榄岩）中橄榄石晶格优选方位（ＬＰＯ）及其晶体弹性刚度系数，计算了地震波速度及其各向异性．研究结果表明，该区地震波各向异性是由橄榄石塑性流动产生晶格优选方位而引起的．与构造背景有关的ＶＰ，Ｖｓ１，Ｖｓ２和△Ｖｓ分布特征表明，中国东南沿海地区上地幔物质流动方向（由ＮＷＷ向ＳＥＥ）与橄榄石［１００］定向排列方向（ａ轴）和ＶＰ最大方向有一致的趋势．  相似文献   

南北地震带的构造特色     

张治洮 《地震研究》1989,12(2):103-114

南北地震带是以青藏高原地壳为主体和兼并了扬子地块西部而成的新生构造实体,具弥漫性边界。构成其基本格架的巨型反S形或缓弧形构造带,分布在中部的弧顶朝南的弧形构造以及发育在东界附近的旋卷构造,成为南北地震带的三大构造特色,它们都是塑性伸展流动的产物。据弧形构造形态实际数据分析表明,地壳物质向南移动的规模,由北往南逐渐加大,从西到东渐逐减小;自北纬31.5°往南,青藏高原物质东移量逐渐加大。  相似文献   

Problems in the determination of plastic and liquid limits of remoulded soils using a drop-cone penetrometer     

Donald A. Davidson 《地球表面变化过程与地形》1983,8(2):171-175

This short communication describes difficulties of sample preparation associated with the determination of plastic and liquid limits using a drop-cone penetrometer. Problems of sample packing, soil moisture distribution and degree of remoulding are identified. These problems are particularly relevant in influencing liquid limit values whilst the effects on plastic limits are less marked. It is concluded that if the need is for the quick determination of liquid and plastic limits for general classification purposes, then the traditional Casagrande and thread methods are adequate. If these limits require to be measured with greater precision using the drop-cone technique, then careful consideration must be given to sample preparation.  相似文献