陕西佛坪五龙岩体的形成环境及其意义   总被引：2，自引：0，他引：2  

王居里 《西北地质科学》1997,18(1):19-24

地质地球化学特征表明，佛坪地区五龙岩体形成于扬子板块和秦岭微板块碰撞的晚期阶段，属同碰撞型花岗岩。岩浆以穹窿作用的方式主动上隆侵位，岩浆活动对佛坪穹窿核部基底结晶杂岩的抬升及佛坪穹窿的形成具有重要的动力学意义。  相似文献   

Rediscovery of the golden snapperlutjanus inermis (peters, 1869) (perciformes: lutjanidae) in the gulf of California     

José Julián Tavera  José Cruz-Agüero 《Ocean Science Journal》2006,41(3):191-193

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Supporting brace sizing in structures with added linear viscous fluid dampers: A filter design solution          下载免费PDF全文

Julián M. Londoño  David J. Wagg  Simon A. Neild 《地震工程与结构动力学》2014,43(13):1999-2013

Viscous fluid dampers have proved to be effective in suppressing unwanted vibrations in a range of engineering structures. When dampers are fitted in a structure, a brace is typically used to attach them to the main structure. The stiffness of this brace can significantly alter the effectiveness of the damper, and in structures with multiple dampers, this can be a complex scenario to model. In this paper, we demonstrate that the effects of the brace compliance on the damper performance can be modelled by way of a first‐order filter. We use this result to formulate a procedure that calculates the stiffness required by the supporting brace to provide a specified effectiveness of the damping action. The proposed procedure assumes that viscous dampers have been sized in a previous design step based on any optimal methodology in which, as is usually the case, the presence of supporting braces and their dynamic effects were neglected. Firstly considering a one degree‐of‐freedom system, we show that the proposed method ensures a desired level of damper efficiency for all frequencies within a selected bandwidth. Then the analysis is extended to the case of multi‐degree‐of‐freedom systems to show that the design criteria can be applied in a straightforward and successful manner to more complex structures. © 2014 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.  相似文献   

考洲洋化学耗氧量(COD)的含量特征   总被引：1，自引：0，他引：1  

杨美兰  林钦  甘居利  王小平  王增焕 《广东海洋大学学报》2001,21(4):27-31

1999年2月和8月对考洲洋海水、表层沉积物COD含量进行了调查研究.结果表明考洲洋海水COD含量为0.82～2.71 mg·L-1,表层沉积物COD含量为0.44～10.45 mg·L-1,其水质质量达到我国国家二类海水水质标准(COD＜3 mg·L-1).海水与表层沉积物COD含量平面分布总的呈西北部水域和湾中部水域向湾口降低的趋势.表层沉积物COD含量与有机质、硫化物含量呈显著的正相关(P＜0.05).与粤东邻近的网箱养殖水域比较,海水COD含量居中,表层沉积物COD含量较低.  相似文献   

新疆巴尔鲁克地区加曼铁列克得岩体花岗闪长岩的地球化学和年代学研究          下载免费PDF全文

胡 洋王居里  王建其令伟伟 《地质科学》2018,(2):594-614

本文对新疆巴尔鲁克地区加曼铁列克得岩体花岗闪长岩进行了锆石U-Pb年代学、岩石地球化学和Sr-Nd-Hf同位素研究,探讨其岩石类型、构造背景和岩石成因。LA-ICP-MS锆石U-Pb定年表明,花岗闪长岩的成岩年龄为318.2±3.6 Ma,形成时代为晚石炭世。岩石高硅、富钠,碱含量中等,Mg#介于53.9～56.6,属于准铝质钙碱性花岗岩类（A/CNK = 0.91～0.97）,轻重稀土分馏较明显且富集轻稀土（La_N/Yb_N = 8.55～10.10）,Eu异常不明显,富集大离子亲石元素Ba、K、Sr,亏损高场强元素Nb、Ta、P、Ti。同位素特征显示,岩石具有低I_Sr值（0.703 82～0.704 24）、正ε_Nd（t）值（+6.96～+7.74）,年轻的t_DM1值为0.74～0.61 Ga,锆石ε_Hf（t）值为+12.6～+14.7,t_DM2为519～396 Ma。综合地质、地球化学和年代学特征,认为加曼铁列克得花岗闪长岩为未分异的Ⅰ型花岗岩,形成于晚石炭世俯冲背景下的岛弧环境,可能是由流体参与的新元古代玄武质洋壳部分熔融的产物,岩浆上升过程中受到楔形地幔物质的混染。  相似文献   

Hydrogeochemistry of abandoned Pb sulphide mines: the mining district of La Carolina (southern Spain)   总被引：1，自引：0，他引：1  

M. Carmen Hidalgo  Javier Rey  José Benavente  Julián Martínez 《Environmental Earth Sciences》2010,61(1):37-46

The impact of past mining activities on the quality of groundwater and surface water has been investigated in the mining district of La Carolina (southern Spain, province of Jaén), a region characterised by the presence of mineralisations of Pb–Ag, Cu and Fe sulphides and Ba sulphates. The chemistry of waters from flooded galleries, shafts and drainage adits has been compared with that of surface waters in the same area. Generally, waters present neutral pH, since carbonates neutralise the acidity produced by the oxidation of Fe-bearing sulphide minerals in the mine impacted water. Despite of this natural attenuation process, in most of the cases, the mine groundwater is of low quality and shows high dissolved SO₄ (up to 3.7 g/l), Fe and Mn contents (tens to hundreds mg/l), exceeding the limit established by the guidelines of the World Health Organization for drinking water. Generally, the surface waters are of the sulphate calcium–magnesium to magnesium types, with moderate mineralisation. Post-rebound mine waters caused degradation of receiving watercourses in which the Fe contents are usually high, with values close to 3 g/l, and the mineralisation is greater as the channels run down in the mining zone. During dry seasons a considerable increase of salts and metals dissolved in stream waters was found, due to the decreasing contributions by run-off in this semiarid region, whereas the abandoned mine discharges remained practically constant.  相似文献