新疆黄山杂岩体矿物学特征及其意义   总被引：1，自引：0，他引：1  

钟应先 《矿物岩石》1991,11(1):14-23

黄山杂岩体造岩矿物有橄榄石、斜方辉石、单斜辉石、斜长石、角闪石和黑云母。其中斜方辉石的多色性不是由Fe~(2+)引起,而是由Ti~(4+)引起。单斜辉石结晶后常与岩浆继续发生化学反应,形成一种岩浆岩结构——角闪反应补丁结构。橄榄石中镍含量的亏损程度反映杂岩体曾经历过硫化物熔离作用。单斜辉石Si,Al~Ⅳ,Ti的变化表明杂岩体属于拉斑玄武岩系列。超镁铁岩中K,Ba,Th,Hf等元素反常的地球化学行为是由该岩石中黑云母矿物引起。  相似文献   

短时间尺度周期性热力强迫下流型的低频振荡          下载免费PDF全文

罗哲贤 《大气科学》1991,15(3):97-104

本文在正压涡度方程中引进短时间尺度周期性热力强迫项。在一定的参数范围内,该强迫项可以引起环流指数准两至三周的低频振荡。  相似文献   

The stability and behavior of a frictional system with a two state variable constitutive law     

Michael L. Blanpied  Terry E. Tullis 《Pure and Applied Geophysics》1986,124(3):415-444

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Statistical analysis of time-dependent earthquake occurrence and its impact on hazard in the low seismicity region Lower Rhine Embayment   总被引：1，自引：0，他引：1  

Licia Faenza  Sebastian Hainzl  Frank Scherbaum  Céline Beauval 《Geophysical Journal International》2007,171(2):797-806

The time-dependence of earthquake occurrence is mostly ignored in standard seismic hazard assessment even though earthquake clustering is well known. In this work, we attempt to quantify the impact of more realistic dynamics on the seismic hazard estimations. We include the time and space dependences between earthquakes into the hazard analysis via Monte Carlo simulations. Our target region is the Lower Rhine Embayment, a low seismicity area in Germany. Including aftershock sequences by using the epidemic type aftershock-sequence (ETAS) model, we find that on average the hypothesis of uncorrelated random earthquake activity underestimates the hazard by 5–10 per cent. Furthermore, we show that aftershock activity of past large earthquakes can locally increase the hazard even centuries later. We also analyse the impact of the so-called long-term behaviour, assuming a quasi-periodic occurrence of main events on a major fault in that region. We found that a significant impact on hazard is only expected for the special case of a very regular recurrence of the main shocks.  相似文献   

How can the epikarst zone influence the karst aquifer hydraulic behaviour?   总被引：3，自引：0，他引：3  

Branka Trček 《Environmental Geology》2007,51(5):761-765

The role of an epikarst zone in the karst aquifer hydraulic behaviour was brought into focus in our studies referring to the catchment area of the Hubelj spring (SW Slovenia). This study points out the significance of effects of the fast preferential flow—epiflow, which is the main factor controlling solute/contaminant transport towards the aquifer saturated zone. The so-called epikarstic hypothesis is verified on the basis of the most significant research results that are supported by the most important findings from the literature.  相似文献   

'Driving people crazy': A geography of boy racers in Christchurch, New Zealand     

Ryan Falconer  Simon Kingham 《New Zealand geographer》2007,63(3):181-191

Abstract:   So-called 'boy racers' form a subculture, which is subject to ongoing public scrutiny and media attention, usually negative. This study aimed to deconstruct the term 'boy racer' and to explore the subculture in detail, within the context of Christchurch, New Zealand, using a phenomenological ethnographic approach. This included conducting semistructured interviews and observing the activities of participants. Results show the subculture has a relatively diverse membership and a range of associated behaviours, activities and attitudes. Moreover, performances within the subculture are linked to place, and are seen by other members of the community as threats to normative boundaries.  相似文献   

Analysis of the weightiness of site effects on reinforced concrete (RC) building seismic behaviour: The Adra town example (SE Spain)   总被引：1，自引：0，他引：1  

Manuel Navarro  Francisco Vidal  Takahisa Enomoto  Francisco J. Alcalá  Antonio García‐Jerez  Francisco J. Sánchez  Norio Abeki 《地震工程与结构动力学》2007,36(10):1363-1383

The damage distribution in Adra town (south‐eastern Spain) during the 1993 and 1994 Adra earthquakes (5.0 magnitude), that reached a maximum intensity degree of VII (European Macroseismic Scale (EMS scale)), was concentrated mainly in the south‐east zone of the town and the most relevant damage occurred in reinforced concrete (RC) buildings with four or five storeys. In order to evaluate the influence of ground condition on RC building behaviour, geological, geomorphological and geophysical surveys were carried out, and a detailed map of ground surface structure was obtained. Short‐period microtremor observations were performed in 160 sites on a 100m × 100m dimension grid and Nakamura's method was applied in order to determine a distribution map of soil predominant periods. Shorter predominant periods (0.1–0.3 s) were found in mountainous and neighbouring zones and larger periods (greater than 0.5 s) in thicker Holocene alluvial fans. A relationship T = (0.049 ± 0.001)N, where T is the natural period of swaying motion and N is the number of storeys, has been empirically obtained by using microtremor measurements at the top of 38 RC buildings (ranging from 2 to 9 storeys). 1‐D simulation of strong motion on different soil conditions and for several typical RC buildings were computed, using the acceleration record in Adra town of the 1993 earthquake. It is noteworthy that all the aforementioned results show the influence of site effects in the degree and distribution of observed building damage. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

人类行为对自然生态系统改变的研究——以大洋岛屿为例     

刘岩  张磊 《世界地理研究》2001,10(1):91-97

本文聚焦于人类活动在印度洋和中、高纬度大洋中遥远岛屿的表象，着重阐述了人类行为对自然生态系统的影响，文章通过对建筑、采矿、生物引进，以及旅游业开发等人类活动的若干方面的观察和考证，总结认为世界上不存在孤立地域，没有哪一个环境能够保持与世界的经济和政治体系毫不相干。  相似文献   

Diel changes in the feeding behaviour of Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) in Ellidavatn, a small lake in southwest Iceland     

Bjrn Bjrnsson 《Limnologica》2001,31(4):281-288

In the lake Ellidavatn, southwest Iceland, the diel activity of Arctic char and brown trout was studied in autumn (September) and spring (April) by removing the fish from gillnets every 3 hours for three days. Additional fish samples, evening and morning, were taken at other times of the year. The catch per unit effort was about 10 times higher during the nighttime than daytime for both char and trout. The median weight of char was lowest near the middle of night (80 g) and highest near the middle of day (140 g). The median weight of trout was also lowest near the middle of night (110 g) and highest near the middle of day (330 g). The main diet of char consisted of the cladoceran Eurycercus lamellatus in September and chironomid larvae in April and the main diet of trout was always sticklebacks. In autumn and spring, the feeding was nocturnal in the char but crepuscular in the trout. The median stomach content of char was highest at dawn (0.52% of body weight) and lowest at dusk (0.14% of body weight). It is proposed that nocturnal char shift through the bottom substrate in search for prey. The median stomach content of trout was highest at 09.00–18.00 and 24.00–03.00 hours (0.13–0.18% of body weight) and lowest at 03.00–06.00 and 18.00–21.00 hours (0.02–0.07% of body weight). Different feeding times may help to secure mutual coexistence of char and trout in a small lake. In autumn and spring, the average daily consumption of char was about 0.8% of body weight, less than half their maximum food intake.  相似文献   

赣东加里东变质混合岩带金地球化学特征和地球化学行为     

余达淦  梁荣斌 《华东地质学院学报》2001,24(2):91-97

赣东加里东变质混合岩带 ,是以混合岩体为主体 ,受韧性剪切带控制的多相、多型、递增变质带 ,是受区域深构造控制的热变质带。该带产有茅排式金矿。通过对该带金地球化学特征和地球化学行为研究 ,认为带中金丰度 0 .83× 10 - 9,呈峰式分布 ,为对数及双对数正态分布型式 ,Au与主元素成分无关 ,与微量元素组合是Au -Zn -Li-Pb -Cs ,在韧性剪切过程中Au具活化迁移富集特点  相似文献