新疆巴里坤湖粒度组分分解及其环境指示意义   总被引：1，自引：0，他引：1  

吕雁斌  赵家驹  黄伟  陶士臣  安成邦 《沉积学报》2011,29(1):134-142

选择位于西风影响区的天山东段巴里坤湖湖泊岩芯样品,对沉积物粒度组分进行经验正交函数(EOF)分解,并探讨各分量的环境意义.结果显示,EOF1组分与沉积物粒度小于2μm组分相关系数达0.64以上,并与代表区域有效湿度的碳酸盐氧同位素指标有很好的对应关系,故将EOF1解译为区域有效湿度的替代指标.EOF2组分与粒级为45-...  相似文献   

我国古环境中炭屑的研究现状与展望   总被引：1，自引：0，他引：1  

郭小丽  赵文伟  孙静会  李芙蓉  张科  赵艳 《冰川冻土》2011,33(2):342-348

炭屑是恢复古火灾的一个重要手段,同时也为认识古气候、古植被和古地理提供了重要途径.从炭屑研究方法和应用两个方面总结了国内近年来炭屑研究的进展,提出了炭屑研究中尚需解决的问题,展望未来研究的前景.炭屑的分析方法和现代过程研究可能是今后研究中急需解决的问题,这两个问题的解决可以使炭屑在古环境和人类活动研究中充分发挥其作用....  相似文献   

大陆俯冲带流体活动:超高压变质岩矿物水含量和稳定同位素制约     

陈仁旭  郑永飞  龚冰 《岩石学报》2011,27(2):451-468

对超高压变质岩中含水矿物和名义上无水矿物的地球化学研究,极大地深化了我们对大陆碰撞带地壳俯冲和折返过程中流体体制的认识。就流体体制和化学地球动力学来说,有关研究在大别-苏鲁造山带进行的最为详细,因此已经成为研究大陆俯冲带变质的典型地区。本文以大别-苏鲁造山带为对象,从矿物水含量的角度,结合稳定同位素论述了大陆俯冲带流体活动。超高压变质岩中名义上无水矿物含有大量的水,以结构羟基和分子水形式存在。名义上无水矿物中结构羟基和分子水出溶与含水矿物分解共同构成了折返过程中退变质流体的主要来源。名义上无水矿物所释放的水以富集轻的氢氧同位素为特征,而含水矿物分解则提供了富集D的流体来源。折返过程中,名义上无水矿物降压脱水存在亏损D的分子水的优先丢失和不同形式水之间的相互转化。不同岩性的水含量差异导致了它们在折返过程中不同的流体活动行为。大陆板块俯冲和折返过程中,在不同矿物、不同岩性以及板片不同部位之间存在水的再分配;板片的一部分作为富水流体的源,而另一部分可能作为汇。  相似文献   

天然闪锌矿原位高温X射线衍射研究     

吴婧  李艳  秦善  鲁安怀 《矿物学报》2011,31(4):647-653

对天然闪锌矿进行了原位高温X射线衍射实验研究,结果表明：闪锌矿受热膨胀,27～675℃温度范围内其膨胀系数为25.61×10-6℃-1;随着温度的升高,在543℃时产生中间物相Zn3O（SO4）2,并分解产生红锌矿ZnO;在797℃时中间物相完全消失,同时出现尖晶石结构的ZnFe2O4;加热至1160℃时的产物为ZnO和ZnFe2O4。实验表明,天然闪锌矿的热改性可产生一定比例的红锌矿（ZnO）,其与闪锌矿一起形成二元复合半导体。在光的激发下,该半导体体系产生的光生载流子由一种半导体注入另一种半导体,降低了光生电子-空穴对的复合几率,提高其光催化活性。本文的研究可为热改性提高天然闪锌矿光催化活性提供理论依据。  相似文献   

Morlet小波显著性检验和精度分析在地磁场和地震活动性周期分析中的应用   总被引：3，自引：0，他引：3       下载免费PDF全文

尹继尧  朱元清  宋治平  张国民  薛艳  刘杰 《地震学报》2011,33(5):663-671

首先通过对加入随机噪声的合成信号进行Morlet小波变换并进行显著性检验, 分析所得信号的周期成分的显著性和非显著性, 然后研究信号周期长短、 信号观测时间段长短与精度之间的关系．在此基础上,以活动周期比较稳定的太阳黑子活动作为实例分析,结果显示本文的精度分析和显著性检验方法对于周期谱的精度和显著性研究是可行的．最后将该方法应用于全球地震活动周期谱的分析,求出全球地震活动周期谱及其显著性与精度．研究结果表明,在利用Morlet小波分析地磁场和地震活动性周期时引入显著性检验,并结合本文给出的精度, 可以从数据中提取出周期谱及其显著性和精度．   相似文献   

Spatial sensitivity of seismic hazard results to different background seismic activity and temporal earthquake occurrence models     

Nazan Yilmaz  M. Semih Yucemen 《Soil Dynamics and Earthquake Engineering》2011

Spatial sensitivity of seismic hazard results to different models with respect to background seismic activity and earthquake occurrence in time is investigated. For the contribution of background seismic activity to seismic hazard, background area source with uniform seismicity and spatially smoothed seismicity models are taken into consideration. For the contribution of faults, through characteristic earthquakes, both the memoryless Poisson and the time dependent renewal models are utilized. A case study, involving the assessment of seismic hazard for the Bursa province in Turkey, is conducted in order to examine quantitatively the influence of these models on seismic hazard results. The spatial variation of the difference in Peak Ground Acceleration (PGA) values obtained from these different models is presented in the form of difference maps for return periods of 475 and 2475 years. Best estimate seismic hazard maps for PGA and Spectral Accelerations (SA) at 0.2 and 1.0 s are obtained by using the logic tree method.  相似文献   

Geological Structure and Quaternary Activity of the Zhangjiakou Fault, Northern China     

Zhou Yueling  You Huichuan  Zhou Jianglin  Shao Cuiru  Zhang Zhengyu 《中国地震研究》2011,25(1):70-81

Based on detailed field investigations,this paper describes the geometrical characteristics and tectonic activities of the Zhangjiakou fault at the northwest of Beijing. This fault strikes mainly northwest to west,short parts of which strike near east to west,dipping north,and extends over a length of 70km. It is a major geological and geomorphological margin,controlling the neotectonic movement in this region. On the south side of the Zhangjiakou fault are the Late Quaternary unconsolidated deposits,forming basins; while on the other side are Mesozoic volcano debris and Pre-Mesozoic metamorphic rocks, forming lower mountains and hills. The Zhangjiakou fault consists mainly of high-angle inverse strike-slip fault and partially of normal strike-slip fault. Among these,the north-dipping NW-NWW-trending secondary faults,constituting the main fracture of the fault,have inverse characteristics; those near the EW-trending secondary faults are links of the former faults,with a smaller length and normal faulting characteristics. Thus,the Zhangjiakou fault is a north-dipping inverse and partially south-dipping normal strike-slip fault. The Zhangjiakou fault has been continuously active since the Quaternary. With the exception of the western end extension,which has been active since the late Pleistocene, the main part of the fault has been active since the Holocene. The central main segment of the Zhangjiakou fault is more active. Since the mid-late period of the late Pleistocene,the average vertical slip rate of a single fault has been over 0. 07mm /a ～ 0. 30mm /a. The Zhangjiakou fault has multi-slip surfaces,and the total vertical slip rate reaches 1. 33mm /a,estimated from the Qingshuihe river terraces and the relevant drilling data.  相似文献   

利用重力资料与GPS数据研究伽师及邻区近期地壳运动特征   总被引：1，自引：1，他引：0  

刘代芹  李杰  王晓强  李辉  朱治国  李桂荣 《中国地震》2011,27(2):182-191

利用重力资料和GPS数据研究伽师及邻近地区地壳运动特征,首先对2005～2009年该区域流动重力观测资料进行平差计算,绘制出以1年为尺度的重力场变化的等值线图.分析表明,伽师及邻近地区近年来重力场变化相对活跃,且有一定的规律,最大重力异常值达到150×10 -8m·s-2.其次,利用2005 ～2009年该区域GPS数据在统一框架下进行重新解算,并利用理论计算得到该地区每年的面膨胀值.研究表明,该区域地壳面压缩、面膨胀交替出现,正负交界处往往是剪应变值增大的地区,即地震易孕育区域.最后探讨了重力与GPS(面膨胀)二者在地壳形变、地球动力之间的响应关系.研究表明,震前伽师及邻区重力值主要显示正变化,震后则呈现出大面积负值区域,说明压陷(面收缩)和向北扩张(面膨胀)作用交替进行,这与GPS计算出的面膨胀结果是一致的.  相似文献   

我国青藏块体地区未来几年地震危险性分析     

陈荣华  李志海 《内陆地震》2011,25(1):6-11

研究了我国青藏块体地区每一地震活跃幕里地震活动的主体地区、地震活动强度和地震活动持续时间,认为2008年四川汶川8.0级地震的发生可能意味着我国青藏块体自1995年或1997年开始的地震活跃幕已经进入后期,同时也意味着这一地区自1920年以来更长时间尺度里的地震活动期也进入了收尾阶段.未来几年青藏块体地震活动水平为7级...  相似文献   

Plant Species Mediate Rhizosphere Microbial Activity and Biodegradation Dynamics in a Riparian Soil Treated with Bensulfuron‐methyl     

Changming Yang  Yulai Wang  Jianhua Li 《洁净——土壤、空气、水》2011,39(4):338-344

A pot experiment was conducted to investigate microbial characteristics and the biodegradation process of bensulfuron‐methyl (BSM) in a rhizosphere soils planted with different riparian plants. The results showed that microbial population decreased with BSM addition in the rhizosphere, especially for bacteria and fungi. The activities of the dehydrogenase (DHase) were stimulated firstly, due to BSM addition, but then were inhibited, and recovered to the initial level, while the activities of the phosphatase and urease showed obviously decreasing trend throughout the whole experiment. Rhizosphere soil substrate‐induced respiration (SIR) was depressed by BSM, especially at the initial 14 days of incubation. Compared to Zizania aquatica and Phragmites australis, Acorus calamus showed a significantly (p < 0.05) higher DHase activity and larger SIR in the rhizosphere soils treated with BSM, which means that A. calamus can effectively alleviate inhibitory effect of the sulfonylurea herbicide addition on microbial activity. There were significant (p < 0.05) differences in microbial degradation dynamics of BSM in the rhizosphere soils among three kinds of riparian plants. A. calamus displayed a significantly (p < 0.05) higher degradation efficiency of BSM in the rhizosphere soils, followed by Z. aquatica and P. australis. The residual BSM concentration in A. calamus rhizosphere soil was 23.1 and 32.2% lower than that in Z. aquatica and P. australis rhizosphere soils, respectively, indicating a greater improvement effect on biodegradation of BSM in A. calamus rhizosphere soils.  相似文献