以海原断裂甘肃老虎山段为例浅析走滑断裂古地震记录的完整性——兼论古地震研究中的若干问题     

刘静徐锡伟  李岩峰冉勇康 《地质通报》2007,26(6):50-660

在简单介绍海原断裂老虎山段松山探槽点古地震工作的基础上,分析了制约走滑断裂上古地震记录完整性的因素。松山探槽点跨断裂开挖的2个探槽揭示颜色和粒度不同的地层互层的沉积序列呈近水平面状展布。在断裂带内地层发生错断、旋转和拖曳等变形现象。多个层位上的这种变形表明该点揭示了6次古地震事件。炭屑的~(14)C年龄限定了6次事件均发生在距今3500～3900年以来,其中最新的4次事件从老到新分别为0～410aAD、890～1000年之后不久、1440～1640 aAD和1990年景泰-天祝Mw5.8级历史地震。该序列及其他例子表明连续的、高沉积速率的微构造环境是走滑断裂上探槽选取的重要原则。  相似文献   

Erratum to “The Berit transect of the Tauride thrust belt, S Turkey: Late Cretaceous–Early Cenozoic accretionary/collisional processes related to closure of the Southern Neotethys” [Journal of Asian Earth Sciences 27 (2006) 108–145]     

Alastair H.F. Robertson  Timur Ustamer  Osman Parlak  Ulvi Can Ünlügen  Kemal Tal&#x;  Nurdan &#x;nan 《Journal of Asian Earth Sciences》2007,29(5-6):978-980

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THE STUDY OF RETRIEVAL THEORY AND METHODS FROM SATELLITE REMOTE SENSING FOR METEOROLOGICAL PARAMETERS OVER EASTERN ASIA—PART Ⅱ:ISPRM AND VSPRM2          下载免费PDF全文

黎光清  董超华  张文建  张凤英  王保华  冉茂农  吴雪宝  王维和  潘宁 《Acta Meteorologica Sinica》2000,(4)

Based on the practice of improved simultaneous physical retrieval model(ISPRM),in the lightof the functional analysis approach,the variational simultaneous physical retrieval model(VSPRM)has been developed.Its approximation of 1st degree is VSPRM1,which is identicalwith the ISPRM.Its approximation of 2nd degree is VSPRM2,more advanced than the VSPRM1.This paper has analyzed the function of VSPRM2,pointing out the potentiality of synergy retrievalof this model.Also,it has dealt with the problem of parameterization of water vapor's kernelfunctions and retrieval of water vapor remote sensing.Because of the characteristics of this strong ill posed inverse problem,prior information mustbe used wisely in order to get the accurate calculation of radiance R.In the previous paper,wediscussed how to build the best first guess field,the way to determine the P_s and to correct thecalculation of radiance.In this paper,we continue discussing in depth about the calculation oftransmittance,the determination of surface parameters and the selection for an optimumcombination of channels for the low-level sounding.The long-term experiment and comparison work under operational environment have shownthat the ISPRM is useful for retrieval of temperature and water vapor parameters over Chinaincluding the Tibetan Plateau,and it further proves the scientific nature of well-posed inversetheory.  相似文献   

Age, origin and significance of a new middle MIS 3 tephra horizon identified within a long-core sequence from Les Echets, France     

DANIEL VERES  SIWAN M. DAVIES  BARBARA WOHLFARTH  FRANK PREUSSER  STEFAN WASTEGÅRD  LINDA AMPEL  ANNE HORMES  GÖRAN POSSNERT  JEAN-PAUL RAYNAL  GÉRARD VERNET 《Boreas: An International Journal of Quaternary Research》2008,37(3):434-443

A new tephra has been identified within a long core (EC 3) sequence recovered from Les Echets, near Lyon, France. This visible tephra was discovered as part of a high resolution multiproxy re-investigation of the Les Echets sequence. Independent chronological information suggests that the tephra is c . 2 000–45 000 years old, and geochemical analysis indicates that it is of basanitic composition. The latter suggests a possible origin in the Eifel; however, as yet, no other volcanic events or deposits can be correlated to the Les Echets tephra. New sedimentological and chronological data are presented indicating that the tephra falls within an interval that most likely correlates with Dansgaard–Oeschger events 12-9. Thus, this tephra could potentially be an important middle MIS 3 marker horizon in central Europe if it can be traced in other palaeorecords.  相似文献   

黄河干流营养盐分布与变化趋势   总被引：4，自引：0，他引：4  

马永星  臧家业  车宏  郑莉莉  张波涛  冉祥滨 《海洋与湖沼》2015,46(1):140-147

河流是海洋获取陆源物质的主要途径,河流营养盐含量和结构的变化会对海洋生态环境产生重要影响。为了解黄河干流营养盐的基本情况及影响因素,于2012年7月(汛期)对黄河流域水体和土壤进行了综合调查,并结合历史资料分析了悬浮颗粒物和营养盐等的变化特征及对黄河物质输送的影响。结果表明:各参数受地势和人类活动的影响明显,表现出不同的分布特征。营养盐和悬浮颗粒物在上游浓度较低,在中游相对稳定,下游浓度有一定程度升高;相比于贵德而言,黄河利津段悬浮颗粒物、溶解硅和硝酸盐分别增加了近66%、60%和800%。磷限制是黄河营养盐限制的主要特征,且氮磷比呈升高趋势;与资料对比发现,黄河氮增加约1倍,硅下降60%后相对稳定,而磷略有下降。从目前分析看,支流与干流的氮营养盐构成有显著差异。在沿岸表层土壤营养盐含量较高的区域,河段内营养盐含量也较高。流域人类活动是黄河氮营养盐含量增加的重要因素;流域降水减少、水土保持等导致的物理侵蚀作用减弱是黄河硅和磷减少的重要因素;自1986年后,流域泥沙减少导致河流溶解硅降低了约34%,这值得进一步关注。  相似文献   

20世纪南极菲尔德斯半岛毛皮海豹食谱比例变化的同位素混合模型比较分析     

黄涛  张灿  蔡思盈 《海洋学报》2015,37(8):117-125

稳定同位素比值分析已成功用于示踪动物的食物来源研究,近年来已发展了多个同位素混合模型用于计算混合物中多来源物质的组成比例。本文以过去百年来南极菲尔德斯半岛南极毛皮海豹(Arctocephalus gazella)毛发的C、N同位素数据为基础,运用同位素混合模型中的欧几里得距离法、线性模型和贝叶斯模型进行计算、分析和比较,得到毛皮海豹食谱中南极磷虾(Euphausia superb)、南极电灯鱼(Electrona antarctica)和尼氏裸灯鱼(Gymnoscopelus nicholsi)所占比例随时间的变化趋势。各模型计算得出的结果可分为两组,分别是欧几里得距离法公式(1)和(2)的结果,表现为近百年来毛皮海豹食谱中Euphausia superb比例与其毛发稳定N同位素比值呈同步上升的趋势;第二组为欧几里得距离法公式(3)、线性模型和贝叶斯模型的结果,Euphausia superb比例与毛皮海豹毛稳定N同位素比值呈反相关关系。综合对比研究区域气候、海冰环境变化背景和已有的南极磷虾种群密度调查资料分析,第二组模型结果与实际情况较为相符,可用于讨论食物比例的时间变化趋势。近百年来,菲尔德斯半岛毛皮海豹食谱中Euphausia superb的比例显著下降,很可能是由于区域气候快速变暖和海冰的消退造成的。本文的计算结果指示西南极半岛气候变暖已显著影响到区域海洋食物链变化。  相似文献   

基于COS-2S模型的ADCP海浪方向谱估计     

郑威  杨立  惠力  刘敏  王志  冉祥涛 《海洋测绘》2015,35(1):41-44

美国RD公司声学多普勒流速剖面仪(ADCP)使用的波向估计算法是迭代的最大似然算法(IMLM),IMLM可以准确估计出主浪向,但波向估计结果在主浪向以外其他方向上存在由噪声带来的能量分布,使得估计结果变得不准确。设计了基于COS-2S模型的波向估计方法,模型中只含有主波向,算法在准确估计主波向同时有效去除其他方向上噪声带来的能量分布。将一种混合遗传算法(HGA)代替遗传算法(GA)应用到波浪模型的参数求解中,HGA相对GA收敛更快,可有效找出全局最优解。仿真分析和实测数据表明,HGA和IMLM都能准确估计出波浪的主浪向,但HGA可有效去除主浪向以外其他方向上噪声带来的能量分布,HGA比IMLM更加适用于海洋各种噪声存在条件下的测量环境。  相似文献   

Composition and Origin of Ferromanganese Crusts from Equatorial Western Pacific Seamounts     

WANG Guozhi  JANSA Luba  CHU Fengyou  ZOU Can  SUN Guosheng 《中国海洋大学学报(英文版)》2015,(2):217-227

In the equatorial western Pacific, iron-manganese oxyhydroxide crusts(Fe-Mn crusts) and nodules form on basaltic seamounts and on the top of drowned carbonate platform guyots that have been swept free of pelagic sediments. To date, the Fe-Mn crusts have been considered to be almost exclusively of abiotic origin. However, it has recently been suggested that these crusts may be a result of biomineralization. Although the Fe-Mn crust textures in the equatorial western Pacific are similar to those constructed by bacteria and algae, and biomarkers also document the existence of bacteria and algae dispersed within the Fe-Mn crusts, the precipitation, accumulation and distribution of elements, such as Fe, Mn, Ni and Co in Fe-Mn crusts are not controlled by microbial activity. Bacteria and algae are only physically incorporated into the crusts when dead plankton settle on the ocean floor and are trapped on the crust surface. Geochemical evidence suggests a hydrogenous origin of Fe-Mn crusts in the equatorial western Pacific, thus verifying a process for Fe-Mn crusts that involves the precipitation of colloidal phases from seawater followed by extensive scavenging of dissolved trace metals into the mineral phase during crust formation.  相似文献   

多时相Sentinel-1A InSAR的连盐高铁沉降监测分析     

何秀凤  高壮  肖儒雅  罗海滨  冯灿 《测绘学报》2021,50(5):600-611

多时相InSAR技术具有探测大范围毫米级地表形变的能力,已被广泛应用于地面沉降监测.近几年,应用多时相InSAR技术监测以高铁为代表的大尺度人造线状地物形变备受关注.本文将C波段SAR数据用于高铁沿线路基形变监测,应用相位稳定性分析和改进的StaMPS技术来增加相干性点的密度和形变参数解算的稳定性.采用研究区时间跨度为21个月的47景Sentinel-1A数据,对连(云港)盐(城)高铁及其沿线区域进行多时相InSAR分析,并利用同时期连续的北斗导航卫星系统(BeiDou navigation satellite system,BDS)观测数据对线性沉降速率和时序位移分别进行监测分析,进而对比验证二者的沉降监测结果.研究结果表明:利用C波段的Sentinel-1A数据能够获取毫米级的线性形变速率和时序位移序列,InSAR与BDS二者平均时序位移均方根误差为3.8 mm,与BDS监测结果相比取得很好的一致性,且连盐高铁线路整体表现稳定.  相似文献   

A DIAGNOSTIC ANALYSIS OF AIR TEMPERATURE ANOMALY MODE OVER CHINA IN 2009/2010 WINTER BASED ON GENERALIZED EQUILIBRIUM FEEDBACK ASSESSMENT (GEFA) METHOD     

江志红  吴燕珠  刘征宇  温娜  赵灿 《热带气象学报(英文版)》2015,21(2):121-130

By using the observed monthly mean data over 160 stations of China and NCAR/NCEP reanalysis data, the generalized equilibrium feedback assessment(GEFA) method, combined with the methods of EOF analysis, correlation and composite analysis, is used to explore the influence of different SST modes on a wintertime air temperature pattern in which it is cold in the northeast and warm in the southwest in China. The results show that the 2009/2010 winter air temperature oscillation mode between the northern and southern part of China is closely related to the corresponding sea surface temperature anomalies(SSTA) and its associated atmospheric circulation anomalies. Exhibiting warming in Northeast China and cooling in Southwest China, the mode is significantly forced by the El Nio mode and the North Atlantic SSTA mode, which have three poles. Under the influence of SSTA modes, the surface northerly flow transported cold air to North and Northeast China, resulting in low temperatures in the regions. Meanwhile, the mid-latitude westerlies intensify and the polar cold air stays in high latitudes and cannot affect the Southwest China, resulting in the warming there.  相似文献