Fault zone structures of northern and southern portions of the main central fault generated by the 2008 Wenchuan earthquake using fault zone trapped waves   总被引：1，自引：0，他引：1  

Songlin Li  Xiaoling Lai Zhixiang Yao  Qing Yang Geophysical Prospecting Center  China Earthquake Administration  Zhengzhou  China Institute of Geophysics  Beijing  China 《地震学报(英文版)》2009,(4):417-424

The rupture process of the May 12,2008 MS8.0 Wenchuan earthquake was very complex. To study the rupture zones generated by this earthquake,four dense temporary seismic arrays across the two surface breaking traces of the main-shock were deployed in July and recorded a great amount of aftershocks. This paper focuses on the data interpretation of two arrays across the central main fault,the northern array line 1 and southern array line 3. The fault zone trapped waves recorded by the two arrays were used to st...  相似文献   

陆相特殊沉积的研究方法及气候意义   总被引：1，自引：0，他引：1       下载免费PDF全文

田馨  向芳  罗来  宋见春 《地学前缘》2009,16(5):71-78

陆相沉积形成于地圈与水圈、大气圈和生物圈的交界面上,比海相地层更有效地记录了地球表层环境的信息。通过对沉积岩中沉积物的粘土矿物、气候指数、氧同位素测温等研究,获得关于气候干湿冷暖的信息。基于对这些常用方法的研究,提取出一些陆地上的特殊沉积,如：陆相红层、沙漠沉积体系、蒸发岩、煤及油页岩等所包含的丰富气候信息。沙漠代表干旱炎热气候;陆相红层的出现反映高温氧化环境,其在干旱和潮湿的热带气候下都能形成;芒硝代表干冷的气候环境;石膏则代表干热,水体盐度高,蒸发作用强的气候条件;煤层/油页岩一般形成于温暖潮湿的气候环境。对特殊沉积的研究可以用来重建古气候和恢复大陆古环境。  相似文献   

Potential of quartz OSL dating on moraine deposits from eastern Tibetan Plateau using SAR protocol     

XianJiao Ou  LiuBing Xu  ZhongPing Lai  Hao Long  Zhong He  QiShun Fan  ShangZhe Zhou 《Quaternary Geochronology》2010,5(2-3):257-262

Optically stimulated luminescence (OSL) dating methods have been widely applied in Quaternary glaciology. However, glacigenic deposits are considered in general as problematic for OSL dating, mainly because they are transported shorter distances prior to burial and are usually partially bleached. Thus, most researchers choose glaciofluvial and glaciolacustrine sediments (with relatively longer transportation times) for OSL dating when constraining the age of glaciation. In this study, four samples were collected from a lateral moraine series at Zhuqing Village, northern margin of Queer Shan Mountain, eastern Tibetan Plateau, in order to investigate the applicability of OSL dating for morainic deposits. Quartz grains (38–63 μm) were extracted and measured using single aliquot regenerative-dose (SAR) protocol. Internal checks and dose recovery test show that the SAR protocol is appropriate for equivalent dose (D_e) determination. The effect of thermal transfer is small for all samples and the recycling ratio for each individual sample is close to unity. The symmetry in the D_e distributions indicates that quartz grains were well-bleached prior to burial. OSL ages show good agreement with geomorphological and field investigations, and are also concordant with an independent ESR age. It is concluded that: (a) the morainic deposits in Zhuqing were well-bleached and suitable for OSL dating; (b) SAR protocol can be applied to morainic deposits for samples under study.  相似文献   

Study of the Mineralization Process of granular apatites in Weng’an Baidou Phosphate Deposit Using Microbeam Analyses     

YANGH Haiying  XIAO Jiafei  LI Yantao  XU Jianbin 《《地质学报》英文版》2017,91(Z1):293-295

<正>1 Introduction Studies of marine sedimentary phosphate rock have lasted decades,scholars proposed some standpoints about mineralization,however,the genesis of mineral deposits remains to be a controversial question(She et al.,2013).There are many viewpoints of mineralization about the Doushantuo phosphorites,Central Guizhou,including biological mineralization(Mi et al.,2010;Shi et al.,2005),  相似文献   

河南新乡第四纪地层划分与沉积环境分析     

郑建彬  陈建强 《现代地质》2017,31(1):81

新乡位于豫西北山地与豫东平原过渡位置,黄河冲积扇的不断发展以及第四纪早期的新构造运动对该区第四纪沉积过程产生影响。通过对新乡多个钻孔岩心进行系统性描述、年龄测试、沉积相分析以及钻孔地层间对比分析,结果显示：黄河冲积扇的发展及黄河主河道的南北向迁移,是研究区第四纪沉积过程的重要影响因素,研究区第四纪沉积相以河流相为主,横向上对比良好;多个场地的钻孔揭示研究区全新统厚度约10 m,平均年龄95 ka左右;更新统上部厚度约69 m,平均年龄129 ka左右;更新统中部厚度约55 m,平均年龄小于829 ka;更新统下部未见底。在第四纪早期,黄河冲积扇主河道在研究区西侧,尚未发育到新乡地区,对该区的影响较小,以细粒的泛滥平原沉积物为主;第四纪中期,黄河冲积扇快速向东部发展,河道迁移至研究区北东侧,沉积了明显的河流相,砂体厚度明显增加;第四纪中晚期,基本继承前期的河流相沉积,随着河道南迁,砂体含量有所下降。受到新构造运动的影响,新乡地区第四纪地层北东部出现沉积间断,并且局部地区出现差异沉降,北东侧地势高于南西侧。  相似文献   

高频基准面旋回控制下浅水三角洲及其砂体发育模式:以松辽盆地扶余油田白垩系泉头组为例^*          下载免费PDF全文

赖洪飞  秦智  王洪君  郑锡  林艳波  鲍志东  李美俊  张云龙  张莉  吴煜潇  宋健  何陵沅 《古地理学报》2017,19(4):609-622

浅水三角洲储集层在陆相湖盆油气勘探中具有重要的意义,但基于密井网资料的精细研究仍十分缺乏。以高分辨率层序地层学和沉积学理论为指导,以松辽盆地扶余油田DT91区块白垩系泉头组四段第Ⅲ砂组14余口取心井的岩心资料和700余口密井网测井资料为对象,分析了高频基准面旋回下浅水三角洲及其砂体的发育规律。研究结果表明: (1)浅水三角洲储集层主要发育在河道、漫溢砂、分流砂坝、天然堤、决口扇和席状砂等6种成因砂体,以河道砂体和分流砂坝砂体为主。(2)在岩心和测井曲线上可识别出河道底部冲刷面、进积—退积作用面、退积—进积作用面和湖泛面等4种基准面旋回物理界面;并识别出3大类、7亚类超短期基准面旋回类型。(3)高频基准面旋回演化过程中,湖泊浅水三角洲沉积区可容空间变化不大,沉积物供给通量在可容空间增长速率(accommodation increasing rate,A)和沉积物供给通量(sediment supply rate,S)的比值A/S变化中起着主导作用,进而控制着成因砂体的数量和空间接触关系。当A/S值由小变大时,浅水三角洲的规模快速变小,成因砂体的数量也相应减少;同时,成因砂体垂向接触方式由下切叠加式→加积叠加式→孤立式变化,砂体平面分布的复合连片程度也发生由高到低的变化。  相似文献   

Characteristics of seismic disasters and aseismic measures of tunnels in Wenchuan earthquake     

Jinxing Lai  Siyue He  Junling Qiu  Jianxun Chen  Lixin Wang  Ke Wang  Junbao Wang 《Environmental Earth Sciences》2017,76(2):94

Over the past few years, accompanied by big and frequent earthquakes, more attention was paid to the tunnel earthquake resistance. To reduce tunnel seismic damage and explore the reasonable aseismic measures, the tunnel earthquake disaster investigation was employed to analyze and summarize the tunnel seismic damage on the basis of Wenchuan earthquake. Fifty-two tunnels near the epicenter of Sichuan Province were investigated: Only 7 tunnels did not show structure damage, 6 tunnels suffered the most serious damage, and the rest appeared damage to various extents. It indicates that most serious seismic damage happens to fault fracture zone, followed by entrance and common section of the tunnel. Additionally, the results display that the typical seismic damage of tunnels is lining cracking, collapsing, dislocation, construction joints cracking, and uplifting of invert, and usually lining cracking and collapsing account for a larger proportion. Therefore, the tunnel aseismic design should emphasize the fault fracture zone and tunnel entrance. Tunnel design should adopt the composite lining structure with shock absorber and whole chain alternative grouting to prevent the lining cracking and collapsing in the seismic fortification zone.  相似文献   

Experimental investigation of fine sediment deposition using particle image velocimetry     

Masoumeh MoayeriKashani  Lai Sai Hin  S. Ibrahim 《Environmental Earth Sciences》2017,76(19):655

In order to create natural and healthy water ecosystems, the impact of hydrological processes in ponds must be identified. Pond structure may affect water quality in many ways. The present study provides a novel insight into some of the hydrological processes as well as how to employ retentions to enhance storm water detention and manage discharge. In this research, particle image velocimetry is utilized to study the two-dimensional collecting efficiency of fine sediments by retention structures with a range of hydraulic features. To examine the hydrodynamic behavior of water mixed with fine particles, a sediment basin was designed. Fluorescent polymer particles (1–50 μm) were subsequently added to this fluid mix. This study demonstrates that gravitational force increases fine particle settlement by over 50% at greater depths. The optimum collecting efficiency of sediments at the water surface was found to be around 80%. It was also determined that flow rate and particle size are directly correlated and that inlets and outlets at higher levels impede fine particle dispersion in the water column. For these reasons, it seems that adjusting the hydraulic parameters may diminish siltation.  相似文献   

Discrete element simulation of mine tailings stabilized with biopolymer     

Rui Chen  Xiaobin Ding  Lianyang Zhang  Yongli Xie  Hongpeng Lai 《Environmental Earth Sciences》2017,76(22):772

This paper presents a series of numerical simulations using discrete element method (DEM) to study the behavior of biopolymer-stabilized mine tailings (MT). Validation is conducted by comparing the DEM results with the experimental data. The macro-behavior comparison shows that the DEM simulations are in good agreement with experimental results. Analysis of the micro-parameters indicates more biopolymer induces larger tensile and shear strengths, confirming the experimental results which show that the strength of MT increases with higher biopolymer concentration. Analysis of the bond breakage pattern suggests that at the same strain level MT stabilized with higher biopolymer concentration show less bond breakage percentage. MT specimen under greater confining pressure develops larger shear band than that under lower confining pressure. Higher biopolymer concentration induces the increase in larger inter-particle bonding strength and thus larger cracking resistance and greater macro-strength.  相似文献   

花岗岩演化与铀钍元素富集的关系:以粤北贵东岩体为例   总被引：3，自引：0，他引：3       下载免费PDF全文

娄峰  李宏卫  陈光明  敖文波  赖中信  卢映新  杨燕娜 《地学前缘》2011,18(1):110-117

对粤北贵东岩体铀钍丰度变化特征的研究表明,原地重熔过程导致铀钍元素向花岗岩体的上方汇聚富集,并造成铀、钍元素在空间上的分离,即在花岗岩体中,铀的丰度带位处钍丰度带之上。陆壳多次原地熔融(重熔)不但导致复式花岗岩体形成,同时造成铀元素在晚期岩体中的富集。贵东岩体内燕山早期岩体铀钍含量的东西差异被认为与卷入熔融的铀源层(寒武-震旦系)的初始埋深有关,而复式岩体铀含量的南北差异,则被解释为与晚期重熔界面倾斜方向所导致的晚期岩体的剥蚀深度有关。高铀含量和高铀钍比值并存往往是晚期岩体埋深较浅的表现,对于深部隐伏矿床的寻找有重要指示作用。  相似文献