东喜马拉雅构造结大陆碰撞以来构造年代学框架及其与哀牢山-红河构造带的对比   总被引：13，自引：0，他引：13  

张进江  钟大赉  季建清  丁林  桑海清 《矿物岩石地球化学通报》2001,20(4):243-244

东喜马拉雅构造结经历了前期楔入和后期垮塌变形.楔入事件发生于～60Ma、～23Ma和～13 Ma,垮塌开始于6～7Ma.哀牢山红河构造带同样经历早期走滑和后期正断,走滑年代分别为58～56Ma、23Ma和13Ma,后期正断开始于5.5 Ma.上述年龄的意义在于～60Ma的变形代表印度与欧亚大陆的初期碰撞;2 Ma为青藏高原及邻区的主变形期;13Ma的变形也代表一次汇聚事件,并形成青藏高原的东西向伸展.6～7Ma以后的垮塌作用代表了青藏高原的快速隆升.  相似文献   

Anisotropy of the upper mantle in Chinese mainland and its vicinity   总被引：2，自引：1，他引：2  

刘希强  周蕙兰  李红  季爱东 《地震学报(英文版)》2001,14(4):359-370

IntroductionAnisotropy is a universal phenomenon in the upper mantle. The mechanisms, which cause elastic anisotropy of in-situ rocks, include lattice preferred orientation of the minerals composing the rocks and preferred orientation of magma chambers. Lattice preferred orientation (LPO) of olivine is widely believed to be the dominant cause of the upper mantle anisotropy. The observational results of the upper mantle anisotropy can be explained by tectonic process relating to plate motion.…  相似文献   

东天山碰撞造山与金铜成矿系统分析   总被引：15，自引：2，他引：13  

杨兴科  程宏宾  姬金生  陈强  罗桂昌 《大地构造与成矿学》1999,23(4):315-332

根据碰撞带不同单元按构造一岩石地层划分原则,分出有序和无序两套地层岩石组合,分属两个不同的构造一火山活动带,碰撞造山与韧性剪切带强时空耦合．碰撞带两侧岛弧火山岩和带内碰撞花岗岩特征和成岩成矿时代、地球化学省等表明其较特殊的碰撞造山和陆内造山成盆多阶段演化特点。与碰撞造山有关的金铜矿分七种成因类型。现划10个成矿区带分属两个古陆边缘成矿系统,金矿成矿可分为五个阶段。金铜矿成带分布与碰撞造山演化有关,空间上北部铜矿带,南部金矿带,为今后进一步找矿指明了方向,提出了具体靶区。  相似文献   

A PRELIMINARY STUDY ON THE METHOD OF SEISMIC INTENSITY ASSESSMENT BASED ON RESIDENTIAL BUILDING DATA AND HIGH RESOLUTION REMOTE SENSING IMAGES          下载免费PDF全文

GUO Jian-xing  ZHANG Yu-xiang  JI Jian-zhong  YUAN Xiao-xiang  XIAO Ben-fu 《地震地质》1979,42(4):968-980

After destructive earthquakes, the assessment result of seismic intensity is an important decision-making basis for emergency rescue, recovery and reconstruction. This job requires higher timeliness by government and society. Because remote sensing technology is not affected by the terrible traffic conditions on the ground after the earthquake, large-scale seismic damage information in the earthquake area can be collected in a short time by the remote sensing image. The remote sensing technique plays a more and more important role in rapid acquisition of seismic damage information, emergency rescue decision-making, seismic intensity assessment and other work. On the basis of previous studies, this paper proposes a new method to assess seismic intensity by using remote sensing image, i.e. to interpret the building collapse rate of a residential quarter after an earthquake by high-resolution remote sensing images. If there already are detailed building data and building structure vulnerability matrix data of a residential area, we can calculate the building collapse rate under any intensity values in this residential area by using the theory of earthquake damage prediction. Assuming that the building collapse rate interpreted by remote sensing is equal to the building collapse rate predicted by using the existing data, it will be easy to calculate the actual seismic intensity of the residential area in this earthquake event. Based on this idea, according to the relevant standard specifications issued by China Earthquake Administration, this paper puts forward some functional models, such as the calculation model of building collapse rate based on remote sensing, the data matrix model of residential building structure, the prediction function matrix model of residential building collapse rate and the prediction model of residential building collapse rate. A formula for calculating seismic intensity by using remote sensing interpretation of collapse rate is also proposed. To test and verify the proposed method, this paper takes two neighboring blocks of Jiegu Town after the Yushu M7.1 earthquake in Qinghai Province as an example. The building structure matrix of the study block was constructed by using pre-earthquake 0.6m resolution satellite remote sensing image(QuickBird, acquired on November 6, 2004), post-earthquake 0.2m aerial remote sensing image(acquired by National Bureau of Surveying and Mapping, April 15, 2010) and some field investigation data. The building collapse rate in the two blocks was calculated by using the interpretation results of seismic damage from the Remote Sensing Technology Coordinating Group of China Seismological Bureau. The seismic damage matrix of building structures in Yushu area is constructed by using the abundant scientific data of the scientific investigation team of the project “Comprehensive Scientific Investigation of the Yushu M7.1 Earthquake in Qinghai Province” of China Seismological Bureau. On this basis, the collapse rate prediction function of different structures in Yushu area is constructed. According to the prediction function of collapse rate and the building structure matrix of the two blocks, the building collapse rate under different intensity values is predicted, and the curve of intensity-collapse rate function is drawn. By comparing the building collapse rate interpreted by remote sensing and the intensity-collapse rate function curve of this two blocks, the seismic intensity of both blocks are calculated to be the same value: Ⅸ degree, which is consistent with the results of the field scientific investigation of the earthquake. The validation shows that the method proposed in this paper can effectively avoid the influence caused by the difference of seismic performance of buildings and accurately evaluate seismic intensity when using remote sensing technique. The method has certain application value for earthquake emergency work.  相似文献   

基于双频磁共振的未知拉莫尔频率地下水探测方法          下载免费PDF全文

刘健楠  田宝凤  嵇艳鞠  蒋川东 《地球物理学报》1954,63(11):4244-4255

在利用地面磁共振方法进行地下水探测时,要求发射频率与拉莫尔（Larmor）频率相同.由于地磁场的不均匀性和噪声干扰,实际测量时无法获得准确的Larmor频率,导致发生偏共振现象.如果假设磁共振或频率偏量未知时,反演得到的含水量和弛豫时间（T₂^*）将存在较大误差.为了解决未知Larmor频率情况下的准确探测问题,本文在频率环测量方案的基础上提出了双频磁共振探测方法,即只需知道Larmor频率的范围区间,通过区间外的两个频率进行偏共振激发,利用频率差值的一半作为频率偏量计算核函数,即可消除未知Larmor频率的影响.通过仿真实验,证明了在电阻率大于100 Ωm时,双频磁共振和偏共振的核函数偏差较小.对于双层含水层模型,双频磁共振和偏共振的信号偏差小于3 nV,因此得到双频磁共振信号可以用偏共振核函数进行反演.通过对假设磁共振、假设偏共振和双频磁共振反演结果的对比,可以得到在未知频率偏量和设定频率偏量改变时,双频磁共振均能得到准确的反演结果.但是,当环境噪声增加和电阻率降低时,反演结果的准确度降低.最后,通过长春市烧锅镇采集数据的反演结果与已知钻探资料进行对比,验证了双频磁共振探测方法的有效性和准确性.  相似文献   

不同框架锚杆布置方式对加固边坡效果影响分析研究          下载免费PDF全文

谭玉强  姬同旭  安邦超 《贵州地质》2020,37(1):98-102

俯斜式锚杆,因其设计相对简单,施工方便,国内外在进行边坡防护时,得到大规模应用,但从其受力特性来看,此种布置方式不能充分发挥锚杆抗拉强度大的这一特点。基于此,本文通过数值模拟的方法对比分析研究了仰斜式、平行式、俯斜式三种不同锚杆布置形式在防治边坡时的加固效果并得到如下结论:在相同的框架梁结构的情况下,就单从监测点的位移变化来看,仰斜式的布置方式要优于平行式布置方式和俯斜式布置方式,俯斜式布置方式为最不利布置方式。当采用仰斜式锚杆进行边坡加固时,锚杆轴力偏大,在锚杆抗拉能力允许的情况下,仰斜式锚杆可充分发挥锚杆的优点,但在实际工程中需适当增加锚杆锚固段长度。采用仰斜式布置形式时,坡面无明显滑动,框架梁基本处于低受力状态,边坡加固效果要明显优于平行式布置方式和俯斜式布置方式。  相似文献   

Chronological and Geochemical Characterisitics of Volcanic Rocks of the Yingcheng Formation in the Southern Songliao Basin: Constraints on the Early Cretaceous Evolution of the Songliao Basin     

CHEN Jingsheng  WANG Liwu  ZHANG Yanlong  GE Wenchun  YANG Hao  JI Zheng  ZHANG Lidong  TIAN Dexin 《《地质学报》英文版》2020,94(4):1276-1300

The discoveries of oil and gas reservoirs in the volcanic rocks of the Songliao Basin(SB) have attracted the attention of many researchers. However, the lack of studies on the genesis of the volcanic rocks has led to different opinions being presented for the genesis of the SB. In order to solve this problem, this study selected the volcanic rocks of the Yingcheng Formation in the Southern Songliao Basin(SSB) as the research object, and determined the genesis and tectonic setting of the volcanic rocks by using LA-ICP-MS zircon U-Pb dating and a geochemical analysis method(major elements, trace elements, and Hf isotopes). The volcanic rocks of the Yingcheng Formation are mainly composed of rhyolites with minor dacites and pyroclastic rocks. Our new zircon U-Pb dating results show that these volcanic rocks were erupted in the Early Cretaceous(113–118 Ma). The primary zircons from the rhyolites have εHf(t) values of +4.70 to +12.46 and twostage model age(TDM2) of 876–374 Ma. The geochemical data presented in this study allow these rhyolites to be divided into I-type rhyolites and A-type rhyolites, both of which were formed by the partial melting of the crust. They have SiO2 contents of 71.62 wt.%–75.76 wt.% and Al2 O3 contentsof 10.88 wt.% to 12.92 wt.%. The rhyolites have distinctively higher REE contents than those of ordinary granites, with obvious negative Eu anomalies. The light to heavy REE fractionation is not obvious, and the LaN/YbN(average value = 9.78) is less than 10. The A-type rhyolites depleted in Ba, Sr, P, and Ti, with relatively low Nb/Ta, indicating that the rocks belong A2 subtype granites formed in an extensional environment. The adakitic dacites are characterized by high Sr contents(624 to 1,082 ppm), low Y contents(10.6 to 12.6 ppm), high Sr/Y and Sr/Yb ratios, and low Mg# values(14.77 to 36.46), indicating that they belong to "C" type adakites. The adakitic dacite with high Sr and low Yb were likely generated by partial melting of the lower crust under high pressure conditions at least 40 km depth. The I-type rhyolites with low Sr and high Yb, and the A-type rhyolites with very low Sr and high Yb, were formed in the middle and upper crust under low pressure conditions, respectively. In addition, the formation depths of the former were approximately 30 km, whereas those of the latter were less than 30 km. The geochemical characteristics reveal that the volcanic rocks of Yingcheng Formation were formed in an extensional environment which was related to the retreat of subducted Paleo-Pacific Plate. At the late Early Cretaceous Period, the upwelling of the asthenosphere mantle and the lithosphere delamination caused by the retreat of the subducted Paleo-Pacific Plate, had resulted in lithosheric extension in the eastern part of China. Subsequently, a large area of volcanic rocks had formed. The SB has also been confirmed to be a product of the tectonic stress field in that region.  相似文献   

羌塘盆地胜利河油页岩芳烃分布特征及意义          下载免费PDF全文

姜德民  季长军 《地质找矿论丛》2020,35(2):197-203

羌塘盆地沉积了多套富含有机质的海相黑色岩系。虽然针对黑色岩系的研究取得了系列成果,但关于胜利河油页岩的沉积环境、有机质来源、热演化程度和生物降解程度等系列问题仍需要进一步讨论。本文针对胜利河油页岩开展了芳烃色谱、质谱分析,讨论胜利河油页岩中芳烃化合物分布特征和意义。研究结果显示:1)胜利河油页岩样品中含有154种芳烃类化合物,其中含量最高的是菲系列化合物,其次是芴系列化合物,其他系列化合物含量较少;芳烃化合物分布具有典型前锋型特征。2)芳烃化合物组成以及相对丰度指示胜利河油页岩生油母质主要来源于低等海生生物,同时检测到一定含量源自于高等植物先质的1,2,5-TMNr、1,2,5,6-TeMNr、海稀松和联苯等化合物,表明高等植物对胜利河油页岩形成有一定贡献,但极其有限。3)高丰度的硫芴和9-甲基菲系列化合物显示胜利河油页岩形成于高还原条件的海相环境,同时O/(O+C)芴系列与S/(S+C)芴系列关系图、硫芴系列/氧芴系列与Pr/Ph关系图也证实了这一点。4)MPI_1、R_c、BF/BeP、4-MDBT/ΣMDBT、DBT/(DBT+MDBT)等成熟度参数综合显示胜利河油页岩处于低成熟—成熟阶段。  相似文献   

论鸟类飞行的起源     

季强  袁崇喜等 《地质论评》2003,49(1):1-3

笔者简要介绍了有关鸟类飞行起源的两种假说,即“飞行的树栖起源”假说和“飞行的奔跑起源”假说,并根据近几年中国辽西发现的化石材料,对两种假说的立论依据和机理进行了分析和评述,初步认为两种可能性均存在,但因奔跑而飞地的机制更为普遍合理,“上树”是一种可能的条件,但既非必要条件也非充分条件。  相似文献   

四维变分同化方法在台风初始化及其数值模拟中的应用--对9608号(Herb)台风的研究结果   总被引：4，自引：2，他引：2  

ZHANG Xiaoyan  WANG Bin  JI Zhongzhen  Qingnong XIAO  ZHANG Xin 《大气科学进展》2003,20(4):612-622

The MM5 and its four dimensional variational data assimilation (4D-Var) system are used in this paper. Based on the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data, the authors generate an optimal initial condition for a typhoon by using the bogus data assimilation (BDA) scheme. BDA is able to recover many of the structural features of typhoons including a warm-core vertex, the correct center position, and the strong circulation.As a result of BDA using a bogus surface low, dramatic improvement is achieved in the 72 h prediction of typhoon Herb. Through several cases, the initialization by BDA effectively generates the harmonious inner structure of the typhoon, but which is lacking in the original analysis field. Therefore the intensity forecast is improved greatly. Some improvements are made in the track forecast, but more work still needs to be done.  相似文献