塔里木盆地北部隆起负反转构造成因机制探讨   总被引：19，自引：1，他引：19       下载免费PDF全文

何文渊  李江海  钱祥麟  郭召杰 《地质科学》2001,36(2):234-240

塔(里木盆地)北(部)隆起中生代以来经历了逆冲上隆,构造反转和再生前陆盆地斜坡带3个阶段,分别与库车前陆盆地构造运动强、弱、强的演化历史相对应。塔北隆起的大型负反转构造形成于白垩纪-中新世。白垩纪之前,塔北断隆作为库车前陆盆地和北部坳陷的相邻单元,发育两组背冲断裂以实现其缩短。在构造宁静期(白垩纪-新第三纪吉迪克期),岩石圈回跳,前缘隆起局部伸展,早期逆冲断块沿着原逆冲断层面下滑形成负反转构造。中新世以后,塔北地区成为库车再生前陆盆地的斜坡区,负反转构造得以保存且有进一步加剧之势。塔北隆起上伸展应力场的产生与深部岩石圈同步挠曲变形过程中波峰和波长的变化有关。  相似文献   

Observations of NO_2 and O_3 during Thunderstorm Activity Using Visible Spectroscopy     

D.B.Jadhav  A.L.Londhe  S.Bose 《大气科学进展》1996,(3)

Simultaneous observations for the total column densities of NO2,O3 and H2O were carried on using the portable Spectrometer (438-450 nm and 400-450 nm) and the visible Spectrometer (544.4-628 nm) during premonsoon thunderstorms and embedded hail storm activity at Pune (18°32'N & 73°51'E),India.These observations confirm the fact that there is an increase in O3 and NO2 column densities during thunderstorms.The increase in O3 was observed following onset of thunderstorm,while the increase in NO2 was observed only after the thunder flashes occur.This implies that the production mechanisms for O3 and NO2 in thunderstorm are different.The observed column density of NO,value (1 to 3×1017molecules cm-2) during thunderstorm activity is 10 to 30 times higher than the value (1×10th molecules cm-2) of a normal day total column density.The spectrometric observations and observations of thunder flashes by electric field meter showed that 6.4×1025molecules/flash of NO2 are produced.The increased to-oil column den  相似文献   

用负刚度及变刚度方法研究粘滑          下载免费PDF全文

何昌荣  张流 《地震地质》1996,18(3):199-211

通过负刚度实验，得到了３００ＭＰａ围压条件下花岗岩锯切面和石英岩剪切破裂面的剪应力－滑动曲线。突发滑动的持续时间从一般位移控制条件下的几毫秒延长到０．５ｓ左右。并在普通函数记录仪上对滑动过程曲线作了全过程的记录。又将压机刚度降为任意设定值，可得到应力降与刚度相关而滑动距离基本不变的结果。这一结果与速度依赖性摩擦本构律及滑动弱化本构律所估计的结果不同，它类似于滑动面几何约束控制的滑动依赖性本构关系  相似文献   

Lightning activity and precipitation structure of hailstorms   总被引：1，自引：0，他引：1  

FENG GuiLi    QIE XiuShu    YUAN Tie & NIU ShuZhen Laboratory of Lightning  Thunderstorm  Cold  Arid Regions Environmental  Engineering Research Institute  Chinese Academy of Sciences  Lanzhou  China  Shandong Research Institute of Meteorology  Jinan  China  Institute of Atmospheric Physics  Chinese Academy of Sciences  Beijing  China  The Meteorological Observatory of Henan Province  Zhengzhou  China 《中国科学D辑(英文版)》2007,50(4):629-639

By using the cloud-to-ground (CG) lightning location data from the lightning detection network of He- nan Province, surface Doppler radar data and standard orbit data of PR, TMI and LIS on TRMM satellite, the spatial and temporal characteristics of CG lightning flashes in 10 severe hailstorms are analyzed. The results show that the percentage of CG lightning in these hailstorms is high with an average value of 45.5%. There is a distinct increase in CG flash rate during the rapid development stage of hailstorms. The hailstone falling corresponds to an active positive flash period, and the increase of CG flash rate is generally accompanied with a decrease of –CG flash rate. The flash rate declines rapidly during the dissipating stage of hailstorms. The precipitation structure and lightning activity in two typical hail- storms are studied in detail. It is found that strong convective cells with reflectivity greater than 30dBZ mainly are situated in the front region of hailstorms, whereas the trailing stratiform region is in the rear part of the hailstorms. The maximum heights of echo top are higher than 14 km. Convective rain con- tributes much more rainfall to the total than stratiform rain, and the convective rain takes about 85% and 97% of the total in the two cases, respectively. Total lightning in the hailstorms is very active with the flash rate up to 183 fl/min and 55 fl/min, respectively. The results also indicate that most lightning flashes occurred in the echo region greater than 30 dBZ and its immediate periphery. The probability of lightning occurrence is 20 times higher in the convective region than in the stratiform region. The result suggests that the lightning information is helpful to the identification of convective rain region. The linear relationship between flash rate and ice water content is disclosed primarily.  相似文献   

Spatiotemporal characteristics of positive cloud-to-ground lightning discharges and bidirectional leader of the lightning   总被引：4，自引：0，他引：4  

Krehbiel Paul 《中国科学D辑(英文版)》2006,49(2):212-224

The negative CG lightning discharges neutralizing negative charges in cloud usually dominate for most of thunderstorms. However, a lot of positive CG light-ning discharges often occur in the disappearing stage of thunderstorms, in the stratiform region of mesoscale convective systems and some supercells producing hail and tornado. Because the positive CG lightning discharges produce larger current of the return stroke and neutralize more charges due to the continuing currents with longer las…  相似文献   

2007—2018年金衢盆地地闪气候特征大数据分析     

许洪泽  周梅  胡慧萍  王芳 《南京气象学院学报》2020,12(3):373-383

本文选取2007—2018年金华地区地闪资料，研究分析金衢盆地地闪大数据的气候特征，及地闪资料与地形、海拔高度的对应关系.结果显示：1）2007—2018年金华地区地闪年均次数为45 481次，年均地闪密度为4.3次·km^-2·a^-1，地闪密度变化范围为2.64~5.92次·km^-2·a^-1；2）2007—2018年金华地区逐年地闪空间分布差异大，各年的空间分布不均匀，地闪主要分布在西南角的仙霞岭及其至会稽山沿线，以及兰溪市、婺城区及金东区交界的金华山，而东南角海拔较高的大盘山和北面的龙门山的总地闪密度高值面积较小；3）将总地闪密度分段与地形、海拔高度对比显示，80次·km^-2以上总地闪密度与高海拔山区有较好的一致性，强地闪（电流强度100 kA以上）密度为5~7次·km^-2的25个点中有23个点分布在海拔208~989 m山区；4）下垫面电阻率较低的三江流域地区地闪密度为金衢盆地内最大的"洼地"，杭长铁路及附近的地闪密度仅接近平均值，这与其他相关研究结论不一致；5）2007—2018年中有41.7％年份的地闪次数和总地闪次数随海拔高度增加，其他年份的地闪强度均值和总地闪强度均值随海拔高度增长，且均通过了显著性检验.  相似文献   

Thermal transformations in laser-heated chloritized annite     

C.?VitiEmail author  G. Di?Vincenzo  M.?Mellini 《Physics and Chemistry of Minerals》2004,31(2):92-101

Chloritized annite from the Irizar granite has been used for laser-heating experiments, following the procedures used for ⁴⁰Ar–³⁹Ar dating (heating steps in the 600–1080 °C temperature range). Four runs, at different temperatures, have been characterized using transmission electron microscopy, electron diffraction, micro-Raman and micro-IR spectroscopies. The water loss was evaluated by thermogravimetry. The chlorite domains break down first forming (001) amorphous layers, that later coalesce to rounded, equant inclusions and finally recrystallize to olivine and spinels plus silica glass. These phases occur within negative crystals hosted in ordered dehydrated annite, produced by dehydration and annealing of the starting annite. Dehydrated annite, olivine and spinels display topotactic relationships, determined by the common orientation of closely packed oxygen layers.  相似文献   

准中地区构造特征分析   总被引：4，自引：0，他引：4  

宋传春  李丕龙  韩文功 《新疆地质》2005,23(4):339-342

准噶尔盆地中部现今呈南倾的大单斜构造背景，中1、3区块中生代曾发育一大型正向构造单元，分析认为属低幅背斜构造．中3、中1区块位于该背斜构造的南、北两翼，受背斜构造的影响较大，而中2、中4区块位于该背斜构造的东侧，受背斜构造的影响较小，中1、中3区块与中2、中4区块分属两个不同的构造单元．准中区块中生界侏罗、白垩系之间存在明显的角度不整合，应划分为两个不同的构造层．研究还发现，准中地区中、新生界具有明显的负反转构造特征．  相似文献   

蒸馏法富集纯化Os实验条件研究及其在负离子热电离质谱测量中的应用   总被引：1，自引：1，他引：0  

李欣尉  杨显德  李超  周利敏  赵鸿 《岩矿测试》2018,37(4):439-447

微蒸馏是富集纯化Os的一项重要化学前处理技术,提高Os回收率对提高Os的负离子热电离质谱(NTIMS)测量精度尤为重要。在微蒸馏过程中,蒸馏温度、吸收液体积、蒸馏时间等对Os回收率具有重要影响,但目前微蒸馏的实验条件不够明确,导致Os回收率不稳定,影响NTIMS测量精度,易增加所得Re-Os年龄误差。本文以自制的含Os溶液为对象,以ICP-MS为测量手段,对微蒸馏过程中多种实验条件对Os回收率的影响进行深入研究,以期获得最佳微蒸馏实验条件,满足后续NTIMS对Os信号强度的测量要求。结果表明:在溶液蒸干温度为120℃并保持15 min,微蒸馏温度为80℃,氢溴酸吸收液体积为15μL,微蒸馏时间为2 h的条件下,获得Os回收率为80%~90%,能够满足多种地质样品尤其是中酸性岩浆岩、热液硫化物等pg级地质样品的NTIMS测量要求,在保证Os信号强度的情况下提高了分析效率。  相似文献   

地球γ射线闪(TGFs)及其物理机制研究进展     

郄秀书  王俊芳 《地球科学进展》2010,25(9):893-906

根据卫星、地面、飞机和气球的探测结果,TGFs和与雷暴、闪电过程有关的高能辐射现象可以大致分为2类:持续时间为毫秒量级的短时间高能辐射,一般认为多数可能与闪电有关;持续时间为几秒甚至更长的长时间高能辐射,一般认为可能与雷暴有关.对已有的TGFs和与雷暴、闪电有关的高能辐射现象的观测事实、理论探索和数值模拟方面的进展进行简要的回顾,并提出目前尚未解决的问题.  相似文献