GEOLOGICAL MARKS OF A POSSIBLE EXTRATERRESTRIAL IMPACT EVENT ON THE BOUNDARY BETWEEN SINIAN/CAMBRIAN IN TIANMENSHAN IN WESTERN HUNAN     

HUANG Huaiyong  WANG Daojing  CHEN Guanghao  YIN Hanhui 《大地构造与成矿学(英文版)》2004,28(1):43-52

Geologic marks related to extraterrestrial impact events, such as impact split gravels, impact brecciate layers, impact dikes, microirghizites, microtektites, especially meteoritic residues, were discovered on the boundary between Sinian/Cambrian at Tianmenshan of Western Hunan, which may possibly demonstrate that an extraterrestrial impact event has ever occurred there on the S/C boundary.  相似文献   

21世纪地震灾害的一些新特点   总被引：2，自引：0，他引：2  

陈颙  彭文涛  徐文立 《地球科学进展》2004,19(3):359-363

灾害定量化是地球科学、工程科学和社会经济科学的交叉领域。人口城市化是全球的发展趋势，特别在第三世界人口城市化的趋势越来越显著。和农村发生突发灾害农民可以很容易地进行自救和互救不同，城市居民对供水、供电、煤气、暖气、通讯和交通等基础设施有很大的依赖性，现代城市在抗御自然灾害方面，比过去任何时候都显得更加脆弱。通过统计，我们发现在灾害损失 L和表征社会财富的GDP之间存在着经验关系：L＝ a＋ b×GDP＋ c×GDP 2其中 a，b，c为正的常数。关系式表明，自然灾害造成的灾害增长要比GDP的增长要快。  相似文献   

北秦岭德河黑云二长花岗片麻岩体的成岩时代--TIMS和SHRIMP锆石U-Pb同位素年代学   总被引：17，自引：6，他引：17  

陈志宏陆松年  李怀坤宋彪李惠民  相振群 《地质通报》2004,23(2):136-141

德河黑云母二长花岗片麻岩体侵位于秦岭造山带北秦岭前寒武纪变质岩系内,遭受了强烈的变形作用改造,具有典型S型花岗岩的矿物组成特征。TIMS和SHRIMP法锆石U-Pb同位素年龄测定结果分别为(964.4±5.2)Ma和(943±18)Ma,两者在误差范围内是一致的。鉴于SHRIMP法锆石微区测年具有更好的代表性,建议以(943±18)Ma代表德河黑云母二长花岗片麻岩的侵位时代。  相似文献   

地球化学场精细结构解析方案与应用   总被引：2，自引：2，他引：2  

陈明何凯  王全明Jacques Yvon 《地质通报》2004,23(2):147-153

为满足勘查地球化学对化探数据处理越来越精细的要求，把人工神经网络和统计分析结合起来形成地球化学场精细结构解析方案。该方案包括对地球化学样品的分类和对各类样品性质的详细研究，目的在于提供便捷的数学和计算机软件工具，以提取化探数据中的深层信息。可以用于：①研究各组样品中元素含量水平和组合特征以解释可能的矿种；②研究元素组合特征与指示元素的关联和区别以揭示可能的成矿作用过程；③研究异常样品的空间组合属性以揭示地球化学场的精细结构；④研究异常样品之间的差异性以缩小找矿靶区；⑤综合分析以确定剥蚀深度和找矿前景。该方案也适用于环境地球化学及矿产资源预测研究。  相似文献   

基于小波变换的遥感影像压缩编码     

谢岩  陈圣波 《吉林大学学报(地球科学版)》2004,(Z1)

基于小波变换的图像压缩方法能在高压缩比的前提下保持好的重建图像质量,它的多分辨率特性与人类视觉系统非常相近,小波变换的编码技术被广泛地应用于遥感影像的压缩中。介绍了小波理论的相关知识,着重对嵌入零树小波、等级树分割、小波数据的形态学表示算法等方法进行了详细的论述,并对图像编码技术的发展方向进行了展望。  相似文献   

柴达木盆地新生代不同层次构造特征   总被引：8，自引：1，他引：8       下载免费PDF全文

郑孟林李明杰  曹春潮张军勇段书府  陈元中沈亚 管俊亚 《地质学报》2004,78(1):26-35

应用柴达木盆地地震、非地震资料进行综合解释研究发现,新生代盆地深、浅层构造存在较大差异,盆地沉积在不同时期受到不同构造格局的控制。古近系受近东西向构造控制,新近系受北西向构造控制,显示了柴达木盆地新生代为不同时期受不同方向构造控制的大型叠合盆地。盆地地层深、浅层构造变形特征不同,深层表现为陡倾的逆冲断裂构造,以断块构造为主要特征;中浅层表现为滑脱褶皱与滑脱断裂构造;地表在背斜核部发育斜列展布的正断层构造。盆地经历了多旋回沉积和多方式的后期改造,不同的构造组合形成了不同的储油气构造模式,认识这一点对于盆地深层的油气勘探,特别是寻找隐蔽油气藏具有重要意义。  相似文献   

江西大吉山五里亭花岗岩单颗粒锆石U-Pb同位素年龄及其地质意义探讨   总被引：29，自引：6，他引：29       下载免费PDF全文

张文兰  华仁民  王汝成  李惠民  陈培荣 《地质学报》2004,78(3):352-358

江西大吉山五里亭花岗岩一直被认为是与大吉山钨矿有关的早阶段花岗岩体 ,时代为燕山早期。但实际上大吉山地区各阶段花岗岩体之间的时空关系并不清楚 ,前人的某些年龄数据也存在相互矛盾之处。本文利用单颗粒锆石 U - Pb化学法 ,对五里亭花岗岩进行了年代学研究 ,获得 2 38.4± 1Ma的岩体侵位年龄 ,这个年龄属印支期。本文还结合某些岩石学、地球化学特征研究及与相邻岩体的对比 ,认为五里亭花岗岩确应归属于印支期 ,因此 ,五里亭岩体与大吉山钨矿没有成因上的直接联系。五里亭花岗岩侵位年龄的厘定和该地区更多印支期花岗岩的不断发现 ,表明印支运动在华南的影响超出了人们以往的认识。在此基础上 ,本文还对华南印支运动和印支期花岗岩的问题进行了简单的讨论  相似文献   

Simulation of oasis breeze circulation in the arid region of the Northwestern China   总被引：2，自引：0，他引：2  

U Shihua  AN Xingqin  CHEN Yüchun 《中国科学D辑(英文版)》2004,47(Z1)

In this paper, the process of oasis-desert circulation (ODC) is simulated by MM5V3.5 model through designing an ideal oasis-desert scheme and assuming that initial atmosphere is at rest (V = 0). The findings showed that the key of forming special oasis boundary structure is the difference of energy and water between oasis and desert. The evaporation of oasis surface consumes heat energy, and the low temperature of oasis causes an oasis breeze circulation (OBC), which drives an ODC with a downdraft over the oasis and an updraft over the desert. Later, the cold, dry and stable boundary over oasis is gradually formed, on the contrary,the atmospheric boundary over desert on the edge of oasis is hot, humid and unstable and its height is about 600 hPa. The updraft over the desert forms a wet ring that acts as a vertical wall weakening the low-level moisture exchange between the oasis and desert. The downdraft of OBC increases the atmospheric stability that reduces the oasis evaporation. The low-level outflow from the oasis (into the desert) prevents the dry, hot air flowing from the desert into the oasis.Thus an oasis self-preservation mechanism may be formed due to OBC. The horizontal area influenced by oasis is twice as oasis area and the vertical range is four times as oasis. The ODC is strong in the daytime and reaches the strongest at 17:00, and the influenced area is the largest at 20:00.  相似文献   

Study of charge structure and radiation characteristic of intracloud discharge in thunderstorms of Qinghai-Tibet Plateau     

ZHAGN Yijun  DONG Wansheng  ZHAO Yang  ZHANG Guangshu  Zhang Hongfa  CHEN Chengpin  ZHANG Tong 《中国科学D辑(英文版)》2004,47(Z1)

The comprehensive observations on lightning discharges were conducted in Naqu area of Qinghai-Tibet Plateau in summer of 2002. The electric structures of thunderstorms and the characteristics of lightning discharges at initial stage were analyzed by using the observation data. The results show that most of intracloud (IC) lightning flashes were polarities inverted in thunderstorms with tripole electric charge structure and occurred between negative charge region located in the middle of the thunderstorm and positive charge region located at the bottom of the thunderstorm. The radiation characteristics of discharge processes in cloud with longer lasting time involved in Cloud-to-Ground (CG) lightning flashes were similar to that of IC discharges.A lot of radiation pulses were produced in these discharge processes. Because the IC discharges took place at the bottom of thundercloud and were near the ground, they may produce more serious damage to equipment on the ground therefore should not be neglected in lightning protection.  相似文献   

Sedimentary environment and development controls of the hydrocarbon source beds:Middle and Upper Proterozoic in northern North China     

BAO Zhidong  CHEN Jianfa  ZHANG Shuichang  Zhao Hongwen  Zhang qinghai  LI Yan 《中国科学D辑(英文版)》2004,47(Z2)

Problem on development control of marine source bed hold in Chinese petroleum industry progression. The Hongshuizhuang Formation,Tieling Formation and Xiamaling Formation in the Middle and Upper Proterozoic are important hydrocarbon source beds in northern North China, and investigation of their sedimentary environments and the controls has great significance for petroleum exploration in North China. Based on sedimentology (sequence stratigraphy), palaeoecology, sedimentary geochemistry, and sedimentary palaeogeography, their development pattern is discussed. All these studies indicate that the development controls of the hydrocarbon source beds include a favorite palaeogeographic location, exceeding propagation of biomes in low and middle latitudes, anoxic environments, enrichment of phosphorus element and the adsorption of clay minerals during the preservation of organic matter in the marine carbonates.  相似文献