华北和北京的酷暑天气 Ⅰ. 历史概况及个例分析   总被引：5，自引：0，他引：5  

谢庄  崔继良  刘海涛  赵思雄  孙建华  陈红  曾庆存 《气候与环境研究》1999,4(4):323-333

如果将日最高气温超过３５ ℃的天气定义为酷暑天气, 则近６０ 年的资料统计表明, 北京出现酷暑天气的年频率高达８１ ％ , 并不少见, 尤以４０ 年代和９０ 年代明显偏多。１９４２ 年６ 月和１９９９ 年７ 月都出现≥４２ ℃的酷暑天气。分析表明, 北京和华北酷暑天气的出现与大环流形势密切相关, 大陆副热带高压维持于华北上空是其主要因素, 空气下沉增温是酷暑的主要机制, 而大城市的热岛效应则可使城区百叶箱气温再增高２ ℃左右。  相似文献   

论碰撞造山带的分类   总被引：26，自引：2，他引：24       下载免费PDF全文

李继亮  孙枢 《地质科学》1999,34(2):129-138

近年来碰撞造山带研究取得了很大进展,为碰撞造山带分类奠定了基础。1992年,Sengor提出了一个三分法的分类。但是,这个分类不能涵盖所有的碰撞造山带,同时其内部还有重叠。本文主要依据参与碰撞的单元,即板块、微板块、前缘弧、残留弧和增生弧,提出一个新的分类方案,即将碰撞造山带分为陆-陆,陆-前缘弧,陆-残留弧,陆-增生弧,弧-弧,陆-弧-陆6种类型。从世界各地的碰撞造山带来看,陆-陆碰撞型是很少见的,也就是说,威尔逊旋回不论在现代还是古代地质历史上都是罕有发生的,而大多数碰撞造山带都是非威尔逊旋回型的。  相似文献   

碰撞造山带的碰撞事件时限的确定   总被引：38，自引：15，他引：23  

李继亮  孙枢 《岩石学报》1999,15(2):315-320

在造山带研究中,引发变形作用和山脉隆升的造山作用的时代是一个重要问题。现在,Ｓｔｔｉｌｅ的造山幕术语已经被人们摈弃了,但是,迄今还有不少地质学家沿用诸如印支运动、燕山造山作用和喜马拉雅造山幕之类的术语。碰撞造山作用是一个在碰撞事件之后的均变过程。碰撞事件没有遗留下任何可以观察到的地质记录,因此,我们必须运用碰撞事件发生前和发生后产生的地质记录来限定碰撞事件的时代范围。在本文中,运用大洋岩石圈消减过程中的沉积作用、岩浆作用和变质作用来限定碰撞下限,运用碰撞后同造山时期的岩浆作用和变质作用以及磨拉石沉积作用来作为碰撞事件的时代上限。所有这些时代标志都是依据地质观察提出的,更多的精确的碰撞事件时代标志还有待于将来进一步的研究  相似文献   

Tectonic facies and the archipelago-accretion process of the West Kunlun,China     

Xiao Wenjiao  Hou Quanlin  Li Jiliang  Brian F. Windley  Hao Jie  Fang Aiming  Zhou Hui  Wang Zhihong  Chen Hanlin  Zhang Guocheng  Yuan Chao 《中国科学D辑(英文版)》2000,43(1):134

A tectonic facies investigation carried out in the West Kunlun, China allows us to have worked out a tectonic model of orogen. The tectonic facies, from the north to the south, are composed of the following: 1. Southern Tarim tectonic realm; 2. North Kudi magmatic arc; 3. Kudi mélange; 4. Kudi micro-continent; 5. main shear zone; 6. Xianan Bridge calc alkaline complex; 7. Mazar-Kangxiwar mélange-accretion complex; and 8. Tianshuihai foreland fold-thrust belt. The tectonic facies 1»5 recorded the history of the northward subduction of the Prototethys and southward accretion of Eurasia in the Late Proterozoic-Early Paleozoic time, while the tectonic facies 6»8 recorded the history of the northward subduction of the Paleotethys and southward accretion of Eurasia in the Late Paleozoic-Early Mesozoic time, that of the tectonic evolution of the passive margin of the Qiangtang block, and that of the docking, and the final amalgamation of the Qiangtang block to the Eurasian continent. The tectonic facies investigation has indicated that a complicated archipelago-accretion orogenesis took place in the West Kunlun orogen, which was the important character of southward growth of the Eurasian continent.  相似文献   

南海北部陆缘地壳结构特征及其构造过程   总被引：5，自引：0，他引：5  

阎全人  王宗起 《地质论评》2000,46(4):417-423

根据“北部湾大陆缘地壳结构ＰＳ转换波测深”等地球物理测量结果,本文研究了南海北部陆缘的地壳结构特征,讨论了其白垩纪以来的构造过程。地球物理测量表明,由陆向海,南海北部陆缘地壳由陆壳、过渡壳变为洋壳,厚度由３４ｋｍ减薄至８ｋｍ左右。垂向上地壳为３层结构模式。陆壳、过渡壳和洋壳的下地壳Ｐ波速度普遍较高。地壳伸展系数的计算表明南海北部陆缘伸展主要发育于陆坡地区。结合区域地质研究,本文认为：南海北部陆缘及  相似文献   

西昆仑甜水海地区前陆褶皱冲断带的构造样式及其演化   总被引：1，自引：0，他引：1  

赵冬冬  李继亮 《地质学报》2000,74(2):134-141

运用碰撞造山带大地构造朴理论,研究了西昆仑甜水海地区三叠系的沉积特征及其构造环境,晚三叠世末羌塘陆块与塔里木板块南缘的晚古生代一早中生代山弧碰撞造成的前陆褶皱冲断带的构造样式及其演化。通过对地层构造岩石组合、沉积环境及其变形强度特征的分析,得出该区三叠纪的沉积是一套典型的深水－半深水的复理石建造,形成于被动大陆边缘的沉积环境;其变形具有典型的前陆褶皱冲断带特征,并将褶皱冲断带按变形特征分５个带。提  相似文献   

Research on catastrophic rock avalanche at Guanling, Guizhou, China   总被引：4，自引：1，他引：3  

Yueping Yin  Ping Sun  Jiliang Zhu  Shengyuan Yang 《Landslides》2011,8(4):517-525

On June 28, 2010, a catastrophic rock avalanche occurred after an extreme rainstorm at Guanling with N 25°59′10′′ in latitude and E 105°16′50′′ in longitude, Guizhou, China. This rock avalanche has a long run-out distance of 1.5 km, with 1.75 million cubic meters of debris instantly burying two villages and resulting in 99 deaths. It originated in the coal measure strata, with the upper part of limestone and dolomite, the middle part of the sandstone with gentle inclination, and the lower part of shale and mudstone, together locally with coals. This kind of unique structure, with hard resistant caprock overlying softer ductile rocks, coupled with the central outflow region at the contact zone, has catastrophic potential for rock avalanches and creates challenges for engineering geological/hydrogeological analysis. The topography showed that the hillside slopes were steeper at the upper portion but gentler in the lower portion, looked like the shape of a “boot.” The upper steep landform easily led to slope instability due to its high static shear stresses, and the wide middle and lower parts provided kinematic conditions for long run-out. Transformation of the larger potential energy into kinetic energy contributed to the formation of a rapid long run-out rock avalanche. The rainfall from June 27 to 28 was the apparent trigger of this catastrophic avalanche. The measured rainfall of more than 310 mm within 24 h exceeded the local historical records that were recorded over the last 60 years. The pore pressure on discontinuities of sandstone had an effect on the slope stability. The valley runoff supplied a saturated base for the long run-out debris, inducing an additional increase of the terminus distance and the increased velocity of the avalanche movement.  相似文献   

Status Quo,Analysis and Suggestions for Public Awareness on Wetland Conservation in China     

ZHANG Xiaoyun  XU Jiliang  YUAN Jun 《湿地科学》2011,9(2):101-106

To understand the status of public awareness on wetland conservation in China,1237 people from 8 provinces or municipality were interviewed by questionnaire.After analysis of the results,88.5%of the interviewees know the word ’wetland’.TV and radio is the main tool for them to get information.More than two thirds of the respondents mainly learn the information on wetland conservation through TV and radio.There are still big gaps among different people in understanding wetland.Only 13.3%of the respondents give a completely right answer on question ’which areas are wetlands’.Most of the respondents cited lakes,marshes and rivers as wetlands,but more than half of them do not regard beaches,reservoirs,paddy fields and fish ponds as wetlands.Most of the people cited wetlands can provide such functions as water conservation,climate regulation,protecting wildlife,removing pollution, but know little about other functions such as flood control,provisioning of aquatic products,and soil retention, and much less about the cultural functions such as recreation,and inherited folk culture.Except for wastewater discharge, nearly half of the general public knows little about other threats of the wetland,while most of the people do not believe that artificial aquaculture will cause threats to the wetland areas.Public awareness on wetland conservation in China needs to be improved.Most of the respondents cited that TV,radio and internet are the most effective ways to publicize information on wetland conservation.More than two thirds of the respondents mainly learn the information on wetland conservation through TV and radio,while 38.0%of the respondents mainly through internet. Specifically,for farmers/fishermen,posters/picture albums can benefit them more than the internet;the undergraduates also expect to learn wetland mainly through posters/picture albums;while for the primary and middle school students, the school education is another valuable source of publicity in addition to TV and radio.Strengthen cooperation with TV stations and broadcasting stations are the best way to raise public awareness of wetland conservation. The authors suggest to strength cooperation with media on wetland conservation,conduct wetland conservation education in middle and primary schools and communities;organize experts and professionals to write books and teaching materials needed for popularizing science,basic education and staff training;develop an internet-based CEPA network system on wetland conservation;conduct public awareness activities in communities,focusing on females in rural areas;build public awareness and education system,improve the public’s awareness on wetland conservation,create good social environment for conserving wetlands.  相似文献   

全新世冲绳海槽北部表层海水温度和初级生产力对黑潮变迁的响应   总被引：2，自引：1，他引：1  

黄小慧  王汝建  翦知湣  王吉良 《地球科学进展》2009,24(6):652-661

在冲绳海槽北部B-3GC孔高分辨率地层年代框架的基础上,利用多种分子生物标志物和生源组分指标,重建了该地区全新世以来表层海水温度和生产力的变化历史.研究发现,U37K-表层海水温度和生产力的变化指示了全新世黑潮及对马暖流分支的变迁.10.6～7.3 ka BP期间,冲绳海槽北部主要受东海陆架冷水团影响,陆源物质输入量增加,初级生产力比较高,表层海水温度较低.7.3～4.6 ka BP期间,黑潮暖流对该区的影响迅速增强,表层海水快速增温,陆源物质输入减少,但是各种生产力指标显示出上升趋势,与该区上升流的出现和迅速发育有关.4.6～2.7 ka BP期间,即全新世普林虫低值事件(PME)期间,表层海水温度明显降低了0.8～1.4℃,陆源物质输入增加,初级生产力和各种生源组分的含量也达到较高水平,说明此时黑潮强度减弱,或者黑潮主流轴向太平洋方向发生偏移,该区再次受到陆架冲淡水的影响.2.7 ka BP以来,虽然黑潮暖流再次影响到该海区,但初级生产力和生源物质输出量继续大幅增高,可能与该地区上升流的持续发育有关.  相似文献   

小麦腥黑穗病气象条件分析及防治措施   总被引：1，自引：0，他引：1  

程鹏  赵吉亮  刘圆渊 《山西气象》2008,(2)

本文主要通过对晋城市2005年、2006年及历年平均气象要素与农业气象观测资料对比,分析气象条件对小麦腥黑穗病农业病害的影响程度,从而提出治理对策。  相似文献