Cephalopods of the ＂Falang Formation＂ （Triassic） from Guanling and Zhenfeng Counties, Guizhou Province, China   总被引：3，自引：0，他引：3  

HAOWeicheng SUNYuanlin JIANGDayong YANGShouren WANGXinping 《《地质学报》英文版》2003,77(4):430-439

The “Falang Formation“ of western Guizhou was previously called the “Halobia Bed“ and considered to be Ladinian in age. It was subdivided upward into the Zhuganpo, Laishike and Longchang members based on ammonites and the Trachyceras multitubertulatum Zone of the Longchang Member was put in the Lower Camian. Here in the present paper, 4 genera and 9 species of ammonites and I nautiloid genus and species collected from the upper part of the “Falang Formation“ (i.e. the Wayao Formation used in this paper, equivalent to the Laishike Member from Guanling and Zhenfeng counties are described. The geological and geographical distribution of these cephalopods, as well as the co-existing conodonts, put the Wayao Formation to the late early Camian.  相似文献   

田间测定沙地水分运动参数初步研究   总被引：2，自引：2，他引：2  

刘元波  高前兆 《中国沙漠》1996,16(1):19-23

采用田间垂直入渗试验法测定了沙地水分运动参数，并得到经验拟合曲线。沙土水分特征曲线表明，当体积含水率θ＞５％时，吸力Ｓ随θ增加而缓慢下降，而θ＜５％时，Ｓ随θ的减小而趋于急剧上升。非饱和导水率Ｋ～θ关系表明，当θ＞１５％时，导水率Ｋ值急剧上升，而θ＜１５％时，导水率Ｋ变化缓慢．  相似文献   

干旱沙区陆面蒸散量与土壤水分关系的数值计算   总被引：10，自引：4，他引：10  

王新平  张利平 《中国沙漠》1996,16(4):388-391

利用电子称重式蒸渗仪（Ｌｙｓｉｍｅｔｅｒ）测定田间蒸散量（ＥＴ），并用中子水分仪同步测定沙面下１０～１５０ｃｍ土壤水分含量，求得含水率Ｗ（％）。通过研究沙区不同植被区域内，土壤剖面不同深度土体含水率Ｗ与ＥＴ的关系，估算出了三种处理（油蒿栽植区、柠条栽植区、裸露沙区）的不同深度土壤水分对蒸散过程的贡献值，模拟出了土壤含水量对区域陆面蒸散量的相关关系式  相似文献   

滇西墨江金厂金矿床时空四维结构模型   总被引：22，自引：1，他引：21  

蔡新平  徐若旺  张宝林  秦大军  梁光河  王杰 《矿床地质》1999,18(1):55-62

对墨江金厂金矿关键性地质问题研究结果表明,矿区金厂韧性剪切带（ＳＺｊｃ）、ＮＷＷ向褶皱构造和金矿超镁铁岩体侵位构造是不同成矿期的控矿构造,金矿床有三种成因类型,分别对应三期三种不同类型的成矿作用。  相似文献   

论奇台县开发利用地下水资源存在的问题及建议   总被引：8，自引：1，他引：8  

李丰德 《地下水》2003,25(1):31-33

本文详细介绍了奇台县地下水区域水文地质条件、地下水资源及地下水开发利用概况，通过大量事实，深刻阐述了奇台县在开发利用地下水资源过程中存在的主要问题，指出由这些问题引起地下水位大范围下降、水量超采，使自然生态遭到破坏，而且严重制约着该县农业可持续发展的严重后果。针对这些问题，提出了对策及建议。  相似文献   

用卡尔曼滤波制作分县温度指导预报的研究          下载免费PDF全文

温兴平  杨晓峰  李月莲 《山西气象》2003,(1):16-17

采用卡尔曼滤波方法建立预报模型，制作出全区分县温度指导预报。通过试运行，并对吕梁地区2002年7月份全区气温预报结果进行检验，系统基本达到预期的效果。  相似文献   

中纬度地区混合云中稳定同位素分馏的数学模拟—以乌鲁木齐降水为例(英)   总被引：10，自引：0，他引：10  

章新平  姚檀栋  田立德  刘晶淼  MasayoshiNAKAWO 《大气科学进展》2003,(2)

介绍的数学模型考虑了混合云中液、固态共存时以及冰面过饱和环境下稳定同位素的动力分馏效应。利用该数学模型,模拟了不同冷却条件下稳定同位素的温度效应。在相同的湿度条件下,湿绝热冷却过程中δ18O随温度的变化率小于等压冷却过程。冰面过饱和比Si的增大意味着动力分馏效应的增大。与平衡态相比,它的作用使得稳定同位素的综合分馏系数减小,从而使得降水中δ18O随温度的变化趋缓。模拟显示,湿绝热冷却过程中大气水线(MWL:=bδ18o+d)的斜率b和常数d均大于等压冷却过程。全球大气水线位于湿绝热冷却过程和等压冷却过程条件下分别模拟的两条大气水线之间。b和d的大小与Si呈正比。Si愈大,动力分馏效应愈强,b和d也愈大。反之亦然。然而,b和d的大小对云中含水量的变化具有低的敏感性。利用动力分馏模式模拟了乌鲁木齐降水中稳定同位素的变化。模拟的稳定同位素比率-温度以及δD-δ18O曲线分别与乌鲁木齐实测的稳定同位素比率-温度同归线以及大气水线有非常好的一致性。  相似文献   

Humidity Effect and Its Influence on the Seasonal Distribution of Precipitation δ18O in Monsoon Regions     

ZHANG Xinping  Liu Jingmiao  He Yuanqing  TIAN Lide  YAO Tandong 《大气科学进展》2005,22(2)

The humidity effect, namely the markedly positive correlation between the stable isotopic ratio in precipitation and the dew-point deficit △Td in the atmosphere, is put forward firstly and the relationships between the δ18O in precipitation and △Td are analyzed for the Urumqi and Kunming stations, which have completely different climatic characteristics. Although the seasonal variations in δ18O and △Td exhibit differences between the two stations, their humidity effect is notable. The correlation coefficient and its confidence level of the humidity effect are higher than those of the amount effect at Kunming, showing the marked influence of the humidity conditions in the atmosphere on stable isotopes in precipitation.Using a kinetic model for stable isotopic fractionation, and according to the seasonal distribution of meanmonthly temperature at 500 hPa at Kunming, the variations of the δ18O in condensate in cloud aresimulated. A very good agreement between the seasonal variations of the simulated mean δ18O and themean monthly temperature at 500 hPa is obtained, showing that the oxygen stable isotope in condensateof cloud experiences a temperature effect. Such a result is markedly different from the amount effect atthe ground. Based on the simulations of seasonal variations of δ18O in falling raindrops, it can be foundthat, in the dry season from November to April, the increasing trend with falling distance of δ18O in fallingraindrops corresponds remarkably to the great ATd, showing a strong evaporation enrichment function infalling raindrops; however, in the wet season from May to October, the δ18O in falling raindrops displaysan unapparent increase corresponding to the small ATd, except in May. By comparing the simulated meanδ18O at the ground with the actual monthly δ18O in precipitation, we see distinctly that the two monthlyδ18O variations agree very well. On average, the δ18O values are relatively lower because of the highlymoist air, heavy rainfall, small △Td and weak evaporation enrichment function of stable isotopes in thefalling raindrops, under the influence of vapor from the oceans; but they are relatively higher because of the dry air, light rainfall, great △Td and strong evaporation enrichment function in falling raindrops, under the control of the continental air mass. Therefore, the δ18O in precipitation at Kunming can be used to indicate the humidity situation in the atmosphere to a certain degree, and thus indicate the intensity of the precipitation and the strength of the monsoon indirectly. The humidity effect changes not only the magnitude of the stable isotopic ratio in precipitation but also its seasonal distribution due to its influence on the strength of the evaporation enrichment of stable isotopes in falling raindrops and the direction of the net mass transfer of stable isotopes between the atmosphere and the raindrops. Consequently, it is inferred that the humidity effect is probably one of the foremost causes generating the amount effect.  相似文献   

水体蒸发过程中稳定同位素的分形机制   总被引：1，自引：0，他引：1  

章新平  田立德  刘晶淼 《地理学报(英文版)》2005,15(3):375-384

The variations of stable isotopes in atm ospheric vapor and precipitation are caused by stableisotopic fractionation during phase changes in w ater cycle. The isotopic fractionation m ainlyhappens in the m ass transportation of stable isotopes from free w…  相似文献   

Comparisons on seasonal and annual variations of δ18O in precipitation     

ZHANG Xinping  YAO Tandong 《地理学报》2004,14(2):193-203

The spatial and temporal variations of stable oxygen isotope in precipitation on different time scales are analyzed according to the data from the IAEA/WMO stations with long survey series in the Northern Hemisphere. Temperature effect is mainly distributed in mid-high latitudes on seasonal scale except for Bamako and Addisababa stations. The δ18O/temperature slope displays the positive correlation against altitude for most of the statistical stations. Amount effect appears primarily in the region south of 30oN and coastal areas. The δ18O/precipitation slope is indirectly proportional to precipitation amount. For some of the sampling stations at mid-high latitudes where their seasonal distribution of precipitation is contrary to that of temperature, coupled with temperature effect, the amount effect appears synchronistically. Either the temperature effect or the amount effect on seasonal scale, there are positive correlations to a certain extent between the annual weighted mean δ18O and the annual mean temperature for almost all the stations. The correlation between composite δ18O and temperature on spatial scale is much more marked, compared with that of individual station. There is a good agreement between 10-year moving average temperature curves I and II, with the values of the former all markedly smaller than corresponding ones of the latter, calculated by the monthly mean series group I and the annual mean series group II, respectively. However, two calculated dδ18O/dT curves display the distinct difference: the variation amplitude of slope series II is larger than that of slope series I. Both curves had similar ascending trend from the 1960s to the 1970s, and then, their variations display the anti-phase. Moreover, the analyses show that there is negative correlation between slope series II and temperature series II. However, the status is different for slope series I and temperature series I. Both series have contrary trend from the 1960s to the 1970s, whereas the same trend since the 1980s.  相似文献