栖霞组沉积地球化学特征及其环境意义

沉积环境的古氧相特征是沉积环境和古海洋特征恢复的重要内容。岩石地球化学特征是判断其形成环境氧化还原条件的重要手段之一。本文以来宾地区铁桥面为重点．通过对栖霞组灰岩的地球化学分析，结合沉积学、古生态学特征．认为栖霞组沉积于贫氧的沉{只背景．是在海水深度和海域的局限程度等沉积条件发生周期性变化的情况下形成的。古氧相地球化学指标V(V十Ni)、Cc/La、U／Th值都适用于该组以钙质沉积为主的沉积物。黄铁矿矿化程度(DOP值)变。化较大．眨映该区多变的古氧相特征。     

磷对金刚石增强型硬质合金复合齿性能的影响

在金刚石增强型硬质合金复合齿基体中添加不同量红磷，可降低复合齿烧结温度，实现低温活化烧结。研究表明：添加0．3％(ωB)P的复合齿基体性能最好，采用化学镀Ni-P合金添加P和球磨添加0．1％P的方式，复合齿超硬部分的磨耗比和复合齿的抗冲击功优于单纯通过球磨添加0．3％P的超硬复合齿。为了实现金刚石增强型硬质合金复合齿的低温活化烧结，磷元素最优的添加方式是化学镀结合球磨的添加方式。     

Impact of habitat heterogeneity on plant community pattern in Gurbantunggut Desert

1IntroductionStudy on the interrelationship between vegetation patterns and their habitat heterogeneity is important to recover and rehabilitate the desert vegetation, stabilize the desert ecosystem and prevent desert expansion. Domestic and foreign researchers have carried out many studies on this topic (Archer etal., 2002; Bolling etal., 2000; Chen etal., 2003; Dasti etal., 1994; Gu etal., 2002, Li etal., 2001; Li etal., 2001; Liang etal., 2003), which have used and refined statistic tech…     

河南省土壤湿度年变化规律

利用河南省土壤墒情预报模型中建立的河南省台站土壤墒情数据库资料，对不同类型土壤湿度进行分析，从而确定不同类型土壤湿度差异、地下水对土壤湿度的影响及河南省土壤湿度的年变化规律。     

民乐、山丹6.1级地震异常及台站实现短临预报的思考

在综合分析了民乐-山丹6.1级地震前张掖中心台范围内震兆异常特征的基础上,总结了本次地震前该台的短临预报过程及存在的问题,对今后台站如何搞好地震短临预报工作进行了探讨.     

REE and (э)Nd of clay fractions in sediments from the eastern Pacific Ocean: Evidence for clay sources

Clay fractions in the non-calcareous surface sediments from the eastern Pacific were analyzed for clay minerals, REE and 143Nd/144Nd. Montmorillonite/illite ratio (M/I ratio), total REE contents ((REE), LREE/HREE ratio and cerium anomaly (бCe) may effectively indicate the genesis of clay minerals. Clay fractions with M/I ratio >1, бCe (0.85, (REE (400 μg/g, LREE/HREE ratio (4, and REE patterns similar to those of pelagic sediments are terrigenous and autogenetic mixed clay fractions and contain more autogenetic montmorillonite. Clay fractions with M/I ratio <1, бCe=0.86 to 1.5, ΣREE=200 to 350 μg/g, LREE/HREE ratio (6 and REE distribution patterns similar to that of China loess are identified as terrigenous clay fraction. The 143Nd/144Nd ratios or (э)Nd values of clay fractions inherit the features of terrigenous sources of clay minerals. Clay fractions are divided into 4 types according to (э)Nd values. Terrigenous clay minerals of type I with the (э)Nd values of -8 to -6 originate mainly from North American fluvial deposits. Those of type II with the (э)Nd values of -9 to -7 are mainly from the East Asia and North American fluvial deposits. Those of type III with (э)Nd values of -6 to -3 could come from the central and eastern Pacific volcanic islands. Those of type IV with (э)Nd values of -13 to -12 may be from East Asia eolian. The terrigenous and autogenetic mixed clay fractions show patchy distributions, indicating that there are volcanic or hot-spot activities in the eastern Pacific plate, while the terrigenous clay fractions cover a large part of the study area, proving that the terrigenous clay minerals are dominant in the eastern Pacific.     

Establishment of apparent quantum yield and maximum ecosystem assimilation on Tibetan Plateau alpine meadow ecosystem

The alpine meadow is widely distributed on the Tibetan Plateau with an area of about 1.2×106kn2. Damxung County, located in the hinterland of the Tibetan Plateau, is the place covered with this typical vegetation. An open-path eddy covariance system was set up in Damxung rangeland station to measure the carbon flux of alpine meadow from July to October,2003. The continuous carbon flux data were used to analyze the relationship between net ecosystem carbon dioxide exchange (NEE) and photosynthetically active radiation (PAR), as well as the seasonal patterns of apparent quantum yield (α) and maximum ecosystem assimilation (Pmax).Results showed that the daytime NEE fitted fairly well with the PAR in a rectangular hyperbola function, with α declining in the order of peak growth period (0.0244 μmolCO2 · μmol-1pAR) ＞early growth period ＞ seed maturing period ＞ withering period (0.0098 μmolCO2 · μmol-1pAR).The Pmax did not change greatly during the first three periods, with an average of 0.433mgCO2· m-2· s-1, i.e. 9.829 μmolCO2· m-2· s-1. However, during the withering period, Pmax was only 0.35 mgCO2 · m-2 · s-1, i.e. 7.945 μmolCO2 · m-2 · s-1. Compared with other grassland ecosystems, the α of the Tibetan Plateau alpine meadow ecosystem was much lower.     

Experimental study on soil CO2 emission in the alpine grassland ecosystem on Tibetan Plateau

The Tibetan Plateau, the Roof of the World, is the highest plateau with a mean elevation of 4000 m. It is characterized by high levels of solar radiation, low air temperature and low air pressure compared to other regions around the world. The alpine grassland, a typical ecosystem in the Tibetan Plateau, is distributed across regions over the elevation of 4500 m. Few studies for carbon flux in alpine grassland on the Tibetan Plateau were conducted due to rigorous natural conditions. A study of soil respiration under alpine grassland ecosystem on the Tibetan Plateau from October 1999 to October 2001 was conducted at Pangkog County, Tibetan Plateau (31.23°N, 90.01°E, elevation 4800 m). The measurements were taken using a static closed chamber technique, usually every two weeks during the summer and at other times at monthly intervals. The obvious diurnal variation of CO2 emissions from soil with higher emission during daytime and lower emission during nighttime was discovered. Diurnal CO2 flux fluctuated from minimum at 05:00 to maximum at 14:00 in local time. Seasonal CO2 fluxes increased in summer and decreased in winter, representing a great variation of seasonal soil respiration. The mean soil CO2 fluxes in the alpine grassland ecosystem were 21.39 mgCO2 · m-2 · h-1, with an average annual amount of soil respiration of 187.46 gCO2 · m-2 · a-1. Net ecosystem productivity is also estimated, which indicated that the alpine grassland ecosystem is a carbon sink.     

Numerical Modeling of Basin-Range Tectonics Related to Continent-Continent Collision

Continent-continent collision is the most important driving mechanism for the occurrence of various geological processes in the continental lithosphere. How to recognize and determine continent-continent collision,especially its four-dimensional temporal-spatial evolution, is a subject that geological communities have long been concerned about and studied. Continent-continent collision is mainly manifested by strong underthrnsting (subduction) of the underlying block along an intracontinental subduction zone and continuous obduction (thrusting propagation) of the overlying block along the intracontinental subduction zone, the occurrence of a basin-range tectonic framework in a direction perpendicular to the subduction zone and the flexure and disruption of the Moho. On the basis of numerical modeling, the authors discuss in detail the couplings between various amounts and rates of displacement caused by basin subsidence, mountain uplift and Moho updoming and downflexure during obduction (thrusting propagation) and subduction and the migration pattern of basin centers. They are probably indications or criteria for judgment or determination of continent-continent collision.     

三峡库区巫山县城新址岩质库岸再造预测

巫山县城新址位于西坪和大宁河两岸.组成该库段的基岩主要为泥岩、粉砂岩、泥灰岩等,岩性较软弱,且地质构造变动强烈,褶皱、断裂发育,岩层破碎,崩塌、滑坡分布较多,库岸再造问题严重;同时,岸坡再造又严重影响着新县城的规划和库岸的防护.因此把稳态坡形类比法应用于巫山县城新址基岩岸坡的再造预测,定量预测库岸的最终再造宽度,以指导新城的规划与建设.