新构造运动与水资源环境     

常丕兴  马致远 《地球科学与环境学报》1998,20(2):46

讨论了新构造运动、新构造与水资源的关系。新构造是水系发育的基础,水系是新构造的反映;新构造运动、新构造对地下水的形成、分布、运移和富集以及水文地球化学性质及其变化都具有重要的控制作用。  相似文献   

五台山绿岩带金矿的Pb同位素地质演化     

田永清  余克忍  常向阳 《地球学报》1997,18(Z1):191-193

五台山绿岩带中各种类型金矿化是地壳演化不同阶段的产物，在成矿作用和矿质来源诸方面均存在着明显的区别。而这些，完全可以通过矿物和岩石普通Pb同位素的组成、构造-化学模式和同位素示踪等分析而获得可靠的依据。  相似文献   

石英击碎与粉末加热40Ar-39Ar定年及其含义讨论     

邱华宁  朱炳泉  常向阳  孙大中 《地球学报》1997,18(Z1):269-271

采用真空击碎技术提取东川汤丹铜矿床石英流体包裹体，进行40Ar-39Ar法年龄测定，获得了逐渐下降的阶梯形年龄谱，表明流体包裹体含有过剩氩；数据点在40Ar/36Ar-39Ar/36Ar图解上构成等时线，年龄为712±33Ma，这一年龄值代表了矿床的形成年龄[1]。随后对其粉末进行40Ar/39Ar阶段加热（100-800℃）分析，形成相对比较平坦的年龄谱，坪年龄为317±6Ma(39Ar占45%，含真空击碎分析在内)，全部加热分析数据点构成的等时线年龄为321±13Ma，这一年龄初步解释为流体包裹体内子  相似文献   

青海可可西里大地构造基本特征   总被引：18，自引：1，他引：18       下载免费PDF全文

边千韬  常承法 《地质科学》1997,32(1):37-46

在可可西里地区发现的晚古生代蛇绿混杂岩及不整合于其上的晚二叠世—早三叠世海滩亚相石英砂岩表明此区曾存在过古特提斯洋,早二叠世末古特提斯基本闭合。晚二叠世—早三叠世为相对稳定阶段。中、晚三叠世海侵,沉积了巨厚复理石。三叠纪末—早侏罗世发生了强烈的造山作用,形成造山带,可可西里地区进入陆内演化阶段。  相似文献   

冻土单轴蠕变过程中结构变化的CT动态监测   总被引：9，自引：4，他引：9  

吴紫汪  马巍 《冰川冻土》1996,18(4):306-311

ＣＴ为岩土材料非破坏的持续检测和内部结构的定量描述提供了可能，利用这一手段观测分析了冻土单轴蠕变过程中结构的变化情况，结果表明蠕变过程中结构缺陷的增生与扩展制约着土的结构的强化与弱化作用，控制着蠕变过程形态特征。易破坏区首先发生于样品的低密段，在软弱段的某一薄弱层面形成一环状低密带，然后向外扩展，最终导致整体结构的破坏。  相似文献   

卫星遥感估测土壤水分的一种方法   总被引：46，自引：1，他引：46  

刘培君  张琳  艾里西尔·库尔班  常萍  李良序  镨拉提  赵兵科 《遥感学报》1997,1(2):135-138,81

对于植被影响土壤水分遥感的大小 ,提出了“光学植被盖度”新概念来衡量 ,并用遥感法进行估测。用分解象元法排除植被干扰来提取土壤水分光谱信息。采用土壤水分光谱法并借助回归分析建立土壤水分遥感的TM数据模型。以此为桥梁 ,建立了AVHRR数据模型  相似文献   

A mean behavior model of aerobic biodegradation in heterogeneous formation     

M. W. Kemblowski  C-M. Chang  I. Kamil 《Stochastic Hydrology and Hydraulics》1997,11(3):255-266

It has been observed that the field biodegradation rates for soluble hydrocarbon plumes are significantly smaller than the aerobic rates observed in the laboratory. It is believed that this difference is related to the fact that in the field oxygen and hydrocarbon must be mixed before the biodegradation reaction can occur, and that the effective degradation rate is controlled by the actual, not mean, concentrations of oxygen and hydrocarbon. In this work, we present a conceptual model of oxygen-mixing limited biodegradation, which indicates that the effective degradation rate should depend on the cross correlation between the oxygen and hydrocarbon concentration fluctuations. This is followed by a development of a rigorous, field-scale model.  相似文献   

Distribution of Cs and Pu in the surface waters of the East Sea (Sea of Japan)     

Dong-Jin Kang  Chang Soo Chung  Suk Hyun Kim  Kyung-Ryul Kim  Gi Hoon Hong   《Marine pollution bulletin》1997,35(7-12):305-312

Surface and subsurface water samples for ¹³⁷Cs and ^239,240Pu analysis were collected in the East Sea (Sea of Japan) during August 1993. The ¹³⁷Cs levels of the surface waters are quite homogeneous in the East Sea (average = 3.1±0.2 mBq kg⁻¹). The ^239,240Pu levels vary from 6 to 10 μBq kg⁻¹ in the surface. ^239,240Pu to ¹³⁷Cs ratios in the surface water are within 0.002 to 0.003. The East Sea may be regarded as a part of the North Pacific Ocean in terms of ¹³⁷Cs dispersal in the surface, where the ¹³⁷Cs contents of the surface seawater seem to be controlled primarily by the atmospheric input. However, since our sampling was made just two months prior to the widely publicized Russian dumping incident on the 17th October 1993, our measurements may provide background data to assess the immediate impact of the Russian dumping on the levels of ¹³⁷Cs and ^239,240Pu in the East Sea.  相似文献   

The role of moisture fluctuations in unsaturated transport     

Ching-Min Chang  Marian W. Kemblowski 《Stochastic Environmental Research and Risk Assessment (SERRA)》1997,11(2):129-143

Within the framework of stochastic theory and the spectral perturbation techniques, three-dimensional dispersion in partially saturated soils with a finite correlation scale of log-hydraulic conductivity is analyzed. The effects of spatial variability of the moisture distribution parameter on the asymptotic spreading behavior of a unsaturated solute plume are assessed. This is accomplished by comparing two asymptotic macrodispersivities and two variance of solute concentration, obtained for a constant moisture content and spatially varied moisture, respectively.  相似文献   

樟子松针叶气孔运动与蒸腾强度关系研究   总被引：8，自引：2，他引：8  

赵文智  常学礼 《中国沙漠》1995,15(3):241-243

本文分析了影响樟子松针叶气孔阻力的主要环境因子及气孔运动与樟子松蒸腾强度、针叶水势的关系。结果表明：光合有效辐射是影响樟子松针叶气孔阻力的主要环境因子，其次是相对湿度，最后是空气温度。气孔关闭是针叶蒸腾强度下降的主要原因，它决定于针叶水势的一个临界值。统计分析表明，２龄针叶气孔关闭的水势临界值在－１６．８ｂａｒ，左右，而１龄针叶气孔关闭的水势临界值至少不在－１２．８－－１９．３１ｂｅｒ之间。  相似文献