鲁中碳酸岩中磷灰石同位素地球化学研究   总被引：6，自引：0，他引：6  

储同庆  沈渭洲 《矿物学报》1997,(1)

鲁中地区分布着100多个碳酸岩体，微量元素含量及稀土配分等均与世界典型碳酸岩相近。而碳酸岩的碳氧及斑晶磷灰石的锶、钛同位素组成与典型地幔物质有差异，与富集地幔颇为近似，从而证实在山东地区陆壳下存在富集地幔源区。  相似文献   

九甸峡工程区断层测年结果研究与讨论   总被引：2，自引：0，他引：2  

储同庆  张韵 《工程地质学报》1996,4(4):61-68

断层的年代测定是研究断层活动性的重要内容之一。然而, 一个工程同一条断层会出现不同的测年结果, 从而引起争议和难予决断。近年来我们通过几个大型工程区域稳定性研究, 对此获得了一些认识。本文以洮河九甸峡地区几条主干断层为研究对象, 采用同位素年龄测定与野外地质调查和显微构造分析相结合的方法, 对断层测年问题作一分析和讨论, 也许对岩土工程断层活动性研究有一定参考价值。  相似文献   

一种新的、快速的碳、氮、硫同位素测定手段──EA－IRMS连线分析技术   总被引：2，自引：0，他引：2  

储雪蕾 《矿物岩石地球化学通报》1996,(4)

一种新的、快速的碳、氮、硫同位素测定手段──ＥＡ－ＩＲＭＳ连线分析技术储雪蕾（中国科学院地质研究所，北京１０００２９）关键词元素分析仪－同位素比值质谱仪，连线分析碳，氮，硫同位素碳、氮、硫三种元素的稳定同位素在地学、生态学、环境科学等领域受到了重视，...  相似文献   

Effects of convection instability due to incompatibility between ocean dynamics and surface forcings     

W. Cai  P. C. Chu 《Annales Geophysicae》1997,15(8):1067-1075

The study demonstrates that an incompatibility between a surface temperature climatology and a given ocean model, into which the climatology is assimilated via Haney restoration, can cause model ocean climate drift and interdecadal oscillations when the ocean is switched to a weaker restoration. This is made using an idealized Atlantic Ocean model driven by thermal and wind forcing only. Initially, the temperature climatology is forcefully assimilated into the model, and an implied heat flux field is diagnosed. During this stage any incompatibility is suppressed. The restoring boundary condition is then switched to a new forcing consisting of a part of the diagnosed flux and a part of the restoring forcing in such a way that at the moment of the switching the heat flux is identical to that prior to the switching. Under this new forcing condition, the incompatibility becomes manifest, causing changes in convection patterns, and producing drift and interdecadal oscillations. The mechanisms are described.  相似文献   

近50年中国地面气候变化基本特征   总被引：403，自引：14，他引：403  

任国玉  郭军  徐铭志  初子莹  张莉  邹旭凯  李庆祥  刘小宁 《气象学报》2005,63(6):942-956

采用国家基准气候站和基本气象站的地面资料,系统地分析了中国大陆地区1951年以来近地表主要气候要素演化的时间和空间特征。结果表明,中国近50 a来年平均地表气温变暖幅度约为1.1℃,增温速率接近0.22℃/(10 a),比全球或半球同期平均增温速率明显偏高。地表气温增暖主要发生在最近的20余年,其季节和空间特征与前人分析结论基本一致。降水量变化趋势对所取时间段和区域范围敏感。1951年以来全国平均降水量变化趋势不明显,但1956年以来略有增加。降水变化的空间特征明显而相对稳定,东北北部、包括长江中下游的东南部地区和西部广大地区降水增加,而华北地区以及东北东南部和西北东部地区降水明显减少。分析还发现,近50a来全国平均的日照时数、平均风速、水面蒸发等气候要素均呈显著下降趋势,但积雪地带的最大积雪深度却有所增加。中国日照时间和水面蒸发量变化的空间特征很相似,减少最明显的地区均发生在华北和华东,新疆次之。影响中国年代以上尺度气候变化的因子错综复杂,人类活动引起的大气中温室气体浓度增高可能在一定程度上影响了中国近50 a来的气候,但考虑到尚存的不确定性,目前仍不能给出明确结论。中国东部大部分地区日照时间和水面蒸发量减少可能均起源于人为排放的气溶胶影响,平均风速减弱也有利于水面蒸发量下降,而在西部地区云量和降水量的变化可能更重要。  相似文献   

The eastward subtropical countercurrent on isopycnal surface in the western North Pacific     

LI Rongfeng  YOU Xiaobao & Peter C. Chu . LASG  Institute of Atmospheric Physics  Chinese Academy of Sciences  Beijing  China  . Department of Oceanography  Naval Postgraduate School  Monterey  CA -  USA 《中国科学D辑(英文版)》2005,48(7)

The classic Sverdrup theory suggests that the water movement in the central subtropical gyre of North Pa-cific be slowly westward or southwestward.In the late sixties of the20th century,the existence of a peculiar eastward narrow flow between20°N and25°N in spring was theoretically predicted.It was named the Subtropical Countercurrent(STCC),although direct observational evidences were not yet sufficient to con-firm whether or not such eastward flow between20°N and25°N was a persistent…  相似文献   

Geochemical and Sr-Nd isotopic study of alkaline syenites in Liangtun-Kuangdonggou, Liaoning Province, China： Evidence for enriched mantle before 1.86 Ga and implications     

任康绪  阎国翰  蔡剑辉  牟保磊  李凤棠  古丽冰  赵凤三  储著银 《中国地球化学学报》2005,24(3):232-242

The 1.86 Ga Liangtun-Kuangdonggou complex (LKC) is one of the oldest alkaline syenite bodies so far discovered in China. This syenite suite has elevated contents of total alkali (K2O Na2O), with an average of 10.50%, and a mean Rittmann Index (σ) of 6.48. The intrusions have slightly higher concentrations of K2O than those of Na2O on a weight percent basis, indicating the rocks belong to potassium-rich alkaline syenite series. Total rare-earth element concentrations (∑REE ) of the rocks are relatively high, ranging from 324×10 -6 to 1314×10 -6, with a mean value of 666×10 -6. The REE patterns are subparallel and rightward steep with (La/Yb)N >33, showing mild negative to positive Eu anomalies (δEu: 0.63-1.15). All samples exhibit strong LILE and LREE enrichments and TNT (Nb, Ta, Ti) and P depletions in multi-element spidergrams. On the εSr(t)-εNd(t) correlation diagram, most analytical data points plot within the enriched mantle field with low ( 87Sr/86Sr)i ratios (0.7045-0.7051) and negative εNd(t) values (-3.72--3.97), falling among those kimberlites from Fuxian County, Liaoning Provinve, from Mengyin County, Shandong Province and the Ⅱ-type kimberlites from South Africa. These characteristics imply that the LKC-rocks may have the same source as the above-mentioned kimberlites, i.e., they have close connections to the materials derived from enriched mantle reservoirs, further revealing that the upper mantle beneath the northeastern part of the North China Plate had been highly enriched before 1.86 Ga. Geodynamically, the LKC-rocks were formed in a within-plate environment with close genetic connections to rift-related alkaline magma activities possibly controlled by ancient mantle plumes.  相似文献   

Target setting and allocation of carbon emissions abatement based on DEA and closest target: an application to 20 APEC economies     

Wu  Jie  Chu  Jun-Fei  Liang  Liang 《Natural Hazards》2015,84(1):279-296

Regarded as an effective method for treating the global warming problem, carbon emissions abatement (CEA) allocation has become a hot research topic and has drawn great attention recently. However, the traditional CEA allocation methods generally set efficient targets for the decision-making units (DMUs) using the farthest targets, which neglects the DMUs’ unwillingness to maximize (minimize) some of their inputs (outputs). In addition, the total CEA level is usually subjectively determined without any consideration of the current carbon emission situations of the DMUs. To surmount these deficiencies, we incorporate data envelopment analysis and its closest target technique into the CEA allocation problem. Firstly, a two-stage approach is proposed for setting the optimal total CEA level for the DMUs. Then, another two-stage approach is given for allocating the identified optimal total CEA among the DMUs. Our approach provides more flexibility when setting new input and output targets for the DMUs in CEA allocation. Finally, the proposed approaches are applied for CEA target setting and allocation for 20 Asia-Pacific Economic Cooperation economies.

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Influence of heterogeneity on unsaturated hydraulic properties: (1) local heterogeneity and scale effect     

Pen‐Yuan Chen  Chu‐Hui Chen  Nien‐Sheng Hsu  Cheng‐Mau Wu  Jet‐Chau Wen 《水文研究》2012,26(23):3593-3603

Spatial heterogeneity is ubiquitous in nature, which may significantly affect the soil hydraulic property curves. The models of a closed‐form functional relationship of soil hydraulic property curves (e.g. VG model or exponential model) are valid at point or local scale based on a point‐scale hydrological process, but how do scale effects of heterogeneity have an influence on the parameters of these models when the models are used in a larger scale process? This paper uses a two‐dimensional variably saturated flow and solute transport finite element model (VSAFT2) to simulate variations of pressure and moisture content in the soil flume under a constant head boundary condition. By changing different numerical simulation block sizes, a quantitative evaluation of parameter variations in the VG model, resulting from the scale effects, is presented. Results show that the parameters of soil hydraulic properties are independent of scale in homogeneous media. Parameters of α and n in homogeneous media, which are estimated by using the unsaturated hydraulic conductivity curve (UHC) or the soil water retention curve (WRC), are identical. Variations of local heterogeneities strongly affect the soil hydraulic properties, and the scale affects the results of the parameter estimations when numerical experiments are conducted. Furthermore, the discrepancy of each curve becomes considerable when moisture content becomes closer to a dry situation. Parameters estimated by UHC are totally different from the ones estimated by WRC. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

内蒙古敖汉旗七家金矿闪长玢岩锆石U-Pb年代学、地球化学及地质意义          下载免费PDF全文

王一珅  刘建明  刘红涛  褚少雄  高帅  陈永安  许腾  武宗林  高玉友 《地质科学》2016,(2):633-653

内蒙古敖汉旗七家金矿构造位置上处于兴蒙造山带与华北克拉通北缘的结合部位, 靠近兴蒙造山带一侧, 是近年来新发现的石英脉型金矿床.区内岩脉以闪长玢岩为主, 且与石英脉型矿体空间关系密切.根据岩脉与矿体的穿插关系, 将其分为成矿前闪长玢岩和成矿后闪长玢岩.LA-ICP-MS锆石U-Pb年代学表明, 成矿前闪长玢岩加权平均年龄为166.3±3.4 Ma, 成矿后闪长玢岩加权平均年龄为128.6±4.5 Ma, 与区域上两期构造-岩浆活动时间(分别为160 Ma左右和128 Ma左右)近似吻合.主量元素特征显示: 二者均属于准铝质, 高钾钙碱性系列; 微量元素特征显示: 二者均富集轻稀土元素、大离子亲石元素(Rb、K)和活泼的不相容元素(U、Pb), 相对亏损重稀土元素和高场强元素(Nb、Ta、Ti), 反映出岩浆来源具壳源特征.主微量元素特征均显示出二者具有岛弧岩浆岩的地球化学属性.另外, 成矿后闪长玢岩有较高的Nb/Ta(18.66~20.27)和Zr/Hf(37.16~39.23)比值, 暗示其岩浆来源具明显的幔源特征.岩石地球化学特征表明, 成矿前闪长玢岩可能起源于太平洋板块俯冲导致的下地壳部分熔融岩浆; 成矿后闪长玢岩可能起源于俯冲流体交代的地幔楔熔融岩浆, 并在其演化侵位过程中伴有地壳物质的混染.结合闪长玢岩成岩时代、岩石成因及区域构造演化, 反映出七家金矿的形成与太平洋板块的西向俯冲密切相关, 矿床在地壳由挤压增厚向伸展减薄的转换过程中形成.  相似文献