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951.
952.
在藏北羌塘坳陷地区晚侏罗世晚期地层中发现石膏及油页岩,对石膏、油页岩及相应的岩石组合基本特征进行了详细观察描述,并采集了大量油页岩、孢粉及双壳类化石样品.结合区域地质及产出石膏及油页岩地层的沉积学特征简要分析,认为北羌塘坳陷胜利地区晚侏罗世时期具有多次海进、海退,从而形成潮坪、泻湖相环境间歇性沉积,而古气候的变化是导致... 相似文献
953.
Fu-Ping Pei Wen-Liang Xu De-Bin Yang Yang Yu Wei Wang Quan-Guo Zhao 《Journal of Asian Earth Sciences》2011,40(2):636-650
LA–ICP–MS zircon U–Pb ages, geochemical and Sr–Nd–Pb isotope data are presented for mafic–ultramafic complexes from the southern Liaoning–southern Jilin area with the aim of determining the nature of the Mesozoic lithospheric mantle and to further constrain the spatial extent of destruction of the North China Craton (NCC). The complexes consist of olivine-websterite, gabbro, dolerite, and gabbro-diorite. Zircons from the complexes show typical zoning absorption, are euhedral–subhedral in shape, and yield high Th/U ratios (1.23–2.87), indicating a magmatic origin. Zircon U–Pb age data indicate that they formed in the Early Cretaceous (129–137 Ma). Geochemically, they have SiO2 = 44.3–49.8%, MgO = 6.8–26.5%, Cr = 102–3578 ppm, and Ni = 31–1308 ppm, and are characterized by enrichment in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), and depletion in high field strength elements (HFSEs) and heavy rare earth elements (HREEs), as well as a wide range of Sr–Nd–Pb isotopic compositions [(87Sr/86Sr)i = 0.70557–0.71119; εNd (t) = ?5.4 to ?20.1; (206Pb/204Pb)i = 15.13–17.85; Δ7/4 = ?11.49 to 16.00; Δ8/4 = 102.64–203.48]. Compared with the southern Liaoning mafic–ultramafic rocks, the southern Jilin mafic–ultramafic rocks have high TiO2 and Al2O3 contents, high εNd (t) values, low (La/Yb)N values, low initial 87Sr/86Sr ratios, and low radiogenic Pb isotopic compositions. These findings indicate that the primary magmas of the southern Jilin complexes were derived from lithospheric mantle that was previously metasomatized by a melt derived from the delaminated ancient lower crust, whereas the primary magmas of the southern Liaoning complexes originated from partial melting of a lithospheric mantle source that was previously modified by melt derived from the broken-off Yangtze slab. Therefore, the lateral extent of the NCC destruction should include the southern Liaoning–southern Jilin area. 相似文献
954.
955.
The objective of this study was to investigate the effects of diurnal temperature fluctuation amplitude (DTFA) on the geothermal regime of the embankment on the Qinghai–Tibet plateau. The investigation was simulated by respectively denoting the diurnal temperatures at the embankment surface, embankment slope, and natural ground surface with sinusoidal waves. The amplitudes of the waves were denoted by 0°C, 5°C, 8°C, and 12°C, respectively. The numerical result shows that the DTFA cannot vary the frequency of the seasonal temperature fluctuation of the underlying soil, but can significantly change the magnitude of the soil’s temperature. The changes include: (1) The high DTFA, such as 12°C, can significantly lead to the warming of the soil under the embankment. (2) Interestingly, when the DTFA at ground surface is 5°C, the underlying soil is in a cooler stage compared to when such DTFA is 0°C, 8°C, or12°C. This interesting result means that the documented model which ignores the diurnal temperature rhythm overestimates the warming of the underlying soil at the low DTFA region and underestimates such warming at the high DTFA region. This result also suggests that the soil under the embankment can be cooled down if the DTFA on the ground surface was maintained at or approximately at 5°C. 相似文献
956.
Tao Pei 《Mathematical Geosciences》2011,43(3):345-362
The task of discriminating between heterogeneity and complete spatial randomness (CSR) for a given point process can be divided into three subtasks: the identification of the point pattern; the determination of the sizes of clusters; and the estimation of the numbers of events in dominant clusters. Many studies have been performed regarding the first and second subtasks. However, limited work has been done on the third aspect; hence, the determination of the number of events in each dominant cluster is still an unsolved problem. In this paper, we provide a solution by constructing a new index which is defined as the ratio between the variance of the (k+1)th nearest distance and that of the kth nearest distance. Our method can be divided into two phases: the detection of point pattern and the estimation of the numbers of events in dominant clusters. These phases can be estimated by the values at which the index abruptly decreases to be less than 1. A comparative study between the existing indices and our index shows the following: (i) our index can indicate the numbers of events in dominant clusters in a relatively objective way, which is different from the K-function revealing the sizes of clustered patterns; (ii) it is a nonparametric index and is easy to implement; and (iii) it demonstrates the highest detection power for differentiating between heterogeneity and CSR. The simulations and two seismic case studies also confirmed the correctness of our method. 相似文献
957.
958.
3种水产病原菌简型基因芯片检测技术的建立 总被引:1,自引:0,他引:1
根据水产养殖中常见的3种病原菌鳗弧菌(Vibrio anguillarum)、嗜水气单胞菌(Aeromonas hydrophila)及迟缓爱德华氏菌(Edwardsiella tarda)的研究资料,筛选3个毒力相关基因toxR、aerA、evpA设计引物和探针,构建简型基因芯片,并使用对虾白斑病综合征病毒(WSSV)variable region的PCR荧光标记产物作为表面化学质控。通过已构建和优化的多重PCR反应条件,获得了3个目的基因的PCR产物;经过芯片制作过程的优化,将探针以终浓度20μmol/L溶于50%DMSO,在室温、相对湿度45%的条件下点印于醛基基片表面。扩增的PCR产物与杂交液混合后,在42℃杂交2 h就可检测到理想的杂交信号。芯片的灵敏度试验结果表明,可以检测到的3种水产病原菌的最低模板DNA为:鳗弧菌3×102拷贝、嗜水气单胞菌5×103拷贝、迟缓爱德华氏菌6×101拷贝。该芯片可成功应用于患病大菱鲆内脏的细菌分离物的鉴定。 相似文献
959.
自动气象站监测运行能力可靠性评估 总被引:1,自引:0,他引:1
自动气象站运行能力的评估,其实质就是对自动气象站可靠性的评估,其目的在于指导自动气象站保障维护体系的建立和健全.借鉴大气透明度定义探讨自动气象站可靠性,解释产品可靠性指数分布的物理意义.根据模型统计分析在修改采集器设计、增加状态检测电路后自动气象站的运行能力(平均无故障时间),计算出实验考核指标.通过试验获得试验产品的平均无故障时间和置信度0.95下的最小无故障时间,并对将投入业务使用的双套站和三套站系统,在平均无故障时间和平均维修周期上做了相关讨论,为科学决策提供相关技术支持. 相似文献
960.
利用卡尔曼滤波数学模型对甘肃省文县阳山金矿带安坝矿段的7个控制点测得的GPS信号、星历和残差进行优化,通过对卫星星历信号图、卫星残差图、矢量表、标准误差表和后验协方差矩阵表几个方面对未使用卡尔曼滤波和使用卡尔曼滤波两种情况得到的数据进行比较,从而得出以下结论:在同一时间、同一地点、同一天气的情况下使用卡尔曼滤波模型能大大提高控制测量的精度。 相似文献