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31.
《Resource Geology》2018,68(3):303-325
The Lujing uranium deposit, located in the southeastern part of the Nanling metallogenic province, is one of the representative granite‐related hydrothermal uranium deposits in South China. Basic geology, geochemistry, and geochronology of the deposit have been extensively studied. However, there is still a chronic lack of systematic research on the genesis and metallogenic process of the deposit. Thus, we recently carried out an electron microprobe and stable isotopic analysis. The main research results and progresses are as follows: Uranium minerals in this deposit include coffinite, pitchblende, and uranothorite, and small amounts of uranium exist in accessory minerals in the form of isomorphism. Coffinite, which occurs predominantly as the pseudomorphs after pitchblende, also occurs as a primary mineral and is locally formed from the remobilization of uranium from adjacent uranium‐bearing minerals. The mineralizing fluid was originally composed of a magmatic fluid generated by late Yanshanian magmatism. The high As content of pyrite in ores may reflect the addition of meteoric water, or the formation water (or both), to the magmatic hydrothermal system. The δ34S values vary from −14.4‰ to 13.9‰ (mean δ34S = −3.9‰), showing a range that is similar to nearby Cambrian metamorphic strata and Indosinian granites, indicating that these host rocks represent the source of sulfur; however, the possibility of a mantle source cannot be completely ruled out. According to our new isotopic data and recent Pb isotopic data, we conclude that the uranium in ores was derived by leaching dominantly from the uranium‐rich host rocks, especially the Cambrian metamorphic strata. The δ13CPDB values (−8.75‰ to 1.40‰; mean δ13CPDB = −5.41‰) and δ18OSMOW values (5.45–18.62‰; mean δ18O = 13.02‰) of reddish calcite from the ore‐forming stage suggest that the CO2 in the mineralizing fluids was derived predominantly from the mantle, with a small component contributed by marine carbonates. Based on these new data and previous research results, this paper proposes that uranium metallogenesis in the Lujing deposit is closely associated with mafic magmatism resulting from crustal extension during the Cretaceous to Paleogene in South China. 相似文献
32.
Y. Y. Huyan T. S. Liu F. J. Jiang X. Z. Chen X. Q. Ma 《Australian Journal of Earth Sciences》2018,65(6):863-875
Residual and movable porosity are significant parameters for characterising petrophysical properties, especially in tight reservoirs. Eight tight sandstone samples from the upper Paleozoic gas-bearing strata in the Kangning area, from the eastern margin of the Ordos Basin, were analysed using nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), petrography, and porosity and permeability tests. The lithology and pore types were identified and classified using petrography and SEM. The residual and movable porosity were obtained with NMR. In addition, NMR was used to visualise pore structure and pore size distribution. The results suggest that the upper Paleozoic sandstones in the study area mainly comprise feldspathic litharenite and litharenite. The sandstone porosity and permeability are low, with means of 5.9% and 0.549 mD, respectively. Four pore types exist in the tight sandstones: residual primary pores, grain dissolution pores, micropores (clay-dominated) and microfractures. The T2 spectra under water-saturated conditions correlate with pore size and can be used to distinguish small and large pores based on the transverse relaxation time cutoff value of 10 ms, which corresponds to a pore diameter of 0.232 μm. Small pores account for 72% of the pores in the tight sandstones. The continuous bimodal T2 spectra suggest good connectivity between small and large pores, despite the low porosity and permeability. In this study, the movable porosity of the major tight sandstone gas reservoirs is higher than the residual porosity, which confirms the effective evaluation of movable porosity to tight sandstone reservoirs, based on NMR experiments. 相似文献
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平端深海偏顶蛤(Gigantidasplatifrons)是南海台西南冷泉区的典型优势物种,鳃丝上皮细胞内共生大量甲烷氧化菌,通过甲烷有氧氧化合成有机物为共生体系提供物质能量,是平端深海偏顶蛤赖以生存的重要能量来源器官,溶酶体在共生体系的营养互作和稳态维持中可能发挥重要作用,本研究使用电镜技术观测了常压培养过程中(0d,30d,90d)平端深海偏顶蛤共生体系中共生菌和溶酶体的动态变化,通过鳃上皮含菌细胞超显微结构的变化研究常压培养对深海共生体系的影响,并探讨溶酶体在宿主—共生菌营养传递和共生菌群稳态维持中的关键作用。研究发现,在原位状态样品中(0d)共生菌和溶酶体呈极化分布,细胞结构完整清晰;蓄养30d后,含菌细胞出现明显破碎,共生菌数量大幅降低,溶酶体数量、范围和消化程度大幅增加,对细胞顶端的甲烷氧化菌进行分解;而90d后,共生菌在溶酶体的作用下消失殆尽,鳃部有明显细胞脱落后留下的坑洞,细胞呈现空泡状,无法明确区分各种细胞组分。上述结果展示了长期常压蓄养过程中鳃上皮含菌细胞中溶酶体与甲烷氧化菌的动态变化,推测当共生菌丢失后溶酶体也同步降低活跃度,平端深海偏顶蛤在共生互作中通过溶酶体主导消化和调控共生菌。 相似文献
35.
针对国内海上风电基础设计没有统一的规范及标准,为提升海上风电基础设计建设的水平,通过对东南沿海某海域海上风电基础的设计进行了有限元计算分析论证,验证了群桩高承台结构设计方案的设计方法和设计参数。分析结果表明该设计的最大应力主要发生在塔筒底座与承台接触部位及钢管桩与承台连接段,应在连接部位加强措施处理;基础竖直位移较小,水平位移相对较大;分界部位应力较集中,刚度不能顺畅过渡,可考虑填充碎石土等方法加强。本研究对海上风电基础设计技术的研究与探索,可为将来制定中国海上风电行业标准提供可靠的依据,对中国未来大批量的海上风电能源的开发有着重要意义。 相似文献
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37.
雪宝顶矿床位于四川省的松潘甘孜造山带中,以出产大颗粒含W-Sn-Be-F-P的矿物而闻名,前人对该矿床已经开展了大量的研究,但缺乏对粗粒矿物的主次痕量元素研究.本次研究采用X射线荧光光谱(XRF)、电子探针(EMPA)和电感耦合等离子体质谱(ICP-MS)技术对矿床中各矿物的主次痕量元素进行测试分析.结果显示,雪宝顶矿... 相似文献
38.
Total electron content processing from GPS observations to facilitate ionospheric modeling 总被引:2,自引:1,他引:1
With the increasing global distribution of high rate dual-frequency global positioning system (GPS) receivers, the production
of a real-time atmospheric constituent definition, total electron content (TEC), has become a beneficial contributor to the
modeling applications used in the assessment of GPS position accuracy and the composition of the ionosphere, plasmasphere,
and troposphere. Historically, TEC measurements have been obtained through post processing techniques to produce the quality
of data necessary for modeling applications with rigorous error estimate requirements. These procedures necessitated the collection
of large volumes of data to address the various abnormalities in the computation of TEC associated with the use of greater
data quality controls and source selection while real-time modeling environments must rely on autonomous controls and filtration
techniques to prevent the production of erroneous model results. In this paper we present methods for processing TEC in real
time, which utilize several procedures including the application of an ionospheric model to automatically perform quality
control on the TEC output and the computational techniques used to address receiver multipath, faulty receiver observations,
cycle-slips, segmented processing, and receiver calibrations. The resulting TEC measurements are provided with rigorous error
estimates validated using the vertical TEC from the Jason satellite mission.
相似文献
Nelson A. BonitoEmail: |
39.
40.
从西菲律宾海底4954 m深的沉积物中分离到一批深海细菌,对其中编号为B2、B5、B6的3株细菌进行了生理、光学显微镜和扫描电镜观察,并且进行了分子水平鉴定。菌落呈圆球形,光滑,3株菌均带有颜色, B6菌呈乳白色, B2和 B5菌分别呈现鲜艳的橙色和红色。扫描电镜观察表明 B2和B6呈杆状,但B6菌外面覆有鞘膜, B5菌呈球状。生理实验表明,3株菌温度生长范围在37℃以下,最适生长温度分别为20、28、28℃,属于耐冷菌范畴。pH耐受范围为6~14,最适pH分别为8、8、12。3株细菌16S rRNA基因序列同源性分析表明,它们分属于芽孢杆菌(Bacillus)、节杆菌(Arthrobacter)、蛋白菌(Acinetobacter)3个不同的菌属。 相似文献