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261.
The scour and deposition pattern around an abutment under constant discharge condition is calculated using a three dimensional(3D) Computational Fluid Dynamics(CFD) model.The Reynolds-Averaged Navier Stokes(RANS) equations are solved in three dimensions using a CFD model.The Level Set Method(LSM) is used for calculation of both free surface and bed topography.The two-equation turbulence model(k-ε and k-ω) is used to calculate the eddy viscosity in the RANS equations.The pressure term in the RANS... 相似文献
262.
流体不混溶性和流体包裹体 总被引:16,自引:4,他引:12
大多数流体包裹体是捕获于均匀体系,但有一部分包裹体捕获自非均匀体系(不混溶体系)。在自然界存在着许多不混溶的过程,这包括基性岩浆和酸性岩浆之间,岩浆与热液,岩浆与CO2,盐水溶液与CO2等。液体的不混溶性对于成矿作用十分重要,这方面有3个典型的例子,第一个是金矿的成矿作用与NaCl-H2O-CO2体系流体的不混溶有着重大的关系;第二个例子是斑岩铜矿;第三个例子是伟晶岩,发现在伟晶岩演化和成矿作用中存在着岩浆和热液的不混溶作用。实际上不混溶的大部分证据是从流体包裹体的研究中获得的。现在的问题是如何来确定哪些包裹体是从不混溶过程中捕获的。这种捕获于不混溶过程中的流体包裹体怎么来确定他的Th和成分。这种捕获于不混溶过程中的流体包裹体怎么与"卡脖子""拉伸作用"中捕获的包裹体和捕获自均匀体系的流体包裹体相区分。 相似文献
263.
黑河下游河岸林植物水分来源初步研究 总被引:28,自引:0,他引:28
通过分析黑河下游极端干旱区荒漠河岸林植物木质部水及其不同潜在水源稳定氧同位素组成(δ18O),应用"同位素质量守恒多元"分析方法初步研究了不同潜在水源对河岸林植物的贡献.结果表明:在黑河下游荒漠河岸林生态系统,在河水转化为地下水和土壤水及水分在土壤剖面再分配的过程中均存在强烈的同位素分馏.对植物水δ18O而言,胡杨、柽柳和苦豆子的δ18O分别为-6.43‰、-6.28‰~和-6.61‰,较苦苣菜(-5.14‰)和蒲公英(-5·52‰)明显偏负.柱状频率图显示胡杨最多能利用93%的地下水,柽柳最多利用90%的地下水.而苦豆子97%水分来源于80 cm土层范围内的土壤水.除0~20 cm土层内的土壤水外,苦苣菜和蒲公英可能还有其他潜在水源.即在黑河下游天然河岸林乔木和灌木较多地利用地下水,而草本植物仍然以地表水为主. 相似文献
264.
中国云南哀牢山含海蓝宝石伟晶岩的起源和成岩模拟实验研究 总被引:1,自引:0,他引:1
The Ailaoshan aquamarine-bearing pegmatites are associated with Proterozoic metamorphic rocks in the southern portion of the Ailaoshan fault-folded complex.The gem-bearing pegmatite mineralization zones of the region occur in areas generally consistent with the regional tectonic trend.The pegmatites are found in metamorphic rocks,migmatites and in the inner/outer contact zones of gneissoid granites. The Rb-Sr isochron drawn for the pegmatites is 26~31 Ma,(i.e.in Himalayan).The homogenization temperatures of melt and liquid inclusions in minerals vary from 185 to 920℃,which are comparable to the inclusions observed in banded migmatites and ptygmatic quartz veins in the surrounding metamorphic rocks. The mineralization fluids of the pegmatite were rich in HCO_3 and CO_2,and their compositional assemblages are comparable to metamorphic fluids.Results of H,O,C,Si etc.isotopic analyses and REE,and Be analyses indicates that the sources of mineralization components that formed the pegmatites are closely associated with metamorphic fluids and the enclosing metamorphic rocks. A pegmatite structure simulation experiment was conducted at high temperature and pressure(840℃and 1,500×105Pa.),with various metamorphic rock samples in a water-rich and volatile-rich environment.When the liquidus was reached,the temperature was gradually decreased at the rate of 5~10℃/day over a time period of three months.SEM energy-dispersive spectrum analyses were performed on the experimental products.A series of pegmatoid textures were observed including zonal texture,megacryst texture,drusy cavities,crystal druses,and vesicular texture along with more than ten types of minerals including plagioclase,microcline,quartz and biotite.Different metamorphic rock melts generated different mineral assemblages.Experiment results revealed that the partial melting of metamorphic rocks could form melts similar to pegmatite magmas. Based upon the geological characteristics,geochemistry,and pegmatite texture simulation experimental results,it is concluded that the mineralization components of Ailaoshan aquamarine-bearing pegmatites came from metamorphic rocks.The petrogenetic model for the origin of pegmatites is related to ultrametamorphism and metamorphic anatexis. 相似文献
265.
爆裂法作为快速测定流体包裹体中二氧化碳(和其它气体)含量的手段及其在勘探中的使用:以中国山东和河北省金矿为例 总被引:1,自引:0,他引:1
Kingsley Burlinson 《岩石学报》2007,23(1):65-71
The acoustic decrepitation method heats a small monomineralic sample and counts pressure impulses as the inclusions burst when they develop high internal pressures. For aqueous fluids, the decrepitation temperature is correlated with the homogenisation temperature, but gas rich fluids give a distinct and characteristic low temperature decrepitation peak which can be used to recognize gas rich fluid inclusions. This information is useful in exploration for Au deposits, which are frequently associated with CO2 rich and sometimes CH4 rich fluids. This distinctive decrepitation occurs because the CO2 rich inclusion fluids expand according to the gas law and develop internal pressures high enough to burst the host mineral grain at temperatures well below their homogenisation temperatures. In contrast, aqueous fluids condense to a liquid and vapour phase during post-entrapment cooling. Upon subsequent heating their internal pressures do not increase significantly until after homogenisation to a single phase occurs and hence they do not decrepitate "prematurely" as gas rich inclusions do. This behaviour is usually regarded as an annoyance in conventional microthermometric homogenisation studies, but can readily be used as an exploration aid to find mineralisation deposited from such gas rich fluids. Decrepitation results on samples from Cowra Ck, NSW, Australia, which have also been microthermometrically measured for CO2 content, show that amounts of less than 5 mole % CO2 are easily distinguished by decrepitation and amounts as low as 1 mole % CO2 may be determinable. Examples of the use of acoustic decrepitation in the study of 6 gold mines in the Shandong and Hebei provinces of China are discussed. 相似文献
266.
内陆盐湖石盐流体包裹体均—温度指示意义的现代过程研究 总被引:6,自引:1,他引:5
Halite precipitation with water and air temperature was observed in detail, and homogenization temperature of fluid inclusions in halite formed in ancient and modem Chaka Salt Lake was studied. Halite precipitates mainly in August every year and largely precipitates between 13 and 15pm at one day when water temperatures reach 20℃ but can seldom reach 30℃. Homogenization temperatures of fluid inclusions in halite formed in Chaka Salt Lake range from 14℃ to 38℃ with an average of 23.7℃. The number of inclusions appears an obvious peak value at homogenization temperatures between 18 - 25℃, which probably represent the water temperature in which halite mainly precipitates when water temperatures reach 20℃. Therefore, homogenization temperatures of fluid inclusions in halite formed in Chaka Salt Lake can wall reflect the water temperature. 相似文献
267.
作为赋存于花岗岩中钨锡矿化勘探指南的流体包裹体异常——前景展望 总被引:1,自引:0,他引:1
Andrew H Rankin 《岩石学报》2007,23(1):3-14
Studies of the distribution and abundance of fluid inclusions in granitic quartz associated with granite-hosted Sn-W mineralization of the British Isles reveal local and regional scale anomalies.At a sampling interval of c.5~50m,inclusion abundances increase towards zones of vein and stockwork mineralization exemplified by case history examples from exploration prospects in the Mourne Mountains of Northern Ireland and the Carrock Fell mining district of northwestern England.These steam aureoles provide a greater exploration target than the zone of visible alteration and mineralization and the lithogeochemical halo.But it is important to link them to geochemical data on fluid inclusion compositions,such as the semi-quantitative data from decrepitation-linked,ICP-AES (D-ICP)analysis,to optimize their exploration potential.Regional scale fluid inclusion anomalies,based on sampling intervals of c. 2km from the Sn-W mineralized granites of southwest England also broadly correlate with zones of intense mineralization in some areas. Regional-scale D-ICP analyses of quartz from SW England granites did not provide any convincing regional scale anomalies linked to mineralization except for positive boron anomalies around the centrally-mineralized Birch Tor area of the Dartmoor granite.Follow-up D-ICP analysis of quartz from stream sediments from this area,however,could be used to discriminate between samples related to mineralization from those draining unmineralized areas,using multivariate statistical analysis.At the present stage of development, the main contribution of fluid inclusion studies to mineral exploration is mostly limited to the conceptual stage where they continue to contribute to ore genetic theory and models.Costs and lack of knowledge transfer between research scientists and mineral explorationists limit their direct use during regional and target selection stages of exploration.Analysis of steam sediment quartz,using the more sensitive ICP-MS technique as a variant of the D-ICP method,appears to offer the greatest potential for future development as an exploration tool. 相似文献
268.
澳大利亚造山型金矿和侵入岩有关金矿系统流体包裹体资料和矿化过程的比较 总被引:15,自引:7,他引:8
T.P.Memagh E.N.Bastrakov Khin Zaw A.S.Wygralak L.A.I.Wybom 《岩石学报》2007,23(1):21-32
We have examined the fluid inclusion data and fluid chemistry of Australian orogenic and intrusion-related gold deposits to determine if similar mineralization processes apply to both styles of deposits.The fluid inclusion data from the Yilgarn craton,the western subprovince of the Lachlan orogen,the Tanami,Tennant Creek and Pine Creek regions,and the Telfer gold mine show that mineralization involved fluids with broadly similar major chemical components(i.e.H_2O NaCl CO_2±CH_4±N_2).These deposits formed over a wide range of temperature-pressure conditions(<200 to>500℃,<100~400MPa).Low salinity, CO_2-bearing inclusions and low salinity aqueous inclusions occur in both systems but the main difference between these two types of deposits is that most intrusion-related gold deposits also contain at least one population of high-salinity aqueous brine.Oxygen and hydrogen isotope data for both styles of deposit usually cannot distinguish between a magmatic or metamorphic source for the ore-bearing fluids.However,sulfur and lead isotope data for the intrusion-related gold deposits generally indicate either a magmatic source or mixing between magmatic and sedimentary sources of fluid.The metamorphic geothermal gradients associated with intrusion-related gold deposits are characterized by low pressure,high temperature metamorphism and high crustal geothermal gradients of>30/km.Where amphibole breakdown occurs in a granite source region,the spatially related deposits are more commonly associated with Cu-Au deposits rather than Au-only deposits that are associated with lower temperature granites.The dominant processes thought to cause gold precipitation in both types of deposits are fluid-rock interaction(e.g.desulfidation)or phase separation.Consideration of the physical and chemical properties of the H_2O-NaCl-CO_2 system on the nature of gold precipitation mechanisms at different crustal levels infers different roles of chemical(fluid-rock interaction)versus rheological(phase separation and/or fluid mixing)host-rock controls on gold deposition.This also implies that at the site of deposition,similar precipitation mechanisms operate at similar crustal levels for both orogenic and intrusion-related gold deposits. 相似文献
269.
四川甘洛赤普铅锌矿床流体包裹体特征及成矿机制初步探讨 总被引:7,自引:1,他引:6
赤普铅锌矿床位于扬子地台西南缘川滇黔成矿区内,是川滇黔地区重要的铅锌矿床之一.通过野外和显微镜下观察,将成矿期形成的石英划分为Ⅰ、Ⅱ、Ⅲ三个阶段.本次选取了21件样品进行研究,对保存于石英、闪锌矿及硅化白云石中的原生包裹体进行的详细研究,赤普铅锌矿床中包裹体类型相对较为单一,以气液包裹体为主.Ⅰ、Ⅱ、Ⅲ阶段石英中流体包裹体均一温度和盐度范围分别为230℃~270℃和2.74~19.68wt%(NaCl),150℃~200℃和3.71~16.99wt%(NaCI)和180℃~220℃和0.70~16.15wt%(NaCl)三个区间.主成矿阶段的闪锌矿流体包裹体的均一温度和盐度范围为127℃~210℃和4.34%~22.17%(NaCl).该矿床成矿流体均一温度和盐度范围主要在130℃~200℃和8.5%~17.0%(NaCl)之间,属于低温、中等盐度铅锌矿床.成矿流体为H2O-NaCl-CaCl2体系;成矿过程中成矿流体始终处于相对还原环境.成矿物质来源于上地壳,成矿流体主要来自围岩地层;成矿机制可能为含金属和舍还原硫流体混合成矿.该矿床应归属于密西西比型铅锌矿床. 相似文献
270.
新疆西天山阿希金矿床流体包裹体地球化学特征 总被引:4,自引:1,他引:3
本文在系统总结前人关于矿床地质特征和流体成矿作用研究成果的基础上,补充开展了热液成矿期石英-碳酸盐阶段石英、方解石和重晶石中流体包裹体的均一法和冷冻法测温,并对石英样品进行了气相色谱测量,对石英流体包裹体中的稀土和微量元素进行了测试.结果表明,矿床具有典型的浅成低温热液金矿的特点,成矿流体总体上盐度很低,多数都集中于0.53~1.57wt%NaCl.成矿流体的主要成分为H2O、CO2和CH4.流体包裹体微量元素与容矿围岩具有继承性,流体中Cu、Ni、Co、Mo、Zn、Pb、V、Sb和Li等的含量较高,可能说明了Cu、Zn、Co、Ni、Bi和Ba等元素在水岩反应过程中更容易进入流体当中.石英流体包裹体中∑REE为13825×10-12~149935×10-12,LREE/HREE为2.63~50.83,δEu为0.70~0.91,表现为Eu的弱亏损.成矿流体的REE配分型式与火山岩具有相同的Eu亏损和右倾配分曲线,表明成矿流体在演化过程中可能继承了早期火山岩的REE特征;但成矿流体的LREE/HREE值比火山岩大,前者的REE配分曲线比后者更加右陡倾斜.这可能与后期变质水和大气降水的混入引起的成矿流体物质组分发生有关. 相似文献