老挝岩浆岩成因

老挝的岩浆活动分为三个阶段:早期古元古代—早石炭世,中期晚石炭世—中三叠世,晚期晚三叠世—第四纪。早期以中酸性及中基性侵入岩、火山岩为主,中期从超基性—酸性均有出露,晚期则为中酸性侵入岩,火山岩及玄武岩。反映不同构造位置及成因。     

A Combined Three-Dimensional Geological-Geostatistical-Numerical Model of Underground Excavations in Rock

Summary. This paper exploits geological and borehole geotechnical data obtained in the exploratory phase of a tunneling project to investigate in a first place if the kriging interpolation scheme may effectively reproduce the spatial variability of rock mass quality (Rock Mass Rating, RMR) in the vicinity of tunnels. For this purpose a quick solver in Fortran has been developed that performs variography analysis of 3D spatial data, fast kriging estimations of RMR between borehole sampling locations at the centroids of the elements of the numerical model, and model validation. For the purpose of an integrated underground excavation design, a step further is made by incorporating into the 3D mechanical numerical model of the rock mass, the three-dimensional (3D) solid geological model, thus coupling the geology with the ground (geotechnical) model (i.e. each element of the numerical model is assigned a geological material). The mechanical properties of each finite difference cell (or Representative Elementary Volume) of the ground model were then prescribed according to its geological type, the spatial heterogeneity of the rock mass expressed quantitatively with the kriging model, and the upscaling calculations of the mechanical properties of the intact rocks determined in the laboratory, based on the size-effect (strength dependence on size) and Damage Theory. Furthermore, a preliminary numerical simulation of the advance of unsupported tunnels in the model of the heterogeneous rock mass was performed for illustration purposes.     

Mass Concentration and Mineralogical Characteristics of Aerosol Particles Collected at Dunhuang During ACE-Asia

Measurements were performed in spring 2001 and 2002 to determine the characteristics of soil dust in the Chinese desert region of Dunhuang, one of the ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The mean mass concentrations of total suspended particle matter during the spring of 2001 and 2002 were 317 μg m?3 and 307 μg m?3, respectively. Eleven dust storm events were observed with a mean aerosol concentration of 1095 μg m?3, while the non-dusty days with calm or weak wind speed had a background aerosol loading of 196 μgm?3 on average in the springtime. The main minerals detected in the aerosol samples by X-ray diffraction were illite, kaolinite, chlorite, quartz, feldspar, calcite and dolomite. Gypsum, halite and amphibole were also detected in a few samples. The mineralogical data also show that Asian dust is characterized by a kaolinite to chlorite (K/C) ratio lower than 1 whereas Saharan dust exhibits a K/C ratio larger than 2. Air mass back-trajectory analysis show that three families of pathways are associated with the aerosol particle transport to Dunhuang, but these have similar K/C ratios, which further demonstrates that the mineralogical characteristics of Asian dust are different from African dust.     

STUDY OF THE POSSIBILITIES OF USING AN AIR MASS TRANSFORMATION MODEL IN TAIYUAN

An AMT-model,consisting of a trajectory model and a one-dimensional boundary layer model,is tested fortrajectories arriving in Taiyuan to study the possibility of using it in Taiyuan.The sensitivity of the model tothe different processes was studied.Some parameters of the model were modified for the purpose of forecast-ing in specific mountainous terrain and dry climate conditions.Results of examples which we have workedout for Taiyuan circumstances for the periods of July(summer)1985 and January(winter)1986,show that the12h runs of the AMT-model are able to reproduce(on historical data)the sounding of Taiyuan.The AMT-modelcontributes fruitfully to short-range weather forecasts(12—36h ahead)during periods of severe air pollution andwhen cold waves occur.     

The mass accommodation coefficient of ammonia on water

The mass accommodation coefficient of ammonia gas on water has been determined by measuring the absorption rate of 50–200 ppm NH₃ in one atm of air or helium into a liquid jet of 97 µm diameter as function of the exposed jet length, and comparing the results with numerical simulations which treat as the only free parameter. The model considers in detail transport of NH₃ by molecular diffusion, penetration of the gas/water interface, hydrolysis in the acidified water, and transport of the solutes from the surface into the jet. A correction is applied for the time evolution of the jet surface speed, using literature data on the fluid mechanics of liquid jets. The result of nine sets of independent measurements is

渝利铁路青石岩段边坡危岩体稳定性评价及防治措施研究

渝利铁路青石岩段为深切河谷型边坡,该边坡表部岩体在风化缷荷作用下结构复杂且稳定性差。此外,浅表层岩体在降雨、地震及工程开挖等影响下,局部已经出现了不同模式不同规模的变形失稳现象,严重影响工程建设和运营期间的安全。因此,本文根据边坡岩体结构特征及风化缷荷特征等工程地质条件,结合不同失稳模式的危岩体,提出了相应的稳定性评价理论和方法。最后,针对不同规模和不同稳定状态下的危岩体提出了有效的防治措施。     

静电场轨道阱质谱在水中溶解性有机质表征中的应用进展

溶解性有机质(Dissolved Organic Matter,DOM)在水生生态环境中广泛存在,影响着水环境中多种物质的生物地球化学性质.分析其组成与含量具有重要的生态环境意义,是生态环境科学领域研究的热点.溶解性有机质组成非常复杂,其分子组成的解析一直是难题.近年来,具有高分辨率、高灵敏度、高通量、高扫描速率等特性...     

Skarn development from limestone adjacent to the Glenrock Granodiorite,Marulan Batholith,New South Wales,Australia

Skarns are developed over two temperature‐time intervals in calcite limestone adjacent to the southern extension of the Glenrock Granodiorite, a pluton of the Marulan Batholith, Southern Highlands, New South Wales. The initial volumetrically‐dominant prograde phase of skarn formation produced a suite comprising bimetasomatic skarn, including pyroxene endoskarn, potassic endoskarn and wollastonite‐bearing exoskarn, together with mineralogically‐zoned vein skarn, massive garnet‐pyroxene skarn and calcite‐vesuvianite skarn. Retrograde replacement is manifested by the development of hydrous silicate minerals, carbonate and cross‐cutting sulphide veinlets.

A genetic model is proposed to account for the development of bimetasomatic skarn in the deposit. Exoskarn geochemistry indicates addition of many components relative to an essentially pure limestone precursor, including Si, Al, Fe, Zr, Zn, S, Mn and Cu, negligible transfer of K, Na and Rb and loss of CO₂. Strontium and Ca loss from the parent limestone is indicated by mass balance calculations at constant volume.

Garnet and pyroxene compositions in the massive garnet‐pyroxene skarn range from Gr₃₀ to Gr₆₆ and Hd₆₁ to Hd₈₇, respectively. Compositions from Gr₆₇ to Gr₉₅ are typical of the vein skarn garnets. Chemical zonation patterns in garnet, pyroxene and vesuvianite are generally characterized by rim Fe depletion relative to cores of grains.

Prograde skarn probably formed at T = 500–580°C; P < 220 MPa. The massive garnet‐pyroxene skarn evolved under conditions of log fO₂ = ‐18.9 to ‐22.9 (assuming a constant fCO₂ of 20 MPa) within the fS₂ stability field of pyrrhotite. Retrograde skarn formed at T < 400°C, possibly under conditions of X_H2O < 0.01.

Vesuvianite plus wollastonite assemblages, present in exoskarn, probably attest to very water‐rich conditions. The marble wall rocks, isolated from the source of skarn‐forming fluids, probably evolved under conditions of minimum X_co2 >0.2. Low temperature CO₂ ‐rich fluid inclusions and prehnite (stable at X_co2 <0.01), present in the marble and skarn, respectively, suggest that substantial differences in X_co2: X_H2O were maintained during cooling.

Observed mineralogical and chemical zonation within the skarn reflects the complex interaction of T, P, fO₂, Xco₂ and other chemical variables such as a_SiO2 and a_Al2O3 throughout the skarn system. No single variable can account adequately for the mineralogical diversity observed in the skarn deposit.     

青海祁漫塔格虎头崖多金属矿区岩体热年代学研究

虎头崖铜铅锌多金属矿床是青海祁漫塔格地区典型的与印支期岩浆侵入活动有关的接触交代矿床,矿区内出露多个不同时代的含碳酸盐地层,金属成矿元素组合复杂,中酸性侵入岩产状多变、岩性多样,成矿岩体及其成矿能力的判别一直制约着该矿区及区域的找矿勘查工作。本文基于详细的野外地质调查,开展了岩体热年代学和岩石地球化学研究。利用LA-MC-ICP-MS锆石U-Pb法,获得二长花岗岩体的年龄为230.3±3.7 Ma(n=13,MSWD=1.4);利用40 Ar-39 Ar法,获得二长花岗岩中黑云母和斜长石矿物的坪年龄分别为229.6±2.3 Ma和219.3±1.8Ma,厘定成岩时代为印支期。对二长花岗岩中不同矿物的岩体冷速率计算结果表明,虎头崖矿区二长花岗岩冷速率相对较快,其热效应较大,具有较大的成矿潜力。二长花岗岩为高钾钙碱性系列岩石,源于古老地壳物质的深熔或重熔,并可能有幔源物质的加入。     

近50年来北极斯瓦尔巴地区冰川物质平衡变化特征

利用长时间序列的冰川物质平衡资料,详细分析了北极斯瓦尔巴地区冰川的物质平衡变化特征以及气候因子对物质平衡的影响。结果表明：近50年来斯瓦尔巴地区冰川物质平衡变化主要呈负平衡、零平衡/略微增长两种状态。冰川净平衡一般为负值,年际变化波动幅度较大且呈负平衡趋势,累积物质平衡表现出长期稳定的负平衡增长态势。除Kongsvegen冰川外,其他冰川不存在短期内的平衡波动。季节变化表现为夏季消融、冬季积累,且夏季消融比冬季积累波动更大,冰川净平衡与夏季消融保持同步变化趋势。冰川净平衡与平衡线高度（ELA）呈负相关（平均相关系数为-0.89）,与积累区面积比率（AAR）呈正相关（平均相关系数为0.84）,该地区大多数冰川AAR减小,说明冰川物质补给处于劣势,冰川物质平衡向负平衡发展。夏季气温升高是斯瓦尔巴地区冰川表面物质加速亏损的直接原因。