Influence of the zone of weakness on dip angle and shear heating of subducted slabs

We study the importance of the zones of weakness and the pattern of downgoing flow in steady-state models of subducting lithosphere, which interacts mechanically and thermally with the ambient mantle. The non-linear system of governing equations consists of (i) the momentum equation in stream function formulation and (ii) the steady-state heat transfer equation including conduction and advection of heat and dissipation. A finite element method has been applied to this system. We consider the viscosity to be a non-linear function of both the temperature and the stream function. In steady-state two-dimensional (2D) flow, the stream function isolines follow material trajectories. They are used to follow the top of the subducting slab, which because of its possible increase in water content, is assumed to have a lower viscosity. The zone of weakness has been thus obtained in the self-consistent fashion since the stream function as well as the temperature are the output from our modeling and no a priori assumptions about the shape of the bending lithosphere are taken into account. It was shown that several orders decrease of viscosity in the zone of weakness is required to obtain the dip angle of about 45°. If the decrease of viscosity is not sufficient enough, the subducted slab either sinks almost vertically or does not exhibit a plate-like behavior. We have also demonstrated that shear heating can unrealistically increase at the zone of weakness for fast subductions if decrease of viscosity is underestimated.     

碳酸盐岩储层缝洞发育带预测:以塔河油田为例

塔河油田碳酸盐岩为古岩溶喀斯特化与受后期构造叠置改造的孔、洞、缝等组成的非均质储层,储层具有规模不同、空间形态不规则、充填性质各异的复杂组合特征以此为对象通过分解地震波场不同特征信号,开发了一系列针对不同储层目标的叠前叠后地震预测技术,不同特征地震预测结果经综合叠置验证分析,实现了残丘体上叠置的孔、洞、缝及古地貌的精细刻画及表征,展示了缝洞空间纵横交错的叠置关系,提高了复杂储层空间展布规律的认识及精确定位。     

应用"极值剔除"和"逐步消空"法建立太原机场11月份辐射大雾预报指标集

本文介绍了利用“极值剔除”和“逐步消空”方法建立太原机场11月份辐射大雾预报指标集的具体过程，并对得出的预报指标进行回报检验，以证实其在业务中的切实可行性。     

南秦岭十里坪锑矿床成矿时代及成因的初步研究

十里坪锑矿床受赵川陆缘隆_滑构造的主滑脱拆离带的控制。矿体呈脉状赋存于韧_脆性主滑脱带上部的脆性次级断层_节理中,矿石类型主要为萤石石英辉锑矿型。围岩为太古宙_元古宙变质岩系,围岩蚀变弱。成矿流体属H2O_CO2_NaCl体系,流体包裹体盐度w(NaCleq)为3.6%～11.3%,均一温度为109～232℃,形成压力大致为800×105Pa。硫、铅同位素研究表明,矿质主要来源于变火山岩围岩;氢、氧同位素显示,成矿流体以大气降水为主,初步将该矿床定为变质岩源就地式大气降水热液矿床。矿石中萤石Sm_Nd等时线年龄为(392±24)Ma,与南秦岭北部晚古生代拗陷区热水喷流_沉积成矿时代相一致,它们都形成于秦岭微板块泥盆纪非造山裂解阶段。     

青铜文物腐蚀过程中的次生矿物

产于不同环境不同地方的青铜文物经矿相显微镜观察、电子探针成分分析和X射线衍射研究表明，在青铜文物腐蚀层中观察到次生矿物——赤铜矿、孔雀石、蓝铜矿、白铅矿和锡石。由上述矿物组成的腐蚀层在青铜器表面形成保护层。腐蚀层细分为红色赤铜矿层、绿色碳酸盐矿物层和黄色锡石层组成，其厚度小于1mm。青铜合金在潮湿条件下的腐蚀比在干旱条件下要严重，另外青铜合金是适用于作高放废物地质处置系统中的废物罐的候选材质。     

储层岩石电性特征的逾渗网络模型研究(英文)

建立能够反映储层孔隙结构、流体特征的逾 渗网络模型,通过数值模拟研究了储层孔隙尺寸、 孔隙形状、连通性、微孔隙的发育状况等对I-Sw曲 线影响的定性规律,研究了地层水矿化度对岩石电 阻率的影响。分析讨论了不同因素对电阻率影响的 相对强度。最后,通过曲线拟合定量地研究了不同 因素对I-Sw曲线的影响规律。研究表明,在上述影 响因素中连通性和微孔隙对I-Sw曲线的影响很大, 其它因素的影响强度较小。地层水矿化度对岩石电 阻率绝对值的影响很大。“非阿尔奇”现象普遍存在, 在低渗透(低连通性)储层岩石中更为明显。     

Photosynthesis-transpiration coupling model at canopy scale in terrestrial ecosystem

At the hypothesis of big leaf, an ecosystem photosynthesis-transpiration coupling cycle model was established by the scaled SMPT-SB model from single leaf to canopy, and model parameterization methods were discussed. Through simulating the canopy light distribution, canopy internal conductance to CO2 can be scaled from single leaf to canopy by integrating to canopy using the relationship between single internal conductance and photosynthetic photon flux density. Using the data observed by eddy covariance method from the Changbai Mountains site of ChinaFLUX, the application of the model at the canopy scale was examined. Under no water stress, the simulated net ecosystem photosynthesis rate fitted with the observed data very well, the slope and R2 of the line regression equation of the observed and simulated values were 0.7977 and 0.8892, respectively (n = 752), and average absolute error was 3.78 μmol CO2 m-2s-1; the slope, R2 and average absolute error of transpiration rate were 0.7314, 0.4355 and 1.60mmol H2O m-2 s-1, respectively (n = 752). The relationship between canopy photosynthesis,transpiration and external environmental conditions was discussed by treating the canopy as a whole and neglecting the comprehensive feedback mechanism within canopy, and it was noted that the precipitation course affected the transpiration rate simulation badly. Compared to the models based on eco-physiological processes, the SMPT-SB model was simple and easy to be used. And it can be used as a basic carbon and water coupling model of soil-plant-atmosphere continuum.     

指数平滑技术在斜坡位移预测中的应用

应用趋势型数据指数平滑模型预测了链子崖危岩体监测点GA的位移量.根据其观测数据呈线性趋势的特点,选取趋势型二次指数平滑的线性预测公式和合适的平滑常数值进行了计算预测.预测结果表明位移预测值与实际观测值之间的误差很小,说明该模型可很好地应用于斜坡变形位移的预测.     

Tetrahedral Plots of the Phase Relations for Basalts

The phase relations of quaternary systems are generally represented by projections onto ternary compositional planes. Such projections often obscure relationships that would only be evident in a three-dimensional tetrahedral plot. The tetrahedral plot requires that compositions of the minerals and melts be transformed into Cartesian coordinates. It is shown here how this transformation is carried out. The application is demonstrated by tetrahedral plots of experimental melt compositions of partially molten lherzolite. Furthermore, the plot can be used to evaluate whether or not a particular basaltic composition represents a primary melt. The methods are applicable to any four-component system.