华北太古宙高压基性麻粒岩的两类PT轨迹及其构造意义:矿物化学和变质作用研究

在华北克拉通桑干构造带中,分布有许多太古宙高压基性麻粒岩,呈大小不等的岩块产于强烈变形的TTG片麻岩、二辉麻粒岩、混合岩和花岗岩中.高压麻粒岩富含石榴石斑晶,斑晶内部钙铝榴石含量明显高于边缘,一般可达25%～28%.许多石榴石含有单斜辉石包体,A12O3含量高达7.4%～11.2%,相应的契尔马克分子比例为12%～18%.这些成分特征指示了早期相对较高的变质压力.石榴石斑晶广泛发育后成合晶反应边,是Pl-Opx-Amp-Mt组合的放射状细粒交生体,邻接的单斜辉石和石榴石斑晶边缘与后成合晶组合近于反应平衡,单斜辉石Al2O3含量小于5%,石榴石边缘的钙铝榴石含量也大大低于核部.这些都显示了压力较低条件下石榴石和单斜辉石的分解.温度压力的计算结果揭示出高压麻粒岩的两类PT轨迹,它们早期的变质作用都表现出较高的压力(1.2～1.45GPa).一部分高压麻粒岩具有顺时针的PT轨迹,并显示升温减压和近等温减压过程.它们很可能形成于晚太古代某种型式的俯冲和碰撞构造过程.另一部分高压麻粒岩具有逆时针的PT轨迹,显示降温降压过程,并且早期变质温度高达1050C.它们很可能来自碰撞之前的岛弧下地壳底部.在碰撞阶段的后期,这些不同成因的高压麻粒岩都被卷入了与碰撞构造直接相关的桑干构造带,经历共同的构造抬升过程.桑干构造带可以认为是构造缝合带.     

凡口铅锌矿床海底热泉喷溢成矿的地质地球化学特征

凡口铅锌矿是发育于海相碳酸盐岩建造中的海底热泉喷溢沉积矿床。在研究矿床地质特征和地球化学特征的基础上,总结了发育于同沉积断裂两侧的矿体的形态、产状,矿石组构,成矿元素、微量元素、稀土元素的组成与分布,成矿温度和流体的性质,提出了热泉成矿作用与海相碳酸盐沉积作用同时演化的结论。     

凡口铅锌矿床海底热泉喷溢成矿的物理化学环境

凡口铅锌矿是发育于碳酸盐岩建造中的海底喷溢沉积矿床 ,以“一大二富三集中”的特点和典型的地质地球化学特征吸引着中外矿床地质工作者。叠层状矿体发育于同沉积断裂的旁侧 ,矿层与灰岩呈沉积接触关系。矿石具沉积碎屑组构 ,黄铁矿、闪锌矿具外生特征。稀土元素组成和硫同位素组成反映矿床与同生作用有关。铅同位素组成具有壳源和下地壳来源铅的特征。矿区主要矿层经历海底热泉喷溢沉积—成岩的演化     

栖霞金矿矿物、流体和同位素特征及意义

栖霞金矿床伴生的黑钨矿是低温热液的产物。成矿流体的成分与典型的大气降水热液组分相类似,其δ１８Ｏ约为－３．６‰～４．５‰,δＤ约为－５６‰～－９５‰,变化范围较大,但这些氢、氧同位素值很好地反映了大气降水在不同温度和Ｗ／Ｒ比值条件下与胶东群变质岩交换后的分布特征,成矿作用以Ｗ／Ｒ比值较低为特点。金矿床的Ｒｂ－Ｓｒ等时线年龄为１２５．８×１０６ａ,与胶东群变质岩系和混合花岗岩的时差较大,矿化物质的Ｓｒ同位素初始比高达０．７１６８,大气降水深循环对流作用是形成栖霞金矿床的主要原因。     

Synchronous structure control of superlarge ore deposits

The control of synchronous structures on formation of superlarge stratabound ore deposits is immense. Based on studies of ore deposits in South Qiniing, northern Guangdong, Langshan and other areas, three new ideas in comparison with examples of ore control of synchronous structures both in China and abroad are proposed: (i) multiorder ore control of synchronous structures, which means that synchronous structures of different orders display different controls on ore deposits; (ii) synchronous structures in different stages of basin evolution display different controls on basin fluid system and ore-forming system; (iii) synchronous strurture accompanying hydrothermal mineralization as a preexisting weak surface in earth crust often reactivate in later tcctono-thermal event to be a channelway for magma or thermal fluids which superimposed on and reformed preexisting ore beds to form large or superlarge composite ore deposits.     

矩形钢筋混凝土水处理池震害预测方法及抗震对策

提出了矩形钢筋混凝土水处理池的一种震害预测方法,并对海口市米铺水厂中的水处理池进行了计算分析,论述了水处理池的对抗对策。     

对流层高层偏北气流在梅雨暴雨中的作用

文中对江淮梅雨暴雨过程中的高低空流场特征及物理过程进行分析．结果表明：对流层上部青藏高原东侧常有高空偏北大风轴汇入南亚东风急流中．在这支强北风轴北端发现高空辐散和辐散的增长．亦即有利于低层辐合上升的持续、发展和加强;表明了低层西南急流与高空青藏高压东侧的偏北强风轴之间的次级环流圈,有利于梅雨暴雨的持续．     

An assessment of the predictability of the East Asian Subtropical Westerly Jet based on TIGGE data

The predictability of the position, spatial coverage and intensity of the East Asian subtropical westerly jet(EASWJ) in the summers of 2010 to 2012 was examined for ensemble prediction systems(EPSs) from four representative TIGGE centers,including the ECMWF, the NCEP, the CMA, and the JMA. Results showed that each EPS predicted all EASWJ properties well, while the levels of skill of all EPSs declined as the lead time extended. Overall, improvements from the control to the ensemble mean forecasts for predicting the EASWJ were apparent. For the deterministic forecasts of all EPSs, the prediction of the average axis was better than the prediction of the spatial coverage and intensity of the EASWJ. ECMWF performed best, with a lead of approximately 0.5–1 day in predictability over the second-best EPS for all EASWJ properties throughout the forecast range. For probabilistic forecasts, differences in skills among the different EPSs were more evident in the earlier part of the forecast for the EASWJ axis and spatial coverage, while they departed obviously throughout the forecast range for the intensity. ECMWF led JMA by about 0.5–1 day for the EASWJ axis, and by about 1–2 days for the spatial coverage and intensity at almost all lead times. The largest lead of ECMWF over the relatively worse EPSs, such as NCEP and CMA, was approximately 3–4 days for all EASWJ properties. In summary, ECMWF showed the highest level of skill for predicting the EASWJ, followed by JMA.     

Estimating Sea-Level Allowances for Atlantic Canada using the Fifth Assessment Report of the IPCC

Abstract

Sea-level allowances at 22 tide-gauge sites along the east coast of Canada are determined based on projections of regional sea-level rise for the Representative Concentration Pathway 8.5 (RCP8.5) from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5) and on the statistics of historical tides and storm surges (storm tides). The allowances, which may be used for coastal infrastructure planning, increase with time during the twenty-first century through a combination of mean sea-level rise and the increased uncertainty of future projections with time. The allowances show significant spatial variation, mainly a consequence of strong regionally varying relative sea-level change as a result of glacial isostatic adjustment (GIA). A methodology is described for replacement of the GIA component of the AR5 projection with global positioning system (GPS) measurements of vertical crustal motion; this significantly decreases allowances in regions where the uncertainty of the GIA models is large. For RCP8.5 with GPS data incorporated and for the 1995–2100 period, the sea-level allowances range from about 0.5?m along the north shore of the Gulf of St. Lawrence to more than 1?m along the coast of Nova Scotia and southern Newfoundland.     

一次华北暴雨过程中边界层东风活动及作用

利用常规气象观测资料、NCEP 1°×1°逐6 h分析资料、微波辐射计资料及FY-2E气象卫星及雷达探测资料,针对2013年6月4日发生在北京及周边地区的一次暴雨过程中边界层东风活动及作用进行了天气学诊断分析,结果表明:对流性暴雨过程伴随有源自东北平原的边界层东风活动,东风活动具有尺度小、降温明显和湿度大等特点。暴雨过程是边界层东风和中低空暖式切变线、偏南风急流和500 hPa短波槽共同作用的结果;东风湿冷空气的锋面抬升和地形抬升作用共同加强了中低层暖湿气流的辐合上升运动,同时东风冷垫和地形抬升作用触发了雷暴的再次发生,相应雷暴具有高架对流特点。东风气流起到了边界层水汽输送作用,中低层偏南暖湿气流为暴雨的产生提供了充足的水汽和不稳定层结条件。