Mineralization time and tectonic setting of the Zhengguang Au deposit in the Duobaoshan ore field,Heilongjiang Province,NE China

The Zhengguang deposit, a representative large gold deposit in the Duobaoshan ore field in NE China, is located in the northeast of the Central Asian Orogenic Belt (CAOB). Ore body emplacement was structurally controlled and occurs mainly at the contact zone between the strata of Duobaoshan Formation and an Ordovician diorite stock. The diorite rocks have a close genetic relationship with Au mineralization. Re–Os isotope dating of Au-bearing pyrite yields an isochron age of 506 ± 44 Ma (MSWD = 15). Based on present and previous dating results, it can be concluded that the Zhengguang deposit formed at ~480 Ma. The mineralization time of the Zhengguang deposit is nearly identical to those of the Duobaoshan and Tongshan deposits, indicating they are all derived from the same metallogenic system. The Duobaoshan-style porphyry Cu–Mo mineralization may exist at deeper levels at Zhengguang. The geochemical characteristics of the Zhengguang dioritic rocks presented in this paper are similar to those of bajaitic high-Mg andesite, and the magmas originated from a mantle wedge metasomatized by melts from a subducting oceanic slab at an active continental margin setting. The Ordovician magmatic–metallogenic events in the Duobaoshan ore field were caused by the westward subduction of an oceanic slab located between the Xing’an and Songliao blocks. It is worth pointing out that the Zhengguang deposit is the oldest known Phanerozoic Au deposit in NE China. Further studies of this deposit will improve understanding of the regularity of ore formation and aid mineralization forecast across the Duobaoshan region.     

An installation system of deepwater risers by an S-lay vessel

Along with the consumption increase of the petroleum products,more countries have transferred their attentions to the offshore fields,especially the deepwater oil and gas reserves.For deepwater exploitation,the risers must be installed to act as the conduits connecting surface platforms to subsea facilities.In this paper,the typical risers sorted by different classes are introduced,and the correspondent installation methods are presented.By investigating the recent projects performed in the deepwater hot spots,and combining the challenges of HYSY201 for riser installation,a lifting device developed for assisting riser installation is proposed and detailed to satisfy the installation of deepwater risers in the LW3-1 Gas Field of in the South China Sea.Tests on both the functions and performances of such a new system exhibit the satisfaction of meeting all challenging requirements of HYSY201 for application to riser installation in waters up to a depth of in the South China Sea.     

天津盛夏降水趋势与初夏华北高压的统计分析

根据初夏(6月)的天气气候演变，预测盛夏(7～8月)的短期气候趋势，一直是急需解决的难题。文章揭示了自1958年以来天津盛夏降水趋势与初夏时节临近地区上空的环流特征之间的统计关系。结果表明，初夏华北高压强时盛夏天津降水偏少，反之盛夏天津降水偏多，不仅逐年的对应关系显著，而且变化趋势相反，转折时期也一致。初步解释了20世纪70年代以前天津(华北)盛夏多雨和80年代至今天津(华北)少雨的物理原因。以此为主要根据建立了初夏对于盛夏天津降水的短期气候预测方法，1998～2003年连续6年预报正确。     

Wave diffraction on arc-shaped floating perforated breakwaters

An analytical method is developed to study the sheltering effects on arc-shaped floating perforated breakwaters. In the process of analysis, the floating breakwater is assumed to be rigid, thin, vertical, and immovable and located in water with constant depth. The fluid domain is divided into two regions by imaginary interface. The velocity potential in each region is expanded by eigenfunction in the context of linear theory. By satisfying continuity of pressure and normal velocity across the imaginary fluid interface, a set of linear algebraic equations can be obtained to determine the unknown coefficients for eigenfunction expansions. The accuracy of the present model was verified by a comparison with existing results for the case of arc-shaped floating breakwater. Numerical results, in the form of contour maps of the non-dimensional wave amplitude around the breakwater and diffracted wave amplitude at typical sections, are presented for a range of wave and breakwater parameters. Results show that the sheltering effects on the arc-shaped floating perforated breakwater are closely related to the incident wavelength, the draft and the porosity of the breakwater.     

中学地理科学实验的六大类型及其案例分析

依据实验的根本目的,为拓展学生对地理过程的理解,体验真实的地理原理,笔者将中学地理科学实验划分为经典实验室实验、时间变化模型实验、类比实验、空间变化模型实验、物理模型实验以及计算机模型实验六大类型,并对每一类型实验进行举例分析,希望以此深化地理科学实验的理论研究、丰富地理科学实验的实践案例、培养学生的地理核心素养,为地理科学实验教学研究提供新的视角。     

作用于平台桩腿的海冰屈曲破坏冰压力随机过程模型及其参数确定

冰对结构的作用过程是典型的随机过程。本文在冰压力过程为平稳过程的假设下，从渤海海冰对平台桩腿作用的大量实测冰压力数据中，选取了２１条冰屈曲破坏时的冰压力时程曲线，对它们进行谱分析后，得到了单点冰屈曲破坏的压力随机过程的谱密度，并确定了谱参数及其跟环境要素的关系，依据文献［１］中冰压力沿圆柱面的空间分布，建立了绕桩腿的冰压力随机场模型，并得到了作用于桩腿的总冰力随机过程及其谱密度。本文的研究成果为平台结构冰激随机振动和疲劳累积损伤分析提供了荷载基础     

云南腾冲青海湖泊沉积物物化参数的特点、环境意义及末次冰消期以来气候环境变化

根据对云南腾冲青海湖泊沉积钻孔样品的粒度特征、总有机碳、碳酸盐、磁化率及年代学分析测试, 探讨了各指标的变化特点及其环境指示意义, 指出了云南高原湖泊沉积物化指标的特殊性及其变化特点。在此基础上, 重建了云南腾冲地区末次冰消期(15830a B.P.)以来沉积环境与气候干湿变化历史。通过青海沉积物年代序列的重建和综合各物化参数分析得出, 云南腾冲地区自15830a B.P.以来总体呈现冷湿-温湿-暖干-温和偏干的气候演变过程, 并可分为4个阶段, 即15830~12790a B.P.气候温凉偏湿; 12790~4680a B.P.为温暖湿润期, 湖泊水位高, 气候湿暖, 降水多; 4680~312a B.P.气候特征呈现出从温湿到暖干气候逐渐演化, 降水减少, 湖泊水位下降; 312a B.P.以来气候特征为前期温和湿润, 后期具有暖干化特征, 反映了近几十年来全球气候变暖导致的气候变化趋势并叠加了研究区人类活动对区域环境的影响。     

冕洞演化与太阳活动周的关系及在日地预报中的应用

冕洞的研究在近二十多年里取得了丰硕的成果。本文回顾了冕洞的发现及观测历史，系统阐述了冕洞的结构特征、形成及演化规律，讨论了冕洞对日地空间产生的影响，冕洞与超级活动区的关系以及冕洞在太阳活动预报中所起的作用，在此基础上利用１９７０—１９９５年的冕洞资料对冕洞的时空分布和磁极性演化规律与太阳活动周的关系，以及冕洞与太阳风速度、地磁扰动等方面进行分析研究，得出以下结论：（１）冕洞在南北半球的分布在形态上基本是对称的，但在冕洞数量上北半球稍占优势；（２）冕洞的盛衰演化呈周期性，表现为赤道冕洞周期与黑子周期是完全一致的，极冕洞周期与黑子周期相位相差１８０°；（３）赤道冕洞的纬度分布随太阳活动周上升而上升，当太阳活动周达到极大值时，它也达到极大，然后再随太阳活动周下降而下降，极冕洞的纬度延伸方向演化与赤道冕洞相反；（４）极冕洞的极场呈１１年周期性，并且极场反转出现在太阳活动峰年期间；（５）太阳风和地磁扰动与冕洞的演化有着密切的关系     

0679香山局地大暴雨的中小尺度天气分析

利用Doppler雷达、地面自动站、Profile垂直风廓线及GPS水汽分布等多种新型探测资料, 对2006年7月9日夜间发生在北京西郊香山附近的局地大暴雨天气的影响系统和γ-中尺度强降雨落区形成的动力机理进行了精细分析。对雷达等本地多种探测资料的精细研究表明:地形辐合回波带是造成这次过程的主要影响系统。地形辐合回波带上中气旋回波块的滚动更迭是大暴雨落区形成的直接原因; 近地面辐合对大暴雨落区强降雨的发生具有重要作用。大暴雨落区形成阶段近地面3种辐合同时存在:平原东南风与山区偏北风风向切变辐合、平原东南风在山脉阻挡作用下的抬升辐合、大暴雨落区中心的γ-中尺度气旋性辐合。研究还表明:山前近地面地形辐合扰动, 向上传播, 引发边界层扰动的动力过程是香山大暴雨落区形成的主要动力源, 而来自东南方向近地面层的暖湿平流为大暴雨提供了有效的水汽和能量。     

云南地壳形变与丽江7.0级地震

本利用滇西、滇中地区大地垂直形变和跨断层短水准、短基线的监测资料进行综合分析论证，其结果表明：１９９６年２月滇西丽江７．０级地震前，该区应力场方向自１９９０年以来产生了由北东－北西的转变，震源区出现高达１０９ｍｍ的垂直差异运动１９９３－１９９６年有７５％的断层形变测点相继出现不同程度的中期、短期和临震异常。大地垂直形变与断层形变的共性演变特性，为强震的预测提供了一个较好的震例。