Premonsoonal water characteristics and circulation in the east central Arabian Sea

The hydrographic structure in the east central Arabian Sea during premonsoon period undergoes significant temporal change in the thermal field of upper 100 m, wherein temperature rises by about 0–5°C on an average from May to June. The major contribution in increasing the surface layer temperature comes from surface heat exchange processes, while the horizontal advective process tends to remove the heat from the upper layer. The geostrophic flow patterns are similar from May to June in the major part of the study area while in the coastal areas off Goa a southerly current sets in June in response to coastal upwelling.     

电磁法在工程地质勘察中的应用

本文采用有场源电磁法勘探粤东沿海广(州)深(圳)珠(海)及深(圳)汕(头)南线等高速公路工程,勘探使用美国GDP—12及加拿大EM—37电磁数据采集系统。文章论述了时间域与频率域的多种电磁法装置在桥梁、互通、遂道及软土公路工程中的地磁物理应用前提及它们的应用环境、工作效率、勘探深度等,低阻覆盖下的地质分层及断层产状性质等问题是本文探讨要点。文中例举了多种装置的电磁异常场剖面图及其曲线形态:对磨刀门桥址西江断裂的电磁异常剖面曲线形态、特征作了构造地质解释,认为该断裂系由两条主干断层组成的蠕滑断层组。上述工程地质解释结论已作为工程勘察设计依据。有的电磁异常已被工程地震及钻探证实。     

胶东地区地质体含金性的地质地球化学评价

通过分析胶东地区各地质体例 的金根率分布模型,金含量的分数维特征,金及相关元素的组合特征天南地北来评价胶来地区各地质体的含金性。结果表明：胶东群,粉子山群,玲珑型花岗岩为金的矿源岩,郭家岭型花岗岩可能即为本区的金成矿提供成矿物质又起到了“热机”的作用。     

台湾岛以东A-24C及A-50C岩芯中的放射虫化石与沉积环境

根据对台湾岛以东海域A-24C,A-50C岩芯中放射虫化石的分析结果,并借助WP3岩芯有孔虫,δ^18O曲线分析,测试资料,对两岩芯地层作了对比与划分,结果显示：两岩芯的上部（A-24C为0～30cm,A-50C为0～35cm）属全新世沉积;下部（A-24C为30～234cm,A-50C为35～163cm）属晚期更新世沉积。 两岩芯中放射虫丰度、分异度的变化与黑潮主流线的摆动密度相关。末次冰期时的低海面导致黑潮主流线移至研究区（125℃E）以东,放射虫丰度,分异度出现低值,有的层位出现零值,而随着海面回升,黑潮逐渐移至现在的位置,放射虫的丰度,分异度出现高值,另外综合该区分析资料,推算两岩芯的平均沉积速率为A-24C岩芯全新世3cm,晚期更新世12.6cm,A-50C岩芯全新世2.9cm,晚更新世12.4cm,晚期更新世沉积速率均大于全新世。     

Determination of source parameters of small earthquakes in the east part of Guandong and south part of Fujian Province

Determination of source parameters of small earthquakes from amplitude ratios of and is studied in this paper when the distribution of the regional seismic network is skew to the earthquakes. The distribution of stations of the seismic network was to one side of the 17 earthquakes chosen from among 39 earthquakes in the east part of Guangdong and south part of Fujiang Province. The distribution of stations was classified into three types according to their relative positions with respect to the chosen earthquakes and the experiments of artificial data were done. Excellent results were also presented in various unfavourable conditions by using the method. As to the 39 small earthquakes recorded by the network in east Guangdong and south Fujian Province from 1982 to 1986, the results can be summarized as follows: Most of the fault planes of the earthquakes apear to be steep. Most of the principal compression stressesP and tensile stressesT are nearly horizontal, concentrating in the WNW-ESE direction. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinia,13, 420–429, 1991.     

东准噶尔巴斯克花岗岩闪长岩锆石U-Pb年龄、地球化学特征及其构造意义

巴斯克花岗闪长岩位于野马泉岛弧内,本文综合野外地质、岩相学、地球化学以及锆石U-Pb年代学等多学科手段,进而为该地区晚石炭世时期构造背景提供岩浆岩约束。岩石地球化学研究表明,岩体主量元素具有高硅、准铝—弱过铝质、钙碱性的I型花岗岩特征;岩石样品稀土元素总量在83.79×10-6至 125.67×10-6之间,且轻/重稀土之间的比值介于5.32至8.63之间(平均值为7.1),指示轻稀土较重稀土富集。Eu 元素轻度负异常 (δEu=0.69~0.89)。样品富集大离子亲石元素(如K、Rb、Ba),且亏损高场强元素(HFSE,如Nb、Ta和Ti)及P, Nb、Ta负异常明显。岩体锆石206U/238Pb加权平均年龄为301.3±2.5 Ma (MSWD=0.33)和310.7±3.6 Ma (MSWD=0.75),表明岩体形成时代为晚石炭世。综合区域地质特征、岩石地球化学和岩浆源区特征,表明东准噶尔地区晚石炭世(310~301 Ma)处于造山带碰撞后的陆壳伸展构造体制,且岩浆具有壳幔混合和分批熔融、增量生长的特征。     

青藏高原东侧常规观测资料对WRF模式预报误差的贡献分析

利用WRFDA-FSO(Forecast Sensitivity to Observation)系统,统计分析2009年和2010年5—10月青藏高原东侧常规地面和高空观测对WRF模式预报误差的贡献。结果表明:地面观测资料各要素中,温度场对模式预报误差贡献最大,风场、气压和水汽场的贡献相对小;四川东部、广西大部和云南南部边缘地区的资料对改进预报产生正贡献较大。高空资料各要素中,温度场对模式预报误差贡献最大,其次是水汽场,风场贡献最小;高空站资料对改进预报产生正贡献较大的区域主要分布在云南大部、贵州西部边缘和广西西北部边缘地区。依据误差统计结果,剔除对改进预报产生负贡献较大的地面和高空站资料后,模式降水和温度预报效果有所改善。     

Estimation of the Threshold Friction Velocities over Various Dust Storm Source Areas in Northwest China

The emission of dust particles into the atmosphere is governed by the aerodynamic and resistant factors,which are quantified by the friction velocity u＊ and the threshold friction velocity u＊t, respectively. The threshold friction velocity u＊t influences the vertical dust flux and dust transport. Based on the micrometeorological data obtained in the springs of 2004 and 2006 over Hunshandake desert area, Loess Plateau,and Gobi desert area, the relationship between dust concentration and friction velocity for the dust events that occurred over Hunshandake desert area was investigated, and the threshold friction velocities over the three different dust source areas were estimated. The results show that the value of dust concentration is low during the preemission stage of a dust storm event, and the rapid increase of friction velocity provides favorable dynamic conditions for dust emission. During the dust emission stage, the dust concentration increases sharply due to mechanical and thermal turbulent mixing. At the calm-down stage, the dust concentration drops nearly linearly with the decreasing friction velocity, on account of the gravitational deposition of larger dust particles. When the dust concentration is higher than 200 μg m-3, it is considered as a dust emission process. According to the criteria, the values of threshold friction velocity over Hunshandake desert area and Gobi region are 0.6 and 0.45 m s-1, respectively. The threshold friction velocity over Loess Plateau depends on the wind direction, due to the complex terrain and inhomogeneous surface. The northwest wind shows the effects of the Mu Us desert in the northwest. The corresponding u＊t is 0.35 m s-1. The south wind exhibits the characteristics of the Loess hilly dunes in the south, and the u＊t is 0.7 m s-1.The large roughness length of the Loess hilly dunes and the large inter-particle cohesion for the clay soil texture increases the local friction velocity. Different threshold friction velocities and occurrence frequencies of strong wind account for different dust emission capabilities for various source areas.     

辽河裂谷东部凹陷粗面岩成因机理探讨

在渤海湾诸盆地中, 唯独辽河盆地东部凹陷发育粗面岩, 引起了国内地质学界的广泛关注。本文通过岩石学特征、构造运动背景和形成环境的综合分析认为: 粗面岩的原始岩浆来源于上地幔的较深部位, 与玄武岩等火成岩属同源岩浆, 但粗面岩经历了更长时间的结晶分异作用; 形成粗面岩的岩浆, 在上涌过程中未经历任何地壳混杂作用, 外部环境属于水下喷发; 构造运动是岩浆活动和火成岩岩性发育及其分布的内因, 东部凹陷沙三中段沉积时期所特有构造运动背景造就了粗面岩发育的内外部环境。     

中国东部夏季降水与东亚垂直环流结构及其预测试验

本文在分析中国东部夏季降水的时空分布特征基础上, 从东亚高、中、低层大尺度环流异常着手, 选取对中国东部夏季降水异常有显著影响的大气环流预报因子, 分别应用逐步回归和最优子集回归法两种统计降尺度方法, 以动力气候模式CAM3.1预报输出的大气环流预报因子为基础, 以中国东部夏季降水的典型空间分布型为预报对象, 建立动力与统计相结合的中国东部夏季降水预测模型, 并对1981～2000年的中国东部夏季降水进行回报试验。结果表明: 中国东部夏季降水具有4类典型的空间分布型式, 且具有显著的准2年和年代际尺度振荡周期; 东亚高、中、低层大气环流异常的特定配置, 对东部夏季降水的空间分布型有显著影响; 使用两种降尺度方案建立的动力与统计相结合的预测模型对中国东部夏季降水异常具有一定的预报技巧, 可以在一定程度上提高动力模式对中国东部夏季降水的预报效果。