地震道空间分辨力研究

在高分辨率地震勘探中，除了了解子波特性对分辨力的影响外，研究地震道在空间任意方向的分辨力变化规律同样是非常重要的.受分辨力估算方法的局限性，除垂直分辨力和水平分辨力外，目前对于空间任意空间方向分辨力变化的研究很少.本文分析了微分法分辨力和广义空间分辨力估算公式的异同.并利用广义空间分辨力公式分析了分辨力随炮检距、观测点位置、深度的变化规律及其内在本质.与此同时，对广义空间分辨力概念进行了图形解释，揭示了其实质.这对于更好地理解和运用广义空间分辨力计算公式具有重要的意义.     

苏北大丰港海域航道临时抛泥区悬沙扩散影响研究

以大丰港航道临时抛泥区抛泥为研究对象,建立苏北辐射沙洲大丰港海域二维潮流泥沙数学模型,研究了航道临时抛泥区抛泥后的泥沙运移特征及对周边航道、锚地的影响。研究表明,在地形和边界的约束作用下,抛泥区的水质点运动具有明显的往复流特征,大潮涨落潮水质点轨迹存在一定的流路分歧;抛泥区抛泥后,高浓度含沙水体呈南北条状形态,轴线与航道基本平行;涨急和涨憩时刻抛泥,悬浮泥沙对航道具有一定的影响,而落急和落憩抛泥,悬浮泥沙对锚地影响相对较大。     

河西走廊地壳稳定性研究进展

北山南部西山煤窑地区侏罗系与白垩系的构造变形记录了中亚地区晚中生代的主要构造演化过程,对揭示中亚地区的陆内变形具有重要意义。综合应用遥感影像、野外地质观测、构造解析及磷灰石（U−Th）/He（AHe）年代学方法,对北山南部西山煤窑地区的构造变形特征及时限进行了详细分析,并在此基础上探讨了动力学机制。西山煤窑地区发育逆冲推覆构造,以二叠纪花岗岩和晚石炭世辉长岩NE向逆冲至下—中侏罗统煤系地层之上为特征,上盘岩系经历剥蚀形成飞来峰,下盘发育叠瓦状逆冲断层,逆冲推覆距离约10 km。晚石炭世辉长岩的磷灰石AHe年龄显示160~130 Ma的快速冷却事件,指示该地区经历了中晚侏罗世—早白垩世早期的挤压变形,可能是亚洲南缘班公−怒江洋与北缘蒙古−鄂霍茨克洋闭合的远程效应。变形的侏罗系的AHe年龄（120~100 Ma）揭示了早白垩世晚期的隆升事件。结合区域构造事件,表明研究区经历了早白垩世晚期的伸展断陷,可能与早期地壳增厚的伸展垮塌作用有关。晚白垩世之后,正断层反转为逆冲断层,将变形的侏罗系与上覆岩系共同压覆在下白垩统之上,指示北山南部构造背景由伸展转为挤压,局部地区经历了弱挤压变形,并改造了先存挤压与伸展构造。

     

THE IMPACT OF DIFFERENT PHYSICAL PROCESSES AND THEIR PARAMETERIZATIONS ON FORECAST OF A HEAVY RAINFALL IN SOUTH CHINA IN ANNUALLY FIRST RAINING SEASON

An ensemble prediction system based on the GRAPES model, using multi-physics, is used to discuss the influence of different physical processes in numerical models on forecast of heavy rainfall in South China in the annually first raining season(AFRS). Pattern, magnitude and area of precipitation, evolution of synoptic situation, as well as apparent heat source and apparent moisture sink between different ensemble members are comparatively analyzed. The choice of parameterization scheme for land-surface processes gives rise to the largest influence on the precipitation prediction. The influences of cumulus-convection and cloud-microphysics processes are mainly focused on heavy rainfall;the use of cumulus-convection parameterization tends to produce large-area and light rainfall. Change in parameterization schemes for land-surface and cumulus-convection processes both will cause prominent change in forecast of both dynamic and thermodynamic variables, while change in cloud-microphysics processes show primary impact on dynamic variables. Comparing simplified Arakawa-Schubert and Kain-Fritsch with Betts-Miller-Janjic schemes, SLAB with NOAH schemes, as well as both WRF single moment 6-class and NCEP 3-class with simplified explicit schemes of phase-mixed cloud and precipitation shows that the former predicts stronger low-level jets and high humidity concentration, more convective rainfall and local heavy rainfall, and have better performance in precipitation forecast. Appropriate parameterization schemes can reasonably describe the physical process related to heavy rainfall in South China in the AFRS, such as low-level convergence, latent heat release, vertical transport of heat and water vapor, thereby depicting the multi-scale interactions of low-level jet and meso-scale convective systems in heavy rainfall suitably, and improving the prediction of heavy rainfall in South China in the AFRS as a result.     

西准噶尔晚古生代地壳组成与生长:来自Sr-Nd-Pb同位素填图的证据

西准噶尔地区晚古生代岩浆活动剧烈,地壳的垂向和侧向增生显著,地壳生长和演化存在多阶段性。本文重点通过Sr-Nd-Pb同位素填图研究,发现西准噶尔地区ε_Nd(t)值为2.29~8.75,(⁸⁷Sr/⁸⁶Sr)_i值为0.697 397~0.708 336,(²⁰⁶Pb/²⁰⁴Pb)_i值为17.4975~19.0352,整体表现为高正ε_Nd(t)、低(⁸⁷Sr/⁸⁶Sr)_i和年轻的地壳模式年龄特征,源区以古生代新生地壳为主,地幔贡献值整体大于50%,深部地壳几乎不存在古老的结晶基底,可以与区域构造地质、地球物理资料作较好匹配。区域晚古生代主要经历3个时期的造山阶段,分别对应造山带演化的第一阶段(中晚石炭世,岛弧为代表的侧向生长为主)、第二阶段早期(晚石炭世—早二叠世,后碰撞阶段的垂向生长为主)和第二阶段晚期(早二叠世—早三叠世,壳幔混源背景下的垂向生长),区域造山作用结束于早三叠世。