一次飑线引发的大风强沙尘暴诊断分析

利用常规探测、地面加密观测、T213数值预报产品和FY-2c/2d红外卫星云图资料,对2008年5月2日河西走廊东部飑线引发的大风强沙尘暴过程进行了天气动力诊断和中尺度分析.结果表明:飑线引发的强风暴是产生强沙尘暴的根本原因.河西走廊东部处在不稳定大气层结中,500hPa阶梯短波槽为飑线提供了大尺度环流背景;700hPa变形场是飑线的触发系统;地面热低压的发展加大了冷锋前后的气压和温度梯度,为对流发展提供了热力不稳定条件;高空急流对于飑线的生成、发展具有重要的作用.     

Research on catastrophic rock avalanche at Guanling, Guizhou, China

On June 28, 2010, a catastrophic rock avalanche occurred after an extreme rainstorm at Guanling with N 25°59′10′′ in latitude and E 105°16′50′′ in longitude, Guizhou, China. This rock avalanche has a long run-out distance of 1.5 km, with 1.75 million cubic meters of debris instantly burying two villages and resulting in 99 deaths. It originated in the coal measure strata, with the upper part of limestone and dolomite, the middle part of the sandstone with gentle inclination, and the lower part of shale and mudstone, together locally with coals. This kind of unique structure, with hard resistant caprock overlying softer ductile rocks, coupled with the central outflow region at the contact zone, has catastrophic potential for rock avalanches and creates challenges for engineering geological/hydrogeological analysis. The topography showed that the hillside slopes were steeper at the upper portion but gentler in the lower portion, looked like the shape of a “boot.” The upper steep landform easily led to slope instability due to its high static shear stresses, and the wide middle and lower parts provided kinematic conditions for long run-out. Transformation of the larger potential energy into kinetic energy contributed to the formation of a rapid long run-out rock avalanche. The rainfall from June 27 to 28 was the apparent trigger of this catastrophic avalanche. The measured rainfall of more than 310 mm within 24 h exceeded the local historical records that were recorded over the last 60 years. The pore pressure on discontinuities of sandstone had an effect on the slope stability. The valley runoff supplied a saturated base for the long run-out debris, inducing an additional increase of the terminus distance and the increased velocity of the avalanche movement.     

焉耆盆地种植冬小麦气候可行性分析

摘要：焉耆盆地种植冬小麦关键在于越冬期气象条件能否保证冬麦安全越冬。通过对焉耆县近60a来冬季气候变化特征分析,年极端最低气温总体呈上升趋势,趋势变化率为0．67℃／10a;极端最低气温与积雪深度成明显的反相关,相关系数r=-0．62,即没有积雪的年份最低气温一般不会特别低;60a中积雪深度不到5cm且最低气温低于-24℃的概率只有14％,正常年份焉耆盆地种植强抗寒性冬麦品种可以安全越冬。2008、2009年冬季偏暖,无稳定积雪覆盖,极端最低气温分别为-17．9℃、-21℃,试种冬麦均获得成功。     

断层内部结构及其对封闭性的影响

先前的研究多考虑断层封堵和开启的2种极端状态,近来的研究认为,在多数情况下断层处于2种之间的状态,只有在静止期具有封闭能力的断层,才有可能对油气起封堵作用。分析断层对流体运移的影响,需要分析断层在演化过程中的内部结构特征。断层可以划分出破碎带、诱导裂缝带和围岩3部分,断层岩和伴生裂缝构成破碎带的主体部分。常见的断层岩包括断层角砾岩、断层泥和部分碎裂岩,它们充填在断层裂缝空间中,断层内部结构受断层形成时的构造应力性质、断层活动强度和围岩岩性因素的控制。从动态角度看,随着断距增加,断层活动伴随着裂缝的发育和岩石的破碎混杂,可用泥质源岩层厚度和断距的比值来划分不同的发育阶段。断层活动期为油气运移通道,在静止时表现出差异性的封闭,通常用断层渗透率和排替压力2个参数来定量评价断层的封闭程度。断层岩渗透率主要受断距、泥质含量、埋深等因素的控制;断层排替压力的预测方法有2种:一种是从断层岩成岩角度分析的"等效埋深法",另一种是分析实测排替压力与主控地质因素的"拟合法"。通过简化的断层模型,建立了渗透率、排替压力与主控因素的预测关系。和储层类似,流体在断层中的运移遵循多孔介质的渗流特征。利用断层两侧的流体压力和油气柱高度并不能直接评价封闭性能,还必须考虑油气充注史和流体压力变化历史。     

SiO2与成矿元素Sb络合作用的实验研究

实验测定了250℃时Sb在含硅和无硅体系中的溶解度。对比研究指出，SiO2的存在明显有利于Sb的溶解，并且Sb溶解度随NaOH浓度的增加而增大。在无硅NaOH体系中，Sb（OH）03基络合物是Sb的主要存在形式。含硅体系中，大量可溶Si的存在，使其有可能与Sb络合形成Sb－Si络合物，在低温贫硫富硅热液中溶解、迁移。体系各种条件的改变，促使SiO2沉淀，是导致Sb－Si络合物不稳定、引起Sb沉淀的主要因素，也是硅化与Sb矿化密切共生的原因所在。     

带有Le'vy噪声的中立型神经网络的反馈控制

针对延迟中立型神经网络系统,研究了反馈控制问题.考虑了带有Le''vy噪声的中立型神经网络,建立了一个适当的Lyapunov函数.通过Lyapunov分析方法并使用一般性Itô公式和LMI技术,得到了闭环系统的均方稳定性准则.最后,通过数值例子证实本文方法的有效性.     

南极布兰斯菲尔德海峡的地球物理场特征与构造发育史

本文分析了“海洋四号”船１９９１年在南极布兰斯菲尔德海峡所采集的地球物理资料。这里的地形地貌、重力异常和磁异常沿东方向呈条带状分布。海峡中的新生代沉积可分为两组沉积系：第一张裂沉积系和第二张裂沉积系。在布兰斯菲尔德海峡西北部,基底发生了断裂,基底断块沿断面下滑,因而在海峡中部形成基底半地堑。通过横穿南设得兰群岛、布兰斯菲尔德海峡和南极半岛的地壳剖面,我们用分层剪切模式解释了在张性应力作用下的岩石圈变形特征。     

Transport and Concentration of Gold in Metamorphic—hosted Reworked Gold Deposits,China

Calculations based on the available thermodynamic data of AuCl ₂ ⁻ and Au (HS) ₂ ⁻ indicate that AuCl ₂ ⁻ is responsible for the transport and enrichment of gold during the stage of pre-concentration in the source bed while Au (HS) ₂ ⁻ is the main gold species involved in the formation of gold deposits in response to hydrothermal reworking. Acid chloride solutions witha _Cl ⁻ > 10° and sulfur-rich solutions with a_Σs in excess of 10⁻² are held as important criteria for gold enrichment in the source bed and for the formation of gold deposits by subsequent hydrothermal event, respectively.