韧性剪切带的变形变质与同构造熔融作用——以中祁连地块宝库河韧性走滑剪切带为例

宝库河韧性剪切带是发育在中祁连地块北缘上的一条向北陡倾,走向近东西,宽约6 km的右行平移型韧性剪切带.剪切带内岩石原岩为泥质岩、基性岩和花岗岩,变质程度达角闪岩相,变形变质温度在685～763±46℃之间,压力在0.62～0.83±0.13 GPa范围内.其内长英质条带非常发育,规模变化较大,分布局部相对集中且受剪切带控制,走向与剪切带一致,平行于叶理,孤立无根,并在后期递进变形过程中发生不同程度的糜棱岩化、布丁化和褶皱,主要成分为长石和石英,明显不同于韧性剪切前或后侵入的花岗岩脉或岩体.长英质条带特征、REE配分模式及剪切带内岩石的变形变质温度说明剪切带内发育的长英质条带与基体是同源的,是在剪切应变过程中剪切热使围岩内部分物质发生动态熔融形成的,是同构造熔融作用的产物.     

Metamorphism of the Basement of the Qilian Fold Belt in the Minhe-Ledu Area, Qinghai Province, NW China

The basement of the central Qilian fold belt exposed along the Minhe-Ledu highway consists of psammitic schists, metabasitic rocks, and crystalline limestone. Migmatitic rocks occur sporadically among psammitic schist and metabasitic rocks. The mineral assemblage of psammitic schist is muscovite + biotite + feldspar + quartz ± tourmaline ± titanite ± sillimanite and that of metabasitic rocks is amphibole + plagioclase + biotite ± apatite ± magnetite ± pyroxene ± garnet ± quartz. The migmatitic rock consists of leucosome and restite of various volume proportions; the former consists of muscovite + alkaline feldspar + quartz ± garnet ± plagioclase while the latter is either fragments of psammitic schist or those of metabasitic rock. The crystalline limestone consists of calcite that has been partly replaced by olivine. The olivine was subsequently altered to serpentine. Weak deformations as indicated by cleavages and fractures were imposed prominently on the psammitic schists, occasionally on me     

标记方法对皱纹盘鲍(Haliotis discus hannai)生理、生长及存活性状的影响

皱纹盘鲍是我国重要的增养殖贝类,近年来养殖产量增长迅速,但现有养殖群体仍存在抗逆性不足、底播增养殖低效等问题。个体身份的标记技术对于皱纹盘鲍人工选育中谱系记录,以及对于底播增殖效果的精准评估等均具有重要作用。采用金属挂片和塑料黏贴标签两种标记方法,比较了标记后皱纹盘鲍生理、生长存活、标记脱落率及被敌害捕食死亡等方面的差异。研究结果表明,与塑料黏贴标签标记和无标记对照相比,金属挂片标记对皱纹盘鲍标记早期生理包括出现黏液时间、心率变化等产生显著影响,对小规格皱纹盘鲍(壳长<3 cm)造成生长下降、死亡率高等影响,而对大规格皱纹盘鲍(壳长>3 cm)标记生成60 d后长时期的生长、存活以及逃避敌害均无显著影响;塑料黏贴标签标记方法与无标记对照组相比,均未对皱纹盘鲍造成显著影响。验证了皱纹盘鲍个体水平下两种标记方法的有效性及适用性,特别是对大规格苗种标记后生长、存活等性状无显著影响。研究结果将为皱纹盘鲍人工选育以及底播增养殖等工作提供有益指导。     

VOLUMETRIC SEDIMENT CONCENTRATION IN DEBRIS FLOWS

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Wave Height Transformation and Set-up Between a A Submerged Permeable Breakwater and A Seawall

In this study, we investigated wave transformation and wave set-up between a submerged permeable breakwater and a seawall. Modified time-dependent mild-slope equations, which involve parameters of the porous medium, were used to calculate the wave height transformation and the mean water level change around a submerged breakwater. The numerical solution is verified with experimental data. The simulated results show that modulations of the wave profile and wave set-up are clearly observed between the submerged breakwater and the seawall. In contrast to cases without a seawall, the node or pseudo-node of wave height evolution can be found between the submerged breakwater and the seawall. Higher wave set-up occurs if the nodal or pseudo-nodal point appears near the submerged breakwater. We also examined the influence of the porosity and friction factor of the submerged permeable breakwater on wave transformation and set-up.     

Taiwan Yushan Snowfall Activity and Its Association with Atmospheric Circulation from 1979 to 2009

Yushan is the most famous location for snow in Taiwan,while snowfall in the subtropical zone is rare.When it is snowing in Yushan,people are experiencing unusually cold and wet weather elsewhere in Taiwan.In this study,Yushan snowfall activity from 1979 to 2009 and the related atmosphere circulation were examined with the Taiwan Central Weather Bureau’s Yushan weather station observations and the National Centers for Environmental Prediction/Department of Energy(NCEP/DOE) reanalysis atmospheric data.To provide a quantitative measure of snowfall events,a snowfall activity index(SAI) was defined in this study.The time series of yearly SAIs shows that Yushan snowfall activity for an active year,such as 1983(SAI =39 153) was ～118 times larger than for an inactive year,such as 1999(SAI=331).Our analyses show that snowfall activity is closely related to the position of the East Asian Trough(EAT) and the strength of the West Pacific High(WPH).In active years,when the EAT shifted eastward and the strength of WPH increased,an anomalous anticyclone occurred in the West Pacific.This anticyclone introduced anomalous southwesterly flows along the southeastern cost of mainland China and over Taiwan,resulting in a wetter-than-normal atmosphere that favored snowfall.Alternatively,in inactive years,a drierthan-normal atmosphere resulted in sluggish snowfall seasons.     

Variability in rainfall threshold for debris flow after the Chi-Chi earthquake in central Taiwan, China

The purpose of this study is to analyze variability in rainfall threshold for debris flow （critical rainfall for debris flow triggering） after the ML 7.3 Chi-Chi earthquake in central Taiwan in 1999. Two study sites with different geological conditions were surveyed in the earthquake area. Streambed surveys were conducted to continuously monitor debris flows between 1999 and 2006. During the 7-year study period, every debris flow event was identified, and the streambed characterized. Results show that the rainfall threshold for debris flow was remarkably lower just after the Chi-Chi Earthquake, but gradually recovered. To date, this rainfall threshold is still lower than the original level prior to the earthquake. This variability in rainfall threshold is closely related to the mount of sediment material in the initiation area of debris flow, which increased rapidly due to landslides resulting from the earthquake. With the increase in sediment material, the rainfall threshold was lowered severely during the first year following the Chi-Chi earthquake. However, heavy rainfalls mobilized the sediment material, causing debris flows and transporting sediment downstream. With the decrease in sediment material, the rainfall threshold recovered gradually over time. Furthermore, debris flows occurred only in the subbasins that had sufficient sediment material to cause significant movement. Hence, these results confirm that the sediment material in the initiation area of debris flow is a crucial component of the rainfall threshold for debris flow.     

地球磁尾和磁层顶磁场变化的随机特性

本文讨论了平板模型下电阻不稳定性使磁力线由对称平衡状态进入随机状态的可能性;给出该模型下以（x,z）为正则坐标的哈密顿函数表达式;在Harris平衡磁场分布下分析了撕裂模不稳定性,驱动重联和涡旋诱发重联引起的磁力线随机特性;估计了两个磁岛相互作用时磁力线进入随机态的临界值.本文结果可用于讨论地球磁层顶和磁尾处磁场的性质.     

A numerical simulation of debris flow and its application

Debris flow is the flow of solid-fluid mixture and was treated as the flow of a continuum in routing in this study. A mathematical model was proposed to describe debris flow including deposition process and then solved numerically with suitable boundary conditions. Laboratory experiments were also conducted for comparison and calibration of the numerical results as well as for investigation of debris flow phenomena. The numerical model was also applied to simulate the debris flow caused by heavy rainfall in Tungman village of Hualien County located in the east of Taiwan on 23 June 1990. The simulated bed topographies in alluvial fan were in good agreement with those obtained from laboratory experiments and field observations.