Contribution to the Marine Lower Triassic Fauna of Southern China

Early in 1936 Dr. T. K. Huang, Messrs. S. F. Sheng, I. Ting andK. S. Tsui during their field work in the Changhsing coal field, NWChekiang, found Scythic pelecypods and ammonoids in the so-calledChinglung limestone of that region. The discovery of Lower Triassic     

火星陨石NWA 8716的岩矿学特征及粗粒橄榄石斑晶的来源

火星陨石可以为研究火星岩浆演化过程提供直接证据并限制其源区特征.通常认为含粗粒橄榄石斑晶辉玻无球粒陨石携带有火星原始地幔的信息,因此选取该类样品Northwest Africa (NWA) 8716为研究对象,进行岩相结构及矿物成分分析. NWA8716由橄榄石、辉石、填隙状熔长石以及其他次要矿物组成.其中橄榄石颗粒有两种级别的粒径,长轴分别约为0.5–1.8 mm和50–400μm.较小橄榄石斑晶内部的熔体包裹体和NWA 8716全岩成分(计算值)均显示明显的轻稀土元素亏损([La/Yb]CI值为0.06–0.1),说明NWA 8716源于一个亏损的火星岩浆池.粗粒橄榄石斑晶的来源对衡量该样品是否能够代表原始熔体成分非常重要.对橄榄石晶体的粒径统计分析发现,粗粒橄榄石斑晶应为堆晶.进一步对铁-镁以及稀土元素分配特征的计算表明NWA 8716并非形成于一个封闭系统,但是计算所得原始熔体成分与全岩成分差异不大,因此粗粒橄榄石斑晶应当来源于与母岩浆成分相似的熔体.总的看来, NWA 8716应当来源于亏损型火星幔源区且演化程度较低.     

Theoretical Analysis of A Buoyant Jet Interacting with Small Amplitude Waves

A new theoretical solution is presented here for the dynamic characteristics of a buoyant jet due to opposing small amplitude waves.The conservation equations of mass,tangential momentum and vertical momentum are solved by the integral method which encompasses the Gaussian profiles of velocity and density.The action of waves is incorporated into the equations of motion as an external force and a new exact solution is obtained to predict the trajectory,velocity distribution and boundary thickness of the buoyant jet over an arbitrary lateral cross section.It is found that the velocity along the centerline is inversely proportional to the ratio of the momentum of the wave to the buoyant jet.The averaged boundary width varies with the fluctuation of the boundary width,the distance from the orifice and the velocity correction function.Owing to the motion d waves,the fluctuation of the boundary width is proportional to the wave steepness.     

基于统计检验法研究Amurian板块相对独立性

Amurian 板块是Zonenshain等提出的提出的东北亚地区内部一个构造亚板块.Amurian板块自提出以来就一直受到地学界的广泛重视.它到底是欧亚大陆的一部分,还是独立于欧亚大陆之外的一个独立次级构造块体?这个问题一直是是东亚,乃至欧亚大陆构造动力学研究的核心问题之一.许多学者从地质和地球物理学两个角度研究了Amurian板块存在的可能性.但是复杂的构造特征和稀少且弥散的地震分布使得Amurian问题充满了争议.全球卫星定位系统(GPS)技术的不断进步使得在短时间获得高精度、大范围、准实时的地壳运动观测数据,并确定地壳运动速度场成为可能.本文利用东北亚地区最新GPS资料,从大地测量学角度对东北亚地区的地壳运动特征进行分析,基于统计检验方法重点研究Amurian板块相对欧亚大陆的独立性及其边界等问题.     

Dimension and frequency of bar formation in a braided river

This paper presents flume and field observations of a bank-confined braided river. Morphological features, including plan form configuration, channel width, and main channel migration, were examined by a series of experiments. Repeated measurements of channel morphology, provided a basis to estimate the relationship between noncumulative frequency of bars and bar area. Additional results from the Dajia River, located in Central Western Taiwan, were presented to provide a reference data set for comparing the laboratory and field data. The results indicate that the relationship between bar length and width can be predicted by a simple best-fit power function relating to self-similarity characteristics. The Hurst index by Walsh and Hicks (2002) provides acceptable predictions of the bar length and width observed in the experiments and confirmed by the field investigations. Eexperimental and field results both show that large river width yields a uniform distribution of bar areas with the similar discharge, leading to a large value of exponent (β) in the model. The river width is confirmed to be a critical parameter in the main channel shift. A small increase in channel width likely increased rapidly the shift cycle.     

卫星跟踪卫星模式中轨道参数需求分析

首次基于半解析法利用GRACE(Gravity Recovery and Climate Experiment)双星K波段星间速度误差、GPS接收机轨道误差和加速度计非保守力误差影响累计大地水准面精度的联合模型开展了卫星跟踪卫星模式中轨道参数的需求分析.建议我国将来首颗重力卫星的平均轨道高度设计为400 km和平均星间距离设计为220 km较优.此研究不仅为我国将来卫星重力测量计划中轨道参数的优化选取以及全球重力场精度的有效和快速估计提供了理论基础和计算保证,同时对将来国际GRACE Follow-On地球重力测量计划和GRAIL(Gravity Recovery and Interior Laboratory)月球重力探测计划的发展方向具有一定的指导意义.     

矿山坑道內无线电波透視矿体的試驗

一、引言无线电波在地球物理探测中的应用,最早的一次试验是由A.A.彼特罗夫斯基于1928年在苏联外高加索某一硫化矿床上进行的,而且得到了由硫化矿体所引起的无线电波“阴影”。     

春季华南在冷空气垫上空南支西风中低压槽东移时的天气过程分析

春季,冷空气进入华南以后,青藏高原以东往往在低空出现一层较薄的冷空气垫。在高空平直的西风环流下,沿南支西风急流带,有低压槽在冷空气垫之上东移,地面高气压区域中常有低压槽和锋生出现。本文查考了1958—1962年3—5月华南地区这类天气过程,并讨论了这类天气形势下的降水和雷暴的短期预报。     

青藏高原加热对东亚地区夏季降水的影响

东亚地区降水主要集中在夏季,是亚洲夏季风系统的重要特征.本文利用NCEP再分析资料和CRU的降水资料,分析了青藏高原非绝热加热对东亚夏季降水的影响.结果表明,东亚地区夏季降水的分布形势与青藏高原非绝热加热变化有很好的相关关系.由于高原非绝热加热可在亚洲东部沿海地区强迫出类似Rossby波列的大气环流低频振荡结构,而此低频波可以影响到西太平洋副热带高压的形态和位置变化,从而使得东亚夏季降水的形势发生变化.而青藏高原非绝热加热的形态从春季到夏季有很好的持续性,春季高原加热与夏季东亚的降水形势分布也有很好的相关.本研究中采用的青藏高原非绝热加热指数可作为东亚夏季降水预测的一个指标,亚洲季风降水不仅受赤道太平洋海温的影响,青藏高原地区的非绝热加热对其也有显著的影响作用.