A 16 ka climate record deduced from δ^13C and C/N ratio in Qinghai Lake sediments, northeastern Tibetan Plateau

1 INTRODUCTION δ13C in organic matters from lacustrine sedi- ments varies with several factors including aquatic plants, vegetation type in the catchment, atmos- pheric CO2 concentration, climate (temperature and precipitation), and properties of water, …     

Submicron polyphase inclusions in garnet from the Tananao Metamorphic Complex, Taiwan: a key to unravelling otherwise unrecognized metamorphic events

Kyanite and staurolite occur in the Tananao Metamorphic Complex as submicron inclusions in almandine‐rich garnet from a metamorphosed palaeosol weathering horizon, near Hoping, eastern Taiwan. Quartz, rutile/brookite and zircon are also found as associated submicron inclusions in garnet. Employing the reaction ilmenite+kyanite+quartz=almandine+rutile, and the breakdown of staurolite and quartz as thermobarometers, these submicron‐scale minerals formed at >8.3–8.8 kbar and < 660–690 °C. This P–T estimate is different from that (i.e. 5–7 kbar and 530–550 °C) derived from matrix minerals, which include almandine‐rich garnet, muscovite, chlorite, chloritoid, plagioclase, quartz and ilmenite. These results suggest that submicron inclusions in garnet‐like materials may record portions of the otherwise undocumented prograde path or provide information about previous metamorphic events and thus yield new insights into orogenic belts.     

数字地球与跨学科研究浅析

对数字地球的应用模式、关键技术等方面进行了研究。基于数字地球日益成为信息建设的热点 ,本文讲述了数字地球与跨学科研究的关系 ,分析了数字地球的特征。     

乔治王岛菲尔德斯半岛的地温特征和岩石热物理性质

1985—1986年度和1986—1987年度在菲尔德斯半岛对地面温度进行了测量,共获得129个数据,并对带回的样品进行了岩石热导率测量,共获得210个数据。本文在分析和归纳这些数据的基础上对菲尔德斯半岛的地温特征和岩石热物理性质进行了初步探讨。     

Stabilization of Bottom Hole Temperature With Finite Circulation Time and Fluid Flow

As an alternative to finite element or finite difference modelling, analytical solutions are derived by the method of Laplace transformation and numerical results obtained for several models of the bottom hole temperature stabilization. Included in the models are the finite circulation time, the thermal property contrast between the borehole mud and the surrounding formation, and the presence of radial or lateral fluid flow in the formation, all of which are found to have significant effects on the dissipation of the thermal disturbance induced by drilling.
The mud circulation is considered to have the effect of either maintaining the borehole mud at a constant temperature or supplying a constant amount of heat per unit length per unit time to the borehole. For small circulation times, the former reduces to the 'zero circulation' model in which the mud circulation creates an instantaneous temperature anomaly at the hole bottom; for small borehole radii, the latter reduces to the line source model and the traditional 'Homer plot'.
For typical drilling operations in which the bottom hole temperatures are measured several hours to several tens of hours after the hole is shut in, the new models generally predict higher equilibrium formation temperatures than does the Horner plot. However, predictions from the various models converge if the BHTs are taken after the hole has been shut in for a period which is greater than about five times the circulation period.     

A VLBI study of 20 southern extragalactic radio sources

This paper describes a 5 GHz VLBI survey in the southern hemisphere. The first observation of 23 extragalactic radio sources was conducted in November 1992. Twenty VLBI images were obtained, of which 15 sources show core-jet structure, one has a two-sided jet, and three sources are unresolved. No compact double source was found. Eleven of the 16 sources with core-jet (including a two-aided jet) show evidence of jet bending. In addition, four sources appear to be superluminal, of which three sources are new.     

麻城1932年6．0级地震区地球物理场与深部环境研究

研究了麻城地区重、磁异常场特征，经反演计算获得了深部结构特征。对重力布格异常利用Ｐａｒｋｅｒ－Ｏｌｄｅｎｂｕｒｇ快速位场反演方法计算出莫霍面的展布，对航磁异常利用对数功率谱法和矩谱法计算出居里面深度。在此基础上，探讨该震区深部蕴震条件。主要结论是：①麻城－团凤断裂带为该区切割较深的主要控震构造；②１９３２年麻城６．０级地震发生在区域重力异常等值线梯度最大处，磁力异常区两局部正异常间的低值带，莫霍面及居里面隆起区边缘；③发震部位有其特定的深部蕴震构造及应力蕴震条件。     

The physical framework of the dependence between channel flow hydrographs and drainage network morphometry

The physical basis of the linkage between magnitude and timing of channel flow hydrographs and drainage network morphometry is reviewed. Small Hortonian and structurally Hortonian networks are analysed using numerical runoff simulation. For Hortonian networks the variability of the geometry of individual channels and subcatchments within each Strahler order has generally little effect upon the overall character of the hydrograph in channels of higher order. If the network is also structurally Hortonian, the analysis of the simultaneous formation, travel, and concentration of the hydrographs in all channels of the network can be simplified to a sequence of one representative hydrograph per channel order. This approach is used in this study. Three major runoff processes control the flow hydrograph characteristics: the overland flow process which determines the water supply to the drainage network; the channel flow process which translates the hydrograph in space and time; and the drainage network process which concentrates and magnifies the flow at the junctions of the drainage network. Functional relations for the hydrograph peak, timing, and flow velocity are presented. For a given uniform rainfall and infiltration rate, the peak of the channel flow hydrograph is shown to increase geometrically with channel order, and its magnitude is directly related to the bifurcation ratio. The travel time of the peak also increases geometrically with channel order, and it is directly related to the channel length ratio over velocity ratio. The flow velocity of the peak changes in a downstream direction as a function of the bifurcation and slope ratio. It was also found that for negligible channel storage the channel flow and drainage network processes do not contribute significantly to the observed nonlinear response of a watershed to precipitation.