黑水─泉州地学断面的重磁解释

讨论华南黑水─泉州地学断面的重磁解释。在解释中除应用常规的２．５维重磁异常反演外，还采用等密度线算法构制梯度层密度模型，用于分辨地壳密度细结构，以及计算自由地幔而深度用于分析上地幔密度的横向不均匀性。重磁模拟结果揭示了１０ｋｍ深度内的上地壳构造以及地壳与上地幔密度的分布。提出华南造山带以低密度上地幔为特征，它可能与上地幔的改造有关；四川盆地具有较高的上地幔密度，为未经改造的原始地幔。扬子克拉通与华南造山带的分界线与上地幔密度的分界线一致。根据布格异常、地表岩石密度和地形资料的综合分析，圈定出反映内生成矿作用深部标志的密度倒转区，可作为进一步找矿的远景区。     

傅利叶重建法的数值模拟研究

运用ＣＴ技术中的傅利叶重建法，根据任意所给的两个初始速度模型，用几组平行射线束进行扫描，采集走时数据，并利用走时数据反演速度图象．反演结果与初始模型比较两者基本相符合。由此证明，傅利叶重建法在一定条件下可以用来反演地壳速度结构，并可得到较好的结果．这种方法是ＣＴ技术应用于地学研究的一种新的尝试．     

Multiple intrusions and low-pressure metamorphism in the central Old Woman Mountains, south-eastern California: constraints from thermal modelling

The Old Woman Mountains in south-eastern California are a Late Cretaceous low-pressure metamorphic terrane where multiple magmatic intrusions generated broad regions of elevated metamorphic temperatures. In the Scanlon Gulch area, two sheet-like, Late Cretaceous granitoid plutons are in contact with the Scanlon shear zone, a 1-km-thick sheet of isoclinally folded and transposed metamorphic rocks. The metaluminous Old Woman granodiorite underlies the shear zone and the peraluminous Sweetwater Wash granite overlies it. Both plutons record emplacement ages of ∼74 Ma. Thermobarometry and phase relations in the shear zone suggest that peak metamorphism was at 650 ± 50† C and 4.3 ± 0.5 kbar. Late Cretaceous metamorphic temperatures were less elsewhere in the Old Woman Mountains, away from the intrusions.
One-dimensional thermal models are used to investigate how differences in the time between the emplacement of plutons would affect the thermal evolution of the central Old Woman Mountains. The prediction of a thermal history inferred from petrological and thermochronological data requires the rapid emplacement of the two plutons around the shear zone; simulations with delays of more than 1 Myr in the emplacement of the second pluton failed to predict peak metamorphic temperatures. Calculations which consider only the emplacement of a single pluton yield metamorphic temperatures that are too low. The time separating the intrusions is by far the most sensitive parameter in the calculations; assumptions concerning the treatment of the initial geothermal gradient and the latent heat of crystallization have relatively small effects on the predicted thermal histories. Our results suggest that for certain geometries, relatively short-lived magmatic events involving rapid emplacement of multiple intrusions can produce low-pressure metamorphism.     

Fault dimensions,displacements and growth

Maximum total displacement (D) is plotted against fault or thrust width(W) for 65 faults, thrusts, and groups of faults from a variety of geological environments. Displacements range from 0.4 m to 40 km and widths from 150 m to 630 km, and there is a near linear relationship betweenD andW ². The required compatibility strains (e _s) in rocks adjacent to these faults increases linearly withW and with and ranges frome _s=2×10^–4 toe _s=3×10^–1. These are permanent ductile strains, which compare with values ofe _s=2×10^–5 for the elastic strains imposed during single slip earthquake events, which are characterised by a linear relationship between slip (u) andW.The data are consisten with a simple growth model for faults and thrusts, in which the slip in successive events increases by increments of constant size, and which predicts a relationship between displacement and width of the formD=cW ². Incorporation of constant ductile strain rate into the model shows that the repreat time for slip events remains constant throughout the life of a fault, while the displacement rate increases with time. An internally consistent model withe _s=2×10^–5, giving repeat times of 160 years and instantaneous displacement rates of 0.02 cm/yr, 0.2 cm/yr, and 2.0 cm/yr when total displacement is 1 m, 100 m, and 10 km, and slip increasing by 0.5 mm with each event, gives a good approximation of the data. The model is also applicable to stable sliding, the slip rate varying with ductile strain rate and withW ².     

区域化变量的空间聚类分析

传统的聚类分析方法利用数据对平均值的偏差，研究变量之间的相互关系。当它应用于区域化变量的分类时，因缺乏对区域化变量的空间结构的考虑，对合理解释区域化变量之间的相互关系不利。空间聚类分析方法比较好地解决了这个问题。本文介绍了该方法的基本原理及其算法，并说明了它在非条件模拟及在某矿区中的应用情况     

A review of mathematical models of river planform changes

Different mathematical models of river planform changes exist or are being developed. They are reviewed here by discussing a two-dimensional depth-averaged model, various meander models and a model for the braided Brahmaputra-Jamuna River in Bangladesh. Much emphasis is placed on topics where further research is needed. It is concluded that the models help in understanding the underlying processes, but cannot yet be considered generally valid and easy-to-use software packages. In the hands of experienced geomorphologists or river engineers, however, some of the models do already form valuable tools which allow better predictions of future river planforms.     

Lichens: Lichenometric dating of diachronous surfaces

This paper describes software to accompany McCarroll, D. 1993. ‘Modelling late-Holocene snow-avalanche activity: incorporating a new approach to lichenometry’, Earth Surface Processes and Landforms 18 , 527–539; and McCarroll, D., Matthews, J. A. and Shakesby, R. A. 1995. ‘Late-Holocene snow-avalanche activity in southern Norway: interpreting lichen-size-frequency distributions using an alternative to simulation modelling’, Earth Surface Processes and Landforms 20 , 465–471.     

鲜水河地区现今形变及地球动力学特征

本文根据非线性理论的新方法，稳健估计技术和多核函数等，对鲜水河地区垂直和水平形变监测资料进行了分析处理，获得了鲜水河地区的现今地壳动态信息，从而分析获得鲜水河断裂的现今活动与地震的关系，鲜水河断裂的现今活动模型及其应力状态。     

主应变比异常理论在青海祁连地震预报中的应用

本文利用主应变比异常理论分析了祁连建站以来地应变观测资料，认为肃南──祁连断裂段上及附近发生的地震是由于构造应力场的变化，在引张应力状态下，正断层或走滑断层易于活动而导致的。