四川兴文石林区的喀斯特与洞穴

四川文兴的洞河、龙塘一带，是我国南方重要的峰丛喀斯特区之一。著名的兴文石林风景区即位于其中，世界级规模的大漏斗，大量的流入型洞穴，完整的喀斯特流域，优越的喀斯特发育条件，漫长的喀斯特演化历史，古今不同阶段喀斯特发育的叠置、继承和新生构成了“文兴式”喀斯特的基本特色。本文着重讨论了该区喀斯特与洞穴的形成条件、基本特征，并从一物质与能量的输入-输出系统出发，提出和较详细地讨论了洞穴系统的基本类型组成及其发育的“含水层控制系统演化模式”。     

Distribution and formation of high-fluorine groundwater in China

In China, high-fluorine groundwater, which contains more than 1.0 mg/l fluorine, is mainly distributed in shallow aquifers of unconsolidated deposits in some arid and semiarid areas, deep aquifers of unconsolidated deposits in semiarid areas, as well as in hot springs of bed rock mountainous area and aquifers of fluorite-mine area. Its formation is controlled by regional climate factors, seepage conditions of groundwater, as well as the hydrogeochemical environment. The physicochemical properties of soil mass of the aeration zone play an important role in fluorine concentration in shallow groundwater. In the coastal plain areas, where groundwater is mainly recharged and discharged vertically, and its regime type belongs to the type of infiltration—evaporation, the grain size of soil mass of aeration zone directly influences the amount of fluorine transferred from solid medium into water; and the chemical constituents of the soil mass of aeration zone controls the chemical characteristics of the shallow groundwater, consequently influencing the concentration condition of fluorine in water. Fluorine ion in groundwater continuously migrates and concentrates under the comprehensive influence of many factors. High-fluorine groundwater exceeding the sanitary standard (1.0 mg/l) has an obvious zonality in regional distribution in China. Based on current statistics, there are roughly 50 million people (Zheng Qifu 1986) who have consumed water which exceeds standards in China. In highfluorine groundwater areas, endemic fluorine-poisoning often arises to different extents, affecting human health seriously. At the end of 1983, over 20 million patients were suffering from fluorine-poisoning diseases in China (Xu Guozhang, unpublished data). Therefore, research of the distribution feature and formation mechanism of fluorine ion in groundwater has become an important task.     

Geothermal observations in east Liaoning and haicheng seismic area

We have obtained altogether heat flux data of 23 drill holes including 2 observational holes of thermal flow in the Haicheng seismic area. These data show roughly thermal structure of the crust in eastern Liaoning and in the Haicheng seismic area. The results indicate that there is higher value of heat flow in the belt north by east from Liaoyang to Xiongyue, the average thermal flux being 8.29× 10⁻²J/m²·s (2.0 hfu). The average thermal fulx in the Haicheng seismic area is 9.22×10²J/m²·s (2.2 hfu). Comparing with other known geophysical data of the Haicheng seismic area, we give a geophysical section of comprehensive interpretation. We suppose the low-velocity layer in the lower crust of the Haicheng seismic area is a result from intrusion of large-scale uper mantle substance. High temperature and low velocity mean that the layer has the nature of plastic mechanics. The focal region of the Haicheng earthquake is situated right in the upper part of that plastic layer. Obviously, this result is significant for studying the seismogenic process of the Haicheng earthquake and other intra-plate earthquakes. We attempt to emphasize that observation of heat flow is necessary for earthquake study. Gu Haoding did the actual writing.     

Types and Metallogenic Models of Nickel Sulfide Deposits of China

Most of the sulfide nickel deposits in China occur on the margins of platforms and their outer mobilebelts. The ore-bearing basic-ultrabasic rock bodies were formed in the Proterozoic and Variscan. The types ofmetallogenic rock bodies include ultrahasic-basic complexes related to volcanism in eugeosynclines andultrabasic rock bodies, ultrabasic-basic complexes and basic rock bodies related to deep fractures. On the basisof ore-forming processes and modes, nickel sulfide deposits of China may be divided into two major types:in-situ magmatic liquid unmixing deposits and deep-seated magmatic liquid unmixing injection deposits. Thelatter may by subdivided into four types: single injection deposits, multiple injection deposits, and pulsatory in-jection depositis, and late injection deposits which may inject into either comagmatic rocks or other kinds ofcountry rocks. Two metallogenic models for nickel sulfide deposits are proposed in this paper.     

试论龙门山重力梯度带——兼论松潘、平武、迭溪等地震区的深部构造特征

本文分析解释了三维重力正、反演的计算结果,提出龙门山重力梯度带并不是一个简单的壳幔斜坡或陡坎。并进一步指出该重力梯度带的范围、发震断裂的深浅关系、次级构造的存在及其复杂图象等一系列深部地震地质问题都有待于揭示和认识。地震地质和地球物理两个学科的密切配合有可能回答上述问题,找出强震在龙门山重力梯度带乃至整个南北地震活动带内的蕴育发生规律。这对地震预报和工程地震都是有意义的,也将丰富大地构造的研究内容     

Finite Element-Analysis of an Overfold Using the Viscous Fluid Model

Symmetrical folding of a single layer and folding process of an overfold are analyzed by using the finite element method. In the analysis, the constituent substances are assumed to be isotropic and incompressible and to behave as Newtonian fluids. The penalty function method is used to deal with incompressibility, The results of the analysis are compared with the data measured in the field and with those obtained by the elastopla(?)e finite element analysis, It shows that the overfold geometry may be well simulated by using the viscous fluid model. Thus, a possible mechanism of the formation of overfold is proposed.     

On the Post-Variscan Global Tectonic Stages

After the Variscan Cycle, the global tectonic framework underwent three major adjustments. The first occurred in the Late Triassic-initial Jurassic, the second in the Late Jurassic-early Early Cretaceous and the third in the Late Cretaceous-Eogene. On that basis, the post-Variscan tectonic history is divided into three tectonic cycles——the Indosinian, Yanshanian and Himalayan Cycles. The post-Neocom(k_1~1) andpre-Aptian(k_1~2) tectonic movement marks the end of the Yanshanian orogeny in eastern China and the initiation of the subduction of the Tethyan ocean in western China and represents the boundary between the Yanshanian and Himalayan Tectonic Cycles.     

Gravity field terrain effect computations by FFT

The widespread availability of detailed gridded topographic and bathymetric data for many areas of the earth has resulted in a need for efficient terrain effect computation techniques, especially for applications in gravity field modelling. Compared to conventional integration techniques, Fourier transform methods provide extremely efficient computations due to the speed of the Fast Fourier Transform (FFT. The Fourier techniques rely on linearization and series expansions of the basically unlinear terrain effect integrals, typically involving transformation of the heights/depths and their squares. TheFFT methods will especially be suited for terrain reduction of land gravity data and satellite altimetry geoid data. In the paper the basic formulas will be outlined, and special emphasis will be put on the practial implementation, where a special coarse/detailed grid pair formulation must be used in order to minimize the unavoidable edge effects ofFFT, and the special properties ofFFT are utilized to limit the actual number of data transformations needed. Actual results are presented for gravity and geoid terrain effects in test areas of the USA, Greenland and the North Atlantic. The results are evaluated against a conventional integration program: thus, e.g., in an area of East Greenland (with terrain corrections up to10 mgal), the accuracy ofFFT-computed terrain corrections in actual gravity stations showed anr.m.s. error of0.25 mgal, using height data from a detailed photogrammetric digital terrain model. Similarly, isostatic ocean geoid effects in the Faeroe Islands region were found to be computed withr.m.s. errors around0.03 m     

初论拱坳构造及其与地震的关系——以鄂西江汉地区为例

本文提出了一个大陆新构造基本类型—拱坳构造。对它的构造特征、性质、应力作用状况以及与地震活动的关系进行了初步论述。以鄂西江汉地区发育的拱坳构造为典型作了较详细的剖析。