CRUSTAL ANISOTROPY AND ITS TECTONIC IMPLICATIONS IN THE CHONGQING REGION

The receiver function which carries the information of crustal materials is often used to study the shear-wave velocity of the crust as well as the crustal anisotropy. However, because of the low signal-to-noise ratio in Pms(P-to-S converted phase from the Moho), the crustal anisotropy obtained by shear-wave splitting technique for a single receiver function usually has large errors in general. Recent advance in the analysis method based on Pms arrival time varying with the back-azimuth change can effectively overcome the above defects. Thus in this paper, we utilize the azimuth variations of the Pms to study the crustal anisotropy in Chongqing region for the first time. According to the earthquake catalogue provided by USGS, seismic waveform of earthquakes with magnitude larger than 5.5 and epicenter distance range of 30°~90° between January 2015 and December 2016 are collected from 14 broadband seismic stations of Chongqing seismic network. We carry out the bootstrap resampling to test the reliability of the radial maximum energy method for the observation data. In addition, we also applied the receiver function H-Kappa analysis in this paper to study the crustal thickness and Poisson's ratio. Our results show the crustal thickness ranges from 40~50km, and there is a thin and thick crust in the southern and northern Chongqing, respectively. The crustal average Poisson's ratio ranges from 0.23~0.31, the Poisson's ratio reaches the maximum value in the central part of Chongqing, while the Poisson's ratio in the northern and southern parts of Chongqing is obviously low. We obtain the crustal anisotropy from 9 stations in total. The delay time of crustal anisotropy distributes between 0.08s and 0.48s, with the average value of 0.22s. Among them, the CHS, QIJ and WAZ stations in central Chongqing have relatively large crustal delay time(>0.3s), followed by ROC station in the western Chongqing(0.25s), while the delay time in CHK station in northern Chongqing and WAS station in southern Chongqing are 0.08s, showing relatively weak crustal anisotropy. The fast polarization directions(FPDs)also change obviously from south to north. In southern Chongqing, FPDs are dominant in NNE-SSW and NEE-SWW, while the FPDs in WAZ station change to NWW-SEE, and the FPDs appear to be NW-SE in CHK in the northern Chongqing. In general, the FPDs are sub-parallel to the strikes of faults in most areas of Chongqing areas. Combined with other results from GPS observations, tectonic stress field and XKS splitting measurements, the main conclusions can be suggested as following:The cracks preferred orientation in the upper crust is not the main source of crustal anisotropy in Chongqing area. The crust and lithospheric upper mantle in the eastern Sichuan fold belt(ESFB)and Sichuan-Guizhou fault fold belt(SGFFB)are decoupled, and the deformation characteristics in the north and south parts of ESFB and SGFFB is different. The complex tectonic deformation may exist beneath the mountain-basin boundary, causing the fast directions of crustal anisotropy different from that in other areas of ESFB and SGFFB. The faults with different strikes may weaken the strength of average crustal anisotropy in some areas. The crustal deformation in southern Dabashan nappe belt(DNB)may be mainly controlled by the fault structure.     

中国东南部的晚元古界和裂陷活动带

本文从阐述中国东南部晚元古多旋回火山作用,特殊的火山—沉积建造及有规律的构造组合形式入手,论证了该地区晚元古界地层发育特征和空间上一条重要相区界线,并提出了中国东南部存在一条古裂谷带的观点。通过对古裂谷带特征的详细论述,阐明了古裂谷带的研究对揭示中国东南部多种金属成矿作用和开展第二轮找矿的理论意义和巨大经济价值。     

3D MODEL STUDY ON FOG OVER COMPLEX TERRAIN-PART Ⅰ:NUMERICAL STUDY

A three-dimensional fog model,suitable for precipitous and complex terrain,is designed containing four prognostic variables-wind speed,potential temperature,specific humidity and mixing ratio of liquid water.The model considers turbulent exchange,the long-wave radiation on the ground surface and in the air.the short-wave solar radiation,the evaporation and condensation of moisture and the surface heat budget and so on.In order to make the model run steadily on precipitous and complex terrain,we have improved the method of calculating horizontal pressure gradient force in the terrain coordinate system.The results coincide on the whole with the actual situation.     

论滇东南地区旅游资源的开发战略

根据该区旅游资源的分布，交通条件，经济承受能力及接待条件，笔者认为近期开发的重点是（１）开发喀斯特景观系列旅游产品；（２）建设建水、罗平、邱北３个旅游集散中心；（３）开辟４条旅游主干线；（４）开发八大旅游商品系列。     

中国东南中生代大陆边缘构造—岩浆带的同位素地球化学

根据中生代火山岩和侵入岩的岩石类型与组合及其岩石化学特征等，将中国东南中生代大陆边缘分成陆缘火山（岩浆）弧（Ｃｖａ）、陆缘弧后（间）火山盆地带（Ａｂｖ）和裂陷火山（岩浆）带（Ｒｖ），并深入研究了它们的Ｓｒ、Ｏ、Ｐｂ和Ｓｍ、Ｎｄ同位素组成特征。Ｃｖａ具较低的ＩＳｒ和δ１８Ｏ值及变化较大的Ｐｂ同位素组成与较高的εＮｄ值；Ａｂｖ具较高的ＩＳｒ和δ１８Ｏ值及较稳定的Ｐｂ同位素组成与较低的εＮｄ值；Ｒｖ则具较低（较稳定）的ＩＳｒ值和Ｐｂ同位素组成及变化较大的δ１８Ｏ值与εＮｄ值。由此推断，Ｃｖａ和Ａｂｖ的岩浆均为陆缘亏损地幔与上地壳成分混合形成（前者地幔成分居多，后者以地壳成分为主），Ｒｖ的岩浆则具陆内交代－亏损地幔与较多的下地壳物质混合源的成因特征。     

黔东南花桥金矿床地质特征、控矿因素及找矿方向

贵州锦屏花桥金矿已经有较长的民采历史。通过分析前人的研究成果,以及井下坑道编录和采样工作,得出含硅质有火山碎屑成分的浊积岩对金的富集有控制作用,浊积岩岩性变换的部位易出现含金石英脉等新认识。认为区域基底岩石金的地球化学丰度,矿体围岩岩性及构造地质作用是形成含金石英脉的三要素,并指出断裂破碎带及探索深部隐伏矿体为进一步找矿的方向。     

南岭中段中生代构造-岩浆活动与成矿作用研究进展

对南岭中段北部湘东南地区中生代构造-岩浆活动及成矿作用进行了较系统研究,主要提出以下认识。(1)中三叠世后期—中侏罗世初(早中生代)为板内造山阶段。中三叠世后期在区域NWW—SEE向挤压构造体制下发生强烈的陆内俯冲、汇聚作用,形成大量东倾为主的NNE向逆冲断裂与褶皱。其中茶陵—郴州断裂以东隆起区的隔槽式褶皱形成机制为"厚皮式"而非"薄皮式"。NW向基底隐伏断裂产生强烈左旋走滑,并使构造线产生逆时针旋转,形成了安仁"y"字型构造和水口山—香花岭南北向构造。挤压造山使地壳持续大幅增厚、深部地壳温度持续升高。中三叠世末—晚三叠世后期(233～210Ma)区域挤压应力松弛,被加热的中地壳下部岩石熔融,同时存在幔源基性岩浆底侵,从而于后碰撞环境下产生较大规模的花岗质岩浆活动。晚三叠世末—早侏罗世因同造山上隆伸展作用而形成裂陷盆地,中侏罗世初期在区域NNE向左旋汇聚走滑体制下形成逆冲断裂及山前冲断收缩盆地、NW向右旋走滑断裂等。早中生代板内造山活动的动力机制主要与板块汇聚的远程挤压效应有关。(2)中侏罗世早期—白垩纪(晚中生代)为后造山—陆内裂谷伸展阶段。中侏罗世早期—晚侏罗世(174～135Ma)因岩石圈拆沉而发生大规模花岗质岩浆活动与成矿作用。岩体的被动就位机制、暗色镁铁质微粒包体的发育、Sr-Nd同位素特征、以(高钾)钙碱性岩类为主的岩石组成、构造环境的岩石地球化学判别、大规模有色金属成矿、区域构造演化背景等,指示该时期为后造山构造环境。白垩纪进入强烈的陆内伸展阶段,形成盆-岭构造和相关的离散走滑断裂,广泛发育各类岩脉,局部形成AA型花岗岩小岩体和基性火山岩。热年代学资料暗示盆-岭构造的演化先后经历了构造剥蚀和风化剥蚀-沉积两个阶段。(3)造成湘东南燕山早期花岗岩成矿能力远高于印支期花岗岩的原因,主要是区域构造环境暨构造体制差异,即燕山早期后造山伸展构造体制下岩体中矿质更易于向周围扩散并沉淀,而印支期后碰撞环境弱挤压体制下矿质则被封闭;其次是花岗岩岩石地球化学特征差异,即构造-岩浆演化历史和深部成矿流体的参与使燕山早期花岗岩具有更好的成矿岩石地球化学条件。(4)燕山早期钨锡多金属和铅锌多金属两类矿床组合的形成可能主要与岩石圈结构(厚度)和深部热扰动强度,以及相应的岩浆作用规模和岩体侵位深度等因素有关。     

重庆金佛山泉水地球化学特征及其空间分布意义

2006年7月和9月在重庆金佛山地区选取22个地下水出露的泉点.对泉水的地球化学性质进行详细调查。利用野外和实验室测量手段得到了主要阴离子和阳离子浓度与物理化学参数。分析得知:研究区泉水的水化学类型为Ca-HCO_3和Ca、Mg-HCO_3;结合地质和地貌背景把它们分为6个泉群,分别讨论各泉群的空间分布意义;估算泉水方解石(SI_C)、白云石(SI_D)和石膏(SI_G)的饱和指数,即可反映地层岩性、地形和地下水的运移时间对水质的影响,该区地下水基本上是来自大气降水的下渗.没有深部含水层的上升混合.这些泉水的地球化学特征以及它们的空间分布规律能够很好地反映区内地质状况.该研究可以为金佛山地区地下水资源的调查和环境保护提供基础数据。     

2005~2015年耕地多功能时空演变及其协同与权衡研究——以重庆市沙坪坝区为例

基于2005~2015年近10 a面板数据,在测算重庆市沙坪坝区耕地多功能基础上,探究其时空演变规律、多功能间协同与权衡关系,据此构建耕地空间组织经营模式。结果表明：耕地生产功能、景观游憩功能、社会保障功能及建设空间储备功能时空演变特征差异显著。耕地“生产-景观游憩-社会保障”功能间存在两两协同关系,且协同度均值 “生产-景观游憩”>“社会保障-景观游憩”>“生产-社会保障”;耕地建设空间储备功能与其他3项功能间存在此消彼长的权衡关系。据此构建了“一带两区”即山地休闲农业带、郊野农业游憩区、传统农业提升区的耕地空间组织经营模式。     

重庆市乡村三生空间功能耦合协调的时空特征与格局演化

探究乡村三生空间功能间的互动关系,是当前乡村空间优化过程中亟待解决的关键问题。结合国土空间规划“三生”空间理论与耦合协调模型,定量测算2005年、2010年、2015年重庆市37个区县的乡村三生空间功能及其两两间的耦合度和耦合协调度并进行空间比较和时序分析。结果表明：耦合度呈现低耦合、拮抗、磨合、协调耦合四种类型,耦合协调度呈现中度失调、基本协调、中度协调三种类型;乡村三生空间功能耦合协调的时空格局差异显著,空间上呈现出“西高东低”的格局特征,时间上呈现由低水平耦合向协调耦合发展的波浪式演进特征;乡村三生空间功能两两之间耦合协调状态差异明显,“生活—生态”功能耦合协调情况较差,是未来优化乡村空间的重点方向。