南秦岭柞山地区铅银锌矿成矿规律及找矿模型

南秦岭柞水银洞子—山阳桐木沟铅银锌矿带地处陕西柞山地区中部,位于中秦岭晚古生代弧前盆地的柞水—山阳矿集区内。该带东西长约71 km,南北宽1～7 km。对带内银洞子（铜）铅银菱铁矿床、黑沟铅锌菱铁矿床、桐木沟锌矿床、南沟（银）铅矿床和松林沟铅矿点的地质、矿体、蚀变、矿化规律进行总结,发现矿体均严格产于中-上泥盆统青石垭组,具有明显的时控、层控、岩控及后期热液改造成矿特征,属典型的海底热水喷流沉积-热液改造层控矿床,构成与晚古生代海底热水喷流沉积-热液改造作用有关的铅锌银成矿系列。建立以层控+热液改造为主控矿条件,以青石垭组热水沉积岩+断裂+化探异常+硫化物、重晶石、菱铁矿蚀变分带为组合的找矿模型,对柞山地区金属矿的找矿突破具有重要的指导意义。     

四川会理拉拉铜矿找矿预测模型构建与找矿示范

勘查区找矿预测理论与方法体系是基于全国129个典型矿床的深入研究,以及在勘查项目实践验证基础上总结而形成的一种特别适合生产找矿第一线使用的有效方法。该方法以成矿作用内因(元素的地球化学特征)和外因(地质作用类型)相结合的思路,构建以成矿地质体、成矿构造与成矿结构面和成矿作用特征标志为主要内容的找矿预测地质模型。四川会理地区位于扬子板块西缘,区域成矿地质条件优越,经历多期构造事件叠加,形成了一系列独具特色的铁铜矿床。近年来,在拉拉铜矿的深部及外围已取得了重大找矿突破和进展。本文以会理拉拉铜矿为典型实例及深部找矿预测成果示范,阐述该方法在深部找矿预测中的具体应用过程,得出了如下认识:早期成矿地质体为赋矿火山岩(河口群钠长岩类),成矿构造与成矿结构面主要为基(中)性火山岩与沉积岩的界面及可能的喷溢口;热液叠加期成矿地质体推测为深部隐伏岩体,成矿构造与成矿结构面主要为褶皱、断裂和裂隙。在总结成矿作用特征标志基础上,建立了拉拉铜矿勘查区找矿预测地质模型。通过与地质和物探方法相结合,圈定红泥坡南部为找矿靶区,经钻探验证,发现厚大矿体,打开了区域找矿空间。     

鲁西地区角闪石岩地球化学、矿物学特征及其地质意义

基性-超基性岩脉群通常形成于伸展构造背景,是示踪地幔源特征以及大陆和超大陆破裂的重要标志.鲁西地区角闪石岩为研究古元古代岩浆源和构造演化提供了一个窗口.本文对鲁西地区角闪石岩进行了岩相学、全岩地球化学及角闪石、黑云母电子探针原位分析.角闪石岩具板内构造环境,来自富集地幔.通过角闪石、黑云母成因分析,均具有幔源成因,角闪石结晶温度为702～781℃;结晶压力为29.8～228.8 MPa,结晶深度1～7.5 km,结晶时氧逸度变化范围在NNO+2.68到NNO+3.35之间.结合本次获得角闪石岩磷灰石U-Pb年龄为(1817±35)Ma,认为鲁西地区(1817±35)Ma处于板内拉伸环境,存在幔源岩浆上侵,已进入大陆裂解阶段.     

搬迁农户生计策略与土地利用行为耦合协调度分析--以贵州省习水县为例

易地扶贫搬迁改变了搬迁农户生计策略,同时影响了其土地利用行为,二者之间的耦合协调度直接影响着农户的可持续生计。本文以贵州省习水县易地搬迁农户调研数据为基础,构建以农户生计策略和土地利用行为为子系统的耦合协调度模型,分析2个子系统之间的耦合关系和耦合协调关系。研究表明:纯农型农户、农兼型农户、兼农型农户生计策略与土地利用行为之间的耦合度值介于0.4~0.5之间,水平较低,处于拮抗状态;不同类型农户生计策略与土地利用行为系统耦合协调度值均处于0.39~0.49之间,处于濒临失调阶段,存在较大优化空间;传统的农业生产形式对于改善农户生计无明显效果,引导农户向专业农业型农户转变对于促进移民安置区“人地系统”协调发展大有裨益。研究结果可为农户生计与土地利用的可持续发展提供理论依据。     

Petrogenesis and sedimentary environment of silicate in Late Paleozoic in Kala area of Western Sichuan Province

In order to study the sedimentary environment characteristics of the Late Paleozoic in Kala area of Western Sichuan Province, the authors have conducted the petrological and geochemical analyses of the widely distributed silicate in Qiongyi Formation of Lower Carboniferous and Kawenggou Formation of Upper Permian. The results show that the silicate in the study area belongs to the pure siliceous rocks, with a continuous supply of land-based materials during the deposition process. The average Al/(Al+Fe+Mn) ratio is 0.62, and the silicate shows a biogenic origin by the Al-Fe-Mn diagram. The ratios of Al₂O₃/ (Al₂O₃+ Fe₂O₃), Th/U, Th/Sc, (La/Ce)_N and (La/Yb)_N and tectonic environment discriminant diagram demonstrate that the silicate developed in a shallow-slope depesitional environment in the continental margin. The Ce_anom value is -0.04 to 0.07, and it gradually increases from the Carboniferous to the Permian period, indicating the water body is in an anoxic environment with gradually increasing reducibility. The Garz--Litang basin opened in the Carboniferous period, in accordance with the regional geological evolution, and it continued to expand during the Permian period, with the gradually increasing depth of the seawater within the sedimentary basins.     

2017年辽宁省春夏季精细化气象干旱监测评估

基于辽宁省1114个国家级和区域级地面台站1961年以来的逐日气温和降水观测资料,利用距离平方反比法差值生成了1717个乡镇的气象资料序列,采用气象干旱综合监测指数统计分析了辽宁省2017年4—8月精细化到乡镇的气象干旱特征。结果表明:2017年辽宁省春夏季异常高温,同时降水异常偏少,致使气象干旱不断发展;干旱在4月5日前从中部和北部开始,4月末扩展到西部,5—6月再向东南发展,波及88%的乡镇,7月以来气象干旱程度开始减轻;气象干旱持续时间长的乡镇主要集中在中部和北部,最长持续时间153d;受气温偏高和降水过程的影响,中度以上气象干旱面积呈阶段性变化,且极端干旱的发展伴随高温时段。由于气象干旱不同于农业干旱,在开展为农服务时要因地制宜采取应对措施。     

那曲地区植被NDVI时空变化及成因分析

利用GIS和遥感技术方法分析了2000—2014年那曲地区植被归一化指数(NDVI)的时空分布特征和变化趋势,探讨了NDVI与几种气象因子的关系。结果表明:空间上,研究区植被NDVI在空间上呈自西向东、自南向北逐步增大,高海拔地区小于低海拔地区的分布特点;时间上,近15a的NDVI总体上呈不显著性下降趋势,NDVI变化可以分为3个阶段,分别为2000—2005年较好,2006—2008年略差,2009—2014年好转。植被面积变化趋势表现为西北部植被处于稳定状态的面积居多,变化较明显的区域集中在中部和东南部地区的人口密集区,改善和退化区域呈现交错出现的特点。那曲地区植被变化的主要影响因素为降水量和热量因素引起的,人类活动在较短时间尺度上对植被也有较大影响。     

江汉叠合盆地及邻区中生代以来盆山耦合数值模拟研究

江汉叠合盆地位于扬子地台中部,夹持于秦岭-大别及江南造山带中段之间。中生代以来,先后经历了北部陆陆碰撞、南部陆内挤压造山与断陷、裂陷成盆的演化历程,区域构造体制在中生代发生了重大转换,其中复合、联合了众多的地质现象;盆地历经的海盆、煤盆、盐盆、陆相广盆四个盆地世代详细记录有中国南北大陆联合及东北亚大陆构造体制转换的运动学过程,是认识欧亚大陆东部深层动力地质作用过程的关键地区之一。盆地沉积充填过程可简要概括为前陆、裂陷、坳陷三种基本样式。系统的盆山构造样式及运动学分析结果表明:叠合盆地前陆期发育于同碰撞-造山后作用阶段早期,断、坳陷期发育于造山后作用阶段晚期-非造山裂解阶段。本文运用大陆动力学数值模拟(FLAC软件)方法,从挤压和伸展两方面效验了山-盆演化分别受控于印支-早燕山期的华南与华北陆块的旋转碰撞造山,以及随后的晚燕山-喜山早期碰后陆内俯冲作用所产生的板片断离引起的地幔物质上升与对流作用,晚喜山期太平洋板块俯冲作用以及由此产生的地幔调整等三期动力学系统。为南方中小型叠合盆地动力学解析提供了一种新的思路与研究方法。     

FLOOD MODELLING WITH GIS-DERIVED DISTRIBUTED UNIT HYDROGRAPHS

The concept of a spatially distributed unit hydrograph is based on the fact that the unit hydrograph can be derived from the time–area curve of a watershed by the S-curve method. The time–area diagram is a graph of cumulative drainage area contributing to discharge at the watershed outlet within a specified time of travel. Accurate determination of the time–area diagram is made possible by using a GIS. The GIS is used to describe the connectivity of the links in the watershed flow network and to calculate distances and travel times to the watershed outlet for various points within the watershed. Overland flow travel times are calculated by the kinematic wave equation for time to equilibrium; channel flow times are based on the Manning and continuity equations. To account for channel storage, travel times for channel reaches are increased by a percentage depending on the channel reach length and geometry. With GIS capability for rainfall mapping, the assumption of a uniform spatial rainfall distribution is no longer necessary; hence the term, spatially distributed unit hydrograph. An example of the application for the Waiparous Creek in the Alberta Foothills is given. IDRISI is used to develop a simple digital elevation model of the 229 km² watershed, using 1 km × 1 km grid cells. A grid of flow directions is developed and used to create an equivalent channel network. Excess rainfall for each 1 km × 1 km cell is individually computed by the Soil Conservation Service (SCS) runoff curve method and routed through the equivalent channel network to obtain the time–area curve. The derived unit hydrograph gave excellent results in simulating an observed flood hydrograph. The distributed unit hydrograph is no longer a lumped model, since it accounts for internal distribution of rainfall and runoff. It is derived for a watershed without the need for observed rainfall and discharge data, because it is essentially a geomorphoclimatic approach. As such, it allows the derivation of watershed responses (hydrographs) to inputs of various magnitudes, thus eliminating the assumption of proportionality of input and output if needed. The superposition of outputs is retained in simulating flood hydrographs by convolution, since it has been shown that some non-linear systems satisfy the principle of superposition. The distributed unit hydrograph appears to be a very promising rainfall runoff model based on GIS technology.     

北京及邻近地区中等以上地震地下流体异常识别与特征研究

系统分析了北京及其邻区多年积累的震例资料, 提出该区的地下流体异常分为趋势上升型中期异常、 转折型中短期异常、 突发型短期异常和短临异常等类型。 运用“同一化”思路、 从属函数、 剩余曲线及原始曲线均方差等异常判定方法, 提取了中等以上地震, 特别是5级以上地震的中、 短、 临异常实例。 通过对流体异常特征的统计分析, 给出了北京及邻近地区的中期、 中短期、 短期和短临异常的时间分布特征, 并对地震前各阶段异常的超前时间进行了总结, 该时间可作为发震时间的预测指标。 在实际应用中可为该区的震情判定提供依据。