四川江油马鞍塘中晚三叠世沉积相及层序地层分析

本文对四川江油马鞍塘中晚三叠世地层剖面进行了详细描述,根据岩石组合特征,结合全国岩石地层清理方案将其划分为天井山组和马鞍塘组[1].对天井山组和马鞍塘组进行了详细的沉积相及垂向变化规律研究,并将其划分为四个层序(相当于三级层序),同时讨论了各层序的体系域特征[2].     

水文等值线图特征要素提取研究

阐述了特征要素对水文等值线图网格化的重要性.通过比较分析两种经典的数学形态学骨架提取算法的应用效果,认为最大数字圆盘定义的骨架更接近于水文等值线图的特征要素分布.针对由最大数字圆盘算法得到的骨架线存在的一些不足,对其作消噪、粘合和细化等进一步改进处理.对相关结构元素的形状和大小给出建议.     

四川木洛稀土矿床方解石元素地球化学特征及其成因意义

方解石是木洛稀土矿区常见的一种脉石矿物。对木落稀土矿区郑家梁子矿段方解石元素地球化学研究表明:此类方解石强烈亏损Ti、Mn、Mg、K、Fe,富Ca贫Si,P和Na含量比较稳定,但远低于世界钙质碳酸岩而与沉积碳酸盐岩接近;稀土元素含量较为稳定,∑REE为185.55×10-6~201.43×10-6,LREE为184.01×10-6~195.62×10-6,REE配分模式为LREE富集型,有弱的Eu负异常和强烈的Ce正异常;富集Sr亏损Nb、Zr,其他的Rb、Ba、Th、Ta、Hf、Y、Sc等元素含量较为稳定,均接近中国东部碳酸盐岩平均值。因此,此类方解石为同源流体的结晶产物,主要为沉积热液成因,代表了地幔流体成矿后的一次沉积热液的流体改造。此类方解石可作为氧化型高品位稀土矿和钼铅矿的找矿标志。     

天然沸石曝气生物滤柱脱氮性能及生物再生

对二级天然沸石曝气生物滤柱的脱氮性能和生物再生进行了实验研究.研究结果表明,在进水有机负荷0.8～6.4 kgCOD/(m3·d)、水力负荷1～2 m/h、气水比1:1～4:1的工艺条件下,COD、氨氮和总氮去除率分别达到67%～90%、52%～82%和33%～67%;水中氨氮含量在10～30mg/L时,硝化速率为0.23mg/min.生物再生过程中,微生物不仅硝化解吸氨氮,还可以深入沸石孔道,直接利用沸石吸附的氨氮.分级分段进水可以提高沸石生物再生速度,减少再生时间.     

中国浅成低温热液金矿床

浅成低温热液金矿床在中国传统上称为陆相火山岩型金矿床,主要发现在中国东部,后来在北疆地区也有新的发现.根据产出的大地构造背景,它们集中分布在3个带,并分属于3个成矿时期.它们包括:(1)新生代台湾东部岛弧带;(2)晚古生代北疆岛弧带;(3)中生代沿中朝克拉通北界的大陆边缘带;(4)中生代中国东南沿海地区的大陆边缘带.绝大多数矿床是低硫化型的,只有3个是高硫化型的,另有1个是与碱性岩系有关的Au-Te型矿床.除了中国最大的金矿床金瓜石矿床外,迄今为止中国大陆上的浅成低温热液金矿床总的来说只有较小的经济重要性.在中国东部发现的浅成低温热液金矿床的总储量,与区内广泛分布的中生代陆相火山岩十分巨大的体积极不相称.较古老的成矿年龄,中国东部的中生代和北疆的晚古生代,是中国大陆浅成低温热液金矿床的一个鲜明的特点.根据中国的成矿条件和保存条件的分析,以及与美国西部和俄国东部的对比,提出了中国浅成低温热液金矿床成矿潜力的一个初步评估.北疆可能有较大的寻找浅成低温热液金矿床的潜在重要性.     

Extreme oxygen isotope signature of meteoric water in magmatic zircon from metagranite in the Sulu orogen, China: Implications for Neoproterozoic rift magmatism

Unusual ¹⁸O depletion, with δ¹⁸O values as negative as −10‰ to −4‰ relative to VSMOW, was reported in zircons from ultrahigh-pressure eclogite-facies metamorphic rocks in the Dabie-Sulu orogenic belt, China. But it is critical for the negative δ¹⁸O zircons to be distinguished between magmatic and metamorphic origins, because the ¹⁸O depletion can be acquired by high-T eclogite-facies metamorphism of meteoric-hydrothermally altered low δ¹⁸O rocks. While zircon O diffusion kinetics has placed a reasonable constraint on this, zircon trace element compositions can provide a straightforward distinction between the magmatic and metamorphic origins. This paper reports our finding of unusual ¹⁸O depletion in zircon from granitic gneiss in the northeastern end of the Sulu orogen. Zircon δ¹⁸O values vary from −7.8‰ to −3.1‰ along a profile of 50 m length at Zaobuzhen. They are close to extremely low δ¹⁸O values of −9.0‰ to −5.9‰ for metagranite at Qinglongshan and adjacent areas in the southwestern end of the Sulu orogen. CL imaging suggests that the low δ¹⁸O zircons at Zaobuzhen are primarily of magmatic origin, but underwent different degrees of metamorphic modification. Zircon U-Pb dating yields middle Neoproterozoic ages of 751 ± 27 to 779 ± 25 Ma for protolith crystallization and Triassic ages of 214 ± 10 to 241 ± 33 Ma for metamorphic resetting. However, no metamorphic modification occurs in zircon REE patterns that only indicate magmatic recrystallization and hydrothermal alteration, respectively. Thus, the negative δ¹⁸O zircons are interpreted as crystallizing from negative δ¹⁸O magmas due to melting of meteoric-hydrothermally altered negative δ¹⁸O rocks in an active rift setting at about 780 Ma. The variation in zircon δ¹⁸O values indicates considerable O isotope heterogeneity in its granitic protolith. Zircon Lu-Hf isotope analyses give positive ε_Hf(t) values of 1.6-4.1 and Hf model ages of 1.18-1.30 Ga. This suggests that the granitic protolith was derived from the mid-Neoproterozoic reworking of late Mesoproterozoic juvenile crust. The metagranites at Zaobuzhen and Qinglongshan, about 450 km apart, are two known occurrences of the unusually low δ¹⁸O zircons below −6‰ so far reported in the Sulu orogen. They are similar to each other in both protolith and metamorphic ages, so that they share the same nature of both Neoproterozoic protolith and Triassic metamorphism. Therefore, the locally negative δ¹⁸O zircons may register centers of low δ¹⁸O magmatism during the supercontinental rifting.     

Land cover classification of the North China Plain using MODIS_EVI time series

Moderate Resolution Imaging Spectroradiometer (MODIS) data have played an important role in global environmental and resource research. However, its low spatial resolution has been an impediment to researchers pursuing more accurate classification results. In this research, the high temporal resolution of MODIS was employed to improve the accuracy of land cover classification of the North China Plain using MODIS_EVI time series from 2003. Harmonic Analysis of Time Series (HANTS) was performed on the MODIS_EVI image time series to reduce cloud and other noise effects. The improved MODIS_EVI time series was then classified into 100 clusters by the Iterative Self-Organizing Data Analysis Technique (ISODATA). To distinguish ambiguous land cover classes, a decision tree was built on five phenological features derived from EVI profiles, Land Surface Temperature (LST) and topographic slope. The overall accuracy of the final land cover map was 75.5%, indicating the promise of using MODIS EVI time series and decision trees for broad area land cover classification.     

基于ArcGIS Server的GIS Web服务自动发布关键技术研究

Web GIS技术主要采用GIS Web服务方式对外提供资源访问和空间分析能力。GIS Web服务提高系统资源利用率,扩大信息使用范围,但GIS Web服务主要依赖于服务器端GIS平台提供的可视化工具进行后台发布,前台用户无法根据自己业务需要自动发布GIS Web服务。文中基于ArcGIS Server平台研究一种GIS Web服务自动发布方案,以双丰林业局林政资源服务系统的在线采编模块为例,阐述该案例的应用。     

景观格局在地理国情综合统计分析中的应用——以三江自然保护区为例

为了研究景观格局在地理国情综合统计中的应用,本文以三江自然保护区为例,综合考虑景观格局指数的生态意义并对区域景观的总体结构、斑块特征、多样性及脆弱性进行综合统计分析。研究结果表明,通过景观格局分析可以有效了解区域生态环境状态及地表覆盖格局特征,为地理国情普查综合统计分析生态协调性专题定量化计算提供参考。     

动态GPS精密单点定位三种星历精度差异分析

针对传统的动态GPS中采用不同星历的定位精度问题,给出了无电离层模型数学方程,改正了电离层延迟、对流层延迟、多路径效应、相对论效应以及天线相位中心偏差等误差的影响,采用扩展Kalman滤波解算出每个历元时刻接收机坐标。采用Rapid、Final与RTS共3种不同星历产品计算KPPP,比较了3种不同星历解算结果。对比实验表明:使用Rapid星历计算KPPP结果与Final星历计算结果偏差很小,处于2cm之内,故在时效性要求较高的动态GPS工程应用中可以采用Rapid星历替代Final星历;而使用RTS星历计算结果与Final星历计算结果偏差1.3m,使用RTS星历定位精度低于Final、Rapid星历计算结果,但其具有实时定位的明显优势。