Monitoring and analysis of changes in a wetland landscape in Xingzi county

Wetlands play an important role in water conservation, environmental protection, and biodiversity conservation. Remote sensing is an economical and efficient technique for wetland monitoring which can limit disturbance in sensitive areas and support wetland conservation. In this paper, we used three phases of Thematic Mapper/Enhanced Thematic Mapper plus (TM/ETM+) remote sensing images from October 1989, October 1999, and October 2009 to study wetlands in Xingzi County. The images were segmented using the object-oriented remote sensing image interpretation software eCognition Developer 8.64, then segmented images were classified by slope, digital elevation model (DEM) data, Normalized Difference Vegetation Index (NDVI), Specific Leaf Area Vegetation Index (SLAVI), and Land and Water Masks (LWM) index to produce land type classification maps. Land use change information was obtained by analyzing the superposition of two classification maps of the wetland area from different years. The results showed that landscape patches in Xingzi County displayed fragmentation in their spatial distribution over time. Based on an index of changes in landscape patches, the fastest growing landscape type is grassland, while the fastest decreasing type is irrigated land. Dominant driving factors of changes in Xingzi County’s wetland landscape are population growth and policy changes.     

Landslide susceptibility zonation using GIS and evidential belief function model

The main goal of this paper is to generate a landslide susceptibility map through evidential belief function (EBF) model by using Geographic Information System (GIS) for Qianyang County, Shaanxi Province, China. At first, a detailed landslide inventory map was prepared, and the following ten landslide-conditioning factors were collected: slope angle, slope aspect, curvature, plan curvature, profile curvature, altitude, distance to rivers, geomorphology, lithology, and rainfall. The landslides were detected from the interpretation of aerial photographs and supported by field surveys. A total of 81 landslides were randomly split into the following two parts: the training dataset 70 % (56 landslides) were used for establishing the model and the remaining 30 % (25 landslides) were used for the model validation. The ArcGIS was used to analyze landslide-conditioning factors and evaluate landslide susceptibility; as a result, a landslide susceptibility map was generated by using EBF and ArcGIS 10.0, thus divided into the following five susceptibility classes: very low, low, moderate, high, and very high. Finally, when we validated the accuracy of the landslide susceptibility map, both the success-rate and prediction-rate curve methods were applied. The results reveal that a final susceptibility map has the success rate of 83.31 % and the prediction rate of 79.41 %.     

Seasonal variation and principle of cyanobacterial biomass and forms in the water source area of Chaohu City,China

We investigated seasonal variations in cyanobacterial biomass and the forms of its dominant population(M. aeruginosa) and their correlation with environmental factors in the water source area of Chaohu City,China from December 2011 to October 2012. The results show that species belonging to the phylum Cyanophyta occupied the maximum proportion of phytoplankton biomass,and that the dominant population in the water source area of Chaohu City was M. aeruginosa. The variation in cyanobacterial biomass from March to August 2012 was well fitted to the logistic growth model. The growth rate of cyanobacteria was the highest in June,and the biomass of cyanobacteria reached a maximum in August. From February to March 2012,the main form of M.aeruginosa was the single-cell form; M.aeruginosa colonies began to appear from April,and blooms appeared on the water surface in May. The maximum diameter of the colonies was recorded in July,and then gradually decreased from August. The diameter range of M. aeruginosa colonies was 18.37–237.77 μm,and most of the colonies were distributed in the range 20–200 μm,comprising 95.5% of the total number of samples. Temperature and photosynthetically active radiation may be the most important factors that influenced the annual variation in M. aeruginosa biomass and forms. The suitable temperature for cyanobacterial growth was in the range of 15–30°C. In natural water bodies,photosynthetically active radiation had a significant positive influence on the colonial diameter of M.aeruginosa(P0.01).     

便携式高频地波雷达海流探测长周期工作性能试验

2013年1月29日至3月15日在台湾海峡西南部海域进行了OSMAR-S100便携式高频地波雷达与浮标观测海流数据的长周期对比试验,验证了雷达系统在探测海流方面的准确性、可靠性和稳定性.通过实测海流与雷达矢量流的复相关分析,选定3 m层的海流为对比代表层.试验期间实测流速为0.0~120.0 cm/s,雷达海流有效探测区内的矢量流流速、流向的观测误差较小,能够满足实时监测海洋表层流的需要,高精度区流速、流向的均方根误差分别为9.1 cm/s和24.8°,边缘区的均方根误差为13.3~24.8 cm/s和39.4°~39.6°,与国内外达到业务化运行要求的同类产品实际观测精度相当.     

Observed characteristics of atmospheric ducts over the South China Sea in autumn

The observed characteristics of lower atmospheric ducts over the South China Sea(SCS) were analyzed based on Global Position Systerm(GPS) radiosonde data collected four times daily during autumn open cruises from 2006 to 2012.Duct occurrence,thickness,and strength over the SCS were about 40%,150-m thick,and 8 M units,respectively,which were larger than during the summer monsoon period.Most ducts occurred at heights 1 500 m and these ducts easily trap electromagnetic wave clusters with wavelengths 2 m.Diurnal variation of the SCS ducts appeared evident.They occurred more often at midnight at higher altitudes(about 1 100 m),with a thickest layer of about 145 m and less frequently during the evening at lower altitudes(about 800 m),with a thinnest layer of about 125 m.Moreover,ducts during the daytime at a mean height of about 900 m,with the greatest strength of about 10 M units.Furthermore,all duct variables observed over the SCS in autumn decreased from north to south.These findings are useful not only in the design of radar and communication systems,but also for evaluating possible effects of anomalous propagation on meteorological radar and military applications.     

新疆乌鲁木齐东部早二叠世枕状玄武岩火山岩系的发现及大地构造意义

新疆乌鲁木齐东部野生动物园附近的下二叠统下部发育了一套以枕状玄武岩为代表的火山岩系。该玄武岩在公路上发育有两层,上部一层较厚,可达7～8m,下部一层2～3m。岩枕近圆形、肾状、枕状、条带状或蠕虫状等,多呈顶突底凹。岩枕长轴平行排列,长轴基本顺层面分布;有的岩枕中含大量海百合茎、珊瑚及腕足等生物化石。在TAS图中大部分样品位于玄武粗安岩,而在K_2O-SiO_2图上主要落在低K拉斑玄武岩区间。MnOTiO_2-P_2O_5图解显示以岛弧为主,常量元素的特征总体上更接近岛弧玄武岩。在Hf/3-Th-Ta图解上也以岛弧为主;在Zr/4-2Nb-Y图解显示以火山弧为主,常量元素的特点总体上更接近岛弧玄武岩。微量元素原始地幔标准化蛛网图表明为同源岩浆产物,具高度相似的演化过程,多种微量元素判别图揭示岛弧-弧后盆地环境;稀土总量明显较低,在稀土元素球粒陨石标准化图解上,其稀土分布曲线一致性较好,呈轻稀土富集右倾型,Eu为负异常,揭示了乌东玄武岩岩浆有一定分异。稀土元素配分曲线与弧后盆地玄武岩(BABB)具有很好的一致性。U-Pb和谐年龄为283±8Ma,结合地层及古生物资料推测乌东玄武岩喷发的时间为早二叠世早期。乌东枕状玄武岩-灰岩之下有一套(磨拉石)底砾岩,初定为石炭-二叠系的界限。底砾岩之下为下石炭统的中厚层灰岩,具有明显的喀斯特化,为不整合接触,揭示在两者之间发生了造山作用。通过对新疆乌东早二叠世早期的枕状玄武岩的地质特征、地球化学特征、形成环境和时代的研究,表明乌东一带早二叠世主要为一个岛弧和弧后盆地环境,进一步揭示了北天山北缘石炭-二叠世碰撞闭合造山之后又发生了松弛扩张形成了弧后盆地,海水再度大规模入侵。最终的闭合碰撞造山的时间最早可能在晚二叠世。由于乌东枕状玄武岩在喷出地表后受到了生物化石和陆源碎屑的污染,再加上侵入过程中地壳的污染,使其具有非常复杂的地球化学特点和多解性。乌东玄武岩的研究对于了解博格达山、甚至天山中段在晚古生代的构造沉积演化及造山作用具有重要意义,同时对准噶尔盆地、吐哈盆地及三塘湖盆地油气资源的形成与分布具有重要意义。     

Metallogenic Mechanism and Tectonic Setting of Tungsten Mineralization in the Yangbishan Deposit in Northeastern China

The Yangbishan iron–tungsten deposit in the Shuangyashan area of Heilongjiang Province is located in the center of the Jiamusi Massif in northeastern China. The rare earth element and trace element compositions of the scheelite show that it formed in a reducing environment and inherited the rare earth element features of the ore-forming fluid. The geochemical characteristics of the gneissic granite associated with the tungsten mineralization show that the magma formed in this reducing environment and originated from the partial melting of metamorphosed shale that contained organic carbon and was enriched with tungsten. In addition, in situ Hf isotopic analysis of zircons from the gneissic granite indicates that they probably originated from the partial melting of a predominantly Paleo–Mesoproterozoic crustal source. According to LA-ICP-MS zircon dating, the Yangbishan orerelated gneissic granite has an Early Paleozoic crystallization age of 520.6 ± 2.8 Ma. This study, together with previous data, indicates that the massifs of northeastern China, including Erguna, Xing'an, Songliao, Jiamusi, and Khanka massifs, belonged to an orogenic belt that existed along the southern margin of the Siberian Craton during the late Pan-African period. The significant continental movements of this orogeny resulted in widespread magmatic activity in northeastern China from 530 Ma to 470 Ma under a tectonic setting that transitioned from compressional syn-collision to extensional postcollision.     

Iron isotopic analyses of geological reference materials on MC-ICP-MS with instrumental mass bias corrected by three independent methods

Here we report iron (Fe) isotopic data of three pure Fe solution standards (IRMM-014, GSB Fe, and NIST 3126a) and five widely used geological reference materials (RMs) from the United States Geological Survey and Geological Survey of Japan obtained on a Neptune Plus multi-collector–inductively coupled plasma–mass spectrometer (MC-ICP-MS) in our laboratory over the past 3 years. The instrumental mass bias was corrected by three independent methods: sample-standard bracketing (SSB), Ni doping?+?SSB, and ⁵⁷Fe–⁵⁸Fe double spike?+?SSB. Measurements reveal that both the Ni doping and double spike methods helped calibrate short-term fluctuations in mass bias. Collectively, almost all measurements of RMs yielded δ⁵⁶Fe within?±?0.05 of recommended values, provided that each sample was measured four times on MC-ICP-MS. For the first time, new recommended values for NIST SRM3126a are reported (δ⁵⁶Fe?=?0.363?±?0.006, 2SE, 95% CI; and δ⁵⁷Fe?=?0.534?±?0.010, 2SE).     

Petrogenesis and Tectonic Significance of the Three‐Period Porphyries from the Daruoluolong Cu (Au) Deposit,Tibet, China

正Objective The Daruoluolong deposit is the first high-grade Cu(Au)deposit discovered in the middle section of the Bangonghu-Nujiang(herein after referred to as Ban-Nu)metallogenic belt,which has not been documented about previously.This deposit is located in Shuanghu County of northern Tibet,and its geotectonic position belongs to the