Geochemistry,Zircon U–Pb Analysis,and Biotite 40Ar/39Ar Geochronology of the Maoling Gold Deposit,Liaodong Rift,NE China          下载免费PDF全文

Peng Zhang  Yan Zhao  Peng Chai  Hong‐Zhi Yang  Fu‐Chao Na 《Resource Geology》2017,67(4):426-441

The Maoling gold deposit is located in the southwestern part of the Liaodong rift, NE China, and has estimated reserves of 25 t. In this paper we present the results of an investigation into the geochronology and geodynamic mechanisms of igneous activity and metallogenesis within the Maoling gold deposit. New zircon U–Pb age data, biotite ⁴⁰Ar/³⁹Ar age data, whole‐rock geochemistry, and Hf isotopic analyses are presented in order to constrain the petrogenesis and mineralization of the deposit. Zircon U–Pb dating of the Wolongquan biotite monzogranite and Maoling biotite granite yielded mean ages of 194.0 ± 1.1 Ma and 196.1 ± 1.1 Ma, respectively. All the granites are characteristically high‐K calc‐alkaline, enriched in light rare earth elements and large ion lithophile elements, and depleted in high field strength elements, which is consistent with the geochemical characteristics of arc‐type magmas. The Hf isotope characteristics indicate that the granites formed by partial melting of early Paleoproterozoic crustal material. In addition, biotite ⁴⁰Ar/³⁹Ar dating indicates that the Maoling gold deposit formed at 188.9 ± 1.2 Ma, implying that the mineralization was related to both the granite intrusions. Taking into account previous data on S–Pb–O–H isotopes and our new age data, the Maoling deposit can be classified as an intrusion‐related gold deposit. Taking into account the geology of the study area and adjacent regions, we propose that the Maoling gold deposit and its associated granitic intrusions formed in a geodynamic setting that was dominated by subduction of the Paleo‐Pacific Plate beneath the Eurasian continent.  相似文献   

北京郊区居民日常生活方式的行为测度与空间—行为互动   总被引：7，自引：2，他引：5  

塔娜  柴彦威  关美宝 《地理学报》2015,70(8):1271-1280

郊区化及其对居民日常生活的影响成为近年来城市研究的重要议题。时空行为研究认为推动日常生活方式的郊区化是解决郊区化过程中出现的社会与空间问题的根本措施。从日常生活方式的角度出发,需要利用多维度时空行为指标刻画群体的生活方式类型以分析郊区居民的空间—行为互动机制。本文采用活动空间和出行频率指标构建个体日常生活方式的行为测度方法,并基于2012年在北京上地—清河地区进行的GPS调查数据将郊区居民划分为“空间排斥”、“本地化”、“郊区性”、“两极化”、“城市依赖”五种日常生活方式类型。研究发现不同日常生活方式群体在活动分布、活动频率和交通方式上存在差异;并通过多项logistic模型分析郊区化对于个体日常生活方式的影响,发现工作日居民的日常生活方式受到性别、收入、年龄和工作时长等社会经济属性的影响。同时郊区设施配置直接影响着居民对郊区空间的利用程度,土地混合利用、商业设施密度提高更有可能实现日常生活的郊区化。日常生活方式的行为测度方法有助于分析郊区居民日常行为的复杂性,为理解郊区化提供了独特的视角,为构建城市研究的空间—行为互动理论提供了有力的支持。  相似文献   

民勤荒漠绿洲过渡带灌丛沙堆形态特征及分布格局     

张进虎  唐进年  李得禄  魏林源  满多清  柴成武 《中国沙漠》2015,35(5):1141-1149

以民勤荒漠绿洲过渡带为研究区,通过样方调查,研究了荒漠区、荒漠绿洲过渡区到绿洲内不同梯度生境中灌丛沙堆的形态特征及分布格局。结果表明:(1)3种生境中灌丛沙堆的形态呈极显著性差异(p<0.01);绿洲区灌丛沙堆的平均高度、底面积、纵横断面积和体积均最大,其次为荒漠区,过渡区最小。(2)过渡带3种生境灌丛沙堆的长、短轴之间均呈二次函数关系,但相关程度不同,过渡区相关性最高,相关系数达0.78;绿洲区相关性最低,相关系数为0.57;高度与底面积、体积与高度间均呈幂函数关系,相关系数均在0.59以上;(3)过渡区灌丛沙堆分布密度较大,呈聚集分布,而荒漠区及绿洲区沙堆分布密度较小,均呈随机分布。  相似文献   

基于ISSR分子标记数据的兰州百合核心种质构建方法研究     

李谋强  师桂英  叶树辉  黄彦玮  边小荣 《中国沙漠》2015,35(6):1573-1578

利用ISSR分析获得的数据,研究了依据Nei & Li、SM和Jaccard遗传距离,采用UPGMA聚类法进行逐步聚类筛选核心种质的效果,并最终采用SM遗传距离逐步聚类从175份兰州百合种质中筛选出了37份核心种质。保留了初始种质21.14%的样品,多态性位点数、多态性位点百分率、Nei's遗传多样性指数和Shannon's信息指数的保留率分别为96.08%、96.59%、105.27%、103.62%,t检验表明核心种质的Nei's遗传多样性指数和Shannon's信息指数与原种质没有显著差异,表明构建的核心种质能很好的代表原始种质的遗传多样性。  相似文献   

A model study of the Copper River plume and its effects on the northern Gulf of Alaska     

Yuan Wang  Huijie Xue  Fei Chai  Yi Chao  John Farrara 《Ocean Dynamics》2014,64(2):241-258

A three-level nested Regional Ocean Modeling System was used to examine the seasonal evolution of the Copper River (CR) plume and how it influences the along- and across-shore transport in the northern Gulf of Alaska (NGoA). A passive tracer was introduced in the model to delineate the growth and decay of the plume and to diagnose the spread of the CR discharge in the shelf, into Prince William Sound (PWS) and offshore. Furthermore, a model experiment with doubled discharge was conducted to investigate potential impacts of accelerated glacier melt in future climate scenarios. The 2010 and 2011 simulation revealed that the upstream (eastward) transport in the NGoA is negligible. About 60 % of the passive tracer released in the CR discharge is transported southwestward on the shelf, while another one third goes into PWS with close to 60 % of which exiting PWS to the shelf from Montague Strait. The rest few percent is transported across the shelf break and exported to the GoA basin. The downstream transport and the transport into PWS are strongly regulated by the downwelling-favorable wind, while the offshore transport is related to the accumulation of plume water in the shelf, frontal instability, and the Alaskan Stream. It takes weeks in spring for the buoyancy to accumulate so that a bulge forms outside of the CR estuary. The absence of strong storms as in the summer of 2010 allows the bulge continue growing to trigger frontal instability. These frontal features can interact with the Alaskan Stream to induce transport pulses across the shelf break. Alternatively as in 2011, a downwelling-favorable wind event in early August (near the peak discharge) accelerates the southwestward coastal current and produces an intense downstream transport event. Both processes result in fast drains of the buoyancy and the plume content, thereby rapid disintegration of the plume in the shelf. The plume in the doubled discharge case can be two to three times in size, which affects not only the magnitude but also the timing of certain transport events. In particular, the offshore transport increases by several folds because the plume appears to be more easily entrained by the seaward flow along the side of Hinchinbrook Canyon.  相似文献   

Study on Three-dimensional Visualization for Rock Structure     

He-Jun Chai  Jun-Jie Wang  Sheng-Chuan Tang 《Geotechnical and Geological Engineering》2009,27(3):315-323

The visualization of rock structure is a very useful and important technique in many aspects in geological and geotechnical engineering such as investigating and evaluating the stability of a high rock slope. The conventional method used to visualize rock structure is limited to plotting the orientation of individual discontinuities by using the Schmidt stereographic net. The present paper shows a new technique to visualize the three-dimensional structure of rock masses. The fitting function for three-dimensional rock structure was established based on data gathered from field survey. Two fitting methods by which the discontinuous points gathered from a plane and discrete points from field survey were fitted respectively are suggested. The technique to visualize the three-dimensional structure of rock masses includes many aspects such as projection transformation, blanking and mutual cutting, are investigated. Based on the visualizing technique, the rock structure at the site of Xilupdu dam which is being built in Southwest of China was investigated.  相似文献   

基于生物气候因子聚类的植物群组划分及其中国生物群区模拟   总被引：2，自引：2，他引：0       下载免费PDF全文

黄康有  郑卓  L.Fran 《第四纪研究》2009,29(2):199-210

本研究基于10′×10′空间分辨率运用GIS软件对中国植被分布地理配准数字化,提取获得196个优势植物的地理分布数据以及内插相关的气候因子,运用分位数函数计算获得各个植物地理分布的气候阈值;   在此基础上采用生物气候群组（BAGs）的分类方法,对196个优势植物气候因子数据进行聚类分析,同时结合中国植被的地理分布特征,最后划分出29个BAG组,包括13个乔木组(6个常绿阔叶和2个落叶阔叶群组,4个常绿针叶和1个落叶针叶群组)、10个灌木组(5个常绿灌木和5个落叶灌木群组)和6个草本组。本研究的BAGs划分是建立在较高空间分辨率和定量气候因子阈值的基础上,因此,通过计算获得BAGs气候阈值(包括每日温度变化幅度、地表霜冻频率、月均温度、月降雨量、相对湿度、日照时数和>5℃年积温等),运用生物圈碳循环CARAIB模型,模拟出中国19个生物群区的现代潜在分布。模拟结果较好地表达了中国植被类型的地理分布,尤其较详细地展示了热带、亚热带、温带和高原地区的不同植被类型地理分布格局,但由于东北地区、西部草原以及热带原生植被受人类活动严重干扰,使得模拟结果比该地区的原生植被地理分布的实际面积偏大。总体而言,本研究获得的29个生物气候群组对模拟现代生物群区分布提供了理想的分类依据,其气候阈值也是进行过去和未来生物群区模拟的重要参照数据。  相似文献   

Modeling the long-term variability of phytoplankton functional groups and primary productivity in the South China Sea     

Wentao Ma  Fei Chai  Peng Xiu  Huijie Xue  Jun Tian 《Journal of Oceanography》2013,69(5):527-544

Primary productivity (PP) and phytoplankton structure play an important role in regulating oceanic carbon cycle. The unique seasonal circulation and upwelling pattern of the South China Sea (SCS) provide an ideal natural laboratory to study the response of nutrients and phytoplankton dynamics to climate variation. In this study, we used a three-dimensional (3D) physical–biogeochemical coupled model to simulate nutrients, phytoplankton biomass, PP, and functional groups in the SCS from 1958 to 2009. The modeled results showed that the annual mean carbon composition of small phytoplankton, diatoms, and coccolithophores was 33.7, 52.7, and 13.6 %, respectively. Diatoms showed a higher seasonal variability than small phytoplankton and coccolithophores. Diatoms were abundant during winter in most areas of the SCS except for the offshore of southeastern Vietnam, where diatom blooms occurred in both summer and winter. Higher values of small phytoplankton and coccolithophores occurred mostly in summer. Our modeled results indicated that the seasonal variability of PP was driven by the East Asian Monsoon. The northeast winter monsoon results in more nutrients in the offshore area of the northwestern Luzon Island and the Sunda Shelf, while the southwest summer monsoon drives coastal upwelling to bring sufficient nutrients to the offshore area of southeastern Vietnam. The modeled PP was correlated with El Niño/Southern Oscillation (ENSO) at the interannual scale. The positive phase of ENSO (El Niño conditions) corresponded to lower PP and the negative phase of ENSO (La Niña conditions) corresponded to higher PP.  相似文献   

中国东北部陆缘内生金矿床成因类型、成矿时代及地球动力学背景   总被引：2，自引：0，他引：2  

韩世炯  孙景贵  邢树文  张增杰  柴鹏  杨帆  邱殿明 《吉林大学学报(地球科学版)》2013,43(3):716-733

中国东北部陆缘是我国内生金矿床较为发育的地区之一,以成矿作用复杂、蕴藏丰富的金资源量倍受国内外地质学家关注。通过对该区内生金矿的地质和成矿年代的系统研究,初步将该区内生金矿床划分为中温热液金矿床、接触交代-热液金矿床、斑岩型/类斑岩型金铜矿床和浅成低温热液金矿床4种主要成因类型和3个重要成矿期（170～160 Ma、130～110 Ma和110～90 Ma）。结合同位素地球化学特征,进一步确定中温热液金矿床的成矿物质主要来自下地壳源,成矿作用与中生代燕山早期古太平洋板块俯冲作用引发的中国东部大陆边缘岩石圈减薄及拆沉的动力学过程密切相关;接触交代-热液金矿床的成矿物质来源于年轻地壳,成矿作用与古太平洋板块俯冲引起的岩石圈减薄拆沉的伸展构造背景下的岩浆接触交代作用更为密切;而斑岩型/类斑岩型金铜矿床和浅成低温热液金矿床的成矿物质来源为壳幔混合源,其成矿发生在古太平洋板块向亚洲大陆正北向俯冲转入Izanagi Farallon板块西向俯冲的构造转换期。  相似文献   

Residents′Activity-travel Behavior Variation by Communities in Beijing,China   总被引：3，自引：1，他引：2  

ZHAO Ying  CHAI Yanwei 《中国地理科学(英文版)》2013,23(4):492-505

China’s transition from a planned economy to a market economy has resulted in many changes in its urban structure and society and provided an opportunity for a quasi-longitudinal case study on the relationship between the built environment and activity-travel behavior.This paper draws upon data from an activity diary survey conducted in Beijing in 2007.The survey sample comprised 652 residents living in Danwei(work unit),commodity housing,and affordable housing neighborhoods.On the basis of the three-dimensional geo-visualization analysis of the space-time path and statistical multivariate regression models of daily travel and leisure time,it was found that both residential spatial factors and socio-demographics influence residents’ daily behaviors.The findings show that Danwei residents have less daily travel time than those who live in commodity housing,but people living in affordable housing endure the longest travel time.Daily leisure time is associated more with individual attributes.We argue that although China’s transition is currently gradual,the Danwei system may continue to play significant roles in daily life,and it might provide a valuable model for neighborhood spatial planning.  相似文献