关于滇东北MVT型铅锌矿成矿时代的讨论

滇东北地区是我国重要的铅锌矿产品生产基地,区内发育多个大型密西西比河谷型(Mississippi valley-type,MVT型)铅锌矿床,个别矿床(会泽)达到超大型.前人对该区域的铅锌矿床开展了大量的年代学研究工作,获得了一大批成矿年龄,本文在通过对各类同位素测年方法在该类型矿床中使用存在的弊端进行分析后,基于滇东...     

Changes of soil surface roughness under water erosion process

The objective of this study was to determine the changing characteristics of soil surface roughness under different rainfall intensities and examine the interaction between soil surface roughness and different water erosion processes. Four artificial management practices (raking cropland, artificial hoeing, artificial digging, and contour tillage) were used according to the local agriculture customs of the Loess Plateau of China to simulate different types of soil surface roughness, using an additional smooth slope for comparison purposes. A total of 20 rainfall simulation experiments were conducted in five 1 m by 2 m boxes under two rainfall intensities (0.68 and 1.50 mm min^?1) on a 15° slope. During splash erosion, soil surface roughness decreased in all treatments except raking cropland and smooth baseline under rainfall intensity of 0.68 mm min^?1, while increasing for all treatments except smooth baseline under rainfall intensity of 1.50 mm min^?1. During sheet erosion, soil surface roughness decreased for all treatments except hoeing cropland under rainfall intensity of 0.68 mm min^?1. However, soil surface roughness increased for the artificial hoeing and raking cropland under rainfall intensity of 1.50 mm min^?1. Soil surface roughness has a control effect on sheet erosion for different treatments under two rainfall intensities. For rill erosion, soil surface roughness increased for raking cropland and artificial hoeing treatments, and soil surface roughness decreased for artificial digging and the contour tillage treatments under two rainfall intensities. Under rainfall intensity of 0.68 mm min^?1, the critical soil surface roughness was 0.706 cm for the resistance control of runoff and sediment yield. Under rainfall intensity of 1.50 mm min^?1, the critical soil surface roughness was 1.633 cm for the resistance control of runoff, while the critical soil surface roughness was 0.706 cm for the resistance control of sediment yield. These findings have important implications for clarifying the erosive nature of soil surface roughness and harnessing sloped farmland. Copyright © 2013 John Wiley & Sons, Ltd.     

旅游网站信息流距离衰减的集中度研究

通过百度、Google、Alexa、Cnzz等多种网络搜索引擎和网站访问量统计工具获取了24个旅游网站分省访问量资料,运用Origin软件评估了旅游网站信息流距离衰减的曲线模型,在此基础上深入研究了旅游网站信息流距离衰减的集中度问题。研究经过3个阶段,逐级递进分别应用Zipf定律、地理集中度指数和指数模型3种方法,描述了空间分布的集中性,揭示了本地集中性与经济集中性特征,讨论了本地集中性与指数模型符合性的关系。研究发现:①旅游网站信息流的位序—规模分布符合Zipf定律,以单分形特征为主,其信息流的规模结构主体呈Pareto分布模式,具有明显的空间分布集中性,该集中性表现为随分维值大小而相应变化。②各旅游网站信息流距离衰减的区位商值大于1的省份主要为网站所在省或经济发达省份,距离衰减具有明显的本地集中性和经济集中性特征;各旅游网站信息流距离衰减的空间洛伦茨曲线呈内凹型,且多数网站基尼系数大于0.5,距离衰减的集中度较高、空间分布不均衡。③旅游网站信息流距离衰减的本地集中性受旅游网站性质影响,且其本地集中性越强,指数模型拟合优度指数越高,指数模型与网站数据点的匹配效果越好,各省份访问量越接近标准曲线,与拟合曲线的吻合度越高。④旅游网站信息流距离衰减的集中性特征,为旅游目的地确定目标市场和旅游网站的建设与营销提供了理论支持。     

Monazite trumps zircon: applying SHRIMP U–Pb geochronology to systematically evaluate emplacement ages of leucocratic,low-temperature granites in a complex Precambrian orogen

Although zircon is the most widely used geochronometer to determine the crystallisation ages of granites, it can be unreliable for low-temperature melts because they may not crystallise new zircon. For leucocratic granites U–Pb zircon dates, therefore, may reflect the ages of the source rocks rather than the igneous crystallisation age. In the Proterozoic Capricorn Orogen of Western Australia, leucocratic granites are associated with several pulses of intracontinental magmatism spanning ~800 million years. In several instances, SHRIMP U–Pb zircon dating of these leucocratic granites either yielded ages that were inconclusive (e.g., multiple concordant ages) or incompatible with other geochronological data. To overcome this we used SHRIMP U–Th–Pb monazite geochronology to obtain igneous crystallisation ages that are consistent with the geological and geochronological framework of the orogen. The U–Th–Pb monazite geochronology has resolved the time interval over which two granitic supersuites were emplaced; a Paleoproterozoic supersuite thought to span ~80 million years was emplaced in less than half that time (1688–1659 Ma) and a small Meso- to Neoproterozoic supersuite considered to have been intruded over ~70 million years was instead assembled over ~130 million years and outlasted associated regional metamorphism by ~100 million years. Both findings have consequences for the duration of associated orogenic events and any estimates for magma generation rates. The monazite geochronology has contributed to a more reliable tectonic history for a complex, long-lived orogen. Our results emphasise the benefit of monazite as a geochronometer for leucocratic granites derived by low-temperature crustal melting and are relevant to other orogens worldwide.     

Oxfordian magnetostratigraphy of Poland and its correlation to Sub-Mediterranean ammonite zones and marine magnetic anomalies

A nearly continuous magnetostratigraphic polarity pattern was compiled from several ammonite-zoned carbonate successions of southern Poland and from a composite magnetostratigraphy from the Iberian Range of Spain. The array of sections spans the middle two-thirds of the Oxfordian within the Sub-Mediterranean Province (Cordatum through Bifurcatus ammonite zones). The average paleopole calculated from eight of these Polish sections is at 78.5°N, 184.9°E (δp = 2.6°, δm = 3.5°). The Sub-Mediterranean polarity pattern is consistent with an independent polarity pattern derived from the Boreal-realm sections of the British Isles, and improves the inter-correlation between these faunal realms. Cycle stratigraphy published for these ammonite subzones from southern France enabled temporal scaling of the polarity pattern, thereby facilitating correlation to marine magnetic anomalies M28 through M33 as modeled from deep-tow magnetometer surveys in the Western Pacific. The bases of the Middle and Upper Oxfordian substages as defined in the Sub-Mediterranean zonation in Poland correspond approximately to chrons M33 and M29 of that Pacific M-sequence model.     

鄯勒油田西山窑组层序地层格架及其油气地质意义

运用层序地层学的基本原理和技术方法,建立鄯勒油田西山窑组层序地层格架,划分沉积相,并在此基础上分析层序地层格架内砂体的展布特征和油气的聚集规律,预测研究区岩性油气藏的类型及分布。研究结果表明：西山窑组整体经历了一个先进积、后退积的过程;西山窑组为一个三级层序,其中包含2个四级层序,该组由低位域（LST）的三角洲前缘沉积、湖侵域（TST）的三角洲平原沉积和高位域（HST）的湖相沉积组成。研究区基准面上升期可以寻找砂体上倾尖灭型岩性圈闭,基准面下降期可以寻找砂岩透镜体岩性圈闭。西一、二段沉积的三角洲河道砂体受后期构造运动的影响,可以形成砂体上倾尖灭型岩性油气藏;而西三、四段的湖相浊积砂体,可以形成砂岩透镜体岩性油气藏。     

近16年暖季青藏高原东部两类中尺度对流系统（MCS）的统计特征

利用日本高知大学提供的逐小时分辨率静止卫星云顶黑体亮温（TBB）资料,使用模式匹配算法对2000～2016年（2005年除外）暖季（5～9月）青藏高原东部的两类中尺度对流系统（MCS）进行了识别和追踪,并利用人工验证订正了结果。基于此,利用NOAA的CMORPH（Climate Prediction Center Morphing）降水资料和NCEP的CFSR（Climate Forecast System Reanalysis）再分析资料对高原东部两类MCS进行了统计和对比研究。研究发现,7月和8月是高原东部MCS生成最活跃的季节,然而,此两个月能够东移出高原MCS的比例最小;5月虽然MCS生成数最少,但是移出率高达近40%。对比表明,能够东移出高原的MCS（V-MCS）比不能移出的MCS（N-MCS）生命史更长,触发更早,短生命史个例占比更低。暖季各个月份,相比于N-MCS,V-MCS的对流更旺盛且发展更快,然而,由于其发生频数远低于N-MCS,总体而言,V-MCS对高原东部的降水贡献率仅为15%左右,是N-MCS相应数值的一半左右。高原东部两类MCS的环流特征差异显著,有利于V-MCS发生、维持和东移的因子主要位于对流层中低层（西风带短波槽、西风引导气流、低层风场切变）,而在对流层高层,N-MCS拥有更好的高空辐散条件（其对应的南亚高压更强）。     

旅游网站信息流距离衰减集中性的差异及其检验

在"旅游网站信息流距离衰减形态描述与集中度计算"[1]一文的基础上,从旅游网站性质的角度对旅游网站信息流距离衰减形态与集中性的差异进行指数衰减模型的拟合分析,并应用Zipf定律检验其特征,发现:1)不同性质的旅游网站信息流距离衰减形态存在差异,旅游主管部门网站、旅游企业网站、旅游目的地网站的信息流距离衰减形态分别表现出非常符合指数衰减模型、基本符合指数衰减模型、不符合指数衰减模型特征。2)不同性质的旅游网站信息流距离衰减的集中性存在差异,分别表现出具有明显的本地集中性特征、兼有本地集中性和经济集中性特征、具有明显的经济集中性特征。3)分维值多在0.5左右说明了旅游网站信息流距离衰减集中性较强,分维值的差异说明了不同性质旅游网站信息流距离衰减集中性存在差异。旅游网站信息流的位序-规模均符合Zipf定律,其首位省市均存在于网站所在地或者周边省市,其位序-规模的前四位总体为经济发达省市,说明了旅游网站信息流距离衰减具有本地和经济集中性。4)对旅游网站信息流距离衰减集中性的Zipf检验,证实了空间距离集中性特征的普遍意义。     

基于ArcMap插件的土地利用规划编制方法研究

近几年来,GIS在土地利用规划领域得到了广泛的应用.但是受到规划的复杂性等因索的影响,GIS也表现出了缺乏针对性等缺陷.本文根据规划编制的具体要求开发了一个土地利用规划编制插件.此插件可以无缝地集成到ArcMap中.在土地利用规划编制过程中使用此插件可以提高工作的效率和精度.此插件提供了一系列数据处理工具和数据库管理工...     

创意城市网络下日本神户设计之都的规划与实践

创意城市是城市复兴和再生的发展模式,创意城市网络是推动创意城市发展的全球性载体。这种跨地域、跨国家、跨大洲的城市网络与创意城市发展的地理过程、空间格局逐步成为新的地理现象。本文以神户为例,分析神户创意城市发展的背景条件,研究其指向设计之都的主导产业与规划内容,探讨其推进设计之都建设的实践与经验。