祁连山东段金塔河流域层状地貌时代与成因探讨

祁连山东段金塔河流域分布着两级夷平面(山顶面与主夷平面)、一级剥蚀面和多级河流阶地,它们是晚新生代青藏高原阶段性隆升的产物。通过电子自旋共振(Electron spin resonance,简写为ESR)、热释光(Luminescgnce,简写为TL)、红外释光(Infra-red stimulated luminesomce,简写为IRSL)和^14C等绝对测年手段并结合区域对比的研究表明,该区山顶面形成于老第三纪,主夷平面形成于中新世至上新世,剥蚀面解体于1．4MaB．P．左右。其后金塔河流域发育5～6级阶地,形成时代大致为1．24MaB.P.、0．78Ma.B.P.、0．14MaB.P.、0．06MaB.P.、0．03MaB．P．和0．01MaB．P．。结合河流阶地的形成年代、发育特征以及邻区阶地的发育模式研究表明,它们应是构造隆升以及气候变化双重作用下的产物。     

若尔盖盆地河流古洪水沉积及其对黄河水系演变问题的启示

青藏高原东部若尔盖盆地古湖泊消亡、黄河贯穿盆地、黄河源区现代水系格局形成,是黄河发育演变史上的重要事件,也是青藏高原东部水文环境变化的转折点。关于其发生年代问题,目前尚无确切结论。本文根据野外考察所获资料和实验室测试分析数据,结合历年来前人多方面研究的结果,针对若尔盖盆地古湖泊消亡与黄河贯穿盆地的年代问题,进行比较全面的分析论述与展望。其中在玛曲—欧拉秀玛河段的最新研究,发现由古洪水沉积物记录的黄河特大洪水事件,发生在OSL年龄(13590±1200)~(12980±1090) a期间,其洪水主要来自于若尔盖盆地上游广泛分布的高山冰川的冰雪融水。这证明在末次冰消期Bolling-Allerod全球性相对温暖阶段,黄河就已经贯通若尔盖盆地,流经玛曲—欧拉秀玛断陷谷地,并且发生了若干次特大洪水事件。可见从河流古洪水沉积学、年代学与水文学新途径的研究,将会为解决黄河贯通若尔盖盆地的年代问题提供直接的证据。     

重庆地区末次冰期气候变化的石笋记录研究

对采自重庆金佛山梁天湾洞穴的1 根长达295 mm的石笋进行了高精度的TIMS-U系定年和碳氧同位素测试分析,建立了末次冰期晚期(31.90~15.21 ka B.P.)长江中游较高分辨率(平均为280 a/mm)的古气候变化序列。从石笋的氧同位素曲线中明显地检出Heinrich事件,并且氧同位素曲线与南京葫芦洞和贵州董歌洞的石笋记录有着良好的对比关系。但明显的差别是,重庆地区石笋的同位素记录表明,该地区末次冰期晚期古气候是受西南季风和东南季风双重影响的。     

共和盆地末次冰消期以来的植被和环境演变

在青藏高原共和盆地中的内陆湖泊--达连海获取40.92 m长的湖泊岩芯(DLH钻孔),选用植物残体作为测年材料,利用AMS14C测年技术建立可靠的地层年代序列,对岩芯进行孢粉分析,重建该地末次冰消期以来的古植被和古环境。末次冰消期以来达连海周围山地在14.8～12.9Cal ka BP和9.4～3.9 Cal ka BP时段曾发育森林,气候较湿润,达连海附近盆地发育的荒漠草原盖度增加或演化为草原;在15.8～14.8 Cal ka BP、12.9～9.4 Cal ka BP 和3.9～1.4 Cal ka BP 时段该地气候比较干旱,依据干旱的程度周围山地森林退化或消失,盆地内发育盖度较低的荒漠草原或草原化荒漠。1.4 Cal ka BP以来湿度有所增加,发育草原植被类型。依据植被的演替历史推断该地气候的变化历程是15.8～14.8 Cal ka BP 干旱,14.8～12.9 Cal ka BP 湿润,12.9～9.4 Cal ka BP干旱,9.4～3.9 Cal ka BP湿润,3.9～1.4 Cal ka BP干旱,1.4～0 Cal ka BP湿润。达连海的孢粉记录与附近青海湖的孢粉结果对比,发现两地植被发育基本一致。末次冰消期Bølling-Allerød 时期,山地森林发育;新仙女木事件发生时森林萎缩;全新世中期两地针叶林发育达到鼎盛,之后逐渐减少至消失。早全新世达连海森林扩张的时间滞后于青海湖,主要与两地森林树种的不同和植被演替的时间差异有关。该区森林发育的全盛时期在中全新世,这与石笋记录到的亚洲季风强盛时期在早全新世不相一致,可能与植被复杂的响应机制有关。     

地貌形态指数反映的青藏高原东北部宛川河流域新构造活动

宛川河为黄河的一级支流,位于青藏高原东北部的兰州盆地东部.该区域历史时期曾发生多次6级以上地震.以DEM数据为基础,通过河流水系分析和地貌形态指数的计算,讨论了区域新构造活动特征.山前曲折度指数(SMF)在宛川河北为1.03~1.18,在兴隆山北前缘为1.83~2.88;河谷宽高比指数(VF)在宛川河北部为0.36~2.34,在南部的兴隆山为0.55~13.SMF与VF值的大小和分布特征表明研究区新构造活动活跃,且宛川河以北(前人推测有断层存在)新构造活动的活跃程度更高.流域盆地非对称性指数(AF)在宛川河北部东南端的异常揭示存在掀斜断块和褶皱运动;结合裂点分布和沟谷错断等地貌特征,发现宛川河北正断裂的东南端也存在西北--东南向走滑活动.     

小兴安岭东部9.0 ka B.P.以来沼泽发育与古环境演变研究

对迄今为止所发现的小兴安岭东部全新世最早发育的沼泽剖面进行14 C测年、孢粉分析、粘土矿物分析、泥炭植物残体鉴定 ,根据获得的信息 ,综合分析 ,相互印证 ,研究了 9.0kaB .P .以来沼泽发育、植被演替、气候变化与古地理环境演变过程。结果表明 ,本区植被演替经历五个阶段 ,即针叶林 (90 0 0aB .P .～ 830 0aB .P .)→针阔混交林 (830 0aB .P .～ 6 80 0aB .P .)→以栎、榆、胡桃为主阔叶林 (6 80 0aB .P .～ 30 5 0aB .P .)→以桦为主阔叶林 (30 5 0aB .P .～ 2 35 0aB .P .)→以松为主的针阔混交林 (2 35 0aB .P .～ 0aB .P .)。与之相对应 ,气候变化序列为 :寒冷较湿→温和略湿→温暖湿润→温凉较湿→冷凉湿润 ;沼泽发育也相应地可划分为五个时期 :沼泽孕育期 ,富营养沼泽萌发期 ,富营养沼泽旺盛发育期和中营养沼泽孕育期 ,沼泽进一步扩大发育期和中营养沼泽形成期 ,沼泽继续扩大发育期和贫营养沼泽形成期。沼泽最早开始发育始于年代为 70 95± 90aB .P .。汤洪岭 12支线沼泽剖面可作为该区全新统的标准剖面     

塔里木河下游生态保护目标和措施

针对2000-2009年塔里木河下游10次生态输水后生态环境的变化情况,提出新的生态保护目标：在距河500 m以内以胡杨(Populus euphratica)为主的重点保护带,地下水埋深保持在≤4 m,植被总盖度达到0.4~0.5;500~1 000 m为基本保护带,以柽柳(Tamarix spp.)为主,地下水埋深为4~6 m,植被总覆盖度达到0.3以上;＞1 000 m为一般保护带,随着输水累积量增加,地下水埋深达到6~8 m,使现有植被不再退化;沿河两岸1 000 m的植被保护恢复总面积应达到1 028 km2;用水均衡法和潜水蒸散法重新估算的大西海子的下泄水量为2.3×108 m3 ,比原规划减少了1.2×108 m3 ,其中2.0×108 m3为维护生态所用,另外还有0.15×108~0.3×108 m3为向台特玛湖输水的水量;应保持输水连续性,大西海子以下年泄水量不小于0.36×108 m3;为了保证向下游输水,必须加强水资源调控,通过整治源流,使到达干流的水量为44.2×108 m3 ,干流严禁开荒,加强对防护堤修建后生态环境变化的监测,下游采用漫溢漂种增加植被面积。     

西伯利亚板块旋转漂移运动刍议

西伯利亚板块是世界上古老的地质构造单元之一。根据板块构造理论，该板块当今的地表形态和地理位置，是其经过不断迁移，与其它板块不断发生碰撞的结果。本文试从展现板块的水平运动特点出发，着重揭示西伯利亚板块在各地质时期的运动状态，从而阐述该板块自寒武纪以来的旋转漂移的全过程。     

沙粒启动机制的理论分析

从理论上对沙粒的初始启动与垂直抬升作了理论分析。结果指出,沙粒脱离地面的位置顺序是沙平面上凸拐点处、斜面上外突较大的地方、极大值点、水平面、极小值点以及凹槽的拐点处;提出了沙丘的平化运动、缩移运动与持相运动;气动力起沙的条件是:小粒径沙粒、大风、涡度场(与水平风同符号)、不稳定(层结不稳定与切变不稳定)以及粘性流;冲击起沙的条件是:大粒径沙粒、小风、涡度场(宜与水平风反符号)、稳定大气以及湍流;最后提出了沙尘暴启动的交替循环机制。     

Ecological metrics and methods for GPS movement data

The growing field of movement ecology uses high resolution movement data to analyze animal behavior across multiple scales: from individual foraging decisions to population-level space-use patterns. These analyses contribute to various subfields of ecology – inter alia behavioral, disease, landscape, resource, and wildlife – and facilitate novel exploration in fields ranging from conservation planning to public health. Despite the growing availability and general accessibility of animal movement data, much potential remains for the analytical methods of movement ecology to be incorporated in all types of geographic analyses. This review provides for the Geographical Information Sciences (GIS) community an overview of the most common movement metrics and methods of analysis employed by animal ecologists. Through illustrative applications, we emphasize the potential for movement analyses to promote transdisciplinary GIS/wildlife-ecology research.     

用创新思维破解风沙运动机理——两种理论体系核心的剖析

从地理学视角首次将风沙运动分解为内核和外延两部分,提出沙粒起动是风沙运动的内核,将沙粒起动后的一切输移表现界定为外延。流体起动和跃移质冲击起动是构成内核的两个实体。利用这一创新理念,对风沙物理学和风沙地理学两种理论体系的不同核心展开讨论。结果表明:能否区分内核两个实体的不同本质属性和能否摆正两个实体的互动机理是导致两种理论不同核心的形成和出现许多分歧的根源。本文深化了对风沙运动内涵的理解,从理论上突破了R.A.拜格诺长期用一扬一贬沙粒两种起动观引领沙坛学术潮流的核心理念。     

中国华北山地的层状地貌与喜马拉雅构造运动

层状地貌是在较短的距离内 ,从海岸到山顶的坡面上多级分布的阶梯状地貌。一般来说 ,它反映了地壳的构造运动。但并不是所有的层状地貌都是这样。只有地壳活动时期的火山喷发、砾石扇和地壳稳定时期的风化壳、古河道发育的层状地貌才能表明地壳的一次大的构造运动。据此认为 ,中国华北山地的喜马拉雅运动起始于始新世 ,至渐新世结束了第一幕。中新世是喜马拉雅运动的较激烈期 ,至上新世结束了第二幕。自第四纪进入了第三幕的第一亚幕 ,也就是新构造运动。自晚更新世进入了第三幕的第二亚幕 ,即最新构造运动。现在 ,第三幕尚未结束     

Constrained free space diagrams: a tool for trajectory analysis

Time plays an important role in the analysis of moving object data. For many applications it is not sufficient to only compare objects at exactly the same times, or to consider only the geometry of their trajectories. We show how to leverage between these two approaches by extending a tool from curve analysis, namely the free space diagram. Our approach also allows us to take further attributes of the objects like speed or direction into account. We demonstrate the usefulness of the new tool by applying it to the problem of detecting single file movement. A single file is a set of moving entities, which are following each other, one behind the other. Our algorithm is the first one developed for detecting such movement patterns. For this application, we analyse demonstrate the performance of our tool both theoretically experimentally.     

Interpreting the Civil Rights Movement: Place,Memory, and Conflict

Produced over the past decade, monuments and museums dedicated to the Civil Rights movement of the 1950s and 1960s have desegregated America's memorial landscape. Tracing a broad arc across the US South, the material elements of this landscape — historic markers, monuments, parks, registered buildings, and museums — present a distinct challenge to representations of an elite, white American past. This challenge, however, is offered in a distinctly gendered manner, inasmuch as the role of women in organizing and leading the movement is obscured. Further, the historical narratives concretized at these sites are mediated by conventions associated with civil rights historiography and the tourism development industry. The result is a complex, sometimes ironic landscape. Via the narratives they embed and the crowds they attract, these landscapes are co‐constitutive with contemporary politics of representing the past in the United States. This paper offers an overview of current memorial practices and representations of the Civil Rights movement found at the country's major memorial landscapes.     

Why GPS makes distances bigger than they are

Global navigation satellite systems such as the Global Positioning System (GPS) is one of the most important sensors for movement analysis. GPS is widely used to record the trajectories of vehicles, animals and human beings. However, all GPS movement data are affected by both measurement and interpolation errors. In this article we show that measurement error causes a systematic bias in distances recorded with a GPS; the distance between two points recorded with a GPS is – on average – bigger than the true distance between these points. This systematic ‘overestimation of distance’ becomes relevant if the influence of interpolation error can be neglected, which in practice is the case for movement sampled at high frequencies. We provide a mathematical explanation of this phenomenon and illustrate that it functionally depends on the autocorrelation of GPS measurement error (C). We argue that C can be interpreted as a quality measure for movement data recorded with a GPS. If there is a strong autocorrelation between any two consecutive position estimates, they have very similar error. This error cancels out when average speed, distance or direction is calculated along the trajectory. Based on our theoretical findings we introduce a novel approach to determine C in real-world GPS movement data sampled at high frequencies. We apply our approach to pedestrian trajectories and car trajectories. We found that the measurement error in the data was strongly spatially and temporally autocorrelated and give a quality estimate of the data. Most importantly, our findings are not limited to GPS alone. The systematic bias and its implications are bound to occur in any movement data collected with absolute positioning if interpolation error can be neglected.     

Interpreting the Civil Rights Movement: Place,Memory, and Conflict

Produced over the past decade, monuments and museums dedicated to the Civil Rights movement of the 1950s and 1960s have desegregated America's memorial landscape. Tracing a broad arc across the US South, the material elements of this landscape — historic markers, monuments, parks, registered buildings, and museums — present a distinct challenge to representations of an elite, white American past. This challenge, however, is offered in a distinctly gendered manner, inasmuch as the role of women in organizing and leading the movement is obscured. Further, the historical narratives concretized at these sites are mediated by conventions associated with civil rights historiography and the tourism development industry. The result is a complex, sometimes ironic landscape. Via the narratives they embed and the crowds they attract, these landscapes are co-constitutive with contemporary politics of representing the past in the United States. This paper offers an overview of current memorial practices and representations of the Civil Rights movement found at the country's major memorial landscapes.