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81.
Robust climate warming has led to significant expansion of lakes in the central Tibetan Plateau. Using remote sensing
data, our quantitative analysis indicates that Siling Co, a saline lake in a characteristic endorheic basin in the central
region of the Plateau, has expanded more than 600 km2 in area since 1976. Particularly since 1995, the lake has significantly
expanded in response to increasing precipitation, decreasing water surface evaporation caused by weaker winds
and less solar radiation, and increased glacier meltwater draining to the lake. Glacier–lake interactions are important in
governing lake expansion and are also part of a feedback loop that influences the local climate. Worsening climatic
conditions (decreased precipitation and increased temperatures) that could have caused the lake to shrink during
1976–1994 were offset by increasing glacier meltwater feeding the lake, which made the lake nearly stable. We
demonstrate that this pattern changed during 1995–2009, when glacier meltwater actually decreased but participation
runoff increased and evaporation decreased, leading to expansion of the lake. If climatic conditions became suitable for
further lake development, which would be indicated by expansion in lake area, glacier meltwater could be saved in a
stable reservoir. 相似文献
82.
Lower slopes of the Sandia Mountains are characterized by granitic corestone topography and weathering-limited slopes with thin grusy colluvium and weakly developed soils. In contrast, thick soils with illuvial clay and pedogenic carbonate have developed below aplite outcrops. Aplite is resistant to chemical decomposition, but physically weathers to blocky clasts that enhance surface roughness and erosional resistance of colluvium, promoting accumulation of eolian fines. Thick B horizons on aplite slopes indicate limited erosion and prolonged periods of stability and soil development. Accretion of eolian material limits runoff and prevents attainment of a steady-state balance between soil production and downslope transport. 相似文献
83.
固体化学盐样作为我国西部地区特有的矿产资源,目前缺乏盐湖样品分析相应的国家标准,在分析固体化学盐样的实验室对该类样品的分析方法没有统一规范,因此对固体化学盐样监测数据的合理性检验显得尤为重要。文章结合《地质矿产实验室测试质量管理规范》(DZ/T 0130—2006),介绍了氯化物及硫酸盐型固体化学盐样检测数据的质量控制及判断方法,包括在样品加工过程中掌握矿区的盐样类型,提供水分的检测数据;将盐样分析数据的离子质量分数换算为化合物质量分数时,要正确把握各种化合物的换算顺序和原则;利用阴阳离子平衡原理初步判断样品分析质量;充分了解样品的分析结果,根据配盐后各化合物的物理性质,通过分析元素加和判断样品分析质量;通过离子间的关系、加标回收和重复性实验、不同分析方法比对来判断样品分析质量。简要提出了氯化钠、氯化钾、高纯氯化镁、高纯氯化锂等特殊固体盐样的质量控制方法,以保证固体盐样实验室分析数据的准确性和可靠性。 相似文献
84.
高分辨湖泊沉积和孢粉记录对气候、水文变化的响应 总被引：4，自引：2，他引：2
通过对长江中游网湖钻孔高精度分层样品(1.5年/样品)的沉积学和孢粉学研究,试图揭示过去百年网湖在由开放到封闭体系变化中,沉积孢粉与气候、水文动力变化的过程及其相互关系.相关分析和低频滤波分析,反映出沉积物和孢粉的变化对流域降水和长江流量的敏感响应.在过去130年中的多雨洪水年份,湖泊受长江倒灌影响,沉积物以黏土细颗粒... 相似文献
85.
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87.
通过对兰坪盆地野外露头及相关室内研究,分析了区内古近纪的沉积环境、层序特征、沉积相展布及其演化特征。认为古近纪主要发育冲积扇、河流、三角洲和湖泊环境。沉积建造为一个完整的盆地演化旋回:低位期,印度板块向欧亚板块的俯冲挤压造成兰坪走滑拉分盆地的形成,沉积了一套局限的湖盆相红色含膏盐细碎屑岩建造;湖扩期,挤压应力场转变为拉张应力场,湖盆扩大,大面积沉积了一套滨浅湖相紫红、砖红色砂泥岩互层沉积;湖缩期,受晚始新世喜马拉雅运动一幕的影响,应力场再次转变为强烈挤压,东西两侧造山带共同向盆地内推覆扩展,致使盆地范围明显缩小,仅在推覆体前缘形成一系列快速充填的小型山前陆相前陆盆地。层序古地理编图显示,蒸发岩发育于低位体系域,与低位期的沉积充填特点和气候有关,极具有找钾盐矿的前景。 相似文献
88.
Climate variability during the Mid‐Late Holocene has influenced the activity of geomorphic processes in the current periglacial belt of the Sierra Nevada. We studied two types of sedimentary records that reveal a synchronous timing for slope instability in this high semi‐arid massif: solifluction landforms and mountain lake sediments. Lithological and sedimentological properties of both records have recorded numerous cycles of different magnitude of slope processes in the massif. Solifluction deposits record seven phases of solifluction activity and soil development during the last 7 ka bp and lake sediments show evidence of eight periods with increased geomorphic activity in the catchments over the last 6 ka bp . Although present‐day climate conditions do not promote active solifluction processes in the Sierra Nevada, colder and wetter periods during the Holocene triggered solifluction and transported coarse‐grained sediments into the lakes. By contrast, warm phases favoured soil formation and spread an incipient vegetation cover over the headwaters of the highest valleys, diminishing the grain size of the particles reaching the lakes. Lake sediments record an aridification trend in the massif intensifying since 4·2 ka bp that has conditioned solifluction activity to shift gradually to higher elevations. During major cooler phases such as the Little Ice Age active solifluction was recorded back down to 2500 m altitude. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
89.
To describe temporal change in tafone development, an S‐shaped curve equation is proposed: Z = Zc [1 ? (n + 1) exp (? β t ) + n exp (? (1 + 1/n) β t )] , where Z is observed tafone depth, Zc is ultimate tafone depth, t is time, and n and β are constants. The applicability of this model is examined using tafone data selected from seven sites, which are categorized into three different salt‐weathering environments: a spray/splash‐dominant (occasionally wave‐affected) supra‐tidal zone, aerosol‐affected coastal regions, and inland desert areas. The results indicate that the equation can well describe tafone development in each of these environments. An investigation based on the values of n and β, determined through a best fit of the equation to the data, suggests that n characterizes site‐specific environmental conditions and β reflects the magnitude of factors controlling the recession mechanism of tafone surfaces. It is found that (1) the maximum rate of tafone growth dramatically decreases from supra‐tidal, through coastal, to desert environments, and (2) the growing mode of tafoni is different depending on the environmental settings. The erosional force to facilitate the development of tafoni at supra‐tidal sites is estimated to be about 400 times greater than that in the general coastal area. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
90.