赣江樟树河段指向性沉积构造研究     

杨吉根 《华东地质学院学报》1993,16(1):16-23

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Observations of several characteristics of aeolian sand movement in the Taklimakan Desert   总被引：2，自引：0，他引：2  

HAN Zhiwen  DONG Zhibao  WANG Tao  CHEN Guangting  YAN Changzhen & YAO ZhengyiKey Laboratory of Desert  Desertification  Cold  Arid Regions Environmental  Engineering Research Institute  Chinese Academy of Sciences  Lanzhou  China Correspondence should be addressed to Han Zhiwen 《中国科学D辑(英文版)》2004,47(1):86-96

With both sides of the Taklimakan Desert highway line as the study area, three typical aeolian sand landforms, i.e. complex dune ridge, barchan dune and flat sand land, were selected as sand beds for the observation, analysis and research of the characteristics of aeolian sand movement such as aeolian sand stream structure, sand transport intensity, etc. in the Taklimakan Desert. The results show that there is a linear relation between the height and the log of sand transport rate over transverse dune chain, longitudinal dune ridge and flat sand land, i.e. the sand transport percentage decreases exponentially with increasing height. Sand transport rate within the 10 cm height above the bed surface accounts for 80%-95% of the total sand transport rate of the observed height (40 cm), while the sand transport rate in 20 cm occupies 98% of the total amount. Sand transport rate (g·cm-1·min-1) differs greatly with respect to different landform types and different topographic positions. Based on the investig  相似文献   

A distribution‐free statistical method for the spatial characterization of dune granulometry: an example from the Strzelecki Desert,South Australia     

Mark A. Bishop 《地球表面变化过程与地形》2004,29(1):125-131

Distribution‐free statistical methods of comparative data analysis have identi?ed subtle granulometric differences attributed to the evolution of barchan form at Gurra‐Gurra waterhole. Geomorphic locations on the barchan dunes display statistically signi?cant grain‐size differences that assist in the interpretation of aeolian processes. In summer, very ?ne sands mantle the dunescape and are the fraction that most affects the parameters of sorting and skewness. The sur?cial sedimentological character is one of subtle contrasts between the processes of grain winnowing and intergranular protection. The second and third moment measures are parameters that best demonstrate the spatial granulometric differences. Dune‐forming processes at Gurra‐Gurra have produced dune sands that have a very narrow range of grain size, which, in turn, re?ects textural and mineralogical maturity, and hence an extensive transport history. The statistical techniques employed in this study can also be used for the comparison of temporal (seasonal) sedimentological change, and for the granulometric analysis and association of process for dunes of different morpho‐types. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Aeolian modification of moraine soils,Whiskey Basin,Wyoming, USA     

Michael T. Applegarth  Dennis E. Dahms 《地球表面变化过程与地形》2004,29(5):579-585

Soils along catenas of Pinedale (15–20 ka) and Bull Lake (100–130 ka) age moraines at Whiskey Basin in the Wind River Range, Wyoming, USA, were sampled to assess the effects of aeolian processes on soil development here. Aeolian processes appear to have in?uenced soils by both depositing sediments and eroding topsoils. Pedogenic silt (often used as an indicator of wind deposition) accumulated in the Bull Lake soils moderately correlate with pedogenic clay accumulated, suggesting that ?ne sediments may have been deposited and incorporated into soil formation here. Following removal of previous topsoil by wind during Pinedale glaciation, Bull Lake B horizons have developed into contemporary A horizons. These data further link aeolian processes to soil development on piedmont moraines throughout the Wind River Range. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

济南张夏黄土堆积及其成因分析   总被引：1，自引：0，他引：1       下载免费PDF全文

张祖陆  辛良杰  姜鲁光  黄萍 《古地理学报》2005,7(1):98-106

鲁中南山地西北边缘的山麓地带、大沙河沿岸阶地广泛分布厚度不一的黄土堆积。其中出露在河岸阶地的济南市长清区张夏镇的黄土物质来源复杂，既有西北气流，东部渤海湾气流搬运而来的物质，又有当地生成的坡洪积碎屑物质。张夏黄土下部呈现明显的水流侵蚀痕迹，中间夹有围岩碎屑，应属于风成-洪积、坡积成因的黄土状土。  相似文献   

Measurement of water content as a control of particle entrainment by wind     

Cheryl McKenna Neuman  Greg Langston 《地球表面变化过程与地形》2006,31(3):303-317

Of all controls on particle transport by wind, which include texture, crusting, vegetation cover and roughness, the role of water content is one of the most difficult to parameterize because of its high degree of spatial and temporal variability and its operation at a particle‐scale level directly at the surface. This study demonstrates that measurement of the distribution of brightness for all pixels in an image, now routinely employed in digital photography, is strongly correlated with gravimetric water content. Wind tunnel experiments further suggest that measurement of the distribution of β, as normalized against the brightness of the dry sand surface, is very useful in determining the order of magnitude of the mass transport rate (q). Finer resolution will likely never be achieved because of the heterogeneity of the particle transport phenomenon. Analysis of the variability in surface brightness does suggest that q is governed by the partitioning of momentum to particle motion that terminates in adhesion to surrounding areas of the surface that remain relatively wet. The proportion of surface particles that becomes dry appears to be of less importance. Preliminary work suggests that field application of digital photography in tracking spatial and temporal changes in the water content of beach deposits looks promising. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

一种事件沉积的标志——陆相流水波痕   总被引：1，自引：0，他引：1  

蔡雄飞  顾延生  李长安 《沉积与特提斯地质》1998,18(4):44-48

本文从现代洪水事件作用可以形成大片不对称流水波痕入手,“将今论古”,发现古代地层剖面中也有大量水下至水上的沉积旋回序列,每个旋回单元与下伏岩层为突变接触。水下沉积环境富含不对称流水波痕,水上则为富含泥裂,它们系为洪水事件沉积产物。这些洪水事件具有不同的规模和级别,在地学上具有重要意义。  相似文献   

Stratigraphic evidence for late-Holocene aeolian sand mobilization and soil formation in south-central Kansas, U.S.A.     

Alan F. Arbogast 《Journal of Arid Environments》1996,34(4):403-414

Stratigraphic evidence and radiocarbon dating of sediments from the Great Bend Sand Prairie in Kansas indicates that significant deposits of aeolian sand have accumulated in the region during the late Holocene. Radiocarbon ages obtained from total humates in buried soils suggest that five periods of late-Holocene stability and soil formation are preserved in dune fields at approximately 2300, 1400, 1000, 700, 500 and 300 years B.P. Reactivation of aeolian sand in the past 1000 years has resulted in a variety of well defined, parabolic dunes. In general, events in the region correspond with established chronologies elsewhere on the Great Plains and in particular correlate well with dune fields in north-eastern Colorado. Overall, results indicate that the threshold of landscape stability on the Great Bend Sand Prairie can easily be crossed in the current climatic regime.  相似文献   

Characteristics and Formation Mechanism of Wind Streaks on Mars     

Zhibao Dong  Lü Ping  Chao Li  Guangyin Hu 《地球科学进展》1986,35(9):902-911

Wind streaks with two-dimensional plane shapes are a collective term for a variety of aeolian features that display distinctive albedo surface patterns and they do not have three-dimensional shape. Wind streaks are widely distributed on Mars， and are good proxy indicators of the surface wind regime， and even of global circulation patterns on Mars. However， the study on wind streaks has been largely ignored for a long time. Based on published studies， this paper summarized the types， morphology and formation mechanism of wind streaks. According to the relationship between albedo and obstacles， wind streaks can be divided into six basic types： bright wind streaks， dark wind streaks， mixed-tone wind streaks， splotches and related wind streaks， dune shadow wind streaks and frost wind streaks， of which the bright and dark streaks are the most common and representative， for they are the most abundant types of variable features on Mars. Wind streaks are primarily distributed in the latitudinal zone between 60°S and 60°N with little difference among different types， and they have many shapes such as tapered， fan， oval and parallel shapes due to the diverse obstacles. Considering the relationship between sediment characteristics and aeolian erosion and deposition， bright wind streaks are generally depositional with a consensus and dark streaks are erosional with a controversy. In the absence of Martian meteorological observation data， the retrieval of surface wind regime based on the orientation of wind streaks has good reliability， which helps to understand the modifications of Martian surfaces by wind in the geological context.  相似文献   

新疆东天山地区地球化学勘查方法技术研究   总被引：6，自引：3，他引：6  

张华刘拓  孔牧朱炳林  刘华忠 《地质与勘探》2003,39(6):99-102

系统研究了与新疆东天山地区地球化学勘查方法技术有关的干扰物质及其干扰程度以及在表生条件下风成沙、土壤和盐积层的分布特点、元素分布规律，为地球化学勘查方法制定奠定了理论基础。通过试点测量取得了良好效果。  相似文献