| 沙丘背风侧气流及其沉积类型与意义 |
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| 引用本文： | 哈斯,王贵勇,董光荣. 沙丘背风侧气流及其沉积类型与意义[J]. 沉积学报, 2001, 19(1): 96-100,124 |
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| 作者姓名： | 哈斯 王贵勇 董光荣 |
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| 作者单位： | 1 北京师范大学环境演变与自然灾害教育部重点实验室 北京 100875; |
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| 基金项目： | 国家自然科学基金 !(批准号 :40 0 71 0 1 2 )，教育部高校重点实验室访问学者基金资助 |
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| 摘 要： | 在腾格里沙漠东南缘对现代沙丘表面气流、沉积过程的野外观测结果表明,由于区域气流、沙丘形态及其相互作用等的不同使沙丘背风坡气流发生变化,在此发现三种背风坡次生气流 :分离流、附体未偏向流和附体偏向流。前者以弱的反向流为特征多发生在横向气流条件下坡度较陡的背风坡;后二者具有相对高的风速,其中附体流多发生在坡度缓和的背风坡,其方向在横向气流条件下保持原来的方向,而在斜向气流作用下发生偏转且其强度为原始风入射角的余弦函数。根据背风坡气流方向及强度,作者阐述了不同区域气流环境中沙丘背风坡沉积过程、层理类型及特征,探讨了交错层产状与区域气流方向之间的关系.
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| 关 键 词： | 沙丘背风侧气流 沉积过程 交错层理 古风向 |
| 文章编号： | 1000-0550(2001)01-0096-05 |
| 收稿时间： | 2000-04-25 |
Lee-face Airflow, Depositional Types and Its Significance |
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| HA Si,WANG Gui-yong,DONG Guang-rong. Lee-face Airflow, Depositional Types and Its Significance[J]. Acta Sedimentologica Sinica, 2001, 19(1): 96-100,124 |
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| Authors: | HA Si WANG Gui-yong DONG Guang-rong |
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| Affiliation: | Key Laboratory of Environmental Change and Natural Disaster, the Ministry of Education of China, Beijing Normal University, Beijing 100875 |
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| Abstract: | Field measurement of surface airflow, sand transport and sedimentary p rocesses on the modern dunes (barchan dune, the main ridges and secondary ridges of networks dune) was conducted in southeastern Tengger Desert, to refine aeoli an cross-strata as an indicator of paleaowind direction. It has been found that the v elocity and direction of lee-side secondary airflow varied with dune morphology and primary wind direction and their interactions. Three types of lee-side seco n dary flow occurred in this example, separated flow, attached flow, and deflected flow. These flow is controlled at least two factors, lee-slop morphology and primary wind direction relative to dune crestline. Separated flow, characterized by lower wind velocity, typically occurred on the dunes with steeper (>20°) lee -slop in the conditions where primary wind direction is perpendicular to dune cres tl ine. Attached flow with higher velocity occurred on the gentle lee slop (<20 °) . The attached flow could be deflected in the oblique primary wind environment but not deflected in transverse flow conditions. The direction of the lee-side defl ec ted flow is in accordance with the direction of crestline of dunes regardless of the inci dent angle values of oblique wind. Further analysis has also found that the magn itude of lee-side secondary wind velocity is the cosine function of primary wind di r ection relative to dunes, which can be expressed by natural log cosine relations hip:Ul=Uc{K*ln〔cos(I)〕+A}.0
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| Keywords: | lee face airflow sedimentary processes aeolian cross-strata paleaowind direction |
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