雅丹形态特征吸引人们的长期关注，对其形态的定量描述至今仍讨论热烈且众说纷纭。通过对罗布泊地区风蚀地貌的野外调查和无人机测量，发现普遍存在雅丹共基座现象。分布在同一个基座体上的风蚀残丘称之为共基座雅丹，属于雅丹与基座体的复合。对共基座雅丹和基座体开展雅丹形态参数的测量及分析，结果表明：共基座雅丹长宽比比值集中分布于3∶1~5∶1区间，与鲸背状等流线型雅丹形态表现相似，显示单一风向侵蚀残留特征；雅丹共基座现象是风蚀切穿深一层抗风蚀相对较强的地层形成的风蚀垄岗现象，厚度不等的不同抗风蚀强度地层在垂向上交替出现和受单一风向的风蚀作用是形成该现象的重要因素；通过对雅丹共基座现象的阐释和定量分析，对完善雅丹形态测量、深化雅丹形态变化的理解以及认识差异性风蚀过程具有重要意义。
宋昊泽, 穆桂金, 林永崇, 李文, 唐自华, 秦小光, 赵雪, 张磊, 李康康
. 雅丹共基座现象对雅丹形态测量的影响[J]. 干旱区地理, 2020
, 43(1)
: 48
-55
.
DOI: 10.12118/j.issn.1000-6060.2020.01.06
Yardang is a typical wind
erosion landform which is widely distributed in the world. Because of its various forms and volatility, Yardang’s morphological
characteristics attract people’s long-term attention. How to accurately and quantitatively describe the
Yardang morphology has been discussed enthusiastically and with a lot of
questions still remained. The Lop Nur area is
located in the eastern part of the Tarim Basin in Xinjiang, China. Although there are a
large number of Yardangs in the area and the morphological types are abundant, there is a lack of detailed description of the Yardang
morphology in Lop Nur area. Through the field
investigation of wind erosion landforms in Lop Nur area and the aerial
surveying using unmanned aerial vehicle (UAV), this paper finds that there is a new morphological
combination of Yardangs in the Lop Nur area-the Yardangs which have common pedestal.It is observed
on the high wind erosion ridges that there are often platform surfaces on the
top of the ridges. On this flat platform
surfaces there are many streamlined wind erosion tiny-hills, and they are very
similar to Yardang. Under the platform
surfaces, the wind erosion
ridges are surrounded by cliffs which is like a pedestal, then we call this part of the ridges as pedestal body. The streamlined wind erosion tiny-hills on the same platform surfaces is called the
common pedestal Yardangs, and the Yardangs
which have common pedestal is the combination of Yardangs and the pedestal
body. The measurement and analysis of the Yardangs
morphological parameters were carried out on the common pedestal Yardangs and
the pedestal bodies separately. The results shows
that firstly, the values of length-width (L/W) ratio of Yardangs which have common
pedestal are mainly sit in the range between 3∶1 and 5∶1,very similar to the whale-back or other streamline-appearance Yardangs, showing that the common pedestal Yardangs undergoing
the same wind erosion processing as the whale-back or other streamline-appearance Yardangs. They were all shaped gradually under the single-wind-direction erosion
circumstance. Secondly, the Yardangs which have common pedestal are
morphological combination of Yardangs. This phenomenon is essentially a wind erosion ridge-mound phenomenon when wind broke the former deep and
strong wind-erosion-resistance stratum and cut it into less wind-erosion-resistance strata, and thus the strata of different thicknesses and
different wind-erosion-resistance levels appeared alternately in the vertical
direction which together with the single direction wind erosion produced this
phenomenon as two important factors. Lastly, the measurement
results shows the Yardangs which have common pedestal made the Yardang
morphological characteristics become even more complex and fluctuated, especially in the description of the Yardang spatial
distribution pattern. Through the
interpretation and quantitative analysis, we expect this phenomenon would attract one’s attention. By taking it into consideration, analysis of Yardangs which have common pedestal may
help us improve the Yardangs’ morphological
measurement, understand more about
Yardangs development and discuss the various causes of Yardangs’ morphological diversity.
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