地表风化作用对楼兰地区雅丹地貌发育的影响

Weathering impact on the development of Yardang landforms in Loulan region

风蚀是雅丹地貌发育的主要控制因素,但在特定环境中,其他环境因素也可能起重要作用。通过对楼兰地区雅丹地貌野外调查、测试及室内实验分析,探讨风化作用对雅丹发育的影响。结果发现:新疆罗布泊地区广泛发育雅丹地貌,其中楼兰地区雅丹相对较为矮小,主要发育于全新世沉积岩上,地表没有植被或松散沉积物等覆盖,地层裸露。楼兰雅丹体为黏土质粉砂岩,干燥条件下较为坚硬(硬度> 20 kg·cm^(-2)),抗风蚀能力较强,但是雅丹体表层岩性发生明显软化(硬度<10kg·cm^(-2))。这主要是由于罗布泊地区少量且集中的降水、显著的昼夜温差以及强烈太阳辐射等相互作用造成的。从这些广泛存在的松软层表明,雅丹体表层风化作用速度快于风蚀作用,而表层首先进行的风化作用,对雅丹风蚀作用起很大的促进作用,明显加速了楼兰地区雅丹地貌的发育。因此,受少量降水、昼夜温差和强烈的太阳辐射等影响的风化作用对楼兰地区雅丹地貌发育具有重要的影响。

Wind erosion is the key controlling factor for the development of Yardang factors may also play an important role in certain situation.In this paper,we analyzed weathering to the development of Yardang landforms based on the field investigation and landforms,however,other the possible,influence of lab experiments.The results suggested that multiple types of Yardang landforms can be found in Lop Nur region,Xinjiang Province,China. In Loulan region the Yardang landforms without vegetation cover are all relative short and small,they are all developed on the sediment rock that form mainly in Holocene.The clayey siltstones strata of the Yardang landforms in Loulan region are all hard under dry condition (>20kg ·cm^-2)and with strong resistance to wind erosion.However the top layers (-15cm)of clayey siltstones are softening obviously (<10kg ·cm^-2).This is mainly caused by the combination of the small amount but centralized rainfall,the moisture condensation causing by the diurnal temperature variation and the intense solar radiation.Softening of clayey siltstone on the top of Yardang strata indicates that weathering on the surface of Yardang landforms is obvious faster than wind erosion.The firstly weathering on the Yardang landforms promotes the wind erosion and accelerates the development of Yardang landforms in Loulan region.Therefore,weathering has direct and important influence to the development of Yardang landforms in the study region.