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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Upper Pleistocene-Holocene geomorphic changes dictating sedimentation rates and historical land use in the valley system of the Chifeng region, Inner Mongolia, northern China
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Upper Pleistocene-Holocene geomorphic changes dictating sedimentation rates and historical land use in the valley system of the Chifeng region, Inner Mongolia, northern China

机译：内蒙古赤峰地区河谷系统中的上更新世-全新世地貌变化决定了沉积速率和历史土地利用

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摘要

This study focuses on the late Quaternary landscape evolution in the Chifeng region of Inner Mongolia, China, its relations to the history of the Pleistocene-Holocene loess accumulation, erosion and redeposition, and their impact on human occupation. Based on 57 optically stimulated luminescence (OSL) ages f loess sediments, fluvial sand and floodplain deposits accumulated on the hill slopes and floodplains, we conclude that during most of the Pleistocene period the region was blanketed by a thick layer of aeolian loess, as well as by alluvial and fluvial deposits. The loess section is divided into two main units that are separated by unconformity. The OSL ages at the top of the lower eddish loess unit yielded an approximate age of 193 ka, roughly corresponding to the transition from MIS 7 to 6, though they could be older. The upper gray loess unit accumulated during the upper Pleistocene glacial phase (MIS 4-3) at a mean accumulation rate of 0·22 m/ka. Parallel to the loess accumulation on top of the hilly topography, active fans were operating during MIS 4-2 at the outlet of large gullies surrounding the major valley at a mean accumulation rate of 0·24 m/ka. This co-accumulation indicates that gullies have been a long-term geomorphic feature at the margins of the Gobi Desert since at least the middle leistocene. During the Holocene, the erosion of the Pleistocene loess on the hills led to the burial of the valley floors by there deposited sediments at a rate that decreases from 3·2 m/ka near the hills to 1-0·4 m/ka1 in the central part of the Chifeng Valley. This rapid accumulation and the frequent shifts of the courses of the river prevented the construction of permanent settlements in the valley floors, a situation which changed only with improved man-made control of the local rivers from the tenth century AD.
机译：本研究的重点是中国内蒙古赤峰地区第四纪晚期景观演化，与更新世-全新世黄土积累，侵蚀和再沉积的历史及其对人类占领的影响。基于57个光激发发光（OSL）年龄的黄土沉积物，河流泥沙和洪泛区沉积物堆积在山坡和洪泛平原上，我们得出结论，在更新世大部分时期，该地区也被厚厚的风积黄土覆盖如通过冲积和河流沉积。黄土部分分为两个主要单元，两个主要单元由不整合区分开。低涡黄土单元顶部的OSL年龄大约为193 ka，大致对应于从MIS 7到6的过渡，尽管它们可能更老。在上更新世冰川期（MIS 4-3）期间，上层黄土单元的平均积累速率为0·22 m / ka。 MIS 4-2期间，与丘陵地势顶部的黄土堆积平行，活跃的风扇在大山谷周围大沟壑的出口处运转，平均堆积率为0·24 m / ka。这种共同积累表明，至少从中更新世以来，沟壑一直是戈壁沙漠边缘的长期地貌特征。全新世期间，山丘上的更新世黄土的侵蚀导致谷底被埋葬，沉积物的沉积速率从山丘附近的3·2 m / ka降低到1-0·4 m / ka1。赤峰河谷的中部。这种迅速的积累和河道的频繁移动阻止了在山谷底层建造永久性定居点，这种情况只有随着公元十世纪以来对当地河流的人为控制得到改善，才得以改变。

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