Source Regions and Formation of the Loess Sediments on the High Mountain Regions of Northwestern China
Source Regions and Formation of the Loess Sediments on the High Mountain Regions of Northwestern China
复制标题
DOI：
10.1006/qres.2002.2381
复制
发表时间：
2002-11
影响因子：
2.3
通讯作者：
Jimin Sun
中科院分区：
文献类型：
--
作者：
Jimin Sun
中国西北部高山黄土主要受地形地貌控制，主要分布在天山北坡、昆仑山北坡和伊犁河谷(天山中北部之间)。分布在不同地区的黄土具有不同的时代，最古老的(早更新世)黄土出现在伊犁河谷。地球化学、矿物学和粒度分析表明，三个不同地区的黄土具有不同的物源。北天山和昆仑山的黄土主要来自准噶尔沙漠和塔克拉玛干沙漠，而伊犁流域的黄土主要来自哈萨克斯坦共和国的萨里-伊什科特鲁沙漠。然而，这些沙漠主要是作为淤泥的保持区，而不是原始的源区。粉砂级颗粒的产生主要与冰川磨损和构造引起的岩石剥蚀有关。因此，研究区的黄土可以描述为“山地”黄土，而不是简单的“冰期”黄土或“荒漠”黄土。不同地区的黄土形成机制不太可能是相同的，因为它们依赖于特定的地貌条件和相关的过程。
Abstract Loess on the high mountains of northwestern China is largely controlled by the topographic features, distributed mainly on the northern slopes of the Tianshan and Kunlun Mountains as well as in the Ili Valley (between the northern and central Tianshan ranges). Loess distributed in different regions has different ages, with the oldest (early Pleistocene) loess occurring in the Ili Valley. Geochemical, mineralogical and granulometric analyses demonstrate that the loess in the three different regions has different provenance. The loess on the northern Tianshan and Kunlun Mountains is mainly derived from the Junggar and Taklimakan Deserts, respectively, whereas the loess in the Ili Valley is derived mainly from the Sary–Ishikotrau Desert located in the Republic of Kazakhstan. However, these deserts serve mostly as holding areas for the silts rather than original source regions. The production of the silt-sized particles is mainly associated with glacial abrasion and tectonic-induced rock denudation. Thus, the loess in the studied regions can be described as “mountainous” loess rather than simply “glacial” loess or “desert” loess. It is unlikely that the mechanisms of loess formation are the same in different regions, given their dependence on specific geomorphological conditions and associated processes.