克里雅河中下游流域地表沉积物的粒度与化学元素空间分布

通过对克里雅河流域的实地考察、地形测量、取样,分析其流经沙漠过渡带地表沉积物的粒度、化学元素的空间分布,得出以下结论：河流—沙漠过渡带地表沉积物的粒度组成以>2 φ的粒径为主,粒度特征明显表现出风成特点;化学组成上以Si、Al为主,和上陆壳平均化学组成相比,除Ca、Co、As外都有一定的亏损;不同河段自上游至下游,在不同动力条件下,地表物质粒度特征表现出河漫滩砂与阶地风成砂呈相反的递变趋势;不同河段A-CN-K图解及CIA揭示了克里雅河不同河段地表物质化学风化程度均很低,处于较弱的去Na、Ca阶段,其他元素未发生明显的化学风化或迁移,不同河段化学风化程度差异与物源及地貌格局息息相关;同一河段不同地貌单元,随距河道远近不同,粒度特征与化学风化程度呈现出一定的递变规律;克里雅河平均粒径与一些元素的相关性,说明粒径大小与表征化学风化程度数值的大小有一定关系。总之,在不同空间尺度上,克里雅河地表沉积物理化学特征的分异实质上反映风动力和水动力的差异性分选。

Spatial Distribution Characteristics of the Grain Size and Geochemical Elements of Surface Sediments in the Keriya River

The formation and evolution of dunes on both sides of river is closely related with the river. The research methods adopted such as field survey, topographic measurement and sampling, analyzed the Keriya River’s (located in the western of China) granularity, spatial distribution of the geochemical elements and dynamic factors of the near-surface sediments. The conclusions are as follows: The granularity composition of the Keriya River’s surface sediments is mainly larger than 2 φ, and the aeolian character of the granularity of the Keriya River is more obvious; Si and Al take up a large part of chemical composition, compared with the average composition of geochemical elements of the upper continental crust (UCC) or enrichment factors, all elements except Ca, Co and As are decreased to a certain degree; The characteristic of chemical elements and granularity composition of the near-surface sediments from different sections are similar to that of the upstream Pulu, indicating that one major source of the Keriya River sediments is located in kunlun mountains; From upstream to downstream, under the condition of different power, the granularity characteristic of surface material has the opposite gradient trend between the flood plain sand and terrace eolian sand; The CIA of the Keriya River Basin is below 50, and the A-CN-K ternary diagram shows that a weak chemical weathering by loss of Na and K occurred in these sediments, while other geochemical elements was in a less weathering or leaching process. The difference of the chemical weathering degree of different sections is closely related to its local climate and landform pattern; When different geomorphic units are under the same section, the granularity characteristic and chemical weathering degree have a corresponding grading law from nearby to far apart from the riverbed; The average grain size of the Keriya River is correlated with some enrichment factor of elements, and it shows that particle size controls and affects the processes of chemical weathering to a certain extent. In short, in the different spatial scales, the differentiation about the physical weathering characteristic of the sediment surface of the Keriya River essentially reflects the different separation of wind power and water power. Therefore, the research has important significance for building comprehensive discriminant index of aeolian-fluvial interactions and others aspect.