Formation of Holocene Sand Layers by SEM Analyses in the Zhuye Lake Sediments
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摘要: 猪野泽全新世沉积物剖面中存在砂层和灰绿色湖相沉积层相间分布的现象。本研究对猪野泽QTH01、QTH02剖面砂层的石英砂样品进行扫描电镜分析，且与古湖泊岸堤和现代沙丘砂样做了对比，探讨了猪野泽全新世剖面中部和底部砂层的成因。研究发现，猪野泽QTH01、QTH02剖面样品中大部分石英砂兼具风成结构和水成结构，且水成特征大都覆盖于风成特征之上，V型坑分布频率相对较小，磨圆度特征与现代沙丘样品较为相似，与岸堤石英砂具有相似的结构特征，但剖面砂层不具岸堤典型的斜纹层理。结果说明，猪野泽砂层先经历了风成环境，后期转向湖相沉积，也有少部分砂是通过河流沉积于剖面位置；剖面砂层与岸堤砂层的成因相似，但剖面所在位置并非湖泊岸堤；剖面砂层形成时期风沙活动强烈，湖泊水动力条件稳定，河流对湖泊影响较小。Abstract: Sand layers are commonly embedded in lacustrine sediments from Zhuye Lake. Surface textures of quartz sands of samples from the QTH01 and QTH02 sections in Zhuye Lake were analysized and compared with samples from paleoshorelines and modern sand dunes in the study area. The results showed that samples from the QTH01 and QTH02 sections have characteristics of both typical aeolian and aqueous environments. The characteristics of aqueous environment covered on the features of aeolian environment on the samples of the Zhuye Lake sediments, while the distribution frequency of Vshaped impact pits was not common. The psephicity of samples from the QTH01 and QTH02 sections was similar to samples from modern dunes samples, and the surface textures were similar to paleoshorelines samples. These results suggested that the sand layers of Zhuye Lake had experienced aeolian environment before aqueous environment. The formation of sand layers in Zhuye Lake was similar to sands from paleoshorelines. During the period of sand layer formation, the dust activity was strong; the hydrodynamic conditions of Zhuye lake were stable; and rivers had few impacts to it.
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Key words:
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- Zhuye Lake /
- quartz grain /
- SEM /
- lake sediments /
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