Study of the Last Glacial Loess-Like Deposits in the Coastal Area of South China with Diffuse Reflectance Spectroscopy and Laser Particle Size Analysis
WANG Jing1, 2, 3, CHEN Zhen1, 3, CHEN Guo-neng1, 3*
1. College of the Earth Science and Engineering Geology of Sun Yat-sen University, Guangzhou 510275, China 2. Key Laboratory of Marine Mineral Resources, Ministry of Land and Resources，Guangzhou 510075，China 3. Guangdong Key Laboratory of Geological Process and Mineral Resources Exploration, Guangzhou 510275, China
Abstract：Newly discovered yellow silt widely distributed in the coastal area of south China was analyzed using diffuse reflectance spectroscopy (DRS) and laser particle size（LPS）methods in the present paper. The authors take the lead in trying to synthetically judge the depositional enviro nment, transporting agent and forming mechanism of the yellow silt from angles of output forms of iron minerals as well as grain size distribution features of the samples chose from three representative sections and a drill core. The DRS first derivative curves show the peak height of iron minerals decreasing from hematite （565 nm）to goethite （505 and 435 nm）, which reflects a relatively dry, cold climate that coincides with the aeolian loess widely distributed in the northwest China, but reverses of the fluvial and marine deposits which experienced a well hydration in humid conditions over a long period of time in study area. LPS analysis show that grain size from top to bottom of the sections and drill core are homogeneous and typical of aeolian sediments. The grain size distribution in the yellow silt is characterized by double peaks with main peak of 10～50μm and a secondary peak of <5 μm, similar to that of loess in northwest China but quite different from associated fluvial and marine deposits featured by unidirectional change of allocation mode of the grain size groups. Based on grain size analysis, DRS results, age range of 10～80 ka, and spatial distribution that both of the positive landforms and buried topographies in the coastal area of south China have this kind of sediments, the yellow silt is considered to represent an aeolian deposit formed during the last glacial period, which is called “loess-like deposits” in our study.
Key words：Diffuse reflectance spectroscopy;Laser particle size analysis;Loess-like deposits;Aeolian sediments;Coastal area of south China;Last glacial period
王 晶1, 2, 3，陈 震1, 3，陈国能1, 3* . 华南沿海末次冰期类黄土沉积的漫反射光谱与激光粒度研究 [J]. 光谱学与光谱分析, 2014, 34(11): 2901-2907.
WANG Jing1, 2, 3, CHEN Zhen1, 3, CHEN Guo-neng1, 3* . Study of the Last Glacial Loess-Like Deposits in the Coastal Area of South China with Diffuse Reflectance Spectroscopy and Laser Particle Size Analysis. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2014, 34(11): 2901-2907.
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