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珠江三角洲南部平原PRD05孔稀土元素(REE)的分布特征与晚第四纪沉积环境变化密切相关。随着不同时期沉积环境的波动,稀土元素分布也发生相应的变化。约31000calaBP以前,研究区发育河流环境,受矿物组成和沉积物粒度的影响,ΣREE含量偏低,且重稀土元素(HREE)相对富集。31000—16600calaBP期间,ΣREE含量明显高于前一阶段,并显示轻稀土元素(LREE)富集;稀土元素分布模式表现为河口半咸水环境特征;其上部沉积物经历了末次冰盛期的风化作用,稀土元素分布模式与下部近平行,但LREE的富集程度略高。16600—10300calaBP为冰后期海平面上升初期,研究区发育沼泽环境,由于有机质含量高而导致稀土元素含量普遍较高。10300—5600calaBP为全新世海侵期,研究区持续发育河口湾—浅海环境,其ΣREE含量总体较高,并显示LREE富集;随着水体深度和盐度条件发生多次波动,稀土元素分布特征也表现出小幅度变化。5600calaBP以来,河流作用逐渐增强,并受到潮汐作用间歇性影响,其ΣREE含量显著下降,但波动频繁。
The distribution characteristics of PRE05 REE in the southern part of Pearl River Delta are closely related to the changes of sedimentary environment in the Late Quaternary. With the fluctuation of depositional environment in different periods, the distribution of rare earth elements also changes correspondingly. Before about 31000calaBP, the river environment was developed in the study area. Due to the influence of the mineral composition and grain size, the content of ΣREE was low and the content of heavy rare earth elements (HREE) was relatively high. During the period of 31000-16600calaBP, the content of ΣREE is obviously higher than that of the previous stage, and shows the enrichment of light rare earth element (LREE). The REE distribution pattern shows the characteristics of estuarine brackish water environment. The upper sediments experienced the weathering of the last ice age As a result, the pattern of REE distribution is nearly parallel with the lower part, but the enrichment of LREE is slightly higher. 16600-10300calaBP is the early stage of rising sea level in the late ice period. The marsh environment is developed in the study area, and the content of rare earth elements is generally high due to the high organic matter content. 10300-5600calaBP is the Holocene transgression period. The estuarine-shallow marine environment continues to develop in the study area, and the ΣREE content is generally high and shows LREE enrichment. As the water depth and salinity conditions fluctuate many times, the REE distribution characteristics Also showed small changes. Since the 5600cala BP, the river function has been gradually enhanced and affected by the tidal effect intermittently, its ΣREE content decreased significantly but fluctuated frequently.