南海典型断面表层沉积物稀土元素地球化学及其地质意义

对南海4个典型断面（18°N，10°N，6°N，113°E）75个表层沉积物的稀土元素地球化学进行分析，结果表明:大部分沉积物具有相对较低的稀土元素（REE）含量（平均∑REE为128 ppm）、高的轻重稀土比（LREE/HREE）、弱的Ce负异常和中等Eu负异常，REE关键参数的变化主要取决于地理位置和沉积环境。∑REE与Al₂O₃含量呈明显的正相关，而与CaO呈明显的负相关。陆源和生物碳酸盐源是本区沉积物的两个主要来源。较低的Eu/Eu*和（Gd/Yb）_N比值以及类似上地壳的REE配分模式，表明本区沉积物的源岩主要为后太古宙的长英质岩石。东部次海盆比西南次海盆的沉积物具有更低的LREE/HREE比值和更高的Eu/Eu*比值，指示有年轻火山岩（如吕宋岛弧等）产物带入到南海东部和南海东北部海域。

Geochemical characteristics and geochemical significance of rare earth elements of surface sediments from four typical sections of South China Sea

Seventy-five samples of surface sediments from four representative transects in the South China Sea(SCS, 18°N, 10°N, 6°N; 113°E)were collected for the analysis of rare earth elements (REE) geochemistry.The results showed that the total REE content (∑REE) was relatively low (average 128ppm) in most sediments with high LREE/HREE ratios, low Ce/Ce*, and moderate Eu/Eu* values.The spatial distribution of REE was strongly dependent upon the geographical location and depositional environments.There is a positive correlation between Al2O3 and ∑REE, and a negative correlation between CaO and RREE.Terrigenous component and biological carbonates were the two main sources of sediment in the area.Lower Eu/Eu*, (Gd/Yb)_N and the REE distribution pattern of mast samples indicated that post-Archean felsic rocks are the main source.The relatively low LREE/HREE ratios and high Eu/Eu* values of the sediments in the eastern sub-basin indicated that a few materials from young volcanic rocks (e.g., rocks in the Luzon arc) was transferred to this area.