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南海北部表层沉积物碳酸盐含量和δ18O及δ13C的空间与粒径分布特征及其控制因素
引用本文:李春园,孙蕾,葛璇,喻涛.南海北部表层沉积物碳酸盐含量和δ18O及δ13C的空间与粒径分布特征及其控制因素[J].海洋学报,2013,35(3):246-254.
作者姓名:李春园  孙蕾  葛璇  喻涛
作者单位:近海海洋环境科学国家重点实验室, 福建 厦门 361005;厦门大学海洋与地球学院, 福建 厦门 361005
基金项目:国家自然科学基金项目(40676065)。
摘    要:为深入研究南海北部表层沉积物中碳酸盐的来源及其控制因素,采用湿筛法,对南海北部珠江口、陆架、陆坡及海盆表层沉积物中碳酸盐的含量、δ18O和δ13C及其粒度分布特征进行了研究。结果表明,南海北部表层沉积物中的碳酸盐可能主要以海洋自生碳酸盐为主,其含量在空间上以陆坡显著高于海盆、陆架及珠江口为特征。粒度上,陆架(水深80 m)和浅陆坡(水深550 m)处碳酸盐的粒度分布相对平均,但在珠江口及730 m以深,76.9%~84.5%的碳酸盐分布于小于32 μm的粒级中。另外,珠江口和陆架与陆坡和海盆碳酸盐δ18O和δ13C的空间及粒度分布特征显著不同。珠江口陆架区,在空间上从珠江口向陆架,全样碳酸盐的δ18O和δ13C由轻变重。粒度上,碳酸盐的δ18O和δ13C随着粒径的增大而变重,并且δ18O和δ13C之间正相关,主要受珠江淡水的δ18O及其δ13CDIC控制。陆坡海盆区,空间上,从陆坡向海盆,δ18O略有变轻,δ13C基本不变。粒度上,碳酸盐的δ18O和δ13C随着粒度的增大没有明显的变化趋势,并且δ18O与δ13C之间不相关或负相关。其δ18O可能主要受表层海水的温度控制,其δ13C可能主要受海水δ13CDIC控制。

关 键 词:南海北部    表层沉积物    碳酸盐    碳氧同位素    粒度分布特征    来源与控制因素
收稿时间:2012/1/10 0:00:00
修稿时间:2/4/2013 12:00:00 AM

Spatial and grain size distribution of carbonates content δ18O and δ13C in surface sediments from the northern South China Sea and their controlling factors
LI Chunyuan,SUN Lei,GE Xuan and YU Tao.Spatial and grain size distribution of carbonates content δ18O and δ13C in surface sediments from the northern South China Sea and their controlling factors[J].Acta Oceanologica Sinica (in Chinese),2013,35(3):246-254.
Authors:LI Chunyuan  SUN Lei  GE Xuan and YU Tao
Institution:State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China;College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China
Abstract:Bulk and grain size content, δ18O and δ13C values of carbonates in the surface sediments collected from the Zhujiang Estuary, shelf, slope and basin of the northern South China Sea were analyzed in order to determine the source of carbonates and the controlling factors of δ18O and δ13C of carbonates. The results show that the carbonates in the surface sediments of the northern South China Sea are mainly authigenic. The carbonate contents of the slope are obviously larger than those of the Zhujiang Estuary, shelf and basin. In the Zhujiang Estuary with water depth of 34 m and the basin with water depth of more than 730 m, 76.9%~84.5% of carbonates are distributed in the particles which grain diameter is less than 32 μm. Correspondingly, in the shelf with water depth of 80 m and the slope with water depth of 550 m, the carbonates are evenly distributed among all grain sizes. In addition, the spatial and grain size distribution of δ18O and δ13C of the carbonates in the Zhujiang Estuary and the shelf are obviously different from those in the slope and the basin. In the Zhujiang Estuary and the shelf, the bulk δ18O and δ13C values of carbonates become heavy from the Zhujiang Estuary to the shelf; the grain size distribution of δ18O and δ13C values of carbonates are that the δ18O and δ13C values of carbonates become heavy with the increasing of grain size and the δ18O values are positively related to δ13C values; indicating that the δ18O and δ13C of carbonates in the Zhujiang Estuary and the shelf are mainly controlled by δ18O and δ13CDIC of the water from the Zhujiang River. In the slope and the basin, the bulk δ18O values of carbonates become light from the slope to the basin and the bulk δ13C values of carbonates do not have an obviously variation from the slope to the basin; the grain size distribution of δ18O and δ13C values of carbonates are that the δ18O and δ13C values of carbonates do not have a clear trend with the increasing of grain size and the δ18O values are not or negatively related to δ13C values; indicating that the δ18O of carbonates are mainly controlled by surface seawater temperature and the δ13C of carbonates are mainly controlled by the δ13CDIC of surrounding seawater in the slope and the basin.
Keywords:northern South China Sea  surface sediments  carbonate  carbon and oxygen isotope  grain size distribution  source and controlling factors
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