古红河沉积物稀土元素特征及其物源指示意义  

REE Character of Sediment from the Paleo-Red River and Its Implication of Provenance

作　　者：赵梦[1] 邵磊[1] 梁建设 乔培军[1] 向绪洪[3] 

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]中海油研究总院,北京100027 [3]中国海洋石油有限公司深圳分公司研究院,广东广州510240

出　　处：《地球科学（中国地质大学学报）》2013年第S1期61-69,共9页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目(Nos.91128207;40976023);国家科技重大专项(No.2011ZX05025-006);国家重点基础研究发展规划项目(Nos.2007CB819501;2009CB219400)

摘　　要：莺歌海盆地内的大量沉积物是验证与青藏高原隆升有关的河流流域变化争论的理想材料.因此,对南海西北部莺歌海盆地6口井沉积物样品进行了稀土元素分析,结果发现,位于盆地中央轴部位的N4、N5及N6井沉积物自晚渐新世到更新世具Eu元素正异常的特征,显示其母岩应为红河流域内大量基性-超基性变质岩和火山岩;位于盆地东侧斜坡带的N1和N2井沉积物则受控于以Eu元素负异常为标志的海南岛;位于盆地东南侧的N3井沉积物晚渐新世明显受到基性物源的影响,使Eu元素呈现正异常的特征,到上新世该井沉积物主要受控于海南岛物源.越南中北部马江断裂带中古生界变质岩区以及红河流域的变质岩区为该地区提供了大量基性沉积物,造成该地区沉积物具Eu元素正异常的特征.可以认为,红河源区从晚渐新世一直到更新世时期流域内母岩类型基本保持稳定,没有大的流域母岩类型突变事件发生.因此,如果红河在其演化历史上发生过流域面积袭夺事件,其时间也只能在晚渐新世之前或更新世之后.The REE analysis of the sediment from six wells in Yinggehai basin in northwestern South China Sea finds out that the sediment of N4,N5and N6,located along the axis of the basin,shows positive Eu-anomalies from Late Oligocene to Pleistocene,suggesting that the parent rock should be the basic-ultrabasic metamorphic rocks and volcanic rocks within the Red river catchment;the sediment of N1and N2in the eastern basin are controlled by Hainan Island,which features negative Euanomalies;The sediment of N3in southeastern basin had been influenced by mafic provenance since Late Oligocene,causing Eu positive anomalies,before being dominated by Hainan Island in Pliocene.Both the metamorphic rocks within the Red drainage and the Middle Paleozoic metamorphic rocks along the Song Ma Fault Zone in the central-northern Vietnam,provided a large amount of basic sediment to the basin,resulting in Eu positive-anomalies in the sediment from this area.We believe that the parent rock type within the Red River drainage stayed stable from Late Oligocene to Pleistocene without any abrupt change.Therefore the event must have taken place before Late Oligocene or after Pleistocene if the Red river had been captured at all.

关 键 词：南海 莺歌海盆地 稀土元素 沉积物 地球化学 红河 海南岛 

分 类 号：P595[天文地球—地球化学]