南海及其围区新生代岩浆活动时序与成因研究
发布时间：2018-12-17 17:56
【摘要】：南海及其围区新生代岩浆活动具有相似的特征,根据与南海扩张时间(32~15.5 Ma)的先后关系,将岩浆活动分为三期:扩张前(32 Ma)、扩张期(32~15.5 Ma)和停止扩张后(15.5 Ma)。从岩相学特征可知:扩张前的岩石以三水盆地双峰式岩浆岩组合为代表;根据最新的IODP 349航次的钻孔样品资料,南海海盆扩张期岩浆岩为典型的MORB,而少量的陆缘岩石资料显示,该期岩浆岩为碱性玄武岩;停止扩张后岩浆活动可分为两期,早期以大陆-大洋中脊过渡型拉斑玄武岩为主,晚期以碱性玄武岩为主。除了扩张期南海海盆的MORB,整个新生代的岩浆岩地球化学特征大体一致,与OIB相似,显示地幔源区具有不均一性,由一个DMM和一个EM端元组成,且岩石均表现出明显的Dupal异常特征。对于富集端元的性质和来源、Dupal异常的成因、海南地幔柱是否存在等问题目前存在较大争议。具OIB特征的岩浆除来自地幔柱作用外,地幔交代作用也是重要的产生机制。本文认为碳酸盐流体对地幔源区的交代作用可能在南海地区新生代岩浆活动中扮演了重要的角色。另外,岩浆岩成岩过程的研究也不够全面深入,这些都是在今后的研究工作中需要关注的地方,有待后来进一步的研究。
[Abstract]:The Cenozoic magmatic activities in the South China Sea and its environs have similar characteristics. According to the relationship between the magmatic activity and the spreading time of the South China Sea (32 ~ 15.5 Ma), magmatic activity is divided into three periods: before expansion (32 Ma),). Expansion period (32 卤15. 5 Ma) and after cessation of expansion (15. 5 Ma).) From the petrographic characteristics, it can be concluded that the pre-expansion rocks were represented by the bimodal magmatic assemblage in Sanshui basin; According to the latest drilling sample data of IODP 349 voyage, the extensional magmatic rocks in the South China Sea basin are typical MORB, and a small amount of continental margin rock data show that the magmatic rocks in this period are alkaline basalt. The magmatic activity after stopping the spreading can be divided into two stages: the early stage is continental-oceanic ridge transitional tholeiite and the late stage is alkaline basalt. Except for the extensional South China Sea basin, the geochemical characteristics of the entire Cenozoic magmatic rocks of MORB, in the expansionary South China Sea basin are generally consistent, similar to those of OIB, indicating that the mantle source region is heterogeneous and consists of a DMM and a EM end member. And the rocks show obvious Dupal anomaly characteristics. The origin of the Dupal anomaly and the existence of the mantle plume in Hainan are controversial. In addition to mantle plume, mantle metasomatism is also an important mechanism of OIB magma. It is suggested that the metasomatism of carbonate fluid to mantle source may play an important role in the Cenozoic magmatism in the South China Sea. In addition, the study of diagenetic process of magmatic rock is not comprehensive and thorough, which should be paid attention to in the future research work, and need to be further studied later.
【作者单位】： 中国科学院南海海洋研究所中国科学院边缘海与大洋地质重点实验室;中国科学院大学;中山大学海洋科学学院;
【基金】：同位素地球化学国家重点实验室(中国科学院广州地球化学研究所)项目(SKLIG-KF-14-08) 广东省自然科学基金项目(2015A030313836)
【分类号】：P736.1
本文编号：2384593
[Abstract]:The Cenozoic magmatic activities in the South China Sea and its environs have similar characteristics. According to the relationship between the magmatic activity and the spreading time of the South China Sea (32 ~ 15.5 Ma), magmatic activity is divided into three periods: before expansion (32 Ma),). Expansion period (32 卤15. 5 Ma) and after cessation of expansion (15. 5 Ma).) From the petrographic characteristics, it can be concluded that the pre-expansion rocks were represented by the bimodal magmatic assemblage in Sanshui basin; According to the latest drilling sample data of IODP 349 voyage, the extensional magmatic rocks in the South China Sea basin are typical MORB, and a small amount of continental margin rock data show that the magmatic rocks in this period are alkaline basalt. The magmatic activity after stopping the spreading can be divided into two stages: the early stage is continental-oceanic ridge transitional tholeiite and the late stage is alkaline basalt. Except for the extensional South China Sea basin, the geochemical characteristics of the entire Cenozoic magmatic rocks of MORB, in the expansionary South China Sea basin are generally consistent, similar to those of OIB, indicating that the mantle source region is heterogeneous and consists of a DMM and a EM end member. And the rocks show obvious Dupal anomaly characteristics. The origin of the Dupal anomaly and the existence of the mantle plume in Hainan are controversial. In addition to mantle plume, mantle metasomatism is also an important mechanism of OIB magma. It is suggested that the metasomatism of carbonate fluid to mantle source may play an important role in the Cenozoic magmatism in the South China Sea. In addition, the study of diagenetic process of magmatic rock is not comprehensive and thorough, which should be paid attention to in the future research work, and need to be further studied later.
【作者单位】： 中国科学院南海海洋研究所中国科学院边缘海与大洋地质重点实验室;中国科学院大学;中山大学海洋科学学院;
【基金】：同位素地球化学国家重点实验室(中国科学院广州地球化学研究所)项目(SKLIG-KF-14-08) 广东省自然科学基金项目(2015A030313836)
【分类号】：P736.1
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