西太平洋海山省Magellan海山链MA1-MA10海山的形成年代与成因研究

项目名称： 西太平洋海山省Magellan海山链MA1-MA10海山的形成年代与成因研究

项目编号： No.41506070

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 天文学、地球科学

项目作者： 唐立梅

作者单位： 自然资源部第二海洋研究所

项目金额： 20万元

中文摘要： 西太平洋海山省的海山链记录了白垩世太平洋板块下的岩浆活动，对指示板块运动方向及了解下覆深部地质过程有重要作用，对海山链更细致的剖析是未来的发展方向。Magellan海山链是西太平洋海山省的典型海山链之一，本课题通过对Magellan海山链MA1-MA10海山的40Ar/39Ar年代学和岩石地球化学、Sr-Nd-Pb-Hf同位素的研究，获得海山的年龄，探讨岩浆来源与岩浆演化，结合已有的7座海山的研究结果，建立Magellan海山链完整的年代学框架，揭示岩浆喷发期次，分析海山源区与南太平洋同位素与热异常区热点的对应关系，结合板块重建和区域构造地质背景认识海山链的成因。研究结果对理解小型海山的成因及白垩世太平洋板块的运移有一定意义,也为我国富钴结壳矿区勘探提供进一步的基础地质资料。采用受蚀变影响小的方法进行定年和示踪地幔源区，以及综合多种因素对区域海山链进行精细剖析是本项目的创新与特色之处。

中文关键词： 海山；40Ar/39Ar；年代学；Hf-Nd；同位素；热点；西太平洋

英文摘要： The seamount trails in the West Pacific Seamount Province(WPSP) record the magmatic activities for Pacific plate in Cretaceous, and thus are important to understand the absolute plate motion and deep geological process under the Pacific plate, more detailed analysis of seamounts is needed in the future. Magellan Seamount Trail(MST) is one of the typical seamount Trails in WPSP, this study focus on 10 seamounts(MA1-MA10) of MST, through the research on 40Ar/39Ar geochronology, geochemistry and Sr-Nd-Pb-Hf isotope, to get the age of the seamounts, and discuss the magma source and mgma evolution. Then combine with the results of previous stduy of 7 seamounts to establishment an integrated framework of geochronology for MST, and reveal the relationship of their magma source with the present-day hot spots in the South Pacific Isotopic and Thermal Anomaly(SOPITA), to give a better undertanding of the ptrogenesis of MST combing with the plate reconstruction and regional geological tectonic background. The result is helpful to understand the petrogenesis of small seamounts and the motion of Pacific plate in Cretaceous, and meanwhile offer further basic data to our cobalt ore area. Using better method which has little influence from alteration to do age dating and mantle source tracing, and fine analysis of a regional seamount trail by comprehensive factors are the innovation and features of this study.

英文关键词： Seamount;40Ar/39Ar geochronology;Hf-Nd isotope;hot spots;West Pacific