西太平洋海山区构造分区图编制及玄武岩Nd同位素填图

基于公开的地球物理、地球化学数据以及国内外航次调查积累的海底地形等资料,笔者编制了西太平洋海山区1∶500万构造分区图。西太平洋海山区构造分区图包括1幅主图和3幅辅图,主图为《西太平洋海山区构造分区图》,共划分出了3个一级板块、22个二级分区块体、12个三级分区块体,3幅辅图分别为《西太平洋海山区地质构造图》、《西太平洋海山区布格重力异常图》和《西太平洋海山区εNd(t)等值线图》。本文介绍了构造分区图编制的思路和方法、数据来源和构造单元的划分依据,还通过搜集和整理西太平洋海山区玄武岩εNd(t)同位素数据,在研究区圈定了9个Nd同位素异常区,并讨论了Nd同位素填图结果与地质过程的耦合关系以及其对海山区构造分区的指示意义。

Compilation of tectonic map and Nd isotopic mapping for basalts in the seamount area of Western Pacific Ocean

The Tectonic Map of the Western Pacific Seamount Area(1∶5000000)is compiled based on the topographic and geological data of the COMRA cruises over past years and the latest geophysical and geochemical data.The tectonic map of the Western Pacific seamount area consists of one main map and three auxiliary maps.The main map or the tectonic map of mapping area includes 3 first order plates,22 second order blocks and 12 third-order blocks,while the three auxiliary maps includes the geological structure map of the seamount area in Western Pacific Ocean,the bouguer gravity anomaly map of seamount area in the Western Pacific Ocean and the contour map ofεNd(t)value in seamount area of Western Pacific Ocean.The guiding idea and method adopted by the map compilation,the data source,the content of the map and the division basis of tectonic units are introduced and described in this paper.Based on theεNd(t)data of the basalts in the Western Pacific region,nine Nd isotopic anomaly areas are delineated.The coupling relationship between the Nd distribution pattern and geological processes and its significance to tectonic division of the area are further discussed.