西太平洋洋底高原内部结构与形成演化

Structure and formation of oceanic plateaus in west Pacific Ocean

洋底高原是在深海盆地中最显著的大火成岩省,记录着海洋大规模的岩浆活动,对研究地壳结构、板块构造、地幔动力学乃至地球演化历史都具有重要意义。西太平洋是洋底高原分布最密集的区域,是研究洋底高原内部结构与形成演化的最佳场所。选取西太平洋中最具代表性的6座洋底高原——沙茨基海隆、赫斯海隆、麦哲伦海隆、翁通爪哇高原、马尼希基高原以及希古朗基高原,通过对这6座洋底高原地质概况的简要描述,归纳近年来获得的地球物理与地球化学重要观测结果,揭示其内部结构的共性,包括大面积地形隆起、异常厚的地壳、异常负的地幔重力异常以及形成于洋中脊之上或者附近的位置特征;探索了其形成机制,即地幔柱与洋中脊的相互作用可能是洋底高原的主要成因。

Oceanic plateaus are the most remarkable large igneous provinces in deep sea basins.They document massive magmatism in the oceans,and are important for better understanding crustal structure,plate tectonics,mantle geodynamics and Earth’s evolution history.Oceanic plateaus are most developed in west Pacific Ocean,providing the optimal place to study their internal structure and formation.This paper selects six representative oceanic plateaus within west Pacific Ocean:Shatsky Rise,Hess Rise,Magellan Rise,Ontong Java Plateau,Manihiki Plateau and Hikurangi Plateau.We present brief geologic overview of each plateau and summarize major geophysical and geochemical observations.Based on the common characteristics of these plateaus,including massive topographic uplift,abnormally thick crust,negative mantle gravity anomaly,and formation on or near the mid-ocean ridge;the formation mechanisms are discussed,and the future investigations are suggested,i.e.,interaction between mantle plume and mid-ocean ridge may be the main origin of oceanic plateaus.