印度尼西亚北苏拉威西岛弧岩浆作用及其对板块俯冲起始的制约

板块俯冲起始是板块构造理论的核心内容, 但却研究最为薄弱。印度尼西亚北苏拉威西岛弧是始新世期间开始发育的一个印度洋洋内弧, 其记录了多期次(包括印度洋、马鲁古海和西里伯斯海)的且处于不同演化阶段的俯冲作用及相应的俯冲起始过程, 因此该岛弧是研究板块俯冲起始的天然实验室。本文通过回顾板块俯冲起始研究进展, 结合北苏拉威西岛弧内已有的野外调查、锆石U-Pb定年、岩石地球化学特征等, 以厘清区域内岛弧岩浆的岩石类型、形成时代、空间分布和岩浆活动节律, 制约岛弧岩浆的构造背景和岩浆源区性质等, 并着重关注该岛弧内可能与板块俯冲起始相关的地质和岩石记录, 如弧前玄武岩、玻安岩、俯冲带(SSZ)型蛇绿岩、变质底板等。在此基础上, 综合限定北苏拉威西岛弧记录的印度洋洋壳俯冲历史, 探讨其俯冲起始的时间与地球动力学机制。本文仅抛砖引玉, 期待更多学者参与到北苏拉威西岛弧板块俯冲起始的研究中来。

Arc magmatism of the North Sulawesi Arc,Indonesia, and its constraints on subduction initiation

Subduction initiation is an essential, but the least studied, content of the 'Plate Tectonics Theory'. The North Sulawesi Arc, Indonesia, developed as an intra-oceanic island arc in the Indian Ocean in the Eocene and is a natural laboratory to study subduction initiation, as it has experienced multiple (i.e., the Indian Ocean, the Molucca Sea, and the Celebes Sea) oceanic subduction processes and corresponding subduction initiations. In this study, we first briefly summarize current understanding of subduction initiation, and then provide a comprehensive dataset by synthesizing available field surveys, zircon U-Pb dating, and whole-rock major- and trace-element compositions from the North Sulawesi Arc to: (1) characterize the rock types, crystallization ages, spatial distributions, and magmatic tempo, (2) determine the tectonic settings and mantle/crustal sources of Cenozoic magmatic rocks in the region, and (3) identify subduction initiation-related geological and petrological evidence, such as fore-arc basalts, boninites, supra-subduction zone ophiolites, and metamorphic soles, in the North Sulawesi Arc. Based on previous studies, the above observations and data will be used to constrain the subduction history of the Indian oceanic plate in the North Sulawesi Arc and to investigate the timing and controlling mechanisms of subduction initiation in the region. Sincerely looking forward to more geoscientists setting foot in the North Sulawesi Arc and subduction initiations therein.