Subduction initiation and ophiolite crust: new insights from IODP drilling
Subduction initiation and ophiolite crust: new insights from IODP drilling
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DOI：
10.1080/00206814.2016.1276482
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发表时间：
2017-01
影响因子：
2.6
通讯作者：
M. Reagan;J. Pearce;K. Petronotis;R. Almeev;Aaron Avery;C. Carvallo;T. Chapman;G. Christeson
中科院分区：
文献类型：
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作者：
M. Reagan;J. Pearce;K. Petronotis;R. Almeev;Aaron Avery;C. Carvallo;T. Chapman;G. Christeson
摘要 国际大洋发现计划（IODP）352航次在小笠原弧前获得了与俯冲起始相关的火山活动的高保真记录。位于靠近海沟的深水区的两个站点（U1440和U1441）钻取到了玄武岩及相关岩石；位于离海沟较远的浅水区的两个站点（U1439和U1442）钻取到了玻安岩及相关岩石。两个区域的钻探最终都钻到了推断为席状侵入岩的辉绿岩。玄武岩显然是在俯冲起始之后立即喷发的，其成分与大洋中脊快速海底扩张所产生的极度亏损玄武岩相似，几乎没有或完全没有板块输入。随着俯冲的进行以及火山活动从海沟迁移开，后续产生玻安岩的熔融过程涉及到更亏损的地幔以及更热、更深的俯冲组分。这种火山序列与许多蛇绿岩所记录的相似，支持了俯冲起始、弧前扩张和蛇绿岩成因之间的直接联系。
ABSTRACT International Ocean Discovery Program (IODP) Expedition 352 recovered a high-fidelity record of volcanism related to subduction initiation in the Bonin fore-arc. Two sites (U1440 and U1441) located in deep water nearer to the trench recovered basalts and related rocks; two sites (U1439 and U1442) located in shallower water further from the trench recovered boninites and related rocks. Drilling in both areas ended in dolerites inferred to be sheeted intrusive rocks. The basalts apparently erupted immediately after subduction initiation and have compositions similar to those of the most depleted basalts generated by rapid sea-floor spreading at mid-ocean ridges, with little or no slab input. Subsequent melting to generate boninites involved more depleted mantle and hotter and deeper subducted components as subduction progressed and volcanism migrated away from the trench. This volcanic sequence is akin to that recorded by many ophiolites, supporting a direct link between subduction initiation, fore-arc spreading, and ophiolite genesis.