Tectonic accretion of a subducted intraoceanic remnant arc in Cretaceous Hokkaido, Japan, and implications for evolution of the Pacific northwest
Tectonic accretion of a subducted intraoceanic remnant arc in Cretaceous Hokkaido, Japan, and implications for evolution of the Pacific northwest
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DOI：
10.1111/j.1440-1738.2005.00486.x
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发表时间：
2005-12
期刊：
影响因子：
1.5
通讯作者：
H. Ueda;S. Miyashita
中科院分区：
文献类型：
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作者：
H. Ueda;S. Miyashita
摘要在日本北海道白垩纪增生杂岩中发现了一个增生杂岩，其中含有残留岛弧的碎片。它由火山岩、火山砾岩、具有岛弧亲和力的中-超镁铁质侵入岩（包括玻安岩）组成，并伴有燧石和变形陆源浊积岩。与现代海洋调查的结果相比，从岛弧火山岩到燧石的保存序列，通过改造火山岩，是洋内残留弧的指示，因为该序列表明在其增生之前，在远洋环境中孤立的非活动弧。俯冲洋壳的年龄在残余弧俯冲之前和之后可能是不连续的，导致增生样式和变质作用的突然变化，如在白垩纪北海道所见。这种洋内残余弧的俯冲表明，白垩纪的俯冲洋板块并不是许多作者以前认为的伊那木板块和/或库拉板块那样的广阔洋板块，而是一个边缘盆地板块，具有像今天的菲律宾海板块那样的弧-弧后体系。
Abstract An accretionary complex, which contains fragments of a remnant island arc, was newly recognized in the Cretaceous accretionary terranes in Hokkaido, Japan. It consists of volcanics, volcanic conglomerate, intermediate to ultramafic intrusive rocks with island‐arc affinity including boninitic rocks, accompanied by chert and deformed terrigenous turbidites. Compared with the results of modern oceanic surveys, the preserved sequence from island‐arc volcanics to chert, via reworked volcanics, is indicative of intraoceanic remnant arc, because the sequence suggests an inactive arc isolated within a pelagic environment before its accretion. The age of a subducting oceanic crust can be discontinuous before and after a remnant‐arc subduction, resulting in abrupt changes in accretion style and metamorphism, as seen in Cretaceous Hokkaido. Subduction of such an intraoceanic remnant arc suggests that the subducted oceanic plate in the Cretaceous was not an extensive oceanic plate like the Izanagi and/or Kula Plates as previously believed by many authors, but a marginal basin plate having an arc–back‐arc system like the present‐day Philippine Sea Plate.