日高衝突帯-前縁褶曲•衝上断層帯の地殻構造
日高衝突帯-前縁褶曲•衝上断層帯の地殻構造
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日高碰撞带 - 前缘褶皱/逆冲断层带的地壳结构
DOI：
10.3720/japt.65.103
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
谷生 伊藤
中科院分区：
文献类型：
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作者：
谷生 伊藤
中新世以来，千岛岛弧与日本东北岛弧的碰撞使日本北海道日高山脉至石狩-低地的地壳结构十分明显。深地震反射研究的最新进展表明，千岛岛弧岩石圈在日高碰撞带下地壳约23 km处发生了拆离。岩石圈的上半部分（上地壳+下地壳上部）在日本东北岛弧上向西逆冲，而下半部分（下地壳下部+上地幔）则下降。东北日本弧岩石圈的楔体向东侵入到拆离的千岛弧岩石圈中。这种结构被称为“脱层楔结构”。在日高山脉的西部前陆地区，西缘褶皱冲断带宽达70多km，前第三系地层均被卷入其中。自碰撞开始以来，该带的活动已向西转移。前陆褶皱冲断带的缩短长度约为60 km，与拆离楔向碰撞方向的缩短长度相当。上述两条证据，即活动的向西移和两个长度的重合，表明褶皱冲断带的发育与拆离楔构造的形成有直接的联系。
The collision of the Kuril arc against the Northeast Japan arc has made a conspicuous crustal structure from the Hidaka mountain range to the Ishikari-Tomakomai lowland, Hokkaido, Japan, since Miocene. Recent advance of deep seismic reflection studies has revealed that the Kuril arc lithosphere is delaminated at about 23km deep in the lower crust in the Hidaka collision zone. The upper half of the lithosphere (upper crust+upper portion of the lower crust) is thrust westward on the Northeast Japan arc, whereas the lower half (lower portion of the lower crust+upper mantle) descends down. The wedge of the Northeast Japan arc lithosphere intrudes eastward into the delaminated Kuril arc lithosphere. The structure is called as a “delamination-wedge structure”. In the western foreland area of the Hidaka mountain range, the west-verging fold-and-thrust belt occurs more than 70km wide involving the pre-Tertiary strata. The activity of the belt has shifted westward since the initiation of the collision. The shortening length in the foreland fold-and-thrust belt is about 60km, which is nearly equal to the delamination-wedge length toward the colliding direction. The two lines of evidence mentioned above, the westward shift of the activity and the coincidence of both lengths, indicate that the fold-and-thrust belt has been growing associated directly with the formation of the delamination-wedge structure.