Extensional deformation in the northern Ryukyu arc indicated by mesoscale fractures in the middle Miocene deposits of Tanegashima Island, Japan.
Extensional deformation in the northern Ryukyu arc indicated by mesoscale fractures in the middle Miocene deposits of Tanegashima Island, Japan.
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日本种子岛中中新世沉积物中的中尺度断裂表明琉球岛弧北部的伸展变形。
DOI：
10.5575/geosoc.106.234
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
O. Fabbri
中科院分区：
文献类型：
--
作者：
O. Fabbri
变形构造中新世中期上大崎组中观察到的（露头规模的正断层和伸展节理）（16-10 Ma）琉球岛弧北方种子岛上出露的久木永群，是两个伸展阶段叠加的结果：（1）NE-SW（平均北纬43度）延伸，有八个地点的断层滑动数据和八个地点的伸展节理或无条纹正断层的充分记录;（2）北西-南东向（平均134 °E）伸展，由一处断层滑动资料和五处节理或无纹状正断层推断。这两个正交延伸可能对应于一个唯一的应力场，在大多数地方，σV=σ1，σ2和σ3轴互换。与琉球岛弧（宫古岛地区）的其他地方一样，中间主轴和最小主轴之间的排列可以通过弧平行拉伸来解释，这是对向海洋迁移的弧曲率增加的响应。11-10 Ma）。目前表现为第四纪海岸阶地的NW-SE向正断层（视N55°E伸展）。
The deformational structures (outcrop-scale normal faults and extensional joints) observed in the upper Osaki Formation of the middle Miocene (16-10 Ma) Kukinaga Group exposed on Tanegashima Island, northern Ryukyu arc, result from the superposition of two stages of extension : (1) a NE-SW (N43°E on average) extension, well documented by fault-slip data from eight localities and by extensional joints or non-striated normal faults from eight localities ; (2) a NW-SE (N134°E on average) extension, inferred from fault-slip data at one locality and by joints or non-striated normal faults from five localities. These two orthogonal extensions probably correspond to a unique stress field with, in most localities, σV=σ1 and permutating σ2 and σ3 axes. Like elsewhere in the Ryukyu arc (Miyako Island region), the permutation between the intermediate principal axis and the least principal axis can be accounted for by arc-parallel stretching in response to the increasing curvature of the oceanward-migrating arc.The tensional stress field has been active since the time of deposition of the Osaki Formation (ca. 11-10 Ma). At present, it is expressed by NW-SE normal faulting (apparent N55°E extension) of Quaternary coastal terraces.