Magnetic structure of the southern Boso Peninsula, Honshu, Japan, and its implications for the formation of the Mineoka Ophiolite Belt
Magnetic structure of the southern Boso Peninsula, Honshu, Japan, and its implications for the formation of the Mineoka Ophiolite Belt
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日本本州房总半岛南部的磁性结构及其对峰冈蛇绿岩带形成的影响
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
R. Morijiri
中科院分区：
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作者：
T. Fujiwara;H. Kinoshita;R. Morijiri
我们在日本本州房总半岛南部及其周围地区进行了陆上和海上磁测，观测到沿峰冈蛇绿岩带沿着的显著大振幅异常，以及在带南部的长波长低异常，其中包含短波长孤立异常。采用三维磁棱柱和磁化强度约为1 A/m的基底模拟了磁结构。在峰冈带，磁棱柱体的顶部位于地表，这些磁棱柱体在垂直方向上是细长的，具有高角度的磁倾角。磁性基底存在于带下浅部。磁性基底沿磁性棱柱体底面延伸，形成地堑构造。在峰冈带的南部，假定在1-3 km深度处存在薄的片状低磁倾角磁棱柱。磁结构反映了峰冈蛇绿岩带形成的构造过程。该带可能是一个大洋板块的碎片，位于古板块边界，起源于低纬度，并通过向北漂移的仰冲作用被搬运到现在的地方。
We conducted onshore and offshore magnetic surveys on and around the southern Boso Peninsula, Honshu, Japan, and observed prominent large amplitude anomalies along the Mineoka Ophiolite Belt, and long wavelength low anomalies to the south of the belt containing short wavelength isolated anomalies. The magnetic structure was modeled by using three-dimensional magnetic prisms and basement with about 1 A/m of magnetization. At the Mineoka Belt, the top of the magnetic prisms is located at the ground surface, and these bodies are elongate in the vertical direction, with high angle magnetic inclinations. Magnetic basement exists at shallow depth beneath the belt. The magnetic basement traces the bottom surfaces of the magnetic prisms and forms a graben structure. In the south of the Mineoka Belt, thin sheet-like magnetic prisms with low magnetic inclinations are assumed at 1–3 km depth. The magnetic structure implies the tectonic process of the formation of the Mineoka Ophiolite Belt. The belt could be fragmented pieces of an oceanic plate emplaced at a paleo-plate boundary, which originated in low latitude and was transported by obduction to the present place via northward drift.