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对侵入Oga半岛两组地层中的14个岩墙进行了古地磁研究,其中七个岩墙的稳定剩磁为正向磁化,六个为反向磁化,还有一个为过渡方向。正、反向磁化岩石及侵入地层之间没有观察到明显的方向上的差别。岩脉趋北东向,具有4°的标准偏移。除了一个具有过渡方向的岩墙外,其它13个岩墙剩磁的平均倾角和偏角分别为:58.3°和-2.8°。与平均场相应的磁极位置和在该半岛及本州岛NE北部的中中新世地层中所观察到的很接近,脉岩岩石表现出中中新世期间的二元火山作用特征,稳定剩磁的方向及双峰态分布支持岩墙是在中新世时期侵入的观点。Oga岩墙走向的优势方位反映出在本州岛东北部的构造旋转完成后中到晚中新世期间应力场的基本趋势。
Paleomagnetism has been studied on 14 of the dikes intruding into two formations in the Oga peninsula. Among them, the stable remanence of the seven dykes is positive magnetization, six are reverse magnetization, and the other is the transitional direction. No significant directional differences were observed between the positive and negative magnetized rocks and the intruded formation. The veins tend northeast, with a standard deviation of 4 °. Except for a rock wall with a transitional direction, the average inclination and declination of residual magnetism in the other 13 dykes are 58.3 ° and -2.8 °, respectively. The magnetic pole position corresponding to the mean field is very similar to that observed in the Middle Miocene strata in the northern part of the peninsula and northeast of Honshu Island. The veins of the petrographic rocks show the characteristics of the binary volcano during the Middle Miocene, The orientation and bimodal distribution of dikes support the view that intrusion during the Miocene period. The predominant azimuth of the strike of the Oga dyke reflects the basic tendency of the stress field during the middle-late Miocene after the structural rotation in the northeastern Honshu Island is completed.