台湾海峡西岸新生代火山岩的古地磁特征分析

Palaeomagnetic characteristics of Neozoic volcanic rocks on the west coast of the Taiwan Strait

本文对台湾海峡西岸福建南部香山、牛头山剖面的晚第三纪佛昙群火山岩进行了古地磁研究。结果表明,该处火山岩形成于地磁场处于反向为主的时期,结合地质资料分析相当于晚第三纪中期;古纬度为22°N,与采样点现纬度(24.2°N)相接近,表明本块体自晚第三纪中期以来无大规模的纬向移动。其古地磁极位置也表明如此;磁偏角为180°与现代磁角反向吻合,反映本块体自晚第三纪以来亦无明显的旋转。

This article is specialized in the palaeomagnetic investigations of Neogene Fuotan Group's igneous rocks, which lie on the south coast of Fujian Province on the west bank of the Taiwan Strait. The outcome shows that the Neogene igneous rocks were formed the period when the geomagnetic field reversal was dominant, which is relevant to middle Neogene according to the geologic information of the study region, and the palaeolatitude is 22°N, reaching approximately to the present latitude 24.2°N of the sample spot. This shows that the mass in question has made no largescale latitude movement since middle Neogene; and its palaeomagnetic polar position says the same thing. The obtained magnetic declination comes into grips with the present one, reflecting the mass also has made no distinct rotation since Neogene.