Paleomagnetism of the Late Cretaceous volcanic rocks of the Shimaoshan Group in Yongtai County, Fujian Province  

作　　者：HUANG Sheng PAN YongXin ZHU RiXiang 

机构地区：[1]State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences [2]Graduate University of Chinese Academy of Sciences [3]Key Laboratory of the Earth's Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences

出　　处：《Science China Earth Sciences》2013年第1期22-30,共9页中国科学（地球科学英文版）

基　　金：supported by National Natural Science Foundation of China (Grant Nos. 40634024 and40821091)

摘　　要：It has been debated whether there was southward movement of the South China Block （SCB） during the Cretaceous. In this study, a paleomagnetic investigation was carried out on the Late Cretaceous volcanic rocks （-88 Ma） of the Shimaoshan Group in Yongtai County, Fujian Province. Rock magnetic experiments showed that magnetite in pseudo-single-domain and multi-domain grain and hematite were predominant magnetic phases. Stepwise thermal demagnetization successfully isolated characteristic directional components at high-temperature interval （〉 500℃） from 383 specimens in 19 sites, which yielded a paleomagnetic pole for the studied section at 83.1°N, 152.6°E （N = 19, A95 = 3.9°）, and the scatter SB = 9.0. The Fisher distri- bution of virtual geomagnetic poles （VGPs） and the consistence of S8 with the expected value at the 95% confidence level in- dicate that the yielded paleomagnetic pole is free of paleomagnetic secular variation influence. The new pole, which is well consistent with that from the Eurasian apparent polar wander path （APWP） curve, suggests no obvious southward movement of the sampling site during the Cretaceous.It has been debated whether there was southward movement of the South China Block (SCB) during the Cretaceous. In this study, a paleomagnetic investigation was carried out on the Late Cretaceous volcanic rocks (~88 Ma) of the Shimaoshan Group in Yongtai County, Fujian Province. Rock magnetic experiments showed that magnetite in pseudo-single-domain and multi-domain grain and hematite were predominant magnetic phases. Stepwise thermal demagnetization successfully isolated characteristic directional components at high-temperature interval (>500°C) from 383 specimens in 19 sites, which yielded a paleomagnetic pole for the studied section at 83.1°N, 152.6°E (N=19, A 95=3.9°), and the scatter S B=9.0. The Fisher distribution of virtual geomagnetic poles (VGPs) and the consistence of S B with the expected value at the 95% confidence level indicate that the yielded paleomagnetic pole is free of paleomagnetic secular variation influence. The new pole, which is well consistent with that from the Eurasian apparent polar wander path (APWP) curve, suggests no obvious southward movement of the sampling site during the Cretaceous.

关 键 词：South China Block Late Cretaceous volcanic rock paleomagnetic secular variation paleomagnetic pole 

分 类 号：P56[天文地球—构造地质学]