雷琼地区第四纪地磁极性年表——火山岩钾-氩年龄及古地磁学证据

雷琼地区火山岩的钾-氩同位素年龄测定和古地磁极性研究表明,新生代在该地区的岩浆活动一直很强烈。火山岩的生成年代不晚于中新世晚期,至更新世岩浆活动尤为强烈。 研究也表明中新世晚期以来这里的地球磁场极性变化规律与近期发表的地磁极性年表大体相符,并肯定了数个尚有争议的短期极性事件的存在。年代为0.58±0.13Ma的反极性火山岩的资料肯定了安比拉（Emperor）事件的存在。研究还证实了布容/松山极性时界线之下和哈拉米洛极性亚时之上有一短期的极性事件,其年代约为0.78±0.03Ma.在奥尔都维和哈拉米洛极性亚时之间存在有另一正极性事件,这可能相当于吉尔萨（Gilsa）事件。

THE GEOMAGNETIC POLARITY TIME SCALE OF QUATERNARY FOR LEICHIONG REGION --THE K-Ar DATING AND PALAEOMAGNETIC EVIDENCES FROM IGNEOUS ROCKS

Both rediometric dating and palaeomagnetic study show a very high magmatic activity during whole Cenozoic. The volcanic rocks in this region were formed no later than the Late Miocene. Considerable magmatic activity appeared during Pleistocene.It is also shown by the present study that the fundamental feature of changes in geomagnetic polarity here since Miocene is in agreement with the polarity time scale published recently and several polarity events of short term which had been in much controversy have been confirmed. The reversed polarity shown by the volcanic rock dated 0.58 ± 0.13 Ma has confirmed the occurrence of Emperor event. It has been also confirmed that there was a short term polarity event dated 0.78 ± 0.03 Ma below the B-M boundary and above Jaramillo subzones. Between Olduvai and Jaramillo subzones there was another normal polarity event which is likely to correspond to the Gilsa event.