手机知网 App
24小时专家级知识服务
打 开
手机知网|搜索

ISEA reversed event in the Cretaceous Normal Superchron(CNS):~(40)Ar/~(39)Ar dating and paleomagnetic results

SHI Ruiping;HE Huaiyu;ZHU Rixiang PAN Yongxin Institute of Geology and Geophysics;Chinese Academy of Sciences Beijing 100029;China

  In order to provide the age for the ISEA(one reversed event in the CNS) a combined rock magnetic,paleomagnetic and geochronologic study has been conducted on two Cretaceous andesitic basalt lava flows from Sanbaoying, Liaoning Province of northeastern China.Rock magnetic investigations show that pseudo-single domain(PSD) titanomagnetite with poor-Ti content is the dominant magnetic mineral in Sanbaoying lava flows.Detailed systematic thermal demagnetization allowed us to isolate two remanence components after removing a low temperature component at 100℃/150℃;an intermediate temperature component with normal polarity at 150℃/200℃-380℃/400℃and the characteristic remanence component(ChRM) with reversed polarity above 400℃/450℃.~(40)Ar/~(39)Ar dating results show that Sanbaoying rocks were erupted at 116.0±0.3 Ma.Combination of paleomagnetic results and ~(40)Ar/~(39)Ar dating indicates that the reversed event recorded in Sanbaoying lavas corresponds to the ISEA event in the CNS.Our age determination for[SEA reversed event provides chronological evidence to study the relevance between global geological events that occurred in the CNS and geodynamo processes.……