【摘要】 江西省修水县杨梅山剖面244个定向样品的岩石磁学研究表明,杨梅山剖面的磁极倒转自上而下分别为布莱克(Blake)反向极性偏移、安比拉(Emperor)反向极性偏移、布容—松山(Brunhes-Matuyama)极性带界线以及上部贾拉米洛(UpperJaramillo)正向亚带;杨梅山剖面样品的磁性矿物为磁赤铁矿;杨梅山剖面浓度(数量)归一化的磁化率变动和深海氧同位素变化具备较好的一致性,该剖面的磁化率变动对应着深海氧同位素自第5阶至第23阶的变化;杨梅山剖面跨越了布容—松山极性带界线以及深海氧同位素的第19阶,中国南方红土的底界年龄可能大于78Ma,即早于中国北方黄土的L8黄土层。更多还原

【Abstract】 This paper presents the results of rock magnetism studies of 244 directed samples collected from Yangmeishan section in Xiushui County,Jiangxi Province.Several geomagnetic polarity reversals can be identified in Yangmeishan section, which, in their topdown order, are Blake reverse polarity excursion, Emperor reverse polarity excursion, the boundary of BrunhesMatuyama polarity zone and the Upper Jaramillo normal subzone.The magnetic mineral in this section is Maghemite, and the susceptibility variations (normalized by consistency) are in remarkable consistency with the variations of the deepsea oxygen isotope, corresponding to the stages from the 5th to the 23rd.Yangmeishan section spans the boundary of BrunhesMatuyama polarity zone and the 19th stage of the deepsea oxygen isotope variations. Therefore, the bottom age of the laterite in South China might be older than 78 Ma, viz. older than the L8 loess in North China.更多还原