近2Ma来东菲律宾海地球磁场相对强度变化的沉积记录  

A GEOMAGNETIC PALEOINTENSITY RECORD OVER THE LAST 2Ma FROM THE EAST PHILIPPINE SEA

作　　者：孟庆勇[1,2] 李安春[1] 蒋富清[1] 徐兆凯[1,2] 朱友生 李德鹏[4] 

机构地区：[1]中国科学院海洋地质与环境重点实验室中国科学院海洋研究所,青岛266071 [2]中国科学院研究生院,北京100049 [3]中海油服勘探事业部,天津300451 [4]国家海洋环境监测中心,大连116023

出　　处：《海洋与湖沼》2010年第4期606-613,共8页Oceanologia Et Limnologia Sinica

基　　金：国家自然基金资助项目;90411014号;中国科学院知识创新工程重要方向资助项目;KZCX2-YW-211号

摘　　要：为了解东菲律宾海沉积物记录的地球磁场相对强度变化,并为研究区的地层定年提供新的手段,对东菲律宾海帕里西维拉海盆西侧F090102孔柱样沉积物进行了系统的古地磁和岩石磁学分析。根据功率谱分析,选择非磁滞剩磁作为归一化的参数,得到约2Ma以来的地球磁场相对强度变化曲线。该曲线与SINT-2000曲线可详细对比,呈比较典型的锯齿状特征,布容期内的记录与800ka以来的SINT-800曲线相符。布容/松山极性转换期呈单强度降低的特征,在极性转换期和极性漂移期,相对强度曲线表现为显著低值。A detailed magnetic analysis has been conducted on the core F090102 from East Philippine Sea.Rock magnetic results demonstrate that the cores preserve a strong,stable remanent magnetization and meet the magnetic mineral criteria for reliable paleointensity analyses.Susceptibility（χ）,anhysteretic remnant magnetization（ARM） and saturation isothermal remnant magnetization（SIRM） were used as the natural remanent magnetization normalizer.However,coherence analysis results indicates that only ARM is more suitable for paleointensity construction.The relative paleomagnetic intensity（RPI） record over the past about 2 Ma was obtained and was further compared to previously published stack records,SINT-800 and SINT-2000.Our new RPI record exhibits asymmetrical saw-tooth pattern of the geomagnetic field intensity and some major declines in paleointensity（DIP） at reversal boundaries as well as geomagnetic excursions.The Brunhes/Matuyama polarity transition was characterized by a single-DIP but not a double-DIP,it may be due to the low sedimentation accumulation rates.The record can be used to refine the chronological framework of the sediment in this region.

关 键 词：沉积物 相对古地磁强度 东菲律宾海 

分 类 号：P731[天文地球—海洋科学]