极地研究Issue(1)：98-110,13.DOI:10.13679/j.jdyj.2014.1.098
南极半岛布兰斯菲尔德海峡沉积物的地磁场长期变化与定年
DATING SED IMENT CORE BY RELATIVE PALEOINTENSITY AND D IRECTION OF GEOMAGNETIC FIELD IN BRANSFIELD STRAIT,ANTARCTIC PENINSULA
摘要
Abstract
Paleomagnetic and rock magnetic studies are undertaken in sediment core D1-7 of Bransfield Strait,Antarctic Peninsula,to obtain continuous variation of relative paleointensity (RPI)and direction of geomagnetic field.The lithologies of the core are mainly gray soft and plastic clay,a dark tephra layer at the lower part 2.20-2.21 m with sharp lower contact and gradual upper contact.Combined with AMS 14 C dating of bulk sediment and foram (Wang R J,et al,unpublished data),RPI and direction of geomagnetic field provide a continuous time scale of the last 8 ka,among which RPI comparing with Laguna Potrok Aike lake of South America produced 5 tie points,mean-while,inclination comparing with this record results in additional 4 tie points.Drastic changes of bottom current (1 100 m,Antarctic deep water)for middle and late Holocene are revealed by anisotropy of magnetic susceptibility (AMS),as well as magnetic concentration,grain size and wet density.These changes basically are controlled by summer insolation at 65 °S,therefore by the summer monsoon precipitation in cycles of precession.Millennial scale variations are also observed but no other records with similar resolution are available to decipher origin and ranges of these climate or environment events.The ages from secular variation are systematically younger than organic dating results.The mixing of different water masses and intermediate,deep water evolution related with Antarctic ice sheet retreat during Holocene are reasonable reasons for complex carbon input in Bransfield Strait.The intensity and direction of geomagnetic field recorded by sediments can avoid this influence and provide reliable age information. An average sedimentation rate of 38 cm·ka-1 for the the last 8 ka in D1-7 suggest a rich and constant terrigenous input in Bransfield Strait,Antarctic.关键词
南极/布兰斯菲尔德海峡/相对地磁场强度/磁倾角/地磁场长期变化Key words
Antarctic/Bransfield Strait/relative paleointensity of geomagnetic field/inclination/secular variation of geomagnetic field引用本文复制引用
葛淑兰,陈志华,刘建兴,黄元辉,王汝建,闫仕娟..南极半岛布兰斯菲尔德海峡沉积物的地磁场长期变化与定年[J].极地研究,2014,(1):98-110,13.基金项目
南北极环境综合考察与评估专项（CHINAREN2013-01-02，CHINAREN2013-03-02，CHINAREN2013-04-01）、国家自然科学基金项目（40876036，41376072）和国土资源部海洋油气资源与环境地质重点实验室开放基金（MRE201211）资助 （）
