东菲律宾海柱样沉积物的磁性特征

MAGNETOSTRATIGRAPHIC AND MAGNETIC PROPERTIES OF MARINE SEDIMENTS FROM THE EAST PHILIPPINE SEA

对东菲律宾海帕里西维拉海盆西侧F090102柱样进行了系统的古地磁和岩石磁学研究,测量了天然剩磁倾角、磁化率、饱和等温剩磁、非磁滞剩磁、-T曲线等磁学参数,进行了磁性地层的划分对比,识别出松山反极性时内的贾拉米洛和奥都维正极性亚时。对磁学参数及其有关比值的研究发现,岩心磁性矿物以低矫顽力磁铁矿为主,可能含有一定的钛磁铁矿。磁性矿物主要是陆源碎屑成因,岩心底段受到海底火山作用的影响。根据磁学参数随深度的变化将岩心分为3段,各段反映了沉积环境和古气候的变化。

A detailed magnetic analysis has heen done on core F090102 from the East Philippine Sea,and the following magnetic parameters were measured： susceptibility （X）, anhysteretic remnant magnetization （ARM）, saturation isothermal remnant magnetization（SIRM）, IRM-300 mT （induced in a field of --300mT） and typical temperature dependence of magnetic susceptibility curves （x-T）, Analyses of magnetic parameters demonstrated that magnetic minerals in the sequence are dominated by low-coercivity ferromagnetic minerals with subordinate high-coercivity antiferromagnetic minerals and are characterized by magnetite （probably including some titanomagnetites）. The results show that the rock-magnetic parameters well correspond to the paleoclimatic variations and sedimentary environmental changes. And a magnetostratigraphic record was obtained. The Bruhnes-Matuyama reversal, the Jaramillo event as well as the Olduvai event during the Matuyama period were identified.