摘要：

本文利用1994－1995年在东海陆架平北地区获取的370个柱状样，对该区残留沉积物作磁性测试和磁性矿物鉴定，以进行陆架残留沉积物磁性特征与深部油气渗漏关系的研究。磁性测试显示本区存在磁化率异常和饱和等温剩磁异常两种磁性异常现象。根据磁性参数特征和多种矿物物理学鉴定结果，确定导致本区磁化率异常的矿物为陆源碎屑磁铁矿，导致剩磁异常的矿物为自生或次生铁硫化物胶黄铁矿和磁黄铁矿。证据显示本区剩磁异常是油气渗漏的产物；而磁化率异常则主要指示古滨海砂的分布。作者提出在本区的油气化探中，剩磁参数是有效的化探磁性指标。

Abstract:

In order to reveal the relationship between magnetic properties of the relict sediment and hydrocarbon seepage, a total of three hundred and seventy vibro-cores were taken from the Pingbei area of the East China continental shelf during 1994-1995.  Six magnetic parameters were used to define the magnetic minerals, which include magnetic susceptibility (χ), SIRM, SIRM/χ, χFD, IRMkmT/SIRM, and S－kmT. The magnetic measurements demonstrate that there are two different types of magnetic anomaly highs, i.e., χhigh and SIRM high. According to the magnetic properties, we propose that the minerals which dominates the χhigh sediment are magnetites, and minerals which cause the SIRM high are iron sulphides such as greigite and pyrrhotite.Magnetic minerals of the two types of magnetic anomaly high sediments were separated.  Identification under reflect light microscopes proves that the magnetic separates from the χhigh is detrital magnetite. Analyses of the SEM-EDX, M?ssbauer Spectrum and XRD demonstrate that the magnetic separates from SIRM high sediment are predominantly greigite and pyrrhotite.The χhighs occur at the sand bodies which are formed during the late Pleistocene transgression. Distribution of the SIRM highs in the study area coincides with that of the tectonic-controlled hydrocarbon traps and geochemical anomalies. This suggests that the iron sulphides generating the anomaly high SIRM in the study area are products of the hydrocarbon seepage. It is thus proposed that the SIRM can be selected as a proper parameter for magnetic detection of oil fields in the study area.