Paleoclimatic and orbital modulation of the geomagnetic field

地磁场的古气候和轨道调制

基本信息

批准号：
16204034
负责人：
YAMAZAKI Toshitsugu
金额：
$ 28.54万
依托单位：
National Institute of Advanced Industrial Science and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

1. We investigated the strength of magnetostatic interaction among magnetic particles in marine sediments. On relative paleointensity estimation, IRM is preferable to ARM for normalizing difference in NRM acquisition efficiency of sediments because ARM acquisition is strongly affected by the magnetostatic interaction.2. We constructed a paleointensity stack during the last 250 kyr in the Northwest Pacific. To obtain reliable relative paleointensity records, it is necessary to exclude horizons that suffer from dissolution of magnetic minerals owing to early diagenesis. The S-ratio, which represents a proportion of low coercivity magnetic minerals, is sensitive to magnetite dissolution, and thus can be used for detecting such horizons.3. We obtained a relative paleointensity record during the last 1.6 m.y. from a sediment core in the North Pacific. The paleointensity and magnetic properties of this core were compared with those from the western equatorial Pacific. Relative paleointensiti … More es of the two areas coincide well, whereas magnetic properties differ greatly. A time-series analysis using a wavelet transform showed that paleointensity records contain variations with a time scale of 100 kyr. Variations of magnetic properties are not synchronous with those of paleointensity, and there is no significant correlation between the two even if they have a common time scale of 100 kyr. We thus conclude that the 100-kyr variations in paleointensity records are of geomagnetic origin, and not caused by magnetic property variations of sediments induced by paleoclimate changes.4. Paleointensity and inclination variations during the last 800 kyr were recovered from cores in the eastern equatorial Indian Ocean (EEI). The area of a large inclination anomaly in the western equatorial Pacific (WEP) does not extend to the Indian Ocean. The model of long-term inclination variations that a weaker dipole field causes a larger relative contribution of persistent non-dipole components is supported. Less

1。我们研究了海洋沉积物中磁性颗粒之间磁相互作用的强度。在相对古显着估计上，IRM优选用于使沉积物NRM采集效率差异的ARM，因为手臂采集受磁相互作用的强烈影响。2。我们在西北太平洋的最后250 kyr期间建造了一块古显着的堆栈。为了获得可靠的相对古意志记录，有必要排除由于早期成岩作用而遭受磁性矿物质的水平。 S-RATIO代表一定比例的低雄性磁性矿物质，对磁溶解敏感，因此可用于检测这种视野。3。我们在最后1.6 M.Y.中获得了相对的古显度记录。从北太平洋的沉积物核心。将该核心的古显着性和磁性与西方赤道太平洋的磁力进行了比较。相对古显着……这两个区域的更多ES很好地重合，而磁性特性则不同。使用小波变换的时间序列分析表明，普雷斯强度记录包含100 kyr的时间尺度的变化。磁性特性的变化与古显着的变化并不同步，即使两者的共同时间尺度为100 kyr，两者之间也没有显着相关性。因此，我们包含的古显微记录中的100公斤变化是地磁起源，而不是由古气候变化引起的沉积物的磁性变化引起的。4。从赤道印度洋（EEI）的岩心中回收了最后800 kyr期间的紫色和倾斜变化。西方太平洋（WEP）的大型倾斜度异常区域并未扩展到印度洋。支持较弱的偶极场的长期倾斜变化模型会导致持久性非偶极组成分的相对贡献较大。较少的