A Test of Paleomagnetic Field Variability at Equatorial Latitudes

隆德0106685地球磁场长期变化（PSV，包括方向和古强度）的古地磁研究需要了解其空间和时间变化模式。目前，我们没有详细的PSV记录在赤道地区之前的最后3000年。然而，最近的几个模型的场的变化需要了解赤道PSV，以正确解释PSV记录在其他纬度，并作出预测可能的发电机源在地球的深内部。 该计划有五个科学目标。(1)恢复两个重复的深海沉积物PSV记录（2）对所有沉积物进行仔细的岩石磁性研究（磁性矿物学，ARM，CHI，加上选定的AMS和滞后测量），以评估环境影响可能会使方向或古强度数据产生偏差的地方，（3）对最终的PSV记录进行详细的统计研究，重点是矢量和VGP角色散的时间变化，（几乎全部）与四极子族发电机源，（4）进行从贝加尔湖（俄罗斯）到Pounui湖的所有全新世PSV记录的比较（新西兰）包括本研究的新记录，（5）将这些岩芯中Laschamp和Blake漂移时间间隔的PSV记录与北大西洋的类似PSV记录进行比较。最终的古地磁数据集将在PI的网站上提供（http：//earth.usc.edu/paleslund）。研究人员以前的工作表明，他们可以从赤道印度尼西亚/菲律宾地区的几个深海岩心中恢复过去13万年的高分辨率PSV记录（包括方向和古强度）。他们的初步PSV数据表明，低古强度的时间在赤道和高纬度带都有较高的PSV角色散，但赤道纬度色散的相对增加似乎更大。假设四极子族的色散水平是纬度的常数，那么发电机源的四极子族可能是拉尚漂移期间中纬度PSV色散的唯一原因！他们还恢复了与Laschamp Excursion时间相当的偏移记录。将这一记录与来自中纬度北大西洋的详细的拉尚远足记录进行比较，表明地球两侧的远足在年龄上几乎相同。这两个区域都具有I类漂移的波形特征，但北大西洋的Laschamp漂移具有两个周期的顺时针循环的横向VGP，而赤道漂移具有两个周期的逆时针循环的横向VGP。建议赤道PSV记录与其他纬度带的数据进行仔细比较，应提供显着的新的洞察磁场变化和发电机过程，导致它。

Lund 0106685 Paleomagnetic studies of the Earth' magnetic field secular variation (PSV, both directions and paleointensity) require knowledge of its spatial and temporal pattern of variability. At present, we have no detailed PSV records in Equatorial regions prior to the last 3000 years. Yet, several recent models of field variability require an understanding of Equatorial PSV in order to properly interpret PSV records at other latitudes and make predictions about possible dynamo sources in the Earth's deep interior. This proposal has five scientific goals. (1) recover two replicate deep-sea sediment PSV records (both directions and paleointensity) spanning the last 130,000 years from Equatorial latitudes in Indonesia/Philippines, (2) carry out a careful rock magnetic study of all sediments (magnetic mineralogy, ARM, IRM, CHI, plus selected AMS and hysteresis measurements) to assess where environmental effects might be biasing the directional or paleointensity data, (3) carry out a detailed statistical study of the final PSV records focussing on the temporal variability of vector and VGP angular dispersion associated (almost entirely) with quadrapole-family dynamo sources, (4) carry out a comparison of all Holocene PSV records extending from Lake Baikal (Russia) to Lake Pounui (New Zealand) including the new records from this study, (5) compare the PSV records of the Laschamp and Blake excursion time intervals in these cores with similar PSV records from the North Atlantic Ocean. Final paleomagnetic datasets will be available on the PI's website (http://earth.usc.edu/~slund). The investigators' previous work indicates that they can recover high-resolution PSV records (both directions and paleointensity) for the last 130,000 years from several deep-sea cores in the Equatorial Indonesia/Philippines region. Their preliminary PSV data suggest that times of low paleointensity have higher PSV angular dispersion in both Equatorial and higher-latitude bands, but the relative increase in dispersion at Equatorial latitudes appears to be significantly greater. Assuming that the quadrapole-family dispersion level is constant as a function of latitude, it could be that the quadrapole family of dynamo sources is the sole cause of PSV dispersion at mid latitudes during the Laschamp excursion! They have also recovered an excursion record equivalent in time to the Laschamp Excursion. Comparison of this record with detailed Laschamp Excursion records from the mid-latitude North Atlantic Ocean suggests that the excursions on opposite sides of the Earth are virtually identical in age. Both regions have waveform characteristics of Class I excursions, but the Laschamp excursion in the North Atlantic Ocean has two cycles of clockwise-looping excursional VGPs while the Equatorial excursion has two cycles of counterclockwise-looping excursional VGPs. Careful comparisons of the proposed Equatorial PSV records with data from other latitude bands should provide significant new insight into magnetic field variability and dynamo processes that cause it.