A Deep-Tow Magnetometer, SEABEAM, and Airgun Study of the Pacific Jurassic Quiet Zone

磁反转模式冻结的“磁带录音机”类比 一直是海洋地壳的重大发现之一 近30年的地球科学研究。虽然海洋 磁线理已经确定回到M38，没有在 比M25更古老的化石尚未被最终证实 是磁场反转造成的 部分困难在于 评估这些最古老的异常是因为它们 特征性的低振幅和明显的短周期。 约翰逊和他的同事们建议建造一个磁力计 它将被拖到海底附近， 线理的来源比传统的舰载或机载 仪器，该设备将检测到特别微妙的特征。 在22天的调查中，约翰逊和他的同事们还将 收集海洋地壳的地形测量数据， 海底地震反射剖面图和SEABEAM条带图， 分别 西部将调查三个地区 已知M25后磁线理的太平洋 以前的研究。这些新数据将使建模研究能够 比较三个研究领域的详细情况。 如果相似之处 波长和振幅，它们将有力地支持 解释它们是磁场的真实记录 逆转 如果未来的海洋钻探恢复并确定 沉积物停留在这些线理，海洋磁性 反转的时间尺度可以延长几百万年 更早的侏罗纪时期

The "tape recorder" analogy of magnetic reversal patterns frozen into oceanic crust has been one of the major discoveries in the last three decades of earth science research. Though marine magnetic lineations have been identified back to M38, none in the Pacific that are older than M25 have yet been proven conclusively to result from field reversals. Part of the difficulty in evaluating these oldest anomalies results from their characteristically low amplitudes and apparently short periods. Johnson and his colleagues propose to construct a magnetometer that will be towed near the seafloor, and being closer to the source of the lineations than conventional shipboard or airborne instruments, this device will detect especially subtle features. During 22 days of surveying, Johnson and his colleagues will also gather topographic measurements of the oceanic crust and the seafloor with seismic reflection profiles and SEABEAM swath maps, respectively. Three regions will be surveyed in the western Pacific where post-M25 magnetic lineations are known from previous studies. These new data will allow modelling studies to compare details among the three study areas. If similarities in wavelength and amplitude are found, they will strongly support the interpretation that they are true records of magnetic field reversals. If future ocean drilling recovers and dates the sediments resting on these lineations, the marine magnetic reversal time scale could be extended several millions of years further back into the Jurassic.