IODP Ex. 323 shipboard rock magnetic measurements of Quaternary deep-sea sediments from the Bering Sea identified a dramatic bimodal character to the sediments, alternating between sediments with strong natural magnetic remanence (NRM) and magnetic susceptibility (chi) and those with order-of-magnitude lower values. We now generally associate the high-magnetic-intensity sediments with interglacial/interstadial times and the low-magnetic-intensity intervals are generally associated with glacial/stadial conditions. This pattern can be largely correlated among all seven IODP Ex. 323 sites. We have now completed more detailed rock magnetic measurements on selected u-channeled sediments from these sites. U-channel rock magnetic measurements indicate that the high-intensity sediments contain relatively coarser magnetic grains (sand/silt) associated with coarser siliciclastic sediments while the low-intensity sediments contain finer magnetic grains (silt) associated with finer siliciclastic sediments. We associate the coarser magnetic grains and overall coarser clastic sediments with warmer intervals when more open water conditions permit sediment flux from the continental shelves. The finer magnetic grains and associated finer clastic sediment are largely derived from sediment reworking and redeposition associated with slope processes and deep-sea contour currents when ice cover was more permanent. We have corroborated the grain size variability with magnetic hysteresis measurements and clastic grain size analysis. The clastic grain size distributions of the coarser versus finer grained sediments are significantly different; coarser grained sediments have a broad grain size distribution with 50–60 μm mean grain size, while finer grained sediments have a much more narrow grain size distribution with 15–20 μm mean grain size. The finer grain size distribution is consistent in range and mean grain size to North Atlantic deep-sea sediment deposited as drift deposits by contourite deposition (Heezen and Ruddiman, 1966; Johnson et al., 1988). The dominant magnetic mineral in all sediments is detrital magnetite. Early sediment diagenesis plays a minor role in the overall rock magnetic variability of the Bering Sea deep-sea sediments due to the overall large clastic grain size. The magnetic variability that we see in the Quaternary Bering Sea sediments appears to be comparable to other studies from this region. VanLaningham et al. (2009) attribute deposition of the Meiji drift, directly south of the deep-water exit from the Bering Sea, to sediments derived from the Bering Sea. They see a bimodal distribution in the types of sediments that are deposited with younger arc rocks during interglacials and older continental rocks during glacials. That is consistent with our coarser Interglacial magnetic sediments derived primarily from shelf rocks rich in recent volcanics versus deeper Bering Sea sediments associated with reworking of older Bering Sea sediments during the glacials. We also note the strong similarity in timing of strong versus weak magnetic intensity sediments of Lake Elgygytgyn, about 1000 km to the NW of the Bering Sea, Both seem to be controlled by the degree of intermittent open water conditions, more so in the interglacials and very little in the glacials, but operating on a finer scale than simple glacial/interglacial cycling.

IODP Ex。对白令海第四纪深海沉积物的323船载岩石磁测量结果表明，这些沉积物具有显着的双峰特征，在具有强自然剩磁（NRM）和磁化率（chi）的沉积物与具有较低数量级的沉积物之间交替价值观。现在，我们通常将高磁强度的沉积物与冰期/星际间的时间联系起来，而低磁强度的间隔通常与冰川/星际条件有关。在所有七个IODP Ex中，该模式都可能具有很大的相关性。323个站点。现在，我们已经完成了对来自这些地点的选定u沟道沉积物的更详细的岩石磁测量。U通道岩石磁测量表明，高强度沉积物包含与较粗硅质沉积物相关的相对较粗的磁性颗粒（沙/粉砂），而低强度沉积物包含与较细硅质沉积物相关的较细的磁性颗粒（粉砂）。当更多开放水域条件允许沉积物从大陆架流出时，我们将较粗的磁性颗粒和整体较粗的碎屑沉积物与较暖的间隔联系起来。当冰盖更持久时，较细的磁性颗粒和相关的较细的碎屑沉积物主要来自与斜坡过程和深海轮廓流相关的沉积物再加工和再沉积。我们已经通过磁滞测量和碎屑晶粒度分析证实了晶粒度变异性。粗粒与细粒沉积物的碎屑粒度分布有显着差异。粗粒状沉积物的粒径分布较宽，平均粒径为50–60μm，而细粒状沉积物的粒径分布较窄，平均粒径为15–20μm。较细的粒度分布在范围和平均粒度上均与通过轮廓沸石沉积作为漂移沉积物沉积的北大西洋深海沉积物一致（Heezen和Ruddiman，1966； Johnson等，1988）。所有沉积物中主要的磁性矿物是碎屑磁铁矿。早期沉积物成岩作用在白令海深海沉积物的整体岩石磁变化中起着较小的作用，这是由于整体碎屑颗粒较大。我们在白令海第四纪沉积物中看到的磁变率似乎与该地区的其他研究具有可比性。VanLaningham等。（2009年）将明治漂流的沉积物归因于白令海沉积物，该沉积物直接位于白令海深水出口以南。他们发现在间冰期沉积在较年轻的弧形岩石和在冰期沉积在较老的大陆岩石的沉积物类型中存在双峰分布。这与我们较粗的冰期间磁性沉积物相吻合，这种沉积物主要来自盛产最新火山岩的层状岩石，而较深的白令海沉积物则与冰期中较旧的白令海沉积物的返修有关。我们还注意到Elgygytgyn湖的强磁和弱磁沉积物在时间上的高度相似性，