Paleomagnetic Field Variability 100-200,000 YBP: A Test of the Relationship Between Excursions and Secular Variation

隆德9526940 该提案要求提供资金，以便从最近从布莱克/巴哈马外脊（位于北大西洋西部（北纬35度，西经72度）的深海沉积物漂移存款）中采集的一组28个活塞岩心（平均长度20米）中，恢复氧同位素阶段5和阶段6内的重复、详细的PSV、漂移和古强度记录。 所有取芯沉积物的年龄都小于20万年（ 18 O阶段6），并有至少10厘米/千年的沉积速率;大多数在更新世期间的速率大于20厘米/千年。美国物理学会以前对布莱克/巴哈马外脊沉积物的古地磁和沉积物磁性研究清楚地表明，这些岩心中记录了古磁场长期变化（PSV），而且不同岩心的PSV记录可以很容易地相互关联。 其中最重要的方面，这以前的工作是第一个完整的记录Laschamp偏移（42 ka）。 该漂移记录的独特矢量和古强度模式及其与莫诺湖漂移（28 ka）的自相似性表明，它们是由相同类型的核发电机过程形成的。 来自我们三个新岩芯的初步古地磁数据清楚地表明，这些记录还包含两个额外的偏移：“布莱克事件”（约1000年）。125 ka），首次定义的布莱克/巴哈马外脊（史密斯和福斯特，1969年），和琵琶湖我？ excursion（游览）170 ka）。 初步的古地磁数据表明，布莱克偏移看起来像一个真正的反极性间隔内的最早的氧同位素阶段5。 另一方面，琵琶湖一号游览看起来更像是莫诺湖和拉尚游览。 拟议中的研究将提供关键的新信息，开发一个新的模型PSV和偏移之间的关系，并将在古磁学界产生广泛的影响。

Lund 9526940 This proposal requests funds to recover replicate, detailed PSV, excursion, and paleointensity records within oxygen isotope stages 5 and 6 from a group of 28 piston cores (20 m average length) that has recently been recovered from the Blake/Bahama Outer Ridge, a deep-sea sediment drift deposit in the Western North Atlantic Ocean (35o N, 72o W). All of the cored sediments are less than 200,000 years old ( 18 O Stage 6) and have sedimentation rates of at least 10 cm/kyr; most have rates greater than 20 cm/kyr during the Pleistocene. The PIs previous paleomagnetic and sediment magnetic studies of sediments from the Blake/Bahama Outer Ridge clearly show that paleomagnetic field secular variation (PSV) is recorded in these cores, and that the PSV records from the different cores can be easily correlated among them. One of the most significant aspects of this previous work is the first complete record of the Laschamp excursion (42 ka). The distinctive vector and paleointensity pattern of this excursion record and its self-similarity to the Mono Lake excursion (28ka) argue that they were formed by the same style of core dynamo process. Preliminary paleomagnetic data from three of our new cores clearly indicate that these records also contain two more excursions: 'Blake event' (ca. 125 ka), first defined from sediment cores of the Blake/Bahama Outer Ridge (Smith and Foster, 1969), and the Biwa I? excursion (ca. 170 ka). Preliminary paleomagnetic data indicate that the Blake excursion looks like a true reversed polarity interval within the earliest interval of oxygen isotope stage 5. On the other hand, the Biwa I excursion looks much more like the Mono Lake and Laschamp excursions. The proposed research will provide critical new information for developing a new model of the relationship between PSV and excursions and will have a broad impact in the paleo-magnetics community.