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

该提案要求资金用于恢复氧同位素阶段5和6的复制、详细的PSV、偏移和古强度记录，这些记录来自于最近在北大西洋西部（35o N, 720 W）的深海沉积漂移沉积Blake/Bahama外脊中回收的28个活塞岩心（平均长度为20 m）。所有岩心沉积物年龄均小于20万年（18 O期6），沉积速率至少为10 cm/kyr；大多数在更新世的速率大于20cm /kyr。PIs以往对Blake/Bahama外脊沉积物的古地磁和沉积地磁研究表明，这些岩心记录了古磁场的长期变化（PSV），并且不同岩心的PSV记录可以很容易地在它们之间进行对比。这项先前工作最重要的方面之一是首次完整记录了拉尚漂移（42 ka）。该偏移记录的独特的矢量和古强度模式及其与莫诺湖偏移（28ka）的自相似性表明它们是由同一类型的岩心发电机作用形成的。来自三个新岩心的初步古地磁数据清楚地表明，这些记录还包含另外两个偏移：“布莱克事件”（约125 ka），首次定义于布莱克/巴哈马外脊（Smith and Foster, 1969）的沉积物岩心，以及Biwa I？漂移（约170 ka）。初步的古地磁资料表明，布雷克偏移在氧同位素第5阶段最早的阶段内看起来是一个真正的极性反转区间。另一方面，琵琶湖1号短途旅行看起来更像莫诺湖和拉尚短途旅行。该研究将为建立PSV与位移之间关系的新模型提供重要的新信息，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.