Paleointensity of the Earth's Magnetic Field Using Basaltic Glass

造成古强度数据集严重局限性的主要原因是难以获得可靠的结果。测量不仅耗时，而且成功率相对较低，尽管在样本选择方面非常小心。一是要求材料具有热残余，自获取以来没有改变，在实验过程中也没有改变。此外，材料应该在实验室中以可复制的速率冷却，并且应该具有几个百分点的相对精度。玄武岩玻璃已经从深海钻探计划的数百个已知年龄的异常洞中恢复。玻璃在形成时被淬火，冷却的速度可以在实验室中很好地近似。它可以检查是否有变化，并表明它在塞利尔实验中不容易改变。最后，来自MORB的玄武岩玻璃似乎含有单畴低钛磁铁矿。可以找到有足够力矩的碎片，用我们的设备很容易测量；从东太平洋隆起的0年和2640年喷发中获得的这些碎片获得了很好的古强度数据，从其他玄武岩玻璃中也可以获得类似质量的数据，无论年龄如何。PI将进行玄武岩玻璃的古强度研究。

The principal cause of the severe limitations of paleointensity data sets is the extreme difficulty of obtaining reliable results. Not only are the measurements time consuming, but the success rate is relatively low, despite great care in sample selection. One requires, a material possessing a thermal remanence, that has not altered since its acquisition and does not alter during the experiments. Furthermore, the material should have cooled at a rate reproducible in the laboratory, and should be datable with a relative precision of a few percent. Basaltic glass has been recovered from hundreds of Deep Sea Drilling Program holes from anomalies of known age. Glass is quenched at formation and the rate of cooling can be well approximated in the laboratory. It can be inspected for alteration and shown that it does not readily alter during the Thellier experiment. Finally, basaltic glass derived from MORB appears to contain single domain low-Ti magnetite. Shards can be found that have sufficient moments to be readily measured with our equipment; such shards obtained from 0 and 2640 year eruptions of the East Pacific Rise have yielded excellent paleointensity data and similar quality data can be obtained from other basaltic glass regardless of age. The PI will carry out a paleointensity study of basaltic glasses.