Fundamental Magnetic Constants and Palaeomagnetic Recording Fidelity of Greigite (Fe3S4)

灰长岩（Fe3S4）是一种强磁性矿物，在地质记录中得到越来越多的认识。它被广泛地与异常磁化联系在一起，使地球磁场行为和沉积序列环境变化的分析复杂化。特别是，北极是一个前沿地区，国际社会正在积极努力了解过去的气候变化。北极沉积物中灰长岩的存在使得很难确定古地磁观测是来自高纬度地区独特的磁场变化，还是来自与强磁相互作用的灰长岩颗粒簇相关的异常场记录。尽管人们越来越认识到灰长岩在地质记录中的重要性，并且与其他重要的陆相磁性矿物相比，灰长岩的关键基本磁性参数仍然未知。这使得不可能模拟微尺度的磁性特征，以测试簇状灰长岩的自生生长是否可以解释通常与灰长岩相关的异常磁化。PI研究小组最近的工作已经能够确定进行这种建模所需的3个关键参数中的2个。我们请求资金来确定剩余的关键参数并进行建模，这将为评估灰长岩的古地磁记录保真度提供基础。这项工作将有利于寻求了解高纬度地磁场行为的国际古地磁界和广泛使用古地磁记录构建气候变化年表的古气候界。灰长岩的生长也与天然气水合物的形成有关。因此，拟议的工作也可以提供参数，使灰长岩能够用作沉积序列中以前存在的甲烷水合物的示踪剂。

Greigite (Fe3S4) is a strongly magnetic mineral that is being increasingly recognised in the geological record. It is widely associated with anomalous magnetizations that complicate analysis of Earth's magnetic field behaviour and environmental change in sedimentary sequences. In particular, the Arctic is a frontier region where active international efforts are being made to understand past variations in climate. The presence of greigite in Arctic sediments makes it difficult to determine if palaeomagnetic observations result from unique magnetic field variations at high latitudes or from anomalous field recording associated with strongly magnetically interacting clusters of greigite grains. Despite the increasing recognition of the importance of greigite in the geological record, and in contrast with other important terrestrial magnetic minerals, key fundamental magnetic parameters for greigite remain unknown. This makes it impossible to model micro-scale magnetic characteristics to test whether authigenic growth of greigite in clusters can explain the anomalous magnetizations commonly associated with greigite. Recent work in the PI's research group has enabled identification of 2 of the 3 key parameters required to undertake such modelling. We request funds to determine the remaining key parameter and to undertake modelling that will provide the basis for assessing the palaeomagnetic recording fidelity of greigite. This work will benefit the international palaeomagnetic community who seek to understand high latitude geomagnetic field behaviour and the palaeoclimate community who widely use palaeomagnetic records to construct chronologies of climate change. Greigite growth is also associated with gas hydrate formation. The proposed work could therefore also provide parameters that would enable greigite to be used as a tracer for the former presence of methane hydrates in sedimentary sequences.