Absolute paleointensities on cretaceous kimberlites in Botswana

超时提供了一个非凡的机会，以测试各种理论和模型，关于对流在地球的液体外核和产生的地磁场。为了获得一个完整的地球发电机的图片，除了古方向，这主要是在过去确定的古强度的确定是至关重要的。到目前为止，只有少数研究收集了过去160 Ma的强度数据。他们的结果的巨大变化导致了三种不同的模式的长期古强度变化（1：较低的平均古强度在中生代比在新生代; 2：显着较高的强度在过去的0.3马比之前; 3：高的平均古强度在白垩纪正常超时，CNS）。需要更多高质量的数据，特别是CNS能够确认或拒绝这些模型，并在不同的地球发电机理论之间做出决定。白垩纪的金伯利岩，这是相当多的南部非洲，可能会提供一个机会，以获得大量的强度数据的CNS。本研究的目标是，因此，在博茨瓦纳的金伯利岩管的各种样品，并检查其是否适合paleointensity测定。以往的研究主要集中在它们的古方位特征上，得到了非常可靠的数据，由此产生的古磁极构成了非洲视极移路径的重要组成部分，然而，无论是在原地还是在实验过程中，由于冷却速率、剩磁的磁各向异性和磁畴状态偏差的差异，古强度的确定都变得复杂，并可能出现进一步的问题。因此，计划进行详细的岩石磁性和古方向的研究，结合古强度测定，以获得完整的知识，在金伯利岩的剩磁收购过程。如果古地震强度测定成为可能，我们将能够显著增加古地震强度数据集。

Superchrons provide a remarkable opportunity to test the various theories and models regarding convection in the Earth’s liquid outer core and the generation of the geomagnetic field. To obtain a complete picture of the geodynamo, determination of the paleointensity is crucial in addition to paleodirections, which were mainly determined in the past. So far only few studies have collected intensity data for the last 160 Ma. The great variety of their results led to three different models of long-term paleointensity changes (1: lower mean paleointensity during the Mesozoic than during the Cenozoic; 2: significantly higher intensity in the last 0.3 Ma than prior to that; 3: high mean paleointensity during the Cretaceous Normal Superchron, CNS). Much more high quality data is needed especially for the CNS to be able to confirm or reject these models and to decide between the different theories of the geodynamo. Kimberlites of cretaceous age, which are quite numerous in southern Africa, may provide an opportunity to obtain a high amount of intensity data for the CNS. The target of this study is, thus, to sample a variety of kimberlite pipes in Botswana and to check their suitability for paleointensity determination. Previous studies, which have focused on their paleodirectional characteristics, yielded very reliable data and the resulting paleomagnetic poles form an important part of Africa’s apparent polar wander path. However, alterations, either in situ or during the experiment, complicate paleointensity determination and further problems may arise due to differences in cooling rates, magnetic anisotropy of the remanence and magnetic domain state bias. It is therefore planned to carry out detailed rock magnetic and paleodirectional studies in combination with paleo-intensity determinations in order to gain complete knowledge about remanence acquisition processes in kimberlites. If paleointensity determinations turn out to be possible, we will be able to significantly increase the paleointensity data set.