1. Effect of shock pressure on magnetic minerals (Mineral magnetism of shocked ferrimagnetic minerals)
Impact cratering has significantly contributed to the formation and reshaping of planetary bodies in our Solar System. This includes the modification of magnetic properties of crustal lithologies present in impact structures and in different parent meteorites. On Earth, magnetite and pyrrhotite is a major magnetic mineral in the lithosphere. Moreover, these magnetic minerals are also present in meteorites, which mostly suffered some degree of shock pressure. However, the effects of shock waves on the intrinsic magnetic properties of magnetite and pyrrhotite, as well as exotic minerals from meteorties like cohenite (Fe3C), remain poorly understood. Especially, a lack of information exists on the correlation between shock-induced magnetic and microstructural changes. This study investigates the effects of shock waves on magnetic and structural behavior of magnetite and pyrrhotite experimentally shocked to pressures of 5, 10, 20 and 30 GPa. These data are compared with observations from impacted rocks of Lockne (Sweden), Chesapeake Bay (USA), Nördlinger Ries (Germany), Elgygytgyn (Russia), Bosumtwi (Ghana) and Lonar (India) impact structures.
2. Thermomagnetic investigations on young pyroclastic deposits from volcanoes in Mexico: emplacement dynamics
Recently active volcanic structures in Germany and Mexico (Mytina Maar, Popocatepetl, Nuevo de Toluca) will be sampled. The sampling strategy is to collect samples over a several meter thick pyroclastic flow and over a lahar deposits at several distances to the summit. Different deposition types will be compared using ore microscopy, microprobe chemical analyses and thermomagnetic curves. The aim of the study is to investigate the depth- and distance-dependent thermomagnetic behavior of pyroclastic deposits in order to contribute to a better understanding of the thermal histories of titanomagnetite-bearing pyroclastic volcanic rocks. In a second step these results will also be applied on older pyroclastic flows of an age of >10.000 to 100.000 years and 1 Ma years in order to understand the secondary overprint of the primary cation distribution, like it has been observed in the Quarternary (0.3 – 0.7 Ma) Mytina maar (Lied, Msc thesis). This study is in cooperation with Luis Alva, UNAM, Mexico.
For Bachelor- and Master theses on magnetic research please contact Agnes.