Terrestrial iron oxides, such as hematite, goethite and magnetite, form specifically cemented concretions in sandstones using an aqueous diagenetic solution. According to the new results, the timeline on which concretions are formed could be much larger than current estimates. The basis for this claim is a magnetic record of the Jurassic Navajo Sandstone in Utah. The record contains fluctuations of remanent magnetization, which could prove the inversion of the Earth's magnetic field. This observation suggests that the time axis of the accumulation of iron concretions is comparable to the time axis of the accumulation of marine iron-manganese nodules, which contain a complex magnetic record. The occurrence of extremely slow changes in iron deposition in sandstones also helps to better understand the origin of concretions. In addition, terrestrial concretions provide an analogy for the "blueberries" found by the Mars rover Opportunity on Mars. These concretions probably underwent similar formation processes and could record inversions of the early magnetic dynamo on Mars.
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:451550 |
| Date | January 2021 |
| Creators | Smrčinová, Lucie |
| Contributors | Kletetschka, Günther, Adamovič, Jiří |
| Source Sets | Czech ETDs |
| Language | Czech |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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