A geophysical investigation on the northern part of Utö was carried out between 2020 and 2021 to asses the extent of the iron ore (BIFs) and the iron bearing sulfides that have been surveyed and mined in the past. The survey using analog field equipment combined magnetometry, gravimetry, susceptibility, leveling, density, and thin-section microscopy. Magnetic measurement reduction method was done through SGU’s communicated advice and modeling software was used. Additionally, an in depth literature analysis was performed to understand the historical context of mine operations to aid interpretation. The results of the multidisciplinary analysis show a number of observations. The interpolated local magnetic anomaly and the gravimetric results fit well with current SGU magnetic and Bouguer anomaly maps. The crosscutting magnetic profile between Nyköpingsgruvan and Långgruvan remains anomalously high despite the volume of removed ore. Susceptibility results confirmed past reports of localities where iron bearing sulfides were found and provide evidence to early ore formation and fluid mobilization. The 2D Bouguer anomaly profile revealed deformation structures reported in literature and also suggests a possible volume of remaining iron ore. Rediscovered meta-tuffite and ignimbrite rock samples were collected and petrological analysis infers a high resolution lithology. Newly discovered literature and material of previous geophysical surveys determined iron ore depths up to 1000 meters. Despite the amount of survey data the results are concluded to be coarse in resolution but can be improved.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:su-227843 |
| Date | January 2023 |
| Creators | Flanders, Nicole |
| Publisher | Stockholms universitet, Institutionen för geologiska vetenskaper |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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