Three-dimensional modelling of the Källfallsgruvan iron oxide deposit, Riddarhyttan ore field, Bergslagen, Sweden: Integrating existing and new data to aid understanding of structural controls and mineral exploration

• Main Author: Spahic, Edna
• Format: Bachelor Thesis
• Language: English
• Published: Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser 2021
• Subjects: Three-dimensional modelling; Mineral exploration; Bergslagen; Riddarhyttan ore field; Källfallsgruvan iron-oxide deposit; Geology; Geologi; Geosciences; Multidisciplinary; Multidisciplinär geovetenskap; Fennoscandian
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-86083

The Bergslagen ore province, located in the Fennoscandian shield in the south-central part of Sweden hosts several metallic mineral deposits, one of them being the Källfallsgruvan iron-oxide deposit in the Riddarhyttan ore field, situated in a high-strain shear belt denoted as the West Bergslagen Boundary Zone (WBBZ). An accurate 3D geological model of the Källfallsgruvan iron-oxide deposit has been generated to aid understanding of the ore body geometries and calculating volume and tonnage. The methodology of this study consisted of assessing existing data in the form of legacy mine maps and to integrate new data from field work, drill core logging and 3D geological modelling. The work has resulted in structural interpretations that are put in the context of the regional structural framework in Bergslagen consisting of three deformation events (D1, D2 and D3) and two metamorphic events (M1 and M2). The field work resulted in six rock units being defined used to construct a geological map, in addition the structural measurements resulted in a hypothetical semi-regional fold and evidence of ductile strike-slip/dip-slip shearing. Logging of drill cores resulted in three rock units being defined, two of them related to the mineralization and one characterizing the host rock (± local variations), correlating to the observed host rock from the field work. The rock units discovered from both the field work and drill core logging are all interpreted to be the metamorphic products of volcanic rocks subjected to alteration of varying degree. Based upon geological field observations with subsurface data and 3D geological modelling it is concluded that, 1) The deposit comprises multiple ore bodies that jointly resemble an S-shaped synform that is steeply inclined-upright, moderately-steeply plunging towards the southwest with an axial plane striking northeast-southwest. The deposit is interpreted to be geometrically controlled by an F2 fold, possibly displaying an interference pattern of type 1, favouring progressive ...