A Geological and geophysical synthesis of the Svartliden Project, Sweden and its application in defining gold exploration targets.
thesisposted on 2023-05-26, 00:55 authored by Laurent, Y
The Svartliden Project is located in north central Sweden, 7Skm west-northwest of the town of the Lycksele. The geology comprises of a Palaeoproterozoic package of intercalated turbiditic sedimentary rocks and extrusive coherent and non-coherent basaltic rocks. Gold mineralisation is associated with diopside +green amphibole +silica +arsenopyrite. Alteration is best developed along the intersection lineation between bedding and the primary cleavage. Mineralisation is concentrated in areas of low shear strain formed by the pressure shadow effect from the regional rotating syn-orogenic granitoids. Pyrrhotite is the most pervasive sulphide and is found as a primary mineral in carbonaceous sediments and as a late-stage sulphide in the \Mineralised Zone\". Pyrrhotite is responsible for the conductivity chargeability and along with magnetite the magnetic susceptibility found in the Svartliden shear zone. Ground magnetic and electromagnetic surveys were carried out over the project area. The ground magnetics does not differentiate the magnetite-bearing volcanics from the pyrrhotite-bearing carbonaceous sediments and the \"Mineralised Zone\". The ground electromagnetic survey defines high conductive zones generated by the pyrrhotitebearing sediments and the \"Mineralised Zone\" within resistive granitoids and volcanics. Downhole apparent resistivity IP and magnetic susceptibility were conducted on three drillholes along 1700mB. The magnetic susceptibility as with the ground magnetics is unable to differentiate magnetite-bearing volcanic rocks from the pyrrhotite-bearing units. Apparent resistivity has an inverse correlation with chargeability. Log transformation of the ground in-phase EM data delineates first- and second-order conductive anomalies. First-order anomalies represent the pyrrhotite-bearing carbonaceous sedimentary unit. Second-order anomalies represent the pyrrhotite-bearing \"Mineralised Zone\". Second-order anomalies calculated from in-phase EM data can be used to target areas for gold exploration at both a project and regional scale."
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