There has been no geologic mapping reported on the Jeesiö property. Most of the project area is covered by a few metres of glacial till and outcrop is very scarce. Regional mapping is largely based on geophysical interpretation. GTK’s regional 1:200,000 mapping program indicates that much of the property is underlain by Archean-aged clastic sedimentary rocks which is intruded by younger Paleoproterozoic-aged gabbro sills and granitic rocks.
In Orogenic-type deposits, structure controls gold emplacement. Most of the Jeesiö property lies south of the Venejoki structure. Only a few sections of the property are situated to the north of the Venjoki structural break. In this area, the property is underlain by quartzite and Paleoproterozoic-aged gabbro sills as well as biotite paraschist and mafic volcanic rocks.
The Venjoki structure is over 100 km long and lies 5-to-25 km south and is subparallel to the Sirrka structure. The Venjoki structure represents a thrust zone where Paleoproterozoic and Archean-aged rocks were pushed northward over the Central Lapland Greenstone Belt. North to NE strike-slip shear zones related to this regional thrust are associated with several gold occurrences in the region.
Typically in Orogenic-style deposits in greenstone environments host gold bearing veins that are enveloped by alteration haloes consisting of iron-carbonate + sericite + sulphide to various amounts of chlorite, calcite and locally magnetite. Pervasive chromium-or vanadium rich green micas (fuchsite and roscoelite) as well as ankerite with zones of quartz carbonate stockwork are also common in shearedd ultramfic rocks.
For additional details, please refer to the Technical Report.
1Niiranen,T., I. Lahti, I., Nykanen, V.(2015) The Orogenic gold potential of the Central Lapland Greenstone Belt, Northern FennoscandianShield. In W.D. Maier, R. Lahtinen, H. O’Brien, Eds., Mineral Deposits of Finland (pp733-752). Elsevier Inc.