jyrki parkkinen - sotkamo reports/130821... · jyrki parkkinen sotkamo silver ... (surpac) was run...

August 2013 Parkkinen: Sampo 3D 1

Jyrki Parkkinen Sotkamo Silver Deposit at Sotkamo: Geological Model of EM Sampo Soundings


Summary In purpose to find possible deep extensions of the Sotkamo Silver Deposit, Sotkamo, GTK committed EM Sampo (Gefinex 400S) soundings at the site during 2011-2012 under the lead of Geophysicist Matti Niskanen who also created the first 3D models to visualise conductive zones. Both the original models by Niskanen and the complementary work presented here indicate that the Deposit extends to the depth of more than 1400 m while the extensions may bend towards an upright position and westwards. An EW oriented vertical, weakly conductive shear seems to crosscut above zone at the depth of about 600-1500 m. The conductive zone, extension of the Deposit, can be called Exploration Target (JORC 2012) because it forms a liable extension to the Sotkamo (Taivaljärvi) Deposit as to the shape and position and in accordance to known geological structures. Moreover, the zone has been penetrated by six drill holes containing Sotkamo type silver ore intersections (Table 1). Expected volume of the Exploration Target is > 20 Mt and grade 60 g/t Ag at the cut off grade of 30 g/t Ag.

Contents: Summary About the Author Background Data Methods Figures Results References Appendix

About the Author: This 3D modelling and resource estimate were made by the independent Consultant, European Geologist, PhD Jyrki Parkkinen, who holds a Qualified Person Status under the European Federation of Geologists and who is qualified to make statements according to JORC and Ni 43 101 Codes.


Background EM Sampo (Gefinex 400S) surveys by GTK at Sotkamo were run in two phases, 2011 (Niskanen 2012) and 2012 (Niskanen 2013), Geophysicist Matti Niskanen planned and lead these surveys and he also created the first 3D models for conductive zones using Oasis Montaj software, This report aims to describe results of geological modelling of above surveys and Niskanen’s interpretations. In this work also structural information of the Sotkamo Deposit has been important (Parkkinen 2010, 2012). Data Original data is composed of vertical soundings and arranged in a form similar to drill core database and divided into four groups: Ohm2011 (survey phase 2011), Ohm1000 (survey 2012, coil separation 1000 m) Ohm 400 (survey 2012, coil separation 400m) Ohm 1270 (survey 2012, coil separation 1270-1400 m). Measurements were composited into 5 m samples. Composites were classified and the classes were given colour symbols (Figs. 1A-C). Ohm-m values 1-500 stand for the best conductivity, values 500-1500 fair to weak conductivity and values > 1500 very weak conductivity. Typically, Sotkamo type deposit would give 1-2000 ohm-m values according to Niskanen. Composites from 1 to 1500 ohm-m of the four soundings groups are shown in Figs 2-4. Methods A variography (Surpac) was run for the classified composites to define parameters for interpolation. It appeared that Ohm400 samples exhibited a too small variation for geostatistical treatment (meaning: no conductive zones). For all other groups parameters were found and the interpolations of composite samples were carried for each group separately in a block model and using the Inverse Distance2

method. For the interpolation a block model in the SW-NE direction and with blocks sized 20*50*50 m (width*length*depth) was created. Solids to imitate conductive zones or lenses were then constructed according to block values. The results are shown in Figs. 5-7.


ohm-m ohm-msymbol min max luokka määrä %red 0 100 100 741 2.21red 101 500 90 1424 4.24green 501 800 80 1879 5.60green 601 1500 70 4031 12.01blue 1501 5000 60 5348 15.93grey 5001 12000 50 6104 18.19grey 12001 25000 40 5982 17.82grey 25001 30000 30 5215 15.54grey 30001 45000 20 1791 5.34grey 45001 105000 10 840 2.50grey 1014020 1259646 0 208 0.62

33563 100.00

Figures 1 A/B/C A.  Classification of soundings. B-C. Coloured composite samples Search ellipsoids (red, blue).

CLASS AMOUNT


Exploration SolidOhm20110hm10000hm1270Ohm400

Regional lineation

Regional lineation

Figure 2 Surface projection: Sotkamo Sampo results: 1 – 1500 ohm-m. Brown body = Exploration Solid (Parkkinen 2009).

Figure 3 Projection towards SE: Sotkamo Sampo results: 1-1500 ohm-m.


Regional lineation

Figure 4 Looking from the NE to the SW: Sotkamo Sampo results, 1-1500 ohm-m.


Exploration SolidOhm20110hm10000hm1270Ohm400

Figure 5 Exploration Solid with primary Sampo solids created for the qualified three sounding groups and representing extensions to the Sotkamo Deposit. According to Matti Niskanen, depths < -1400 m are more or less unsure and they should not be included in the Exploration Target but as a speculative continuum.


Figures 6 A/B Pictures from above: A.  Exploration solid and primary solids. B.  As above but secondary cross-cutting solids added.


Figures 7 A/B A.  All Sampo solids with regional aeromagnetic map (GTK). B.  All Sampo solids with regional electric map (GTK). The arrow shows the southern surface edge and the direction of the proposed shear zone.


Figure 8 The Sotkamo Silver Deposit, mine plan, and models for the Exploration Target. The models extend to the depth of 2000 m while the lower portion below -1400 m should be considered speculative, so far.

Results The extension model to the Sotkamo Silver Deposit, as described here and called the Exploration Target, is estimated to contain a more than 20 Mt potential resource and, analogically to the Exploration Solid (Parkkinen 2010a), with a silver grade of ~60 g/t and the cut off grade being 30 g/t Ag.


References Niskanen M. 2012. Electromagnetic SAMPO soundings at Taivaljärvi. GTK, Eastern Finland Office M185K2011 24.1.2012 Kuopio Niskanen M. 2013. Electromagnetic SAMPO soundings at Taivaljärvi 2013. GTK, Eastern Finland Office M178K2012, Kuopio. Parkkinen J. 2010a. The Taivaljärvi Ag-Zn-Pb-Mn Deposit, Finland; Review and Update of Mineral Resource Estimates. Sotkamo Silver Archives. Parkkinen J. 2010. Rakenneanalyysin ja geostatistiikan synteesi. Geologi 62, 238-243. Parkkinen J. 2012. Unfolding Taivaljärvi. Geologi 64, 70-74.

holeid from to agppm Length holeid from to agppm LengthR-‐110 581.9 583.9 202 2 R-‐100 627.36 629.7 34 2.34R-‐110 583.9 586.01 11 2.11 R-‐100 629.7 631.57 75 1.87R-‐110 586.01 588.22 49 2.21 R-‐100 631.57 633.76 178 2.19R-‐110 588.22 590.8 22 2.58 R-‐100 633.76 635.79 29 2.03R-‐110 590.8 593.73 89 2.93 R-‐100 635.79 638.36 22 2.57R-‐110 593.73 596.21 92 2.48 R-‐100 638.36 640.8 78 2.44R-‐110 596.21 598.24 93 2.03 68.10714 13.44R-‐110 598.24 600.24 80 2 holeid from to agppmR-‐110 600.24 602.24 355 2 R-‐102 612.37 614.11 63 1.74R-‐110 602.24 604.46 82 2.22 R-‐102 614.11 615.45 150 1.34R-‐110 604.46 606.62 39 2.16 R-‐102 615.45 617.11 39 1.66R-‐110 606.62 607.92 40 1.3 R-‐102 617.11 618.58 50 1.47R-‐110 607.92 609.15 43 1.23 R-‐102 618.58 619.72 35 1.14

92.1522936 27.25 66.49796 7.35holeid from to agppm holeid from to agppm

R-‐106 603.9 605.95 35 2.05 R-‐129 556.03 558.05 92 2.02R-‐106 605.95 607.6 58 1.65 R-‐129 558.05 560.06 46 2.01R-‐106 607.6 609.9 363 2.3 R-‐129 560.06 562.37 31 2.31R-‐106 609.9 611.75 840 1.85 R-‐129 562.37 563.9 8 1.53R-‐106 611.75 614 29 2.25 R-‐129 563.9 566.07 5 2.17R-‐106 614 615.9 67 1.9 R-‐129 566.07 569.07 198 3R-‐106 615.9 618.3 26 2.4 74.15644 13.04R-‐106 618.3 620.4 67 2.1 holeid from to agppmR-‐106 620.4 622.4 172 2 R-‐83 622.25 624.28 82 2.03R-‐106 622.4 624.43 31 2.03 R-‐83 624.28 627.28 23 3R-‐106 624.43 627.3 35 2.87 R-‐83 627.28 629.68 40 2.4

147.8367521 23.4 R-‐83 629.68 633.28 30 3.6R-‐83 633.28 636.28 53 3

42.65574 14.03

Table 1. Drill hole intersections crossing the Sampo conductive zones, interpreted as deep extensions to the Sotkamo Deposit.


Appendix Interpretations by Matti Niskanen and present models compared. Original survey extended below the depth of -2000 m but Matti Niskanen concerned the depths below -1400 m uncertain and therefore his Interpretations only cover the depth zone between -200 and -1400 m. The top limit is set to avoid possible bias by surfacial conductive zones. Parkkinen’s model extends to the depth -2000 m, since geostatistical continuity allows it.

Figure 1 A/B Sotkamo Deposit (Exploration Solid) (brown) and Sampo interpretations, isosurfaces 1500 ohm-m (blue) and 500-1100 Ohm-m (red). A From above. B From the NW.


Figure 9 A, B Colours as in Fig. 8. A Sampo isosurfaces and the model for the structural extensions of the Deposit. B Sampo isosurfaces and the model for zones cross-cutting the extension.

Figure 10. Sampo isosurfaces and the models for the extension and the cross-cutting Zones seen from the NW above.

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