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Laguna Site Investigation Geological and Geotechnical Models Petteri Somervuori, Espoo, 25+26.8.2014 1.

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Presentation on theme: "Laguna Site Investigation Geological and Geotechnical Models Petteri Somervuori, Espoo, 25+26.8.2014 1."— Presentation transcript:

1 Laguna Site Investigation Geological and Geotechnical Models Petteri Somervuori, Espoo, 25+26.8.2014 1

2 2 Petteri Somervuori Espoo, 25+26.8.2014 Contents: Geological background (very short) Modelling Data coverage Foliation/schistocity Fracture/weakness zones Rocktypes Rock quality Uncertainties Summary

3 Geological Background Pyhäsalmi ore is massive sulpphide deposit surrounded by volcanics and an alteration halo. About 60% of rocks are felsic volcanics in mine scale. Schictosity (foliation) is quite clear. Felsic rocks are altered near ore at the upper part. Felsic rocks are sheared near ore at the deeper parts. About 40% of rocks are mafic volcanics. Schictosity is quite clear near ore but quite massive far away the ore area. The pegmatites occur usually as dikes of variable thickness. Usually veins are 0.1-2.0 meter wide and might be very long. The pegmatites intruded in many stages. So their composition varies a little bit. More pegmatites are found from east side of ore than west. Other minor rocktypes occurs 3 Petteri Somervuori, Espoo, 25+26.8.2014

4 Geological Background 4 Petteri Somervuori, Espoo, 25+26.8.2014 North Fault Laguna investigation target area Ore Volcanics form a fold around ore separated by faults in north and south Foliation model Imprication fault model Level section Z 1150 South Fault

5 Modelling Data coverage – Density of drilling investigations varies inside target volume – Latest drilling investigations concentrated close to level 1400 – Investigation drilling penetrates rock more in east-west direction than in south-north – There is less rock quality data from Q’-index than RQD 5 Petteri Somervuori, Espoo, 25+26.8.2014

6 6 Petteri Somervuori, Espoo, 25+26.8.2014 Distance from the drillholes ≤100 m ≤ 250 m ≤ 500 m

7 7 Petteri Somervuori, Espoo, 25+26.8.2014 Tunnel

8 8 Petteri Somervuori, Espoo, 25+26.8.2014 Less Q-index logging than RQD RQD logs only (black ones)

9 Modelling Foliation/Folding – Important information Guide for modelling rocktypes, fracture zones and rock quality in 3D For building anisotropic strength model of rock mass – Background Pyhäsalmi mine’s models of foliation Observations in mine tunnels about foliation Foliation follow the shape of the orebody 9 Petteri Somervuori, Espoo, 25+26.8.2014

10 10 Petteri Somervuori, Espoo, 25+26.8.2014 Foliation model by Pyhäsalmi mine, Model and tunnel observations

11 Modelling Foliation/Folding – Process of foliation modelling Raw core logging observations of foliation orientation Means planes from stereoplot clusters 2D trace interpretation 3D trace plane model 11 Petteri Somervuori, Espoo, 25+26.8.2014

12 12 Petteri Somervuori, Espoo, 25+26.8.2014 Raw foliation orientationsStereoplot of selected data Mean planes

13 13 Petteri Somervuori, Espoo, 25+26.8.2014 Mean planes generated from raw data2D interpretation of foliation for 4 levels

14 14 Petteri Somervuori, Espoo, 25+26.8.2014 Digitised interpretation for 4 levels Fault

15 15 Petteri Somervuori, Espoo, 25+26.8.2014  Final 3D foliation model generated using dip and dip direction of mean planes

16 Modelling Weakness/Fracture Zones – Only one major fracture zone is found (FZ1) – Drillholes penetrate FZ1 in west and indicate bad rock quality and also weak rocktypes like heavily weathered granite (korppukivi) and rocktypes including graphites – Inluence zone for FZ1 can be recognise where rock quality starts gradually decrease – Deformation zone starts in north side of area partly before modelled influence zone 16 Petteri Somervuori, Espoo, 25+26.8.2014

17 17 Petteri Somervuori, Espoo, 25+26.8.2014 Drillhole intersections of FZ1 FZ1 core intersections hole_iddepth_from PH-101648.0 PH-102387.0 PH-104577.0 R-2241999.0 R-2242929.0 R-2246770.0 FZ1 influence intersections starts hole_iddepth_from PH-101600.6 PH-102333.3 PH-104501.2 R-2241954.0 R-2242830.3 R-2246736.3 Influence zone FZ1 core

18 18 Petteri Somervuori, Espoo, 25+26.8.2014 Graphites Granites

19 19 Petteri Somervuori, Espoo, 25+26.8.2014 Known imprication fault in west fits well with FZ1 Foliation and fracture observations are used in modelling FZ1

20 20 Petteri Somervuori, Espoo, 25+26.8.2014 FZ1 modelled CoreInfluence zone

21 Modelling Weakness/Fracture Zones – Minor fracture zones are primaly modelled based for RG classification and secondly for RQD classification, the direction of minor planes are based on foliation and fracture observations – Minor fractures are observed as short drillcore intersections, and the distance between drillholes is quite long – The rock quality is not as poor as in FZ1 – One uncertain estimate is done to model continuty between minor fracture zones and drillholes, called FZ2 21 Petteri Somervuori, Espoo, 25+26.8.2014

22 22 Petteri Somervuori, Espoo, 25+26.8.2014 FZ2 Level -1400 Minor fracture zones and FZ2

23 Modelling Rocktype models – Main rocktypes are mafic vulcanic (EVULK) 47%, felsic vulcanic (HVULK) 37% and pegmatite 7% – 3D modelling is done for main rocktypes (thicker pegmatite veins close to level 1400 are modelled) – In 3D modelling, observations of foliation was used for directions and dips – Shorter observations of weaker minor rocktype locations need to taken account when evaluating exact location of Laguna caverns 23 Petteri Somervuori, Espoo, 25+26.8.2014

24 24 Petteri Somervuori, Espoo, 25+26.8.2014 Foliation observations were used for modelling 3D modelSection from level 1400

25 25 Petteri Somervuori, Espoo, 25+26.8.2014 200 m offset from ore Ore FZ1 FZ2 Level 1400 FZ2

26 Modelling Rock quality – Rock quality is estimated spatially by block model interpolation from logging data – Rock quality (Q’-index) on block model excluding FZ1 => mostly very good or good=> No blocks below Good class – Rock quality (RQD) on block model excluding FZ1 => mostly excellent, some good and fair classes close to FZ1 and in south + north + upper parts – Main differencies between RQD and Q’ models are coming from older exploration holes which are only RQD logged 26 Petteri Somervuori, Espoo, 25+26.8.2014

27 27 Petteri Somervuori, Espoo, 25+26.8.2014 Mafic volcanic Felsic volcanic Pegmatite Q-index (Rock quality) cumulative frequency of logged values from drillhole excluding FZ1 and it’s influence zone 50% 30% 70% 1% <1% >=Extremely good (20%) >=Very Good (50%) >= Good (98%) Fair or less <2%

28 28 Petteri Somervuori, Espoo, 25+26.8.2014 Mafic volcanic Felsic volcanic Pegmatite Average Excellent (97%) <=Fair <10%, <=Poor <4% RQD (Rock quality) cumulative frequency of logged values from drillhole excluding FZ1 and it’s influence zone <=10%

29 29 Petteri Somervuori, Espoo, 25+26.8.2014 Block modelling Modelled attributes are GSI and RQD Area is distributed into 5 domains: Domain 1 = FZ1 Domain 2 = FZ1 influence zone Domain 3 = North sector Domain 4 = Centre sector Domain 5 = South sector Domain 1: Spherical search, composite includes only entries inside the FZ1 Domain 2: Spherical search, composite includes only entries inside the FZ1 influence zone Domain 3-5: Ellipsoid search, composite includes only entries outside the FZ1 and the influence zone Estimation with inverse distance weighting Search distances and directions Round 1: 100 m; Round 2: 250 m; Round 3: 500 m Domains 3: 046/-59; Major/Minor 2 Domains 4: 022/-74; Major/Minor 2 Domains 5: 175/-75; Major/Minor 2

30 30 Petteri Somervuori, Espoo, 25+26.8.2014 No blocks below Good quality (Q’-index) outside FZ1 Level 1400

31 31 Petteri Somervuori, Espoo, 25+26.8.2014 Level 1400 Good area for Caverns

32 Uncertainties Pegmatite dykes – Continuity and direction are uncertain, however less pegmatites have found on western side from orebody 32 Petteri Somervuori, Espoo, 25+26.8.2014

33 33 Petteri Somervuori, Espoo, 25+26.8.2014 Hvulk (Felsic volcanic)

34 Uncertainties Drilling direction and density – Pegmatites and minor weakness zones might exist between drillholes, now drilling more in east-west direction 34 Petteri Somervuori, Espoo, 25+26.8.2014

35 35 Petteri Somervuori, Espoo, 25+26.8.2014

36 Uncertainties Folding – Direction and dip of foliation changes more in lower part where orebody ends – Fold is more tight and observations close to level 1400 show quite straight lines? – Lump of felsic vulcanic penetrates through mafic => geology is less predictable – Minor weakness zone FZ2 related to that zone is very uncertain 36 Petteri Somervuori, Espoo, 25+26.8.2014

37 37 Petteri Somervuori, Espoo, 25+26.8.2014 Mafic volcanic penerates through Fold is more tight in level 1400

38 Uncertainties Less homogenious rock/ weaker/ more foliated – It is important to evaluate heavily foliated and/or core sections that contain weaker minerals – In next figure, foliation intensity is higher and rock is less homogenious inside north fault based on two different drillholes 38 Petteri Somervuori, Espoo, 25+26.8.2014

39 39 Petteri Somervuori, Espoo, 25+26.8.2014 Foliation intensity varies and rock can be less homogenious R-C-1 Note Depth 218-229m Mafic volcanic, +skarn, +carbonate veins, +narrow pegmaties etc.. Mafic volcanic Mafic volcanic less homogenious and heavily foliated Fault

40 Summary Only one major fracture zone is found in west side, which dimensions are now well known Rock quality is good or better (98%) in areas focused during investigations No water leakages found Mafic volcanic would be ideal for main Laguna caverns Foliation intensity/direction and weaker minerals have to taken account More detailed investigations are needed in next phase focusing into smaller area 40 Petteri Somervuori, Espoo, 25+26.8.2014

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