Mineralizing event with tungsten and associated elements at Ymer Island, central East Greenland.

Transcription

1 Mineralizing event with tungsten and associated elements at Ymer Island, central East Greenland. Presentation at GEUS mineral ressource assessment workshop on tungsten, December 4th, 2013 by John Pedersen 1

2 West Ymer Island Noa Dal Margeries Dal From Gilotti and McClelland 2008 Geol Soc America, Memoir 202 2

3 Exploration history west Ymer Island 1953 Finding of galena bearing quartz vein (Eha 1953, MOG 111,2) 1969 Sampling of lead mineralization at Noa Dal (NM) 1974 HMC sampling locate scheelite grains in streams (NM) 1975 First report on float samples with scheelite at S. Margeries Dal (NM) 1979 Outcrops with scheelite located in S. and N. Margeries Dal (NM) 1980 Surface sampling at S. and N. Margeries Dal tungsten localities (NM 1981 Shallow diamond drilling at S. and N. Margeries and Panoramafjeld (NM) 1983 Diamond drilling at S. and N. Margeries (NM) 1984 Finding of float samples with gold, antimony and arsenic in Noa Dal (NM) 1986 Outcropping Au-Sb-W-As mineralization found at Noa Dal (DTU-NM) 1992 Profile sampling of vein structure in Noa Dal (Nunaoil) 2008 Skytem survey (TEM and magnetics) (NunaMinerals) 2011 Bulk sampling of tungsten locality at S. Margeries Dal (NunaMinerals) 3

4 HMC prospecting at west Ymer Ø Panoramafjeld Noa Dal Margeries Dal 4

5 Chasing scheelite grains in the streams (HMC samples) 5

6 Ultra violet lamp equipment 6

7 Stratigraphy Eleonore Bay SuperGroup From Henriksen 2005, GEUS 7

8 Geological map west Ymer Ø Blue: Andree Land Group (Lim-Dol Series (14-20)) Red: Ymer Ø Group (Multicol. Series (7-13)) Yellow: Lyell Land Group (Quartzite Series (1-6)) From H.J. Bengaard 8

9 Mineral occurrences south Margeries Dal From Harpøth et al. 1986, Geoscience 17 9

10 South Margeries Dal From NunaMinerals - Anders Lie presentation 10

11 Breccia zone on slope at south Margeries Dal 11

12 Breccia with scheelite 12

13 Microphoto of scheelite with Qz Lim quartz Sch Qz 13

14 Core drilling at south Margeries Dal 14

15 Map of drilling at south Margeries Dal for tungsten From SP1/84, Nordisk Mineselskab A/S 15

16 Section of drilling at south Margeries Dal for tungsten From SP1/84, Nordisk Mineselskab A/S 16

17 Winkie drilling for W and Sb at North Margeries Dal in gully formed along faults 17

18 Geological map at north Margeries Dal Drill position From Harpøth et al. 1986, Geoscience 17 18

19 Schematic profile at north Margeries Dal From Harpøth et al. 1986, Geoscience 17 19

20 Sampling by percussion drilling 20

21 Map of drilling at north Margeries Dal W lens Sb lenses From SP1/84, Nordisk Mineselskab A/S 21

22 How much have been found? Locality Tonnage Grade WO3 Tonnes/strike m S Marg W 75,000 2,5 % 350 N Marg W 42,000 0,7 % 330 N Marg Sb 108,000 3,5 % 650 To locate 1 million tons W ore: prove 3000 m strike length Expected grade say 1 to 2 % WO3 From SP1/84 Nordisk Mineselskab A/S 22

23 Vein structure at S-side of Noa Dal 23

24 Details from vein structure 24

25 Sampling of vein structure at deeper stratigraphic levels 25

26 Sample results from area named Top scree Best segment: 30 m wide, 150 m long with 0,25 ppm gold, 1800 ppm arsenic, 1,0 % antimony and 100 ppm tungsten. 26

27 Arsenic in sediment samples 27

28 Gold in sediment samples 28

29 Tungsten in sediment samples 29

30 Antimony in sediment samples 30

31 Zonation around an intrusive complex Reduced intrusion-related gold systems W From Hart 2007, Geol Ass Canada, Special Paper no 5 31

32 Do a circular structure at Noa Dal supports the existence of a deep seated granite? Granite? From NunaMinerals A/S 32

33 Granites at base of EBG From Gilotti and McClelland 2008 Geol Soc America, Memoir

34 Age, metal source and precipitation The mineralizing event is of Caledonian Age with same Sr isotope signature as the Caledonian granites (c. 400 Ma) (Stendal and Frei 2008, Geol Soc America, Memoir 202). Based on lead isotopes, the metals originated from Neoand Meso- Proterozoic metasediments (Jensen 1994). Precipitation of scheelite took place between 170 and 240 degrees (Kornerup-Madsen in Pedersen & Stendal 1987). Host rock lithology controlled precipitation with limestone as the most favourable host rock for scheelite. 34

35 Deposit potential The deeper seated tungsten type of mineralization (wolframite?) associated with arsenic and gold, does not seem to comply with grade requirement. Tungsten trapped along faults within the limestone beds (scheelite) returns 300 tons of tungsten ore with 1 to 2 % W for each strike meter. The tiny areas investigated compared with the widespread occurrence of faulting within the proper lithology makes it likely that commercial tonnages exist, but they may be difficult to find. 35

36 Thank you View from Blomsterbugten at Noa Dal 36