hunt for ore deposits - recent findings and current...
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Society of Economic Geologists (Society of Economic Geologists (SEGSEG))
Advancing Science & DiscoveryAdvancing Science & Discovery
•• Representing Representing 5300 5300 members in members in 100 100 countriescountries
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•• HighHigh--quality conferences, seminars, publications (Economic Geologyquality conferences, seminars, publications (Economic Geology))
•• Assists in the development of all economic geologists Assists in the development of all economic geologists
•• Short courses, workshops, field tripsShort courses, workshops, field trips
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Hunt for Ore Deposits - Recent Findings and Current TrendsSurigao, Philippines
D.J.Kirwin : June 9-10th, 2011
Diatreme breccia, Rosia Montana, Romania
MAAR
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Generalised model of a Maar Volcano/Diatreme illustrating
the position of various breccia types within a diatreme system
VENT
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Vent explosion, Ukinrek Maar, Alaska, 1977(Photo - R. Russell on 6 April 1977, Alaska Department of Fish and Game)
Ukinrek Maar, Alaska (Photo - C. Nye)
Tower Hill, near Warrnambool, western Victoria, Australia. A maar volcano with several scoria cones. The volcano erupted approximately 25,000 years ago.
(photo – Victoria Museum)
The maar deposits are well exposed in this wall and consist mainly of The maar deposits are well exposed in this wall and consist mainly of
phreatomagmatic deposits interspersed with magmatic (scoria) deposits.phreatomagmatic deposits interspersed with magmatic (scoria) deposits.
Tower Hill maar structure, Victoria, Australia.Tower Hill maar structure, Victoria, Australia.
(photo – Victoria Museum)
The maar deposits consist of basaltic ash, lapilli, bombs, and country rock fragments
derived from the underlying Tertiary Port Campbell Limestone.
Tower Hill marr, Victoria, Australia. (photo – Victoria Museum)
TERMINOLOGY
Volcaniclastic Kimberlite
Pyroclastic kimberlite
Resedimented kimberlite
Diatreme kimberlite
(From Mitchell, 1986)
Hypabyssal Kimberlite
Dykes, Sills, Sheets, Root zones
Orapa Diamond Mine, Botswana
Bedded Kimberlite, Orapa Diamond Mine, BotswanaBedded Kimberlite, Orapa Diamond Mine, Botswana Basement Basement megamega--clastclast ((66xx44xx44mm –– 170170TT)) -- OrapaOrapa Diamond MineDiamond Mine, Botswana, BotswanaBasement Basement megamega--clastclast ((66xx44xx44mm –– 170170TT)) -- OrapaOrapa Diamond MineDiamond Mine, Botswana, Botswana
(From Jensen, 2003)1 km Cresson Pit in July 2000. (From Jensen, 2003)
Cresson mine manager
Dick Roelofs showing
the Cresson Vug to an
amazed Hildreth Frost
and Ed De La Vergne
on November 26,1914,on November 26,1914,
as depicted in a
contemporary woodcut
engraving.
(Reprinted in Beebe and
Clegg, 1955)
Generalized outline of the
Cresson blowout showing
the location of the Vug.
Modified from Loughlin
and Koschmann (1935).
8x4x10m – 35,000 oz/month
3-D portrayal of Cresson
Pipe, looking north.
Note elliptical-shaped cross
section, and bifurcation at depth.section, and bifurcation at depth.
Shape along the margin of the pipe
are shown in red.
(From Jensen, 2003)
Oblique section through one of the
lamprophyre breccia pipes in the
‘Trail system’.
Note the large egg-shaped, rafted
blocks of porphyritic phonolite with
pervasive K-feldspar + specularite
alteration (purple color).
(From Jensen, 2003)
Diatreme Breccia, Cripple Creek-CC3, Colorado, USA (From Jensen, 2003)
Montana Mineral Deposits Map, USA Montana Tunnels Au Mine, USA
Carbonised Wood Clasts, Montana Tunnels Au Mine, USA Diatreme Breccia, Montana Tunnels Au Mine, USA
Baia Mare Au districtBaia Mare Au district
Rosia Montana, Golden Quadrilateral
(From Cornelius, 2005)
100 m
Diatreme Breccia, Boldut Mine, Cavnic, Baia Mare, Romania
Gengzhuang Au Mine, Shanxi Province, China
Diatreme Diatreme BBrecciareccia,, Maar Maar FFaciesacies, Gengzhuang Au Mine, Shanxi Province, , Gengzhuang Au Mine, Shanxi Province, ChinaChina
Diatreme Diatreme BBrecciareccia,, Gengzhuang Au Mine, Shanxi Province, Gengzhuang Au Mine, Shanxi Province, ChinaChina
Late Late Stage Stage SphaleriteSphalerite Veins,Veins, Gengzhuang Au Mine, Shanxi Province, Gengzhuang Au Mine, Shanxi Province, ChinaChina
SulphideSulphide MatrixMatrix MineralisationMineralisation,, Gengzhuang Au Mine, Shanxi Province, Gengzhuang Au Mine, Shanxi Province, ChinaChina
Borneo Geology Map, Indonesia Kelian Au Mine, East Kalimantan, Indonesia
Stratigraphic Section of Kelian Au Mine, East Kalimantan, Indonesia
Kelian Au Mine, East Kalimantan, Indonesia
Kelian Au Mine, East Kalimantan, Indonesia Kelian Au Mine, East Kalimantan, Indonesia
Kelian Au Mine, East Kalimantan, Indonesia Kelian Au Mine, East Kalimantan, Indonesia
Whispy textured juvenile clasts
Accretionary balls in rock flour matrix
Matrix supported lithic
Philippines
(Adapted from
Mitchell & Leach, 1991)
Emma & Heine Pits,
Placer Au Mine,
Mindanao
Placer Geology
Diatreme Breccia, Heine Pit, Placer Au Mine
Limestone Clasts, Heine Diatreme, Placer Au Mine
Carbonaceous Zone,
Heine Pit, Placer Au Mine,
Mindanao
Diatreme Breccia, Ntina, Placer Lake Leonard Diatreme, North Davao, Philippines
Tuff Apron Lake Leonard Diatreme, Mindanao, PhilippinesTuff Apron Lake Leonard Diatreme, Mindanao, Philippines
Philsaga Mining Corporation Location Map, East Mindanao
Tambis Geology Map,
East Mindanao
DiatremeDiatreme Breccias Outcrop, Breccias Outcrop, TambisTambis
Diatreme Breccias, Tambis
MaarMaar Sediments, Sediments, TambisTambis
Maar Sediments with Carbonaceous Layers, Tambis
Maar Sediments with Carbonaceous Layers, Tambis
Interpreted Tambis intrusive-breccia complex schematic section
(from Medusa Mining website)
Wafi - Golpu, Papua New Guinea(from Harmony website)
• Major mineralised system with multiple phases
Copper - Gold
Gold
• The system currently contains resources comprising 644 Mt :
16 Moz Gold
Exploration Potential
16 Moz Gold
4.8 Mt Copper
55 Kt Molybdenum
39 Moz Au Eqv.*
• Excellent near mine and regional exploration potential
✱ refer Harmony or Newcrest website for July 2010 resource statement . Resource figures quoted as 100%. Gold equivalent based on US$ 950 oz Au, US$4,412/t Cu at 100% recovery for both metals. Molybdenum not included in metal equivalents. (from Harmony website)
Resource Characteristics
• GOLPU
Large copper gold
porphyry-high grade
Cylindrical shape
amenable to block
caving
* Gold equivalent is calculated using a gold price of US$950/oz Au and US$4,412/t Cu at 100% recovery for both metals
Wafi
Golpu
• WAFI
Structurally controlled
epithermal gold
deposit
High sulphidation
system (+oxide)
(from Harmony website)
Open Along Strike - Recent Success, March 2011 (from Harmony website)Critical Assessment of the Facts..
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